ASDs are commonly encountered and occur in one-third of adults with CHD (Fig. 56–16; see also Figs. 56–11 and 56–13). Various types exist, but secundum ASD present in the area of the fossa ovalis is the most common, accounting for 75% of defects.167 Ostium primum defects associated with endocardial cushion defects and inlet-type VSDs occur in 20% of cases. Sinus venosus defects (usually superiorly located) occur in 5% of patients. The rarest type is unroofed coronary sinus. Associated lesions may occur and include pulmonary stenosis, VSD, mitral valve abnormalities (regurgitation or stenosis), and syndromic problems such as Down syndrome and Holt-Oram syndrome. Most cases of ASD are sporadic, but familial cases of ASD have been reported, especially in patients with coexistent prolongation of the PR interval.168
Various types of atrial and ventricular septal defects (ASD and VSD, respectively). The heart is viewed from a right anterior oblique projection, and the right ventricular and right atrial free walls have been removed. 1. Secundum-type ASD. 2. Primum-type ASD. 3. Superior sinus venosus ASD. 4. Inferior sinus venosus ASD. 5. Coronary sinus ASD. 6. Perimembranous VSD. 7. Muscular VSD. 8. Inlet VSD.
ASDs often go unrecognized for the first two decades because of the indolent clinical course and benign findings on physical examination. Careful inspection of the ECG usually demonstrates a characteristic RSR′ complex in the anterior precordial leads with a rightward QRS axis in patients with secundum-type defects and left-axis deviation in those with primum-type ASD (Fig. 56–17). Initial diagnosis in adulthood is common, and survival into adulthood is the rule. However, life expectancy is not normal in unrepaired patients, with mortality increasing by 6% per year after 40 years of age.169,170 Progressive symptoms of dyspnea on exertion and palpitations frequently occur in adulthood and are caused by increasing right-sided chamber enlargement, pulmonary hypertension, RV failure, tricuspid regurgitation, and atrial arrhythmias. Patients with large ASDs causing left-to-right shunts develop RV volume overload, which is relatively well tolerated for the first two decades but thereafter results in right heart failure and arrhythmias. The subsequent increase in serum BNP levels and decrease in exercise capacity are correlated with the magnitude of left-to-right shunting.171 The degree of left-to-right shunt may increase with age as LV compliance decreases and systemic arterial resistance increases after the fourth decade of life. Paradoxical embolism may occur, but is a rare complication. The risk of infective endocarditis is low unless the patient has coexistent valvular disease (eg, cleft mitral valve).
A. A 12-lead electrocardiogram (ECG) of a 30-year-old woman with a large secundum-type atrial septal defect (ASD; 42 mm in diameter by transesophageal echocardiography) and moderate pulmonary artery hypertension (PAP = mm Hg). Note the right-axis deviation and tall precordial R waves consistent with right ventricular enlargement or hypertrophy. There is evidence of right atrial abnormality. B. An ECG of 33-year-old man with a primum-type ASD surgically repaired at 3 years of age. Note the continued presence of a characteristic RSR complex in lead V1 and QRS left-axis deviation.
Surgical repair via direct suture of small defects and patch closure of larger defects has been performed for more than 40 years and has been efficacious and safe provided the pulmonary arterial resistance is not severely elevated.167,172 Closure of small defects (< 1 cm) in asymptomatic patients diagnosed after 25 years of age is controversial, with no significant difference in clinical outcomes between medically and surgically treated patients followed for over 20 years.173 A retrospective study by Konstantinides et al174 of 179 patients diagnosed after the age of 40 years with a Qp:Qs ratio of 1.5:1 or greater demonstrated a relative risk of 0.31 for patients who underwent surgical closure, as compared with patients treated medically (P = .02). Estimated probability of survival was 95% at 10 years for surgically treated patients and 84% for patients treated medically. Predictors of increased mortality in the surgical group included older age at operation, advanced heart failure (NYHA class III or IV), Qp:Qs ratio of 2.5:1, pulmonary artery systolic pressure above 40 mm Hg, and pulmonary vascular resistance above 1.6 Wood units. Nonfatal clinical outcomes such as supraventricular arrhythmias occurred with similar frequency between the two groups. However, the operations carried out in this study did not include atrial arrhythmia surgery (maze or Cox-maze procedures), which is known to decrease arrhythmia recurrence in patients undergoing surgical ASD closure.175 A prospective, randomized study by Attie et al176 of surgical versus medical management of ASD in 241 patients older than 40 years of age did not demonstrate similar survival advantages over a median follow-up of 7 years. However, a significantly lower percentage of patients in the surgical group reached the composite end point of heart failure, recurrent pneumonia, peripheral or pulmonary embolism, or death (P = .0046), leading the authors to conclude that surgical closure should be performed in all patients with an ASD and pulmonary artery systolic pressure below 70 mm Hg and Qp:Qs ratio above 1.6:1.
Pulmonary artery vasodilator therapy with prostaglandins, endothelin blockers, and phosphodiesterase-5 inhibitors may reduce pulmonary arterial pressure and resistance to a level that allows consideration of shunt closure in these patients, but this should only be considered at centers experience in the management of such patients.177 Current ACC/AHA guidelines recommend consideration of closure if pulmonary artery pressure is less than two-thirds of systemic level, pulmonary vascular resistance is less than two-thirds of systemic vascular resistance, or there is a positive response to either pulmonary vasodilator therapy or test occlusion of the defect.6 Pulmonary vasoreactivity testing and a trial of pulmonary vasodilators for several months may help risk stratify patients with borderline pulmonary pressures for closure. In a study by Balint et al,178 many patients with ASDs and pulmonary arterial hypertension continued to have elevated pulmonary artery pressures after closure, and 15% had persistent severe pulmonary hypertension. Closure is contraindicated in patients with severe irreversible pulmonary arterial hypertension and no evidence of left-to-right shunt.6 Severe pulmonary hypertension in patients with ASD usually represents the coincidence of idiopathic pulmonary hypertension or pulmonary hypertension secondary to another process (eg, scleroderma) and ASD.28 Unlike patients with large, unoperated, nonrestrictive central shunts (eg, VSD) who experience pulmonary hypertension from birth and develop pulmonary vascular disease within the first few years, patients with large ASDs of similar shunt magnitude do not necessarily develop severe pulmonary hypertension, and right-to-left shunting or the onset of pulmonary hypertension is delayed into late adulthood.179 However, a large ASD may well contribute to the development of pulmonary hypertension, but may not be the sole cause of the underlying pulmonary vascular disease in a cyanotic patient. Patients with trisomy 21 (Down syndrome) may develop accelerated pulmonary vascular disease in the presence of ASD (primum or secundum).
