The Transition From Conventional Congenital Surgery to Advanced Heart Failure Therapy
The management of congenital heart disease has historically been dominated by anatomical repair, staged palliation, valve intervention, relief of obstruction, and reconstruction of abnormal vascular pathways. These strategies have transformed survival, allowing a large proportion of patients born with complex congenital defects to reach adolescence and adulthood. However, successful anatomical correction does not necessarily create a normal cardiovascular system. Many patients remain exposed to abnormal ventricular loading, surgical scars, prosthetic material, residual lesions, arrhythmogenic substrates, pulmonary vascular abnormalities, or unconventional ventricular morphology. Consequently, a subgroup eventually progresses from a surgically manageable congenital condition to a chronic advanced heart failure phenotype.
The critical clinical transition occurs when the therapeutic objective can no longer simply be described as correction of anatomy. In earlier stages, the surgeon may improve ventricular loading by closing a residual shunt, replacing a dysfunctional valve, relieving an outflow obstruction, reconstructing a conduit, treating pulmonary artery stenosis, or correcting an arrhythmia. At the end-stage, however, these interventions may fail to reverse progressive myocardial dysfunction. Repeated operations can become increasingly hazardous because of adhesions, altered anatomy, collateral vessels, prior prosthetic material, increased bleeding risk, and cumulative organ dysfunction. The question therefore changes from “What anatomical lesion can be repaired?” to “Can the circulation still be rescued, and if not, which advanced therapy offers the greatest probability of durable survival?”
This distinction is particularly important in congenital cardiac surgery because the same ventricular ejection fraction can represent profoundly different physiological states. A systemic right ventricle, for example, may deteriorate despite relatively preserved conventional measurements. A Fontan circulation may develop severe exercise intolerance and venous congestion without the classic phenotype of left-sided systolic heart failure. A patient with repaired tetralogy of Fallot may develop progressive right ventricular failure driven by pulmonary regurgitation, ventricular arrhythmia, pulmonary vascular disease, or adverse ventricular-ventricular interaction. Thus, end-stage disease should be recognized through an integrated assessment rather than a single numerical threshold.
Advanced heart failure therapy becomes relevant when symptoms, ventricular dysfunction, hemodynamic compromise, recurrent admissions, escalating diuretic requirements, refractory arrhythmias, progressive end-organ dysfunction, or dependence on intravenous inotropes indicate that conventional therapy is no longer maintaining an acceptable physiological reserve. Current heart failure guidance recognizes mechanical circulatory support and transplantation as established therapies for selected advanced heart failure patients, while congenital-specific literature emphasizes that ACHD patients require individualized assessment because their anatomy and physiology may make standard criteria less reliable. [1–5]
The timing of this transition is crucial. Referral that occurs only after irreversible hepatic, renal, pulmonary, or neurological injury may eliminate otherwise reasonable options. Conversely, implantation of a mechanical device or listing for transplantation too early can expose patients to major procedural and lifelong risks without sufficient expected benefit. The ideal strategy is therefore anticipatory: identify the trajectory toward end-stage failure, determine whether an anatomical or electrophysiological intervention remains capable of altering that trajectory, and simultaneously begin advanced heart failure evaluation before physiological collapse.
In this setting, mechanical circulatory support is not simply an alternative to transplantation. It can function as a bridge that changes the patient’s trajectory. A ventricular assist device may stabilize systemic perfusion, reverse secondary organ dysfunction, improve transplant candidacy, and provide time for donor allocation. Temporary support may rescue a patient from acute decompensation while the underlying diagnosis and reversibility are clarified. Transplantation, meanwhile, replaces the failing circulation rather than attempting to repair the increasingly complex native anatomy.
The modern congenital heart failure pathway therefore represents a continuum rather than a binary choice. Conventional surgery, catheter intervention, electrophysiology, mechanical support, and transplantation should be considered sequentially and, when appropriate, simultaneously. The central challenge is identifying when continued anatomical intervention has diminishing returns and when the patient should be transferred to an advanced heart failure/transplant program.
Why End-Stage Heart Failure in Congenital Heart Disease Is Fundamentally Different
End-stage heart failure associated with congenital heart disease cannot simply be treated as acquired cardiomyopathy occurring in a patient who happens to have a congenital diagnosis. The anatomy, ventricular morphology, surgical history, vascular connections, pulmonary circulation, and prior interventions fundamentally alter the mechanisms of circulatory failure. This difference has practical implications for diagnosis, pharmacological treatment, mechanical support, transplantation, and prognosis.
In conventional acquired heart failure, particularly ischemic or dilated cardiomyopathy, the clinician generally understands the relationship between ventricular geometry, pressure-volume loading, myocardial contractility, and systemic circulation. In congenital disease, these relationships may have been permanently modified by surgery. A patient with an atrial switch operation has a systemic right ventricle; a patient with congenitally corrected transposition may have a morphologic right ventricle supporting the systemic circulation; and a Fontan patient has no conventional subpulmonary ventricle. These configurations create failure mechanisms that cannot be captured adequately by left ventricular ejection fraction.
The congenital patient may also have multiple simultaneous causes of deterioration. A systemic right ventricle may develop myocardial fibrosis, tricuspid regurgitation, chronotropic incompetence, atrial arrhythmias, coronary perfusion abnormalities, and systemic ventricular dysfunction. A Fontan patient may experience elevated venous pressure, reduced preload, low cardiac output, pulmonary vascular dysfunction, lymphatic complications, protein-losing enteropathy, plastic bronchitis, arrhythmias, and progressive hepatic disease. These mechanisms interact rather than occurring independently.
Another distinction is the importance of residual and acquired anatomical lesions. Before diagnosing irreversible myocardial failure, the team must ask whether the circulation is being mechanically compromised by a residual obstruction, significant valve regurgitation, conduit dysfunction, pulmonary artery stenosis, aortopulmonary collateral burden, intracardiac shunting, or other correctable problem. Failure to identify such a lesion can result in premature transition to transplantation when a surgical or catheter-based intervention could have restored meaningful physiological reserve.
The evidence base is also different. Many large randomized heart failure trials excluded patients with complex congenital anatomy. As a result, guideline-directed therapy is often extrapolated from acquired heart failure populations. The ACHD literature repeatedly emphasizes that evidence is comparatively limited, heterogeneous, and frequently derived from retrospective cohorts or expert consensus. This does not mean that conventional heart failure therapy is useless; rather, it means treatment must be individualized according to the underlying physiology. [2,3,5]
Mechanical circulatory support presents an even greater divergence. Standard LVAD implantation assumes a relatively predictable left ventricular cavity, inflow geometry, mitral valve anatomy, aortic position, and systemic circulation. Congenital patients may have unusual ventricular orientation, intracardiac baffles, conduits, previous ventricular incisions, deformed chambers, abnormal great-vessel relationships, or extensive collateralization. The device may therefore require customized surgical planning.
Transplantation also differs. Prior sternotomies and thoracotomies create dense adhesions. Aortopulmonary collaterals may cause substantial bleeding. Pulmonary hypertension can complicate donor right ventricular adaptation. Sensitization from previous operations, homografts, prosthetic materials, blood transfusions, or ventricular assist devices may increase immunological complexity. In Fontan patients, liver and lymphatic disease can transform an isolated heart transplant into a potential multi-organ transplantation problem. Contemporary reviews describe prior cardiac surgery in the large majority of ACHD transplant recipients and emphasize the frequency of complex reconstructive procedures during transplantation. [6]
Therefore, the defining feature of end-stage congenital heart failure is not merely severe ventricular dysfunction. It is the failure of a uniquely constructed cardiovascular system. The therapeutic response must consequently be physiology-based, anatomy-aware, and anticipatory.
Major Congenital Phenotypes Predisposed to End-Stage Heart Failure
Several congenital phenotypes have a particularly high likelihood of progressing to advanced heart failure. These groups should not be treated as interchangeable because the mechanism of failure and suitability for mechanical support differ substantially.
The first major phenotype is the patient with a systemic left ventricle that has undergone multiple repairs but progressively develops ventricular dysfunction. Examples include patients with repaired ventricular septal defects complicated by chronic volume or pressure loading, complex left-sided obstructive lesions, and selected forms of repaired tetralogy or truncus physiology in which ventricular dysfunction becomes dominant. In these patients, the anatomy may resemble conventional heart failure more closely, and durable LVAD therapy can sometimes be technically feasible. Nevertheless, previous operations can significantly complicate cannulation and outflow graft routing.
