Figure 84.1. Anatomic Types of Interatrial Communications (see text for description). Atrial septal defect (ASD) 1° denotes primum ASD; ASD 2° denotes secundum ASD.

    In young adults, the dominant interatrial shunt is from left-to-right because left atrial pressure and both inflow and outflow resistances exceed those in the right atrium. The degree of subsequent left-to-right shunting determines the amount of right heart volume overload and is dictated by the size of the defect as well as the diastolic properties of the heart. Decreasing compliance of the left-sided cardiac chambers noted with increased aging (due to a multiplicity of contributors including increasing prevalence of diabetes, systemic arterial hypertension, atherosclerosis, and myocardial senescence) may contribute to increased left-to-right shunting and symptomatology, despite stability of defect dimensions, as patients grow older.

    Pulmonary vascular disease leading to pulmonary hypertension develops in 5–10% of patients with untreated ASD, although this development may not be solely attributable to increased left-to-right flow. Clinical presentation, physical examination findings, and laboratory features are summarized in table 84.1.

Table 84.1 ATRIAL SEPTAL DEFECT

    In the past, adult survivors with uncorrected ASDs were demonstrated to have reduced life expectancy. More recently, data suggest increased risk of atrial fibrillation and symptomatic respiratory issues prompting hospitalization in those with uncorrected ASD. Therefore, persons with ASD and a significant shunt (evidence of otherwise unexplained right heart dilation +/− Qp/Qs >1.5:1) should be offered closure.

    Secundum ASD can often be closed percutaneously if anatomically appropriate; results appear both safe and effective. Increasing use and subsequent analyses from national registries including data from congenital catheterization-based interventions are expected to shed greater light on such outcomes. Surgical closure is required for primum ASD, sinus venosus defects, and coronary sinus septal defects. The long-term prognosis after repair for patients younger than 25 years is comparable to that of the general population. Patients repaired at an older age, particularly those over 40–50 years, may have decreased comparable long-term survival and may experience higher rates of comorbidities including atrial arrhythmias and right-heart failure.

VENTRICULAR SEPTAL DEFECT

A ventricular septal defect (VSD) is a communication between the ventricles and is the most common congenital anomaly seen in children; it may be an isolated defect or associated with complex cardiac disease. Several classification systems exist for defining VSD. Figure 84.2 illustrates the location of various VSDs, which may be classified as membranous (conoventricular), muscular, conal septal (subpulmonary), or atrioventricular (AV) canal-type.

    The size and location of the VSD and the relative resistances in the pulmonary and systemic vasculature are determinants of hemodynamic significance. Accordingly, left-to-right shunting at the ventricular level leads to volume overload to the left-sided chambers. Rarely, excessive flow to the pulmonary vasculature over time may result in changes that can eventually lead to elevated pulmonary vascular resistance with reversal of flow (Eisenmenger syndrome [ES], see below). Clinical presentation, physical examination findings, and laboratory features are summarized in table 84.2.

Table 84.2 VENTRICULAR SEPTAL|DEFECT

    Some VSDs become smaller over time and may close spontaneously, particularly those in the membranous and muscular septum. However, moderate or large VSD should be offered closure if there are otherwise unexplained symptoms of congestive heart failure, a significant left-to-right shunt (Qp:Qs >1.5:1), evidence of significant left ventricular volume overload, elevation of pulmonary arterial pressures without significant elevation of pulmonary vascular resistance, or significant aortic regurgitation associated with conal septal VSD. Closure of a VSD in the setting of Eisenmenger Syndrome (ES) can result in right ventricular failure and sudden death and is therefore contraindicated.

    The outcome of patients with small VSD (without pulmonary hypertension or evidence of left ventricular volume overload) that do not require closure is generally excellent. However, 25-year survival rates correlate to size of the VSD, with decreased survival found in those with larger shunts. For those who have undergone closure with normal pulmonary arterial pressures, life expectancy is normal whereas those with pulmonary hypertension at the time of repair have decreased survival. Complications may include endocarditis, arrhythmias, and aortic insufficiency for both repaired and unrepaired patients.

PULMONARY STENOSIS

Right-sided outflow tract obstruction can occur at various levels, including valvar (at the level of the pulmonary valve), supravalvar (above the level of the pulmonary valve), or subvalvar (either at the infundibular or subinfundibular level). Pulmonary stenosis (PS) may be associated with various genetic disorders including Noonan and Alagille syndromes. Hemodynamically significant PS can lead to right ventricular (RV) pressure overload with ensuing RV hypertrophy and failure. Clinical presentation, physical examination findings, and laboratory features are summarized in table 84.3.

Table 84.3 PULMONARY STENOSIS

    The natural history of valvar PS is quite favorable with survival comparable to that of the general population. With mild valvar PS (Doppler peak instantaneous gradient <30 mm Hg by echocardiography), there is little progression of disease, and these patients can be followed without intervention. Based on natural history studies that did not include clearly defined criteria for either intervention or follow-up, intervention remains recommended for individuals with severe PS. In the presence of symptoms, peak instantaneous Doppler gradient >50 mm Hg (less gradient if RV dysfunction is present), and less-than-moderate pulmonary insufficiency, percutaneous balloon valvuloplasty is considered the procedure of choice for repair of valvar PS in the absence of a hypoplastic annulus. Surgical repair using commissurotomy is indicated for more complex lesions, and valve replacement may be necessary if there is significant accompanying pulmonary insufficiency. Patients who have undergone surgical or catheter-based pulmonary valvotomy in childhood have excellent survival, however many will require re-intervention, particularly for sequelae of pulmonary regurgitation, in adulthood.

MODERATE LESIONS

COARCTATION OF THE AORTA

Aortic coarctation is most commonly a discrete narrowing in the aortic isthmus just distal to the left subclavian artery and can be considered a diffuse arteriopathy. A bicommissural aortic valve is present in >50% of subjects with aortic coarctation, and it may be associated with additional left-sided obstructive lesions (Shone’s syndrome) and VSDs