Transcatheter device closure of secundum-type ASD was first performed in 1976 by Mills and King.157 Advancements in device design and catheterization technology have led to the availability of a variety of occlusion devices (see Fig. 56–11).180,181,182 Transcatheter device closure compares favorably with surgical closure in terms of efficacy and is associated with shorter hospital stays and fewer postprocedural complications.181,183 Appropriate patient selection is imperative and may be accomplished via a variety of noninvasive and invasive imaging methods.184,185,186,187 Transcatheter device closure techniques have supplanted surgery at many institutions as the method of choice for ASD closure in properly selected patients; complications are rare. Short-term complications have included device embolization, aortic root or atrial wall perforation, and cardiac tamponade.188 Mid- and long-term complications include thrombus formation, device erosion into the aortic root, atrial dysrhythmias, and infective endocarditis. The use of platelet inhibitors for at least 6 months after device closure is recommended to decrease the risk of device thrombosis.189 The long-term outcomes of device closure using the Amplatzer septal occluder are excellent, as evidenced by no deaths and minimal complications in 151 patients followed for 6.5 years after ASD closure.190
Ventricular Septal Defect
Isolated VSD is the most commonly encountered form of CHD in the pediatric population (see Fig. 56–16). This is not the case in the adult population for a number of reasons.191,192
Most children with hemodynamically significant defects are diagnosed and undergo repair in childhood because they develop signs and symptoms of LV enlargement and failure. Children growing up in developing countries often go undiagnosed and unrepaired well into adulthood because of absent or intermittent medical attention.
Small unrepaired perimembranous or muscular VSDs often spontaneously decrease in size or close with age. However, small VSDs initially encountered in adulthood (in patients older than 20 years of age) are unlikely to close spontaneously.
Large nonrestrictive defects that are not surgically corrected within the first 2 years of life result in incompletely reversible pulmonary vascular disease and are associated with increased mortality in childhood (see Fig. 56–3).
Therefore, the spectrum of isolated residual VSD encountered in the adult patient usually consists of:
Small restrictive defects or defects that have closed partially with time. The pulmonary vascular resistance is not significantly elevated, and the left-to-right shunt magnitude is mild (Qp:Qs ratio ≤ 1.5:1). The intensity of the precordial holosystolic murmur is inversely related to the size of the defect; therefore, a disturbingly loud and harsh precordial holosystolic murmur in a patient with VSD should be viewed as a reassuring sign, not a cause for alarm.
Large nonrestrictive defects in cyanotic patients who have developed the Eisenmenger complex, with systemic pulmonary vascular resistance and shunt reversal (right to left).
Patients with moderately restrictive defects (Qp:Qs ratio ≥ 1.6:1 and ≤ 2:1) who have not undergone closure for some reason. These patients often have mild to moderate pulmonary hypertension.
Patients who have had their defects closed in childhood. These patients may have small, but generally inconsequential, VSD patch leaks that may be identified by careful color and two-dimensional Doppler scanning of the entire interventricular septum during echocardiographic examination.
Small restrictive defects of the muscular or membranous septum may be watched conservatively without the need for operative intervention. Patients are at increased risk for endocarditis as a result of the turbulent, high-velocity jet impinging on the septal leaflet of the tricuspid valve that partially closes many perimembranous defects. Six percent of patients with small perimembranous defects may develop aortic valve prolapse and resultant aortic regurgitation that may be progressive.193 The prolapsing aortic valve cusp (usually the right coronary cusp) may partially or completely close the VSD. Aortic valve repair or replacement may be necessary in patients with aortic regurgitation who develop exertional symptoms or progressive LV dilatation.113,194 In a long-term follow-up registry, the overall survival rate was 87% for all patients with unoperated VSD.179 For patients with small defects (Qp:Qs ratio < 1.5 and low pulmonary artery pressure), the survival rate was 96% at 25 years. Patients with moderate and large defects fare worse, with 25-year survival rates of 86% and 61%, respectively. Those with cyanosis (Eisenmenger complex) had a much lower 25-year survival rate of 41.7%.
In patients with large nonrestrictive VSD, pulmonary vascular disease begins at or soon after birth with abnormal vascular remodeling; if the VSD is not surgically repaired, patients eventually develop obliterative pulmonary vascular disease.192 Systemic pulmonary vascular resistance results in a balanced bidirectional shunt or shunt reversal and cyanosis, a condition first described by Eisenmenger in 1897 and coined “the Eisenmenger complex” by Maude Abbott in 1927.195 Survival is generally decreased in these patients, although with proper medical care and protection against certain risks (eg, dehydration, endocarditis), survivors have been reported into the seventh decade of life.47,196 Patients develop compensatory erythrocytosis, which is an appropriate response to the decreased systemic oxygen saturation from right-to-left shunting of deoxygenated blood. Phlebotomy is not warranted unless patients develop symptoms of hyperviscosity (headache, visual changes) that are refractory to hydration. As a matter of fact, routine phlebotomy does not reduce cerebral complications and leads to iron deficiency anemia. Microcytic iron-deficient red blood cells carry less oxygen and are less deformable in the microcirculation than iron-replete red blood cells, thus resulting in worsening cyanosis and increased cerebral complications, which are properly treated by judicious iron repletion.47
Patients with small restrictive defects (Qp:Qs ratio ≤ 1.5:1 and low pulmonary artery pressure) are generally asymptomatic and should be managed conservatively and followed up regularly.179 Although antibiotics for endocarditis prophylaxis are no longer recommended by the ACC/AHA guidelines, patients are at increased risk for endocarditis.113 Patients should be instructed in dental and skin care. Small defects with aortic valve prolapse and aortic regurgitation may be repaired to avoid progressive aortic regurgitation.197 Larger defects may be repaired in the absence of severe pulmonary hypertension and severely elevated pulmonary vascular resistance (> 10 Wood units × m2), which incurs a high perioperative risk.198,199 Postoperative life expectancy is not normal, but has improved over the past 50 years with improved surgical techniques and experience. Postoperative conduction defects are common, but complete heart block is rare in the current era. The postoperative risk of infective endocarditis is low. Transcatheter device occlusion of muscular and perimembranous VSD is feasible, and trials demonstrate a good safety and efficacy profile.200,201,202,203 Complete heart block has been noted to occur in up to 6% of children and 1% of adults.200,202
Atrioventricular Septal Defects
Atrioventricular septal defect is an umbrella term used to describe endocardial cushion defects representing a spectrum of lesions involving the atrial and ventricular septum, AV valves, and LV outflow tract (LVOT). The defects are classified into “partial” or “complete” forms. In the partial form, patients have a primum ASD but no VSD (see Fig. 56–16). The complete form includes both a primum ASD and an inlet VSD (see Fig. 56–16). The deficiency of the inlet ventricular septum along with abnormalities of the AV valves (overriding, straddling, or cleft) produces an elongated LVOT that has characteristically been described as having a “goose neck” appearance on left ventriculography. Subaortic stenosis (SAS) is a common association often caused by chordal attachments of the cleft anterior mitral valve to the LV outflow septum (Fig. 56–18). SAS may also occur de novo after surgical repair because of a discrete fibrous membrane.204
A. Transesophageal two-dimensional echocardiographic image as viewed from the transgastric view, demonstrating a cleft (C) in the anterior mitral leaflet (AML). B. Continuous-wave Doppler across the mitral valve and left ventricular outflow tract (LVOT) performed form the transgastric position, demonstrating mitral regurgitation (MR) through the cleft AML and severe subaortic stenosis (SAS) with a maximum velocity of 4.67 m/s, caused by chordal attachments from the AML to the LVOT. PA, main pulmonary artery; PML, posterior mitral leaflet; RV, right ventricle (RV).