The second major phenotype is systemic right ventricular failure. This includes patients with complete transposition of the great arteries after atrial switch procedures and patients with congenitally corrected transposition of the great arteries. The morphologic right ventricle is exposed to systemic pressure throughout life. Initially it may compensate through hypertrophy and remodeling, but chronic systemic loading can eventually result in systolic dysfunction, systemic atrioventricular valve regurgitation, fibrosis, arrhythmias, and progressive heart failure. Systemic RV failure is particularly challenging because standard LVAD strategies cannot automatically be transferred to the right ventricle.
The third phenotype is the failing Fontan circulation. Fontan physiology is fundamentally different because pulmonary blood flow is driven largely by venous pressure rather than by a dedicated subpulmonary ventricle. Long-term Fontan failure can manifest as ventricular dysfunction, preserved-ejection-fraction heart failure, elevated venous pressure, chronotropic incompetence, lymphatic abnormalities, arrhythmias, protein-losing enteropathy, plastic bronchitis, renal dysfunction, hepatic fibrosis, or a combination of these. The failing Fontan therefore represents a circulation-level disorder rather than an isolated ventricular disorder.
The fourth phenotype includes patients with complex biventricular repairs who have accumulated multiple residual lesions and repeated interventions. These patients may have prosthetic valves, conduits, patch material, aortic abnormalities, pulmonary artery distortion, ventricular aneurysms, arrhythmias, and extensive collateral vessels. In such patients, a conventional surgical approach may technically remain possible but offer little long-term benefit relative to its operative risk.
The fifth phenotype consists of pediatric patients with congenital heart disease who develop acute or progressive myocardial failure after repair or palliation. Infants and small children introduce additional challenges because device size, vascular access, anatomical space, anticoagulation, and developmental considerations restrict available mechanical support strategies. Pediatric ventricular assist devices have nevertheless demonstrated an important role as bridges to transplantation, particularly when prolonged support is required. Studies of Berlin Heart EXCOR experience show that VAD support can provide a clinically meaningful bridge to transplantation, although complications such as stroke, bleeding, and pump thrombosis remain important. [7,8]
The phenotype also influences transplant candidacy. A patient with isolated systemic LV dysfunction may be evaluated using a framework relatively similar to non-congenital heart failure. In contrast, a Fontan patient requires assessment of hepatic fibrosis, pulmonary vascular resistance, collateral burden, lymphatic disease, protein loss, renal function, and previous surgical anatomy. Similarly, systemic RV patients require careful assessment of systemic atrioventricular valve function, ventricular interaction, pulmonary pressures, arrhythmias, and the feasibility of mechanical support.
The concept of phenotype-specific risk is therefore essential. The term “end-stage congenital heart failure” describes a final physiological state, but it does not describe a single disease. Advanced therapy must be tailored to the underlying congenital architecture. This is one reason multidisciplinary congenital heart disease programs are so important: transplant surgeons, congenital surgeons, advanced heart failure specialists, imaging specialists, electrophysiologists, intensivists, hepatologists, and transplant coordinators must interpret the same patient from different physiological perspectives.
Pathophysiology of Ventricular Failure in Repaired Congenital Heart Disease
Ventricular failure in congenital heart disease is produced by a complex interaction between pressure overload, volume overload, abnormal ventricular geometry, myocardial fibrosis, altered coronary physiology, neurohormonal activation, arrhythmia, and surgical remodeling. The final common pathway is inadequate forward flow relative to systemic metabolic demand, but the route to that endpoint varies substantially among congenital phenotypes.
Pressure overload is particularly important in systemic right ventricular physiology. A morphologic right ventricle is structurally adapted to pump against a low-pressure pulmonary circulation. When it becomes systemic, its wall undergoes adaptive hypertrophy. Initially, this adaptation may preserve systolic function. Over time, however, increased wall stress, abnormal myocardial architecture, ischemia, fibrosis, and adverse remodeling may develop. Systemic tricuspid regurgitation can further increase volume loading, creating a vicious cycle in which ventricular dilation worsens valve coaptation and valve regurgitation increases ventricular volume burden.
Volume overload is another major mechanism. Residual shunts, significant valve regurgitation, pulmonary regurgitation, and abnormal vascular connections may expose the ventricle to chronic excessive volume. The resulting dilation can initially maintain stroke volume through the Frank-Starling mechanism but eventually becomes maladaptive. Increased wall stress, functional valve regurgitation, reduced contractile efficiency, and electrical instability may follow.
Surgical injury and scar formation contribute to both mechanical and electrical dysfunction. Ventricular incisions, patch repairs, cannulation sites, and myocardial manipulation can create regions of fibrosis or dyssynchrony. A patient may therefore develop heart failure not solely because the ventricle is weak, but because different myocardial regions contract inefficiently or because arrhythmias reduce effective cardiac output.
The pulmonary circulation is equally important. Elevated pulmonary vascular resistance can increase right ventricular afterload, compromise Fontan flow, and affect transplant candidacy. In Fontan physiology, even modest abnormalities of pulmonary vascular resistance can become clinically significant because there is no subpulmonary ventricle to generate additional driving pressure. Pulmonary artery distortion, collateral flow, hypoxemia, and endothelial dysfunction may therefore contribute to progressive circulatory failure.
Neurohormonal activation also occurs, but the response may differ from classic HFrEF. Congenital patients may have combined systolic, diastolic, chronotropic, vascular, and valvular abnormalities. Consequently, an apparently preserved ejection fraction does not necessarily indicate preserved circulation. Particularly in Fontan patients, low cardiac output can coexist with a relatively preserved ventricular ejection fraction because the dominant problem may be preload limitation, venous hypertension, or pulmonary vascular resistance rather than primary ventricular contractile failure.
End-organ dysfunction then becomes both a consequence and an amplifier of cardiac failure. Renal dysfunction increases volume-management difficulty. Hepatic congestion and fibrosis are particularly important in Fontan patients. Malnutrition, protein loss, intestinal dysfunction, and chronic inflammation may reduce physiological reserve. Once several organ systems become involved, the probability of successful isolated cardiac intervention may decrease.
This pathophysiological complexity explains why a single biomarker or echocardiographic measurement should not determine advanced therapy. The evaluation must integrate symptoms, exercise capacity, ventricular function, filling pressures, pulmonary pressures, arrhythmias, valve disease, oxygen saturation, end-organ function, and trajectory over time.
The ultimate goal is to distinguish potentially reversible circulatory failure from irreversible myocardial or systemic failure. If a residual lesion can be corrected, surgery or catheter intervention may restore ventricular performance. If the dominant problem is progressive myocardial failure despite optimized anatomy, advanced heart failure therapy becomes more appropriate. This distinction is central to avoiding both undertreatment and premature transplantation.
Recognizing the Patient Who Has Entered the End-Stage Heart Failure Phase
The diagnosis of end-stage heart failure in congenital heart disease should be viewed as a longitudinal assessment rather than a single clinical event. The most dangerous error is waiting until the patient presents with profound cardiogenic shock, severe renal dysfunction, hepatic decompensation, or ventilator dependence before considering advanced therapies. At that point, options may become substantially narrower.
Clinical deterioration may appear gradually. Increasing exercise intolerance, reduced school or occupational performance, progressive fatigue, worsening dyspnea, orthopnea, edema, abdominal distension, recurrent admissions, escalating diuretic requirements, or recurrent arrhythmias should prompt reassessment. In children, growth failure, feeding intolerance, developmental concerns, and inability to participate in age-appropriate activity may be more informative than traditional adult heart failure symptoms.
Objective evaluation should include serial echocardiography and, where appropriate, cardiovascular magnetic resonance. The aim is not simply to measure ejection fraction but to characterize ventricular volumes, systolic function, diastolic function, valve regurgitation, ventricular interaction, scar, great-vessel anatomy, and flow distribution. Cardiopulmonary exercise testing can provide valuable information about functional reserve when the patient is stable enough to perform it. Peak oxygen consumption, ventilatory efficiency, blood pressure response, oxygen saturation, and chronotropic response can help identify patients whose physiological reserve is declining.
Hemodynamic catheterization is particularly important when advanced therapy is being considered. It can clarify filling pressures, cardiac output, pulmonary vascular resistance, oxygen saturations, shunts, Fontan pressures, and the contribution of pulmonary vascular disease. In complex congenital anatomy, invasive hemodynamics can sometimes reveal a correctable lesion that was not apparent from noninvasive imaging.
Biomarkers such as natriuretic peptides may support assessment but should not be interpreted in isolation. Congenital physiology can produce biomarker patterns that do not perfectly parallel symptoms or ventricular function. Similarly, preserved ejection fraction should not reassure clinicians when the patient has severe exercise limitation, elevated filling pressures, progressive congestion, or low output.