Approximately 5% of infants with CHD have AV septal defect, with two-thirds of patients having the complete form.205 Trisomy 21 and other chromosomal abnormalities are frequently associated, and these patients usually have the complete form. The natural history of partial AV septal defect patients depends on the size of the defect and, in many ways, these primum ASDs behave in a similar manner to secundum ASD (see earlier). Patients with Down syndrome may have accelerated pulmonary vasculopathy, resulting in pulmonary hypertension at an earlier age. Mitral valve regurgitation, secondary to the presence of a common AV valve and “cleft” (see Fig. 56–18), if present, leads to greater left-to-right shunt magnitude and earlier signs of pulmonary hypertension and heart failure. Patients with complete defects that are unrepaired in infancy or childhood frequently develop severe pulmonary hypertension and eventual shunt reversal, characteristic of Eisenmenger syndrome (see earlier).
Surgical repair involves patch closure of the primum ASD and VSD closure in patients with the complete form of AVSD. “Cleft” mitral valve repair should be attempted to restore valvar competence, the assessment of which can be made using intraoperative TEE.206,207 Percutaneous ASD closure of a primum defect is contraindicated given the close proximity of the defect to the tricuspid and mitral valves as well as the ostium of the coronary sinus. Surgical mortality is 15% within the first 30 days after surgery.208 Adverse predictors of mortality include the complete type of AV septal defect, the presence of pulmonary hypertension, and the absence of cleft mitral valve repair. Survival late after operation in a study of 121 patients demonstrated that survival was 80% at 1 year, 78% at 10 years, and 65% at 20 years. Freedom from reoperation was 91% at 1 year, 79% at 10 years, and 76% at 20 years. Mitral valve regurgitation necessitating valve repair or replacement was the most frequent indication for reoperation.
TOF is the most common cyanotic congenital heart malformation and one of the first complex lesions to be successfully repaired. TOF occurs in 7% to 10% of children with CHD. The four characteristic findings in TOF are (1) a malaligned VSD, (2) RV outflow or pulmonary valve or artery stenosis or atresia, (3) a dextraposed over-riding aorta, and (4) RV hypertrophy (see Fig. 56–1A). In the modern era, early surgical repair consisting of VSD closure and alleviation of RV outflow obstruction has gained favor over early palliation with an aortopulmonary shunt followed by intracardiac repair. Surgical outcomes are excellent and dramatically improve prognosis. However, these patients are not “cured” and are at significant risk of developing subsequent electrical and hemodynamic problems. Operated patients with TOF should be evaluated at regular intervals by a cardiologist trained in CHD; any symptoms suggestive of hemodynamic or electrical compromise should spur further investigation. Advances in imaging, medical therapy, electrophysiology, device and resynchronization therapy, and percutaneous intervention provide clinicians with a number of therapeutic options.
The natural history of unoperated patients is in large part determined by the severity of obstruction to RV outflow. A total of 66% of unoperated patients live to 1 year of age, 49% live to 3 years of age, 24% live to 10 years of age, and only 3% of patients reach 40 years of age.209 The chance of survival is greatly diminished when complete pulmonary atresia, instead of a variable degree of pulmonary stenosis, is present. Complications of right-to-left shunting across a nonrestrictive VSD include cyanosis, erythrocytosis, thrombocytopenia, and an increased risk of paradoxical emboli and cerebral abscess formation. Patients are at high risk for developing infective endocarditis. Malignant ventricular arrhythmias and congestive heart failure are major causes of death.
Since Blalock and Taussig performed a successful clinical palliative shunt in 1945, the survival and quality of life for patients with TOF has improved dramatically, truly one of the great accomplishments for cardiovascular medicine in the 20th century (see Fig. 56–1). Surgical palliation consists of systemic arterial–to–pulmonary arterial shunts designed to increase blood flow to the pulmonary arteries. Palliative surgery was followed subsequently by intracardiac repair that included VSD closure and relief of the RV outflow obstruction (see Fig. 56–1). Surgical techniques have changed significantly since the early intracardiac repairs of the 1960s and 1970s. The deleterious hemodynamic and electrical effects of pulmonary regurgitation and ventriculotomy scars have spurred efforts to ensure pulmonary valvar competence and minimize the extent of ventricular incisions. Advancements in surgical repair now confer an 85% survival into adulthood in the United States.210 The technique used for repair depends on the level and extent of outflow obstruction. Simple pulmonary valvar stenosis with a nondysplastic well-developed pulmonary valve requires the least extensive surgery, which consists of VSD and pulmonary valvotomy. More extensive or more severe outflow tract stenoses necessitate a more extensive reconstruction of the RVOT or complete bypass of the RV outflow tract by placement of a valved conduit. The first generation of intracardiac repairs was performed via a large anterior ventriculotomy and frequently included incision of the pulmonary valve annulus and placement of a transannular patch made of pericardium or synthetic material. This technique successfully relieved the outflow tract obstruction but resulted in pulmonary valvar incompetence and severe pulmonary regurgitation (see Fig. 56–9). Pulmonary regurgitation was thought to have minimal adverse clinical consequences, which may be true for the first two decades after transannular patch repair. However, with time, the adverse hemodynamic effects of severe low-pressure pulmonary regurgitation results in RV dilation and increased wall stress. The RVOT in the region of the transannular patch becomes dyskinetic, causing turbulence and energy loss. The tricuspid annulus frequently dilates, and tricuspid regurgitation often occurs. Therefore, the RV suffers under an additive source of volume overload in the presence of tricuspid regurgitation. Additionally, the RV develops “restrictive” diastolic properties that further compromise energy-efficient hemodynamics211 (see Fig. 56–9). Ventricular arrhythmias are more likely to occur under such conditions and often arise from the region of the transannular patch or ventriculotomy suture lines.212 Programmed ventricular stimulation resulting in monomorphic or polymorphic ventricular tachycardia is of prognostic importance in these patients.85 In a cohort of 793 patients with repaired TOF followed for a mean of 21 years, ventricular tachycardia occurred in 4.2%, and sudden cardiac death occurred in 2% of patients.23 Transventricular and transannular repair were associated with ventricular tachycardia and sudden cardiac death. QRS width on the surface ECG has additive prognostic value; 88% of patients with ventricular tachycardia and 63% of patients with sudden death had a QRS duration of ≥ 180 ms.23 Patients invariably have a right bundle branch block that results from early injury caused by surgical VSD closure and ventriculotomy followed by subsequent QRS lengthening secondary to RV dilatation. Therefore, severe pulmonary regurgitation leads to RV dilatation, which in turn leads to systolic and diastolic functional deterioration and increasing QRS duration, creating a vicious cycle; all of these factors combine to increase the risk of malignant ventricular arrhythmias. LV systolic and diastolic dysfunction are additional high-risk markers.93,213,214
Patients with an RV–to–pulmonary artery valved conduit may develop progressive conduit stenosis, but do not usually develop significant pulmonary regurgitation. Atrial arrhythmias are a cause of morbidity and confer a worse prognosis in patients with repaired TOF, especially in patients with tricuspid valve regurgitation and right atrial enlargement.23,215 AV block may occur after initial repair and VSD closure and is usually the result of damage to the conduction system at or below the bundle of His incurred during VSD closure. These patients require implantation of a permanent pacemaker (usually dual chamber) and are often pacemaker dependent. Chronic RV pacing is known to lead to deterioration of biventricular function and dyssynchronous ventricular contraction.216 Biventricular resynchronization may improve dyssynchrony and increase cardiac output.217,218 LV systolic and diastolic dysfunction may occur in the presence of severe pulmonary regurgitation. The interventricular septum bows leftward during diastole, resulting in impaired LV diastolic filling and asynchronous septal contraction. A decrease in LV ejection fraction is ominous.219 Abnormal strain patterns by cardiac MRI are associated with adverse clinical outcomes.20,220 Approximately one in 10 patients will require subsequent reoperation for RV outflow repair, conduit replacement, or pulmonary valve replacement.221 Additional tricuspid valve annuloplasty and right atrial maze cryoablation are often performed in patients with severe tricuspid regurgitation and atrial arrhythmias. In patients with mild or moderate tricuspid regurgitation and dilated tricuspid annular size, tricuspid regurgitation improves after pulmonary valve replacement, regardless of whether tricuspid annuloplasty was performed.222,223 Every effort should be made by the surgeon to excise the ventriculotomy scar tissue that serves as the source of reentrant ventricular arrhythmias. Reoperation carries a low perioperative risk of death.145
Transcatheter pulmonary valve (TCPV) replacement can alleviate RVOT conduit dysfunction whether caused by stenosis, regurgitation, or both, thereby delaying the need for open heart surgery and essentially decreasing the number of operations with their associated morbidities.224 The Melody (Medtronic, Dublin, Ireland) TCPV was the first valve to receive US Food and Drug Administration (FDA) approval, initially under humanitarian device exemption in 2010 and thereafter for clinical use in 2014. The Melody valve is widely used for the treatment of dysfunctional RV–to–pulmonary artery conduits and bioprosthetic valves, and more recently has been used to treat dysfunctional native RVOT lesions. The various Sapien transcatheter bovine pericardial stent valves (Edwards, Irvine, CA; Sapien, Sapien XT, and Sapien 3) are FDA approved for use in the aortic position and are being used by multiple centers for off-label implantation in the pulmonary position. The larger diameter Sapien valves (26 and 29 mm) allow for implantation in large dysfunctional native RVOTs. Short-term follow-up after Melody valve implantation has been promising, with hemodynamic and clinical improvement and acceptable durability of the valve.225 Greater improvement in exercise capacity is seen in patients with both RVOT stenosis and regurgitation, compared with those with only RVOT regurgitation.226 Favorable longer term outcomes were seen after a median follow-up of 4.5 years in 148 patients in the US Melody valve investigational device exemption trial, with a 5-year freedom from reintervention of 76% and a 5-year freedom from explant of 92%.227 Stent fracture and endocarditis have been the primary causes for reintervention.228,229,230,231,232
Stent fracture often occurs in patients with conduits or native RVOT dysfunction, and is likely caused by repetitive stress on the platinum iridium frame (Fig. 56–19). Prestenting before Melody valve placement has significantly reduced the incidence of stent fracture. Also, valve-in-valve implantation is a successful treatment option for Melody valve stent fracture. As for endocarditis, adherence with subacute bacterial endocarditis prophylaxis is imperative; however, data suggest there is an increased risk of infective endocarditis with implanted Melody valves.230,231,233 Other complications, such as conduit or pulmonary artery dissection or rupture, are life threatening but rare and can be treated with covered stent placement. There is a 5% risk of coronary artery compression, but this risk can be reduced by performing simultaneous balloon inflation in the RVOT with coronary or aortic root angiography to test for coronary artery compression. TCPV replacement has also been successfully performed within failed bioprosthetic valves, not as part of RV–to–pulmonary artery conduits, with excellent outcomes. In the subset of CHD patients with native RVOT or RVOT patch repairs, there is a growing body of literature on the utility of commercially available valves used off label.
A. Stent fracture of a Melody transcatheter pulmonary valve. B. After stenting of the fractured stent and placement of a new Melody transcatheter pulmonary valve.
The timing of pulmonary valve replacement in asymptomatic patients remains controversial, especially in the repaired TOF patient. Severe RV dilation or dysfunction and the development of atrial arrhythmias are the most common indications for pulmonary valve replacement in the otherwise asymptomatic patient, although the RV volume threshold for pulmonary valve replacement varies by ACHD center. Therrien et al147 demonstrated that patients with TOF and severe pulmonic regurgitation had normalization of RV end-diastolic volumes after pulmonic valve replacement if the preoperative indexed RV end-diastolic volume was ≤ 170 mL/m2. An indexed RV end-diastolic volume of ≥ 160 mL/m2 or an indexed RV end-systolic volume ≥ 65 mL/m2 has therefore been suggested as an indication for pulmonary valve replacement.146 However, the advent of transcatheter valve therapies may be lowering the threshold for pulmonary valve replacement. Some experts argue that all patients with severe pulmonary regurgitation should undergo pulmonary valve replacement prior to the development of RV dilation or dysfunction.234 This aggressive early intervention approach must be weighed against the procedural risks, the potential for infective endocarditis, and the potential decrease in the internal orifice diameter of surgically placed conduits or bioprosthetic valves with multiple transcatheter pulmonary valve implants over a patient’s lifetime.235
Isolated pulmonary valve stenosis is commonly seen in adults with CHD. The valvar stenosis is typically characterized by a trileaflet valve with fused commissures, as opposed to the more rare dysplastic valve without commissural fusion. The exception is Noonan syndrome, in which a dysplastic and stenotic pulmonary valve is commonly present. RV hypertrophy, including excessive hypertrophy of the infundibulum, occurs in response to RV pressure overload from the stenotic valve. Isolated infundibular stenosis is rare, as is isolated supravalvar stenosis.
Survival into adulthood is usual. Severe pulmonary stenosis that is uncorrected may result in progressive RV hypertrophy, dilatation, and symptoms of right heart failure. Moderate or mild pulmonary stenosis generally does not progress and is well tolerated.