Trajectory is arguably more important than a single measurement. A patient whose ventricular function has declined progressively over three years, whose exercise capacity is falling, and who has developed recurrent admissions may be at greater risk than a patient with a stable but abnormal ventricular ejection fraction. Repeated hospitalization for decompensated heart failure, dependence on intravenous inotropes, refractory ventricular or atrial arrhythmias, worsening renal or hepatic function, and inability to tolerate conventional medical therapy are major warning signals.
Advanced therapy referral should ideally occur before irreversible end-organ injury. Current ISHLT guidance emphasizes structured evaluation of transplant candidates, while congenital-specific literature recommends early referral because anatomical complexity can make evaluation substantially longer than in conventional heart failure. [1,4,5]
The evaluation should simultaneously search for reversible factors. Residual obstruction, significant atrioventricular or semilunar valve regurgitation, conduit failure, pulmonary artery stenosis, arrhythmia, infection, anemia, medication intolerance, and poor adherence may worsen heart failure and potentially be treatable. The presence of one reversible factor does not exclude advanced disease, but it changes the sequence of management.
The practical principle is therefore simple: advanced heart failure should be recognized as a trajectory. The patient should enter the transplant/MCS pathway while there is still sufficient renal, hepatic, neurological, nutritional, and pulmonary reserve to tolerate major surgery. Waiting until every conventional option has failed may sound logical, but in congenital heart disease it can paradoxically eliminate the very advanced therapies that could have changed the outcome.
The Last Opportunity for Conventional Surgery: Reversible Lesions Before Mechanical Support
Before committing a patient to mechanical circulatory support or transplantation, the congenital team must rigorously determine whether a correctable anatomical problem remains. This step is not merely a formality. In congenital heart disease, a seemingly “end-stage” patient may occasionally have severe symptoms driven predominantly by a residual obstruction, valve lesion, conduit dysfunction, abnormal pulmonary blood flow, or arrhythmia.
The first question should be whether ventricular loading conditions can be improved. Severe systemic atrioventricular valve regurgitation can accelerate ventricular dilation and failure. In selected patients, surgical or transcatheter valve intervention may interrupt this cycle. Similarly, severe pulmonary regurgitation after repaired tetralogy of Fallot may produce progressive right ventricular enlargement and dysfunction, and pulmonary valve replacement can be considered when the overall physiology remains recoverable.
Outflow obstruction should also be excluded. Even moderate residual obstruction may be poorly tolerated by a compromised ventricle. In Fontan patients, pulmonary artery stenosis or pathway obstruction can raise venous pressures and reduce cardiac output. Catheter intervention may therefore improve Fontan hemodynamics without requiring transplantation.
Arrhythmia deserves particular attention. Atrial tachyarrhythmias can dramatically reduce cardiac output in Fontan physiology because these patients often depend on coordinated atrial contraction and relatively low filling pressures. Persistent arrhythmia may precipitate a rapid decline that can be partially or completely reversible after rhythm control or ablation. Ventricular arrhythmias in systemic RV patients may similarly reflect a modifiable substrate, although advanced myocardial fibrosis may limit reversibility.
The role of resynchronization and pacing should be considered when electrical dyssynchrony contributes to ventricular dysfunction. Congenital patients may have unusual conduction pathways and prior surgical scars, making device implantation technically challenging. Nevertheless, appropriately selected patients may experience meaningful functional improvement.
Pulmonary vascular disease is another potential target. In selected congenital patients, optimization of pulmonary artery anatomy, treatment of elevated pulmonary vascular resistance, correction of abnormal flow, and management of hypoxemia may improve ventricular loading. However, pulmonary hypertension must be characterized carefully because aggressive vasodilator therapy in the wrong physiological setting may worsen ventilation-perfusion mismatch or systemic output.
The concept of “reversibility” should not be oversimplified. A patient may have both a correctable lesion and irreversible myocardial disease. Correcting the lesion can still be worthwhile, particularly if it improves candidacy for MCS or transplantation. Therefore, the decision is not necessarily surgery versus transplant; in some cases, surgery becomes a bridge toward advanced therapy.
The congenital heart team should also review previous operative records and imaging. The exact surgical anatomy may determine whether an intervention is technically possible. Old operative reports, catheterization data, MRI, CT angiography, and previous homograft information can become essential when planning reoperation or transplant.
This phase is where multidisciplinary review has the greatest value. A congenital surgeon may recognize a reconstructable lesion that an advanced heart failure team considers irreversible. Conversely, an experienced transplant surgeon may identify anatomical features suggesting that repeated reconstruction would merely delay definitive therapy. The final decision should therefore integrate both perspectives.
The critical principle is to avoid two opposite mistakes: declaring failure too early or repeating surgery too late. Conventional surgery remains valuable when it can meaningfully improve the circulation. Once the dominant problem becomes irreversible myocardial or systemic failure, repeated anatomical interventions may increase risk without restoring long-term physiology. Advanced therapy should then move from a theoretical possibility to an active treatment plan.
Systemic Right Ventricular Failure: The Surgical and Mechanical Support Challenge
Systemic right ventricular failure represents one of the most difficult advanced heart failure phenotypes in congenital cardiology. The morphologic right ventricle is designed for a low-resistance pulmonary circulation, yet in patients with atrial switch repair or congenitally corrected transposition, it may support systemic pressure for decades. Initially, the systemic right ventricle may compensate remarkably well. Eventually, however, structural remodeling, fibrosis, systemic atrioventricular valve regurgitation, abnormal coronary perfusion, and electrical instability can produce progressive failure.
The clinical presentation may be subtle. A patient may have only moderately reduced ejection fraction but severe exercise intolerance, systemic venous congestion, atrial arrhythmias, or recurrent hospitalization. Conventional left ventricular measurements therefore cannot be applied mechanically. Longitudinal trends in ventricular volumes, strain, systemic atrioventricular valve function, exercise capacity, and filling pressures are particularly important.
Systemic tricuspid regurgitation is a central issue. It increases volume load on an already pressure-loaded right ventricle. As the ventricle dilates, annular enlargement can worsen regurgitation, creating a self-reinforcing cycle. Valve intervention may therefore have an important role before advanced irreversible ventricular failure. However, once severe myocardial dysfunction and fibrosis are established, valve surgery alone may not provide durable recovery.
Mechanical support is challenging because most durable VAD technology was developed around the geometry of the systemic left ventricle. Cannula position, inflow orientation, ventricular size, trabeculation, septal geometry, and outflow graft routing may differ substantially in a systemic right ventricle. Previous atrial switch baffles can further complicate anatomy and venous pathways.
Nevertheless, systemic RV support is increasingly feasible in specialized centers. The goal is not simply to implant a standard device in an unusual ventricle but to redesign the strategy around the patient’s anatomy. Preoperative CT or MRI may be necessary to determine safe cannulation and outflow graft routes. Intraoperative transesophageal echocardiography helps assess inflow position and ventricular decompression.
Another concern is right-sided physiology and pulmonary circulation. A systemic RV VAD must provide adequate systemic flow without producing excessive suction, ventricular collapse, or unfavorable septal shift. Because the right ventricle interacts strongly with the left ventricle through the interventricular septum and pericardium, mechanical unloading can alter both ventricular geometry and pulmonary flow.
Transplantation may therefore remain the definitive option for selected systemic RV patients. Current literature suggests that adults with congenital heart disease can achieve encouraging long-term outcomes after transplantation despite increased early technical complexity. However, referral should occur before severe end-organ dysfunction or irreversible pulmonary vascular disease develops. [3,6]
The key lesson is that systemic RV failure should be managed proactively. Once severe ventricular dysfunction, valve regurgitation, arrhythmia, and congestion coexist, the patient should not simply be treated with repeated conventional heart failure admissions. The possibility of VAD or transplantation should be discussed while the patient still has adequate organ reserve and functional status to undergo advanced therapy.
The Failing Fontan Circulation: When Palliation Becomes End-Stage Physiology
Fontan circulation is one of the most distinctive physiological states in cardiovascular medicine. It allows patients with single-ventricle congenital heart disease to survive without a conventional two-ventricle circulation, but it does so by directing systemic venous blood toward the pulmonary arteries without a subpulmonary pump. This arrangement is inherently vulnerable to increased venous pressure, limited preload, pulmonary vascular abnormalities, and progressive multi-organ dysfunction.
Fontan failure should not be equated with reduced ventricular ejection fraction. Some patients develop systolic dysfunction, but others have a relatively preserved ventricular ejection fraction while experiencing severe venous hypertension, reduced cardiac output, chronotropic incompetence, arrhythmia, or pulmonary vascular dysfunction. The phenotype can also include protein-losing enteropathy, plastic bronchitis, lymphatic abnormalities, renal dysfunction, and Fontan-associated liver disease.