Mild and moderate degrees of pulmonary stenosis (peak gradient ≤ 50 mm Hg) are well tolerated and generally do not require surgical or percutaneous intervention.93 Infective endocarditis of the pulmonary valve is rare; endocarditis prophylaxis during bacteremic procedures is not recommended.6 Asymptomatic patients with severe pulmonary stenosis and a peak gradient ≥ 60 mm Hg or a mean gradient ≥ 40 mm Hg should undergo intervention to reduce the severity of the stenosis. Symptomatic patients with a peak gradient ≥ 50 mm Hg or a mean gradient ≥ 30 mm Hg should undergo intervention.6
Surgical valvotomy for isolated pulmonary stenosis has been successfully and safely performed for 50 years. Perioperative and late results are excellent, especially if surgery is performed in the first two decades of life.236 Various degrees of pulmonary regurgitation occur and are well tolerated in the short and medium term. Severe pulmonary regurgitation is more common when pulmonary valvectomy or transannular patching is performed, usually for dysplastic valves or narrowed annulus. Severe chronic regurgitation results in progressive RV dilatation and dysfunction with an increased rate of coexistent ventricular and supraventricular arrhythmias (see earlier section Tetralogy of Fallot). The advent and widespread use of transcatheter balloon valvuloplasty in the past three decades have made surgical valvotomy unnecessary in most cases of isolated valvar stenosis (Fig. 56–20).156,237,238 The immediate and midterm results of balloon valvuloplasty in mobile nondysplastic pulmonary valvar stenosis are favorable.239 Subvalvar infundibular hypertrophy often results in a dynamic subvalvar gradient across the infundibulum that often increases after valvuloplasty because of the relief of downstream obstruction. β-Blocker therapy before and after valvuloplasty helps decrease this dynamic gradient and avoid the rare, but catastrophic, severe infundibular stenosis characterizing the “suicide ventricle."240
A. Simultaneous transcatheter pressure recordings in the right ventricle (RV) and pulmonary artery (PA) in a 47-year-old woman with unoperated isolated severe pulmonary valve stenosis before balloon valvuloplasty. Note that the right ventricular systolic pressure exceeds 100 mm Hg except on the beat after an interpolated premature ventricular complex. Also note the absence of systolic deflections on the PA pressure waveform indicative of severe valvar pulmonary stenosis. The maximum pressure gradient between the RV and PA at times exceeds 100 mm Hg. B. Simultaneous RV and PA pressure tracings after transcatheter balloon valvuloplasty, demonstrating a lower RV systolic pressure (40-50 mm Hg) and an increase in PA pressure with clear systolic deflections indicating resolution of severe stenosis. The patient has a residual gradient of 15 to 20 mm Hg consistent with mild stenosis.
Left Ventricular Outflow Tract Obstruction
LVOT obstruction (LVOTO) may occur at the subvalvar, valvar, or supravalvar levels.241 These obstructions to forward flow may present alone or in association with other levels of obstruction, as in the frequent association of a BAV with coarctation of the aorta. LVOTO imposes increased afterload on the LV and, if severe and untreated, results in hypertrophy and eventual dilatation and failure of the LV and life-threatening arrhythmias.
LVOTO is congenital in the majority of patients younger than 50 years of age in the United States; some variants of subaortic obstruction are the exception (eg, subaortic membranes). Patients with LVOTO are at risk for developing infective endocarditis. Fixed SAS may be caused by a discrete fibrous membrane, a muscular narrowing, or a combination of the two. The obstruction may be focal or more diffuse, resulting in a tunnel leading out of the LV. The discrete form of fibromuscular SAS is most frequently encountered (90%), but the tunnel-type lesions are associated with a greater degree of stenosis.242 In some patients with AV septal defects and cleft mitral valve, abnormal accessory mitral valve tissue or chords may cause SAS (see Fig. 56–20B). SAS may be a congenital isolated lesion, but may also be acquired. A BAV is present in 23% of patients.242 SAS may also present as part of a complex of obstructive lesions, as in the Shone complex, which frequently includes parachute mitral valve, mitral stenosis, BAV, and coarctation of the aorta. A total of 37% of patients with SAS may also have concomitant VSDs of the perimembranous type.242
BAV is one of the most common congenital cardiovascular malformations with an estimated incidence of 1% to 2%.243 BAV is sometimes inherited, and family clusters have been studied. Inheritance patterns are autosomal dominant with variable penetrance.244 Variants of BAV range from a nearly trileaflet bicommissural valve with mild cuspal inequality to a unicuspid unicommissural valve. The aortic root tissue structure is abnormal. The histology of the ascending aortic wall demonstrates medial abnormalities that are similar to, but less advanced than, those of the Marfan syndrome.245 Although aortic dilatation above a stenotic BAV has previously been attributed to “poststenotic” turbulence, several studies have clearly demonstrated that dilatation and histologic abnormalities of the ascending aorta in BAV occur irrespective of the degree of valvar stenosis or regurgitation.246
Supravalvar aortic stenosis (SVAS) is the rarest type of LVOTO and is defined by a focal or diffuse narrowing starting at the sinotubular junction and often involving the entire ascending aorta.247 SVAS is frequently associated with Williams-Beuren syndrome, a multisystem disorder with an autosomal dominant inheritance pattern that occurs in 1 in 20,000 births.248
In the absence of LV hypertrophy, dilatation, or failure, intervention in patients with SAS may be safely deferred; however, there should be careful lifelong follow-up for symptoms and stenosis progression. Aortic regurgitation may result from damage to the valve by the turbulent flow caused by SAS. The clinical course of SAS is usually progressive with increasing obstruction and progression of aortic regurgitation in the majority of untreated patients.249,250 The primary hemodynamic effect on the LV is one of increased afterload, resulting in increased intracavitary pressure and wall stress. Patients may present with one of the triad of symptoms associated with severe valvar aortic stenosis (ie, angina, heart failure, or syncope). Patients with SAS are at increased risk for developing infective endocarditis, which frequently involves the aortic valve and often leads to aortic regurgitation.251 Even in the absence of endocarditis, when the Doppler-derived LVOT peak instantaneous gradient reaches 50 mm Hg or above, there is an increased risk of moderate-to-severe aortic regurgitation.252
BAV disease is gradually progressive in the majority of cases. Abnormal folding and creasing of the valve leaflets throughout the cardiac cycle, extended areas of valve contact, turbulent flow, and restricted motion of the leaflets lead to valve damage, scarring, calcification with resultant stenosis, and regurgitation.253 Turbulent flow into the ascending aorta added to the medial abnormalities discussed above may lead to progressive dilatation and an increased likelihood of rupture or dissection.253,254 Atherosclerotic changes have been identified in BAV and are similar to those seen with calcific degenerative stenosis of trileaflet aortic valves. The presence of dyslipidemia may be associated with accelerated progression of BAV stenosis.255,256 Aortic stenosis is the most common complication of BAV. Patients with a mobile BAV have a systolic ejection sound after the first heart sound best heard at the LV apex. This ejection sound is present until valve calcification restricts mobility. Concomitant aortic regurgitation results in an early diastolic decrescendo murmur; when well heard at the right mid sternal border, it suggests the presence of a dilated ascending aorta. Evidence of echocardiographic sclerosis can be seen as early as the second decade of life. Thickening and calcification often occur in the fourth decade of life, and only 15% of patients with BAV have a normally functioning valve in the fifth decade.257 Moreover, a BAV predisposes patients to the development of aortic regurgitation. Progression of aortic regurgitation may occur via several mechanisms and, in most cases, is directly correlated with the degree of aortic root and annular dilatation.258 Other mechanisms include leaflet prolapse, degeneration, and retraction. Infective endocarditis of the BAV may cause leaflet destruction and perforation along with intimal dissection leading to a sudden worsening of aortic regurgitation that is poorly tolerated hemodynamically and is a surgical emergency. Aortic dissection is an infrequent, but deadly, complication. Asymptomatic patients with a peak transvalvar systolic velocity of 4 m/s or above are likely to develop symptoms related to stenosis (dyspnea, chest pain, syncope) within 5 years.113,259 The ascending aorta in patients with BAV gradually dilates at a mean of 0.9 mm/year.260,261 The risk of dissection in patients with BAV is estimated to be five to nine times that of the general population, and is highest in patients with concomitant coarctation.262,263 Patients with a BAV and ≥ 55-mm aortic root diameter should be referred for surgical aortic root wrapping or replacement.113
Fifty percent of patients with SVAS may have concomitant aortic valve abnormalities, most commonly a BAV.264 Fatigue stress and shear forces are increased on the aortic valve leaflets in the setting of a poorly distensible sinotubular junction and may result in leaflet thickening and damage with resultant regurgitation, stenosis, or both.265 SAS occurs in 16% of patients and may contribute to aortic valve damage.266 Impaired coronary perfusion may occur because of varying degrees of aortic valve leaflet adhesion to the narrowed sinotubular junction, restricting diastolic filling of the coronary arteries.267 Furthermore, the coronary arteries are subjected to elevated systolic pressures in SVAS, which leads to dilatation, tortuosity, and accelerated atherosclerosis.268
Surgical resection is the intervention of choice for treatment of SAS and is usually done via a transaortic approach. Surgical mortality is low, and complications are generally minimal.269 Surgical management consists of discrete membrane excision or blunt dissection (or both) in focal SAS with focal septal myotomyectomy. Tunnel-type SAS is more surgically challenging and often necessitates application of the Konno-Rastan procedure to reconstruct the LVOTO.270 Concomitant repair of the aortic valve is performed if the severity of the aortic regurgitation is more than mild. SAS recurs in up to 37% of cases after surgical resection.242 In this series, tunnel-type SAS recurred in 71% of patients versus a 14.7% recurrence rate for discrete SAS over 6 years of follow-up. The presence of an immediate postoperative gradient above 10 mm Hg led to progressive recurrent SAS in 75% of patients; therefore, attention must be paid to the excision of all abnormal tissue and removal of the membrane from the anterior mitral leaflet. Progressive aortic regurgitation may develop despite relief of SAS. Percutaneous balloon dilatation of a fixed focal stenosis causes short-term improvement in the gradient and may be considered for palliation of SAS.271 In one case series, 25-year freedom from reintervention was 77%.272
There are currently no proven medical therapies that alter the course of aortic stenosis or regurgitation in patients with BAV. β-Blockers may delay the progression of ascending aortic dilatation.113 Patients with hypertension and aortic regurgitation may benefit from afterload reduction with ACE inhibitors, hydralazine, or calcium channel blockers. However, a randomized, prospective trial of enalapril or nifedipine versus placebo in patients with severe aortic regurgitation revealed no differences in regurgitant volume, LV size, or ejection fraction over 7 years of follow-up.273 Aortic valve replacement should be performed in patients with severe symptomatic aortic valve stenosis. Aortic valve replacement is also recommended in asymptomatic patients with severe aortic stenosis if the LV ejection fraction is < 50% or if the patient is undergoing other cardiac surgery. Surgery may be considered in asymptomatic patients with very severe stenosis with a peak velocity ≥ 5 m/s if patients are assessed to be low surgical risk.113 Because stenosis is secondary to bicuspid commissural fusion, balloon valvuloplasty may safely decrease the gradient and improve symptoms in those without a calcified valve.274,275 Surgical repair or replacement is indicated for patients with severe stenosis (peak instantaneous Doppler velocity of ≥ 4 m/s) who are symptomatic.113 Surgery should also be considered in those with less severe stenosis who have concomitant moderate or severe aortic valve regurgitation or a dilated ascending aorta. Asymptomatic patients with severe BAV stenosis who want to become pregnant or to exercise more vigorously should also be considered for surgery. Severe aortic regurgitation, if associated with symptoms, severe aortic root enlargement, or LV dilatation and decreased ejection fraction, should be surgically corrected.113 Numerous surgical techniques have been used to repair or replace the aortic valve. Valve repair has shown promising results and should be considered if the valve is not calcified.113,276 If valve replacement is needed, bioprosthetic valves are generally preferred in patients older than 65 years, women of childbearing age wishing to avoid warfarin, and patients refusing to take or who are allergic to warfarin. These bioprosthetic valves generally deteriorate over 10 to 20 years and require replacement. Mechanical prostheses have superior durability in patients who can tolerate warfarin. The Ross procedure has been used successfully in patients with BAV and is favored in the pediatric population. However, after the Ross procedure, patients are at risk for developing neoaortic dilatation, progressive aortic regurgitation, neopulmonary homograft regurgitation, and myocardial ischemia.277
Patients with SVAS may undergo surgical enlargement of the narrowed sinotubular region and adjacent ascending aorta if they have symptoms of angina, dyspnea, syncope, or heart failure, or a mean pressure gradient of 50 mm Hg or above. Surgical relief of obstruction consists of excision of a focal stenosis with end-to-end anastomosis of the ascending aorta, patch enlargement of the sinotubular junction, or more complex aortoplasty involving patch placement into two or more sinuses of Valsalva. The Ross procedure has also been used to replace the aortic root in patients with concomitant aortic valve disease. Balloon angioplasty of SVAS does not result in relief of obstruction and risks aortic dissection or rupture.
Coarctation of the aorta in adults is usually a discrete narrowing in the region of the ligamentum arteriosum (Fig. 56–21). More diffuse forms of the disease may involve the arch or isthmus. Coarctation of the aorta occurs in 7% of patients with CHD, and there is a small male predominance of 1.5:1. Coarctation is a diffuse arteriopathy characterized by cystic changes in the aortic media.278 The descending aorta immediately distal to the segment of coarctation is often aneurysmal. A BAV is present in about half of cases. Intracranial aneurysms, often in the circle of Willis, have been detected in up to 10% of patients.279 Adult unoperated patients present with systemic arterial hypertension in the upper extremities. A normal patient should have a 5- to 10-mm Hg increase in systolic blood pressure in the lower extremities compared with the upper extremities. Absence of this increase or presence of a decrease in the lower extremities should arouse suspicion of coarctation.
A. Three-dimensional surface rendered reconstruction of cardiac magnetic resonance angiogram as viewed from a right anterior oblique and cranial projection in a 54-year-old woman with near-interruption of the aorta (Ao). The ascending Ao is moderately dilated, as are the arch vessels. A plethora of bypassing collaterals (coll) are present. Adult unoperated patients present with systemic arterial hypertension in the upper extremities. A normal patient should have a 5- to 10-mm Hg increase in systolic blood pressure in the lower extremities compared with the upper extremities. Absence of this increase or presence of a decrease in the lower extremities should arouse suspicion of coarctation. B. Right lateral projection with collaterals removed during the editing and three-dimensional rendering process. Complete interruption (C) of the aorta is evident.
Unoperated survival is poor, and median survival is only 35 years.280 Patients die of congestive heart failure, aortic dissection or rupture, complications of infective endocarditis, and intracranial hemorrhage from ruptured aneurysms in the circle of Willis.