The first step in evaluating a failing Fontan is to determine whether the Fontan pathway itself can be optimized. Catheterization may identify pathway obstruction, pulmonary artery stenosis, elevated pulmonary vascular resistance, abnormal collaterals, or significant atrioventricular valve regurgitation. Interventions directed at these abnormalities can sometimes improve hemodynamics sufficiently to delay transplantation.
However, progressive failure may eventually become systemic. Chronic elevation of central venous pressure produces hepatic congestion and fibrosis. The liver may become enlarged, stiff, and functionally compromised. Renal perfusion may decline. Lymphatic dysfunction can produce protein loss and pulmonary complications. Recurrent arrhythmias can further decrease output. The result is a form of multi-organ circulatory failure in which treating the ventricle alone may be insufficient.
Mechanical circulatory support in Fontan patients is particularly complex. A VAD can theoretically unload the systemic ventricle, but doing so does not automatically solve the fundamental problem of pulmonary blood flow. In a circulation without a subpulmonary ventricle, pulmonary flow depends on the pressure gradient, pulmonary vascular resistance, intrathoracic pressure, and venous return. Device implantation therefore requires an individualized strategy.
Temporary support may sometimes be used during acute Fontan decompensation, but durable VAD support remains technically and physiologically demanding. The potential objectives include bridge to transplantation, bridge to decision, or in highly selected cases longer-term support. The literature supports considering MCS in selected failing Fontan patients, but evidence remains based largely on specialized-center experience rather than randomized trials. [9,10]
Transplantation remains the definitive therapy for many patients with irreversible Fontan failure. However, the decision is complicated by liver disease. The transplant team must determine whether hepatic abnormalities are predominantly congestive and potentially reversible after heart transplantation or whether advanced fibrosis/cirrhosis has become an independent organ-level disease requiring combined heart-liver transplantation.
The failing Fontan should therefore be conceptualized as a multisystem syndrome. The best time to consider transplantation is not necessarily when the ventricular ejection fraction becomes severely depressed. Instead, referral should occur when the trajectory indicates progressive circulatory failure despite optimization of Fontan anatomy, rhythm, pulmonary vascular conditions, and medical therapy.
Timing Referral for Advanced Heart Failure and Transplantation
Timing is arguably the most important modifiable factor in the management of end-stage congenital heart failure. The transplant evaluation process is more complex in congenital patients because anatomical reconstruction, pulmonary vascular assessment, immunological testing, organ assessment, and surgical planning can require considerable time. Referral should therefore precede the point of irreversible deterioration.
Several clinical patterns should trigger referral. Progressive ventricular dysfunction despite optimized therapy is an obvious indication. Recurrent heart failure admissions, increasing diuretic requirements, inability to tolerate standard medications because of hypotension or renal dysfunction, recurrent ventricular or atrial arrhythmias, progressive exercise intolerance, and dependence on inotropes are additional warning signs. In Fontan patients, protein-losing enteropathy, plastic bronchitis, progressive liver disease, declining oxygen saturation, or refractory arrhythmia may represent advanced failure even when systolic function appears relatively preserved.
The decision should also consider trajectory. A patient with stable moderate ventricular dysfunction may not require immediate transplantation, whereas a patient whose function is deteriorating rapidly deserves urgent evaluation. The rate of decline can be more informative than the absolute value of ejection fraction.
Cardiopulmonary exercise testing can provide useful prognostic information in suitable patients. Peak oxygen consumption and ventilatory efficiency can help characterize functional limitation, although interpretation must account for congenital anatomy, cyanosis, chronotropic incompetence, and pulmonary abnormalities. A poor exercise response should therefore trigger comprehensive reassessment rather than automatically determine transplant listing.
Hemodynamic assessment is central. Elevated filling pressures, low cardiac output, increased pulmonary vascular resistance, or severe Fontan pressures can identify patients whose symptoms have a significant circulatory basis. In patients being considered for transplant, pulmonary vascular resistance is especially important because a donor right ventricle may fail if exposed to severe fixed pulmonary hypertension.
End-organ function should be assessed early and repeatedly. Renal dysfunction, hepatic disease, malnutrition, frailty, and neurological injury can influence candidacy and postoperative risk. Importantly, some organ dysfunction may be reversible after circulatory stabilization. This is one reason timely MCS can be valuable: mechanical support may restore perfusion and venous pressure relationships sufficiently to improve transplant candidacy.
Sensitization should also be evaluated early. Congenital patients may have received multiple blood transfusions, homografts, surgeries, and implanted materials. These exposures can increase anti-HLA antibodies and complicate donor matching. If severe sensitization is discovered only after a patient becomes critically ill, the transplant pathway may be delayed.
The 2024 ISHLT transplant-candidate guidance emphasizes contemporary structured assessment of transplant candidates, including special populations and durable mechanical support. Congenital-specific reviews similarly argue for early referral because advanced therapies are technically more difficult in ACHD than in conventional heart failure. [1,3,4]
The ideal referral point is therefore before the patient becomes dependent on rescue therapy. Advanced heart failure consultation should begin when the clinical trajectory suggests that conventional interventions may soon become insufficient. This allows time to optimize anatomy, investigate pulmonary hypertension, assess liver and renal function, evaluate sensitization, educate the patient and family, and determine whether MCS or transplantation should be pursued.
Mechanical Circulatory Support in Congenital Heart Disease
Mechanical circulatory support provides an artificial method of maintaining blood flow when the native heart cannot generate sufficient systemic output. In congenital heart disease, its role has expanded from an exceptional rescue intervention toward a strategically planned component of advanced heart failure care.
MCS can be temporary or durable. Temporary systems are generally used during cardiogenic shock, acute decompensation, perioperative failure, or as a bridge while determining reversibility. Durable VADs can provide longer-term support and may serve as bridge to transplantation, bridge to recovery, bridge to decision, or destination therapy in selected patients.
The fundamental advantage of MCS is that it can alter the patient’s physiology before transplantation. Improved systemic perfusion can reverse renal dysfunction, reduce hepatic congestion, improve nutritional status, and allow stabilization while a donor organ is sought. In children and adults with congenital heart disease, this bridging function can be particularly valuable because transplantation may require substantial waiting time and extensive surgical planning.
However, congenital anatomy creates unique hazards. The ventricular cavity may be small, distorted, hypertrophied, or surgically reconstructed. Inflow cannula placement may be difficult. The outflow graft may cross unusual structures. Previous conduits and baffles may interfere with surgical exposure. Collateral vessels may increase bleeding. Abnormal venous anatomy may complicate venous return and cardiopulmonary bypass.
The device choice must therefore be anatomy-specific. A patient with a conventional systemic LV and a sufficiently dilated ventricular cavity may be a relatively straightforward LVAD candidate. A patient with a systemic RV requires different planning. A Fontan patient represents an even more complex problem because the circulation lacks a subpulmonary pump.
Complications remain important. Bleeding and thrombosis are intrinsic risks of durable MCS. Stroke can occur because of thromboembolism or hemorrhage. Infection, especially driveline infection, can compromise long-term support and transplant eligibility. Right ventricular failure may develop after LVAD implantation when the right ventricle cannot handle increased venous return. In congenital patients, these risks may be amplified by abnormal pulmonary circulation and previous surgical interventions.
Device support should therefore be considered as part of a broader physiological strategy rather than as an isolated operation. Preoperative optimization, anatomical imaging, anticoagulation planning, pulmonary vascular assessment, nutritional support, infection control, and transplant evaluation should occur in parallel.
Evidence from ACHD literature supports increasing use of MCS in carefully selected patients. Recent reviews emphasize that both temporary and durable support may improve transplant candidacy and provide a bridge for patients who otherwise face high waitlist risk. However, evidence remains limited by small cohorts, anatomical heterogeneity, and institutional experience. [3,4,11]
The most important principle is timing. Implanting a VAD in a patient with severe irreversible multi-organ failure may produce poor outcomes. Implanting it before advanced deterioration may restore organ function and create a successful bridge to transplantation. The challenge is identifying that window before it closes.
Durable LVAD Therapy in Patients With a Systemic Left Ventricle
Durable LVAD therapy is most conceptually straightforward in congenital patients whose systemic ventricle is a morphologic left ventricle. When the ventricular cavity is sufficiently large and the anatomy permits safe inflow and outflow graft placement, the mechanical support strategy may resemble that used in acquired dilated cardiomyopathy. Nevertheless, congenital anatomy still demands detailed preoperative planning.