Excision of the narrowed segment and end-to-end anastomosis of the para-coarctation aorta is the preferred method for initial repair (Fig. 56–22). Subsequent modifications in surgical technique include the use of prosthetic overlay grafts, subclavian patch aortoplasty, and prosthetic tube grafts from the ascending to the descending aorta in patients with complete interruption (see Fig. 56–22). Percutaneous balloon angioplasty with stenting for primary coarctation has gained popularity and has displayed encouraging results. Stent implantation is preferable to angioplasty alone and has excellent long-term outcomes (see Fig. 56–14).281,282
Surgical techniques for repair of coarctation of the aorta. A. Unrepaired coarctation of the aorta. B. Excision of the narrowed segment with end-to-end anastomosis. C. Subclavian flap repair. D. Prosthetic patch aortoplasty. E. Excision of the narrowed segment and placement of a prosthetic conduit. F. Prosthetic conduit placement from the ascending to the descending aorta.
Patients with successfully treated coarctation often continue to have systemic arterial hypertension despite the absence of significant residual coarctation.283,284 Patients who undergo repair in childhood demonstrate very good long-term survival up to 60 years.285 Late repair (> 14 years of age) is associated with higher rates of hypertension and decreased survival.286 Patients with hypertension after late repair are at an increased risk of developing heart failure, atherosclerosis, stroke, and progressive aortic disease.
Complete Transposition of the Great Arteries
Complete TGA refers to a ventriculoarterial discordance characterized by medial transposition of the aorta, which arises anteriorly and rightward from a morphologic RV, and the pulmonary artery arises posteriorly and leftward from a morphologic LV. Simply, the aorta is anteriorly dextraposed and emerges from a normally located RV, and the pulmonary artery is posteriorly levoposed to emerge from the LV (see Fig. 56–2). As a result, the systemic and pulmonary arterial circulations run in parallel, not in series. Therefore, poorly oxygenated blood enters the aorta, and survival depends on the delivery of oxygenated blood to the systemic circulation via a left-to-right shunt. Atrial balloon septostomy (Rashkind procedure) may need to be urgently performed within the first few hours of life to create an intracardiac shunt. Other anomalies often coexist, including VSD (30%), LVOTO (10%), and more rarely, PDA and coarctation of the aorta.205
Surgical intervention in infancy is imperative for survival, and almost all adult patients with this condition have undergone prior correction. However, patients with large nonrestrictive shunts at the atrial, ventricular, or pulmonary arterial levels who may survive into adulthood often develop congestive heart failure in childhood and pulmonary vascular disease thereafter.
The use of balloon atrial septostomy in the infant with TGA, initially described by Rashkind and Miller287 in 1966, allows enough left-to-right shunting of oxygenated blood to palliate the patient. The Senning operation, a description of which was initially published in 1959, followed by the Mustard operation in 1964, involved redirection of atrial blood via baffles to deliver oxygenated pulmonary venous blood to the systemic RV and deoxygenated systemic venous blood to the pulmonary LV (see Fig. 56–2).288,289 The major difference between these two operations is that whereas the earlier Senning operation uses atrial and septal tissue to create the baffles described earlier, the Mustard operation uses extrinsic materials (ie, pericardium) for this purpose. These surgeries were performed in the majority of operated infants and children (usually between 1 and 12 months of age) until the late 1970s and early 1980s. Long-term follow-up demonstrates an 80% 28-year survival rate, with the majority of survivors in NYHA class I.290 Atrial tachyarrhythmias and bradyarrhythmias occur over time, with SND and incisional reentrant atrial arrhythmias being frequent long-term complications. Loss of sinus rhythm is progressive, but usually asymptomatic at rest. Patients often demonstrate evidence of chronotropic incompetence with exercise and may benefit from pacemaker insertion. Reentrant atrial tachyarrhythmias are a worrisome development and are notoriously difficult to treat and may require life-long anticoagulation. These arrhythmias often result in deleterious and poorly tolerated hemodynamic consequences and increase the risk of sudden cardiac death, especially in the presence of RV dysfunction.291 Sudden death is a well-documented occurrence in up to 15% of patients and usually occurs during exercise.290,292 Patients at increased risk for sudden cardiac death are older, have worse systemic RV function, and have a widened QRS complex (> 140 ms).293 Obstruction of the pulmonary or systemic venous baffles (usually the superior vena cava baffle) occurs in a minority of patients and can usually be treated with transcatheter angioplasty and stenting. Baffle leaks are more common than obstruction, and the majority are not hemodynamically significant; only 1% to 2% require intervention because of cyanosis or volume overload. Progressive systemic RV failure does not usually occur in the short and intermediate term, but may be a problem beginning in early adult life. ACE or angiotensin receptor inhibition does not improve exercise performance or decrease serum BNP levels.25,26,294 This may be explained by a lack of activation of the renin-angiotensin system and the presence of another yet unidentified mechanism for progressive systemic RV dysfunction and impaired exercise capacity. β-Blocker therapy, on the other hand, may be beneficial in halting adverse ventricular remodeling, decreasing the risk of life-threatening arrhythmias, and improving exercise capacity.291,295
The late complications sited earlier for atrial switch operations led to the increasing acceptance of the arterial switch (Jatene operation) as the operation of choice.296 This procedure consists of anatomic correction by transection of the aorta and pulmonary artery at a level above the valve sinuses with detachment of the coronary arteries from the aorta. Thereafter, the positions of the transected great arteries are reversed so that the “neo-aorta” emerges from the LV and the “neopulmonary” artery emerges from the RV. The coronary arteries are sutured into place in the neo-aorta. This is a technically challenging surgery but has certain advantages over the atrial switch operations, namely, the LV is the systemic ventricle and the incidence of arrhythmias is lower.297 Some authors have advocated performing the arterial switch operation after “conditioning” the LV with pulmonary artery banding in patients with a previous Mustard or Senning repair. The existing literature indicates a significant surgical mortality and inconsistent LV response to “conditioning” if the arterial switch is performed after childhood.298,299 The long-term outcomes of the arterial switch operation are now becoming available, and the results are encouraging. The 10-year survival rate is 88% in patients without associated lesions such as VSD, in whom the operative mortality is higher and the 10-year survival is decreased to 80%.300 Neo-aortic valve regurgitation occurs in approximately 15% of patients; however, only a minority of patients require reoperation for this problem.301 Neopulmonary artery stenosis or branch pulmonary artery stenosis occurs in a minority of patients and may require transcatheter or operative intervention. Myocardial ischemia related to reimplantation, surgical manipulation, and distortion has been reported, and late deaths because of coronary events may occur in a minority of patients.300
Congenitally Corrected Transposition of the Great Arteries
Congenitally corrected TGA is characterized by AV and ventriculoarterial discordance. From a circulatory oxygenation standpoint, these patients are “congenitally corrected,” essentially “two wrongs make a right,” and the pulmonary and systemic circulations run in series, not in parallel, as with dextro-TGA. There is ventricular inversion, and the respective AV valves follow the ventricles. Therefore, the systemic RV is transposed to the left, and the tricuspid valve goes with it. The left atrium empties into the RV, which then pumps to the leftward and usually anterior aorta (Fig. 56–23). The LV and mitral valve are dextraposed, and the pulmonary artery emerges posteriorly from the LV. Fewer than 10% of patients are free of associated abnormalities, which include VSD (membranous or muscular) in up to 80%, pulmonic stenosis (valvar or subvalvar) in up to 70%, and tricuspid valve abnormalities (usually Ebstein anomaly) in 33%.302
A. Cine-magnetic resonance imaging scan of a 62-year-old woman with congenitally corrected transposition of the great arteries as viewed from a sagittal projection. Note that the left atrium (LA) is connected to the transposed right ventricle (RV) via a tricuspid valve (TV). The aorta (Ao) emerges anteriorly from the RV. B. Axial cut (four-chamber view). Note that the morphologic smooth-walled left ventricle (LV) is dextraposed, thin walled, and not dilated. The right atrium (RA) empties into the LV via the mitral valve (MV). The morphologic RV is transposed to the left along with the TV.