The first consideration is ventricular geometry. Previous surgical repairs may alter the position of the apex, septum, and great vessels. The inflow cannula must be directed toward the appropriate ventricular cavity without obstruction from trabeculations, patch material, prosthetic valves, or abnormal ventricular orientation. Cardiovascular CT and MRI can be particularly valuable for mapping the relationship between the ventricular apex, sternum, great arteries, conduits, and mediastinal structures.
The second consideration is the outflow graft. In congenital patients, the ascending aorta may have undergone previous reconstruction or be displaced by prior operations. The graft must be positioned to avoid kinking, compression, or interference with pulmonary structures. Previous arch surgery may further complicate the surgical field.
The third issue is right ventricular performance. LVAD implantation increases venous return to the right heart. A congenital patient with borderline RV function may therefore develop postoperative right heart failure. This risk can be particularly important in patients with pulmonary hypertension, significant tricuspid regurgitation, or previous right ventricular surgery.
The fourth issue is residual congenital anatomy. A residual shunt can cause recirculation and reduce effective systemic support. Significant aortic regurgitation can create a loop in which blood pumped by the LVAD returns to the left ventricle rather than reaching the systemic circulation. Aortic and mitral valve function should therefore be evaluated before implantation.
LVAD therapy can also serve as a bridge to transplant. The patient’s hemodynamics may improve after implantation, allowing reduction of inotropes and recovery of kidney and liver function. Functional capacity may improve sufficiently to allow rehabilitation while awaiting donor availability.
However, the device should not be regarded as a permanent solution for every congenital patient. Infection, stroke, bleeding, thrombosis, device malfunction, and psychosocial burden remain significant. The decision to implant must consider expected duration of support, transplant candidacy, contraindications, patient goals, caregiver capacity, and the probability that the patient will ultimately receive a donor heart.
Current MCS guidelines emphasize that durable support is most appropriate when anatomy and physiology permit effective unloading and when the anticipated benefits outweigh device-related risks. Congenital-specific reviews reinforce the need for specialized surgical planning rather than direct extrapolation from acquired heart failure populations. [4,11,12]
In practical terms, the best LVAD candidate is often not the patient who is already in irreversible shock. It is the patient with advanced, otherwise refractory heart failure whose organ function remains sufficiently preserved to tolerate implantation and rehabilitation. Early referral therefore remains critical.
Ventricular Assist Devices for the Systemic Right Ventricle
Mechanical support of a systemic right ventricle is one of the most technically demanding applications of durable VAD therapy in congenital heart disease. The fundamental problem is anatomical: the right ventricle was not designed to support systemic pressure, and its geometry differs substantially from the left ventricle for which many durable devices were developed.
Preoperative imaging is therefore essential. Cross-sectional imaging should define ventricular position, chamber size, septal geometry, great-vessel relationships, prior baffles, prosthetic material, and the expected trajectory of the outflow graft. Three-dimensional reconstruction can assist operative planning when conventional two-dimensional imaging is insufficient.
The inflow cannula requires careful positioning. The systemic RV may be heavily trabeculated, hypertrophied, or geometrically distorted. Incorrect inflow positioning can produce suction events, inadequate unloading, hemolysis, or recurrent low-flow alarms. The surgical team must therefore balance maximal ventricular unloading with preservation of stable inflow.
The septum becomes particularly important. Mechanical unloading changes ventricular interaction. Excessive systemic RV unloading may alter septal position and affect left ventricular filling and pulmonary circulation. This is especially relevant in patients with complex ventricular interaction or borderline pulmonary hemodynamics.
Systemic atrioventricular valve regurgitation also requires attention. Severe regurgitation can reduce effective forward flow and perpetuate ventricular volume overload. Depending on anatomy, concomitant valve intervention may be required at the time of VAD implantation.
The pulmonary circulation must also be evaluated. The systemic RV pumps into the systemic circulation, but the pulmonary ventricle remains the morphologic left ventricle. Changes in ventricular interaction and preload after mechanical support can therefore influence pulmonary flow. If pulmonary vascular resistance is elevated, postoperative management becomes more complex.
Systemic RV patients may have extensive collateral or prior surgical anatomy. Previous atrial switch procedures can create baffle pathways that must be assessed for obstruction or leak. Congenitally corrected transposition may have associated ventricular septal defects, pulmonary stenosis, or other anomalies. Each anatomy requires an individualized approach.
Despite these challenges, contemporary experience suggests that durable MCS can be feasible in carefully selected ACHD patients. The literature increasingly supports using MCS earlier when the patient has refractory advanced heart failure and remains a reasonable transplant candidate. [3,10,11]
The key limitation is evidence quality. Most available data come from case reports, small series, registries, and retrospective reviews. Consequently, no universal device configuration can be recommended for every systemic RV phenotype. Institutional expertise and individualized anatomical planning remain central.
The decision should therefore be multidisciplinary. A congenital surgeon, VAD surgeon, imaging specialist, heart failure cardiologist, anesthesiologist, intensivist, electrophysiologist, and transplant team should ideally review the patient before implantation. The objective is not merely to determine whether a device can be inserted, but whether it can produce stable physiology and create a realistic pathway toward transplantation or meaningful long-term survival.
Mechanical Support in Single-Ventricle and Fontan Physiology
Mechanical support in single-ventricle and Fontan patients represents a separate category of advanced heart failure therapy. Unlike biventricular patients, these patients do not have two independent pumps with clearly defined systemic and pulmonary ventricles. The circulation depends on passive pulmonary blood flow and a single systemic ventricle, creating unique constraints on device therapy.
In the pre-Fontan or interstage period, ventricular assist devices may sometimes support systemic output while pulmonary blood flow is maintained through a shunt or other pathway. The exact configuration depends on anatomy, pulmonary vascular resistance, ventricular morphology, and the patient’s stage of palliation. Pediatric mechanical support has demonstrated the ability to bridge selected children to transplantation, although complication rates remain significant.
After Fontan completion, the problem becomes substantially more difficult. The systemic ventricle can be unloaded, but the pulmonary circulation remains dependent on venous pressure and low pulmonary resistance. Excessive reduction in venous pressure can actually impair pulmonary blood flow. Thus, a device that successfully unloads the systemic ventricle may not necessarily restore the entire circulation.
For this reason, Fontan VAD strategies may include unconventional configurations designed to support systemic output while preserving adequate pulmonary blood flow. Some patients may require additional procedures to address pulmonary artery anatomy, collateral circulation, or Fontan pathway abnormalities. The device strategy must therefore be integrated with the entire circulation.
The decision to implant should also consider the possibility of transplantation. In many Fontan patients, VAD support is intended as bridge to transplant rather than destination therapy. The device may stabilize the patient while the transplant team evaluates hepatic disease, pulmonary vascular resistance, sensitization, and surgical anatomy.
The presence of severe Fontan-associated liver disease complicates the equation. If hepatic dysfunction is advanced, isolated cardiac support may not reverse all organ injury. In selected patients, combined heart-liver transplantation may ultimately be considered.
Evidence remains limited. Reviews emphasize that Fontan patients represent one of the most challenging groups for MCS and transplantation. Nevertheless, increasing experience suggests that carefully selected patients can be supported successfully, particularly when managed at centers with expertise in both congenital surgery and advanced heart failure. [9,10]
Timing again determines outcome. Implantation after severe multi-organ failure may be unsuccessful. Earlier support, before irreversible hepatic, renal, or neurological injury, may provide a better bridge to transplantation. The optimal strategy is therefore individualized and should be discussed before the patient reaches catastrophic decompensation.
Temporary Mechanical Circulatory Support and Cardiogenic Shock
Temporary mechanical circulatory support has an important role when congenital patients experience acute cardiogenic shock, postoperative ventricular failure, severe myocarditis, acute decompensation of chronic heart failure, or potentially reversible deterioration. The major advantage is rapid restoration of systemic perfusion while the underlying cause is investigated and definitive therapy is planned.
Extracorporeal membrane oxygenation can provide cardiopulmonary support in patients with profound circulatory collapse. However, ECMO is generally a short-term strategy and does not necessarily unload the ventricle adequately. Prolonged exposure to high ventricular filling pressures may worsen myocardial injury, pulmonary edema, and end-organ dysfunction. Consequently, selected patients may require transition from ECMO to a durable VAD or another support strategy.
Congenital anatomy complicates cannulation. Previous sternotomies can make central cannulation hazardous. Peripheral access may be limited by small vessel size, abnormal vascular anatomy, previous interventions, or chronic hypoxemia. The team must therefore plan cannulation according to the individual anatomy.
Temporary support can also function as a diagnostic bridge. A patient with severe dysfunction may demonstrate myocardial recovery after stabilization if the underlying insult is reversible. In that situation, durable VAD or transplantation may be avoided. Conversely, persistent dependence on support despite correction of reversible causes suggests advanced irreversible failure.
Postoperative congenital patients can be particularly challenging. After complex repair, ventricular dysfunction may result from myocardial stunning, residual lesions, elevated pulmonary vascular resistance, coronary insufficiency, or technical complications. Temporary MCS can provide time to distinguish these causes.
However, ECMO and other temporary devices carry substantial risks, including bleeding, thrombosis, infection, limb ischemia, neurological injury, and inflammatory complications. These risks increase with duration of support. Therefore, the decision should be accompanied by a clear exit strategy: recovery, transition to durable VAD, transplantation, or withdrawal when meaningful recovery is impossible.
The congenital literature emphasizes that temporary support should be integrated into a broader advanced heart failure strategy rather than used as an isolated rescue technology. Pediatric experience has demonstrated that prolonged VAD support can sometimes provide better bridging opportunities than ECMO when a child requires extended stabilization before transplantation. [7,8]
The central concept is “time with purpose.” Temporary support should create time to accomplish a defined objective—recover the myocardium, correct anatomy, evaluate transplant candidacy, reverse organ dysfunction, or transition to durable support. Using temporary MCS without a realistic exit strategy can simply postpone an inevitable decision while exposing the patient to increasing complications.
Bridge-to-Transplant, Bridge-to-Recovery, Bridge-to-Decision, and Destination Therapy
The clinical purpose of mechanical support should be explicitly defined before implantation whenever possible. The traditional terminology includes bridge-to-transplant, bridge-to-recovery, bridge-to-decision, and destination therapy. In congenital heart disease, these categories often overlap because the patient’s trajectory may change after implantation.
Bridge-to-transplant is particularly relevant in ACHD. A patient may be medically suitable for transplantation but too unstable to survive the waiting period. VAD support can restore systemic perfusion and allow rehabilitation while a donor organ is sought. Recent literature suggests increasing use of MCS as a bridge to transplant in ACHD and highlights its potential to improve transplant candidacy. [3,11]
Bridge-to-recovery is possible when the myocardial injury is potentially reversible. This may occur in selected acute conditions, postoperative myocardial dysfunction, myocarditis, or other reversible insults. However, congenital patients with longstanding structural ventricular failure are less likely to recover completely because the underlying myocardial remodeling may be irreversible.
Bridge-to-decision is particularly valuable in complex congenital disease. A patient may present in severe shock without adequate information about pulmonary vascular resistance, liver disease, neurological prognosis, or transplant anatomy. Temporary support can stabilize the patient while the multidisciplinary team determines whether durable VAD, transplantation, reconstruction, or another strategy is appropriate.
Destination therapy is conceptually more difficult in congenital heart disease because many patients are young and may have anatomical or physiological features that make lifelong device support challenging. Nevertheless, for patients who are not transplant candidates because of irreversible comorbidities or other contraindications, durable MCS may occasionally provide long-term support.
The choice among these strategies must be dynamic. A patient initially considered a bridge-to-decision may become a bridge-to-transplant candidate after organ recovery. A patient initially considered transplantable may become unsuitable because of severe infection, neurological injury, or irreversible pulmonary hypertension.
The timing of implantation should therefore be coordinated with transplant evaluation. Waiting until the patient is critically ill may reduce the chance of successful support. Implanting too early may expose the patient to device complications before the indication is clear.
Pediatric data provide important evidence that VAD support can successfully bridge children to transplantation. Studies of Berlin Heart EXCOR have shown post-transplant survival comparable to selected children transplanted without pretransplant MCS, although adverse events remain significant. [7,8]
The most important principle is that MCS is a strategy, not a destination by itself. Before implantation, the team should define what success means: recovery, transplantation, stabilization, or long-term support. This prevents a technically successful device implantation from becoming a clinically unsuccessful treatment pathway.
Heart Transplantation in Congenital Heart Disease
Heart transplantation is the definitive advanced therapy for selected patients with irreversible end-stage congenital heart failure. Unlike conventional surgery, transplantation removes the failing native circulation and replaces it with a donor heart. For congenital patients, this can eliminate systemic ventricular dysfunction, severe valve disease, abnormal ventricular morphology, and some of the hemodynamic consequences of previous repairs.
However, transplantation is not simply a more complex version of standard heart transplantation. The operation must accommodate an altered mediastinum, previous patches and conduits, abnormal great vessels, venous pathways, collateral circulation, and occasionally multiple prior sternotomies. The surgical plan must be developed before the donor heart arrives whenever possible.
Patient selection is equally complex. Transplantation should be considered when symptoms and objective evidence indicate advanced heart failure despite optimized medical, surgical, catheter, and electrophysiological therapy. The evaluation should determine whether pulmonary vascular resistance is acceptable, whether end-organ dysfunction is reversible, whether infection is controlled, and whether the patient has sufficient physiological and psychosocial reserve.
The congenital transplant population is relatively young, which can be advantageous in terms of long-term survival and functional recovery. Contemporary reviews report encouraging long-term outcomes, although early mortality can be higher than in non-congenital recipients because of surgical complexity and comorbidity. A recent narrative review of ACHD transplantation reported one-year survival around 80%, five-year survival around 74%, and ten-year survival around 59% in the analyzed literature, while emphasizing the heterogeneity of the underlying studies. [6]
Pulmonary hypertension is a critical determinant of outcome. A donor right ventricle that has never experienced systemic pressure may fail if exposed to severely elevated pulmonary vascular resistance. Therefore, pulmonary vascular assessment is central to candidacy and may require repeated hemodynamic evaluation or pretransplant optimization.
Sensitization can also prolong waiting time. ACHD patients may have anti-HLA antibodies related to previous surgeries, blood transfusions, homografts, and device exposure. This can reduce the donor pool and increase the risk of rejection. Modern immunological strategies, including desensitization in selected patients, have expanded possibilities but remain specialized.
Transplantation should also be considered before irreversible organ failure. Severe renal, hepatic, or neurological disease may substantially increase postoperative risk. In Fontan patients, the liver becomes particularly important because isolated heart transplantation may not adequately address advanced cirrhosis.
The ISHLT 2024 candidate guidelines provide a contemporary framework for transplant evaluation and specifically incorporate considerations relevant to pediatric and complex populations. [1] The AHA scientific statement on congenital transplantation and MCS also emphasizes the unique anatomical and physiological challenges of this population. [4]
Ultimately, transplantation should be viewed as a planned transition rather than a rescue operation. The best candidates are generally those referred early enough to permit detailed anatomical reconstruction planning, immunological assessment, optimization of pulmonary pressures, nutritional rehabilitation, and management of end-organ dysfunction.
Surgical Complexity During Congenital Heart Transplantation
The technical complexity of congenital heart transplantation arises primarily from what happened before transplantation. The recipient may have undergone multiple sternotomies, thoracotomies, shunt procedures, conduit placements, arch reconstructions, valve operations, Fontan procedures, or systemic-to-pulmonary collateral interventions. Each operation changes the anatomy encountered during transplantation.
Re-entry is one of the first challenges. Dense retrosternal adhesions may increase the risk of injury to the right ventricle, aorta, pulmonary artery, or conduits during sternotomy. Preoperative CT can identify structures immediately behind the sternum and help determine whether peripheral cannulation or alternative surgical strategies are necessary.
Aortopulmonary collateral vessels can create significant bleeding. These vessels may become enlarged in patients with chronic cyanosis or Fontan physiology. If they are not identified and controlled, surgical blood loss can be substantial. Preoperative catheter-based embolization may be considered in selected patients.
The pulmonary arteries may also be abnormal. Previous shunts, Glenn procedures, Fontan connections, or pulmonary artery interventions can produce distortion or stenosis. Reconstruction may be necessary during transplantation to create an adequate pulmonary arterial pathway.
The systemic venous anatomy can be equally complex. Bilateral superior vena cavae, interrupted inferior vena cava, azygos continuation, extracardiac conduits, or intracardiac baffles may require customized reconstruction. The donor heart must be connected to the recipient circulation in a manner that preserves unobstructed systemic and pulmonary venous return.
Great-vessel reconstruction may also be necessary. Patients with previous arterial switch, arch reconstruction, Rastelli procedures, or complex outflow repairs may not have standard relationships between the aorta and pulmonary artery. This can increase operative time and ischemic exposure.