In the minority of patients without associated defects, unoperated survival into adulthood is common, and survival into the eighth and ninth decades of life has been reported.302 Most patients remain undiagnosed until early adulthood. However, these patients have an increased incidence of AV conduction problems and complete heart block with age.303 Complete heart block may be present from birth (in ~10%) and has been reported to develop in 2% of patients per year.304 Systemic morphologic RV dysfunction and congestive heart failure occur in more than 50% of patients with associated lesions by the time they are 45 years of age.303 Ebstein anomaly of the systemic AV valve is common, and regurgitation occurs in over 80% of adults with congenitally corrected TGA. Pulmonary morphologic LV dysfunction occurs less often, but may be present in up to 20% of patients. Aortic regurgitation of some degree is present in 25% of adults, but seldom requires surgical intervention.
Systemic AV (tricuspid) valve regurgitation is a common and progressive problem in these patients that can lead to morphologic RV dilatation and dysfunction if the valve is not replaced.288,305 Early surgical intervention in patients with more than mild tricuspid regurgitation, to prevent systemic ventricular dysfunction, is warranted and is associated with improved intermediate- and long-term outcomes. Patients with a combination of pulmonic stenosis and VSD may be cyanotic because of the right-to-left shunt at the ventricular level. Surgical repair in these patients consists of VSD closure and pulmonary valvotomy or replacement, frequently accompanied by subinfundibular muscle bundle resection. Alternative surgical strategies involving the “double-switch” operation have been described. This surgery involves a Mustard- or Senning-type atrial redirection along with a Jatene-style great arterial switch, thus leaving the patient with a systemic LV after this complex surgery.306 Patients with pulmonic stenosis or atresia and a VSD may undergo a modification of the double-switch operation by baffling of morphologic LV outflow through the VSD to the leftward and anterior aorta and placement of a conduit from the morphologic RV to the pulmonary artery.307 Long-term follow-up after these surgical interventions is limited. Pacemaker placement is indicated for patients with Mobitz type II or complete heart block.
Ebstein Anomaly of the Tricuspid Valve
Ebstein anomaly is characterized by apical displacement of the septal (and often the posterior) leaflet of the tricuspid valve into the RV cavity (Fig. 56–24). The RV is therefore divided into a proximal “atrialized” portion and a distal “functional” portion. The effective volume of the functional RV is often small.308 The anterior leaflet is usually excessively long and may have attachments to the RV free wall. The “atrialized” portion of the RV is usually thin because of a congenital absence of myocardium. The effective right atrium (including the atrialized portion of the RV) is invariably large and becomes more so in the presence of tricuspid regurgitation, which is a very common occurrence. An ASD or patent foramen ovale is present in more than one-third of cases. Other associated lesions are far less common and may include pulmonary stenosis, VSD, and PDA. Ebstein anomaly is commonly found in patients with congenitally corrected TGA (see earlier discussion).
A. Ebstein anomaly of the tricuspid valve in the apical four-chamber view by transthoracic two-dimensional echocardiography. Note the marked apical displacement of the septal leaflet of the tricuspid valve from the level of the true annulus (large horizontal white arrows). The anterior leaflet of the tricuspid valve (small white arrows) is long and redundant and has attachments to the free wall. The functional right ventricle (fRV) is small because much of the right ventricular inflow is “atrialized” (aRV). B. Color-flow Doppler through the tricuspid valve in systole demonstrating severe regurgitation (TR) starting at the apically displaced septal leaflet and directed medially (black arrows). LA, left atrium; LV, left ventricle; RA, right atrium.
The clinical spectrum is variable and is heavily dependent on the severity of the deformity and the presence of associated defects. Patients presenting in infancy represent the worst end of the spectrum, with severe tricuspid regurgitation and a high incidence of associated abnormalities such as pulmonary stenosis or atresia.309,310 Patients surviving into adulthood without surgical valve repair or replacement may develop a variety of signs and symptoms, including cyanosis (because of right-to-left shunting across an ASD or patent foramen ovale), dyspnea and fatigue (as a result of decreased preload and cardiac output), or palpitations. In adolescents and adults, palpitations secondary to atrial arrhythmia are the most common clinical presentation. Ebstein anomaly is often associated with ventricular pre-excitation, which may involve more than one accessory pathway that may be endocardial or epicardial in location and often is challenging to map and ablate from an intravascular approach. Up to 20% of unoperated patients may die from heart failure, and approximately 5% may die suddenly, presumably from atrial or ventricular arrhythmias.311 Heart failure results from RV dysfunction and tricuspid regurgitation, and may be exacerbated by LV fibrosis and dysfunction.
There are numerous variations on the surgical management of Ebstein anomaly.312 Most surgical approaches consist of some form of repair (or replacement if repair is not feasible) of the tricuspid valve, often accompanied by atrial or atrialized ventricle plication, and closure of an interatrial communication.313,314 Eventual reoperation for recurrent tricuspid regurgitation after tricuspid valve repair is expected, and a tricuspid valve replacement is typically undertaken after failure of a repaired valve. With recent advancements in transcatheter valve replacement, valve repair with an annular ring or valve replacement is an increasingly attractive option in adults.315,316 Valve repair may not be feasible in the most severe forms of Ebstein anomaly in which the long anterior leaflet of the tricuspid valve is adherent to the RV endocardium and there is almost complete atrialization of the RV; valve replacement is a good option in this subset of patients. The results of surgery in patients with poor RV function can be improved considerably if the RV is unloaded by a concomitant cavopulmonary (Glenn) shunt, also known as the one-and-a-half ventricle repair.312,317 Furthermore, in the most severe cases with near complete absence of a functioning RV, a univentricular repair leading to a Fontan palliation may be necessary.318,319 Intraoperative radiofrequency ablation or cryoablation (modified maze) and division of accessory pathways that are usually located in the posteroseptal or RV free wall are recommended at the time of valve repair or replacement.320 Overall surgical mortality was 13% in a multicenter analysis, with young age at the time of operation as the only multivariate risk factor.312 The long-term survival and functional capacity of operated patients are very good.321