The donor heart itself must be carefully selected. Size matching becomes important, particularly in patients with altered thoracic dimensions or pulmonary vascular disease. In congenital patients, the surgical team must sometimes consider donor anatomy in relation to the recipient’s reconstructed mediastinum.
The complexity extends beyond the operating room. Prolonged cardiopulmonary bypass and ischemic time can increase postoperative organ dysfunction. Meticulous coordination between donor retrieval, recipient preparation, anesthesia, perfusion, and surgery is therefore essential.
Recent literature emphasizes that a substantial proportion of ACHD transplant cases require additional surgical reconstruction. Detailed imaging, multidisciplinary planning, and early preparation can reduce avoidable delays and improve the probability of successful implantation. [6]
The central surgical principle is anticipation. Congenital transplantation should not be approached as an ordinary transplant with unexpected anatomy discovered after sternotomy. The anatomy should be reconstructed before the operation through imaging, operative reports, catheterization data, and multidisciplinary review. The surgeon should know where the great vessels, conduits, baffles, collaterals, and previous patches are likely to be before the chest is opened.
Pulmonary Hypertension, Collaterals, Sensitization, and Other Transplant Barriers
Several factors can transform an otherwise reasonable congenital transplant candidate into a high-risk or temporarily unsuitable recipient. Pulmonary hypertension is one of the most important because the donor right ventricle may be unable to tolerate a high-resistance pulmonary circulation.
Pulmonary vascular resistance should therefore be measured carefully, but interpretation must account for congenital physiology. High flow through residual shunts or collaterals can distort calculations. In Fontan patients, low cardiac output and altered pulmonary blood flow can make standard formulas less intuitive. Multiple measurements and expert interpretation are often required.
Aortopulmonary collaterals represent another major problem. They can contribute to volume loading, pulmonary overcirculation, surgical bleeding, and postoperative pulmonary complications. Their significance depends on anatomy and physiology, and selected patients may benefit from catheter embolization before transplantation.
Sensitization is particularly important in congenital patients. Multiple operations, transfusions, homograft exposure, and VAD implantation can increase anti-HLA antibodies. Highly sensitized patients may wait longer for a compatible donor and face increased rejection risk. Modern transplant programs may use virtual crossmatching, careful donor selection, and specialized desensitization protocols when appropriate.
Infection must be excluded or controlled. Patients with indwelling lines, VADs, repeated hospitalizations, or protein-losing conditions may have elevated infection risk. Active uncontrolled infection is generally incompatible with immediate transplantation because immunosuppression can convert a manageable infection into catastrophic sepsis.
Renal dysfunction is another important determinant. Congenital patients may develop renal impairment from chronic low output, venous congestion, prior nephrotoxic exposure, or protein loss. Some dysfunction may improve after hemodynamic optimization, whereas irreversible renal disease may require consideration of combined organ transplantation.
Nutritional status and frailty should not be ignored. Chronic cyanosis, protein-losing enteropathy, recurrent hospitalization, and exercise limitation can lead to severe muscle wasting. Nutritional rehabilitation before transplantation may improve resilience.
Psychosocial readiness also matters. Lifelong congenital disease can produce substantial treatment burden. Transplantation introduces medication adherence requirements, infection precautions, frequent surveillance, and major lifestyle changes. The patient and family must understand these demands.
These barriers should be identified early rather than during a crisis. The purpose of early referral is not necessarily immediate listing; it is to discover obstacles while there is still time to correct them.
The transplant process therefore functions as a comprehensive cardiovascular and systemic assessment. A patient may enter the program because of heart failure but ultimately require treatment of pulmonary vascular disease, arrhythmia, liver disease, nutritional deficiency, sensitization, or infection before transplantation can proceed.
Fontan-Associated Liver Disease and Combined Heart-Liver Transplantation
Fontan-associated liver disease is one of the most important extra-cardiac consequences of long-term Fontan physiology. Chronic elevation of central venous pressure and reduced pulsatile hepatic blood flow promote congestion and progressive fibrosis. Over time, some patients develop advanced cirrhosis, portal hypertension, or hepatocellular carcinoma.
The diagnostic challenge is substantial because conventional liver tests may remain relatively normal despite significant fibrosis. Liver stiffness measurements can also be confounded by congestion. Consequently, assessment often requires a multimodal approach incorporating laboratory testing, imaging, elastography, clinical assessment, and in selected cases liver biopsy. [13,14]
The presence of liver disease creates a critical transplant question: will the liver recover after isolated heart transplantation, or has irreversible hepatic disease developed that requires replacement of both organs?
There is no universally accepted single criterion that answers this question. The decision should incorporate the degree of fibrosis, evidence of portal hypertension, synthetic dysfunction, hepatic nodules, varices, splenomegaly, and clinical decompensation. The interpretation should be performed by teams experienced in both Fontan physiology and liver transplantation.
Combined heart-liver transplantation can be considered in selected patients with advanced hepatic disease. The rationale is that replacing the failing heart alone may not reverse established cirrhosis. Conversely, replacing both organs can address the cardiovascular and hepatic components simultaneously.
Recent systematic reviews suggest that combined transplantation can achieve encouraging survival in carefully selected failing Fontan patients. However, comparisons between combined and isolated heart transplantation remain limited by retrospective data, selection bias, and changing transplant practices over time. One recent meta-analysis found that apparent mortality advantages of combined transplantation were less robust after excluding older studies, emphasizing that CHLT should not be considered automatically superior to isolated heart transplantation. [15,16]
This is an important area where overstatement should be avoided. Advanced FALD does not automatically mandate combined transplantation. Some patients with substantial fibrosis may improve after heart transplantation if hepatic disease remains predominantly congestive and reversible. Others with advanced cirrhosis or portal hypertension may be at high risk after isolated heart transplantation.
The decision should therefore be individualized. Serial hepatic evaluation before the patient becomes critically ill is essential. The multidisciplinary team may include congenital cardiology, congenital surgery, transplant cardiology, cardiac surgery, hepatology, liver transplantation, radiology, pathology, and interventional cardiology.
The broader lesson is that Fontan transplantation cannot be separated from systemic organ assessment. The Fontan circulation is a multisystem physiology, and end-stage failure may ultimately require a multisystem therapeutic response.
Perioperative and Post-Transplant Management
The perioperative period after MCS implantation or heart transplantation is particularly vulnerable in congenital patients because the circulation has already undergone extensive reconstruction. Hemodynamic management must account for ventricular interaction, pulmonary vascular resistance, abnormal venous pathways, and altered preload conditions.
After transplantation, the donor heart initially encounters a recipient pulmonary circulation that may be very different from that of a conventional heart failure patient. Pulmonary hypertension can cause acute donor right ventricular failure. Careful control of volume status, pulmonary vascular resistance, oxygenation, ventilation, and inotropic support is therefore essential.
Bleeding can be substantial because of previous surgeries, collateral vessels, anticoagulation, and prolonged cardiopulmonary bypass. Blood-product management should balance the need to control hemorrhage against the risk of further sensitization.
Renal protection is another priority. Congenital patients may enter transplantation with preexisting renal dysfunction. Perfusion optimization, avoidance of unnecessary nephrotoxins, and appropriate postoperative volume management can help reduce acute kidney injury.
Immunosuppression must be individualized. Sensitized patients may require particularly careful rejection surveillance. Patients bridged with VADs may have additional thrombotic and inflammatory considerations. Post-transplant infections remain a major cause of morbidity and require prophylaxis and surveillance.
Arrhythmias can occur after transplantation because of surgical atrial manipulation, electrolyte abnormalities, rejection, or residual conduction abnormalities. Congenital patients may have unique electrophysiological substrates from previous operations, making rhythm management more complex.
Rehabilitation should begin early. Preoperative frailty and prolonged hospitalization can produce significant muscle loss. Physical therapy, nutritional support, and psychological care should be integrated into the recovery plan.
For MCS patients, long-term management includes anticoagulation, infection prevention, device surveillance, education regarding alarms, and emergency planning. These requirements are particularly demanding for children and adolescents, where caregiver competence is central.
Post-transplant care should also address the psychological transition from a lifelong congenital condition to a transplanted circulation. Patients may experience anxiety related to graft rejection, medication adherence, and uncertainty about long-term outcomes. Structured follow-up is therefore essential.
The long-term goal is not simply survival. Functional recovery, exercise capacity, educational or occupational participation, psychosocial health, and quality of life are major measures of treatment success.
Long-Term Outcomes, Quality of Life, and Survival
The rationale for advanced heart failure therapy is ultimately measured by meaningful survival and quality of life. In selected congenital patients, both transplantation and mechanical support can produce substantial functional improvement, but outcomes are influenced by anatomy, timing, comorbidity, and institutional expertise.
ACHD transplant recipients are often younger than typical acquired heart failure recipients, which creates the potential for many years of post-transplant survival. However, early postoperative mortality can be higher because of surgical complexity. Once the early period is survived, long-term outcomes can be encouraging. Contemporary literature demonstrates that carefully selected ACHD recipients can achieve substantial long-term survival. [6]
Mechanical support can similarly improve functional capacity and allow patients to leave the hospital, rehabilitate, and await transplantation. The benefit is greatest when support is initiated before severe end-organ failure develops.
Quality of life is an important endpoint because congenital patients may have lived with exercise limitation and repeated operations since childhood. A successful transplant or VAD strategy can dramatically change daily functioning. However, device dependence introduces its own burdens, including driveline care, anticoagulation, equipment management, and infection risk.
For children, developmental and educational outcomes are especially important. Prolonged hospitalization and chronic heart failure can affect growth, school participation, and psychosocial development. Successful transplantation may therefore provide benefits extending far beyond cardiovascular survival.
The long-term challenge after transplantation is chronic immunosuppression. Rejection, infection, cardiac allograft vasculopathy, malignancy, renal dysfunction, and metabolic complications can influence survival. Lifelong surveillance is required.
In Fontan patients, long-term outcomes are additionally affected by residual hepatic and lymphatic disease. Heart transplantation may correct the circulation but cannot necessarily reverse every consequence of decades of Fontan physiology.
The evidence base remains limited by the rarity and heterogeneity of congenital advanced heart failure. Most studies are retrospective, and patient selection differs considerably among centers. Consequently, outcome estimates should not be interpreted as universal predictions for an individual patient.
Nevertheless, the overall trajectory of the literature is encouraging: advanced therapies are increasingly feasible, and outcomes improve when patients are referred before catastrophic decompensation.
Multidisciplinary Decision-Making and Patient Selection
No single specialty can manage end-stage congenital heart failure adequately. The optimal treatment decision requires integration of anatomy, physiology, surgery, mechanical support, transplantation, electrophysiology, pulmonary vascular medicine, hepatology, critical care, nutrition, rehabilitation, and psychosocial assessment.
The congenital surgeon contributes detailed knowledge of previous operations and reconstructive possibilities. The advanced heart failure specialist assesses trajectory, medical optimization, exercise capacity, hemodynamics, and transplant timing. The VAD surgeon evaluates device feasibility and surgical anatomy. The transplant surgeon determines whether transplantation is technically achievable and anticipates reconstruction.
Imaging specialists provide the anatomical map. Electrophysiologists assess arrhythmia burden and reversibility. Pulmonary vascular specialists determine whether pulmonary hypertension is modifiable. Hepatologists evaluate Fontan-associated liver disease. Intensivists manage acute decompensation and temporary MCS. Transplant coordinators address logistics, donor matching, and psychosocial preparation.
The patient and family must remain central to the decision. Advanced therapies involve major risks and lifelong consequences. The clinical team should explain realistic expectations rather than simply presenting transplantation or VAD as automatic solutions.
A useful multidisciplinary conference should answer five questions:
First, is the current heart failure state reversible?
Second, if reversible anatomy exists, is intervention likely to produce durable recovery?
Third, if recovery is unlikely, is mechanical support technically and physiologically feasible?
Fourth, is transplantation feasible, and what barriers must be corrected before listing?
Fifth, what is the patient’s preferred acceptable outcome?
This structure prevents decisions from becoming specialty-specific. A surgeon may focus on operability, while a heart failure specialist focuses on physiology. Both perspectives are necessary.
Ethical, Psychosocial, and Resource Considerations
Advanced therapies in congenital heart disease raise ethical questions because many patients are young and may face decades of potential survival after successful transplantation. Decisions must balance expected survival, quality of life, procedural risk, donor availability, and resource utilization.
Donor scarcity is a central issue. A patient may be technically eligible for transplantation but face prolonged waiting because of sensitization, blood group, body size, or geographic allocation. MCS can sometimes reduce waitlist mortality but introduces device-related risks and resource requirements.
In children, decision-making also involves parents or guardians while considering the developing patient’s future autonomy. Adolescents require increasing involvement in medication adherence, device care, and transplant education.
Psychosocial factors should be assessed without unfairly excluding patients because of socioeconomic disadvantage. Access to specialized congenital and transplant care varies substantially between regions. The increasing feasibility of advanced therapies therefore creates a parallel challenge: ensuring that appropriate patients can reach centers capable of providing these therapies.
Resource limitations are especially relevant in countries where durable VADs, transplant programs, or pediatric mechanical support may not be widely available. In such settings, early referral to regional or international centers may be critical.
The ethical objective should be to maximize meaningful benefit rather than simply maximize procedural activity. A technically successful operation that leaves a patient with irreversible multi-organ failure may not represent meaningful success.
Emerging Technologies and Future Directions
The future of congenital advanced heart failure therapy will likely be shaped by better mechanical support technology, improved imaging, computational modeling, biomarker development, and increasingly individualized transplantation.
Smaller and more adaptable VAD systems may expand options for pediatric and anatomically complex patients. Improved pump design may reduce thrombosis, hemolysis, and infection. Fully implantable systems could eventually reduce driveline-related complications, although such technology remains an evolving field.
Three-dimensional imaging and computational modeling may allow patient-specific simulation of cannula position, graft routing, and hemodynamic consequences before surgery. This could be particularly valuable for systemic RV and Fontan patients.
Artificial intelligence may also help identify patients at risk of deterioration by integrating longitudinal imaging, laboratory data, exercise testing, rhythm monitoring, and hospitalization patterns. However, predictive models should be validated specifically in congenital populations rather than simply imported from acquired heart failure cohorts.
Regenerative and myocardial recovery strategies remain an area of research. Although complete myocardial regeneration is not currently an established therapy for end-stage congenital failure, future interventions may eventually reduce dependence on mechanical support.
Transplantation may also evolve through improved donor utilization, ex-vivo perfusion, expanded donor criteria, and better immunological matching. These developments could be particularly valuable for highly sensitized congenital patients who currently experience prolonged waiting times.
The most important research need remains prospective congenital-specific evidence. Randomized trials are difficult because the population is small and heterogeneous, but international registries and multicenter prospective studies can provide stronger evidence regarding timing, device selection, and outcomes.
- A Practical Physiology-Based Algorithm for End-Stage Congenital Heart Failure
A practical approach begins with recognizing deterioration early. Progressive symptoms, recurrent admissions, worsening ventricular function, declining exercise capacity, refractory arrhythmia, increasing congestion, or end-organ dysfunction should trigger advanced evaluation.
The second step is anatomical reassessment. The team should search systematically for residual obstruction, valve dysfunction, conduit failure, pulmonary artery abnormalities, shunts, collateral burden, or other correctable lesions.
The third step is physiological characterization. Echocardiography, cardiovascular MRI, cardiopulmonary exercise testing, rhythm assessment, laboratory evaluation, and invasive hemodynamics should be used according to the clinical phenotype.
The fourth step is to determine reversibility. If a correctable lesion is likely to restore meaningful ventricular or circulatory function, intervention should be considered. If severe myocardial dysfunction persists despite optimized anatomy, advanced therapy should move forward.
The fifth step is early transplant/MCS referral. Referral does not automatically mean listing or device implantation. It allows detailed assessment of pulmonary vascular resistance, renal function, hepatic status, sensitization, anatomy, psychosocial readiness, and surgical feasibility.
The sixth step is phenotype-specific device planning. A systemic LV may be suitable for conventional durable LVAD strategies. A systemic RV requires specialized planning. Fontan patients require individualized circulation-level strategies, and some may ultimately proceed directly to transplantation.
The seventh step is to define the objective of MCS: bridge to transplant, bridge to recovery, bridge to decision, or destination therapy.
The eighth step is multidisciplinary reassessment after stabilization. A patient supported with MCS may recover renal and hepatic function and become a better transplant candidate. Conversely, new complications may change the strategy.
The final principle is that transplantation should not be viewed as the failure of congenital cardiac surgery. In selected patients, it is the logical final stage of a successful lifetime strategy that first achieved survival through anatomical repair and later requires replacement of a failing circulation.
The modern approach to end-stage congenital heart failure is therefore neither “operate again” nor “transplant immediately.” It is a physiology-based continuum: identify reversible anatomy, optimize the circulation, recognize irreversible failure early, deploy mechanical support when appropriate, and proceed to transplantation before advanced organ dysfunction closes the therapeutic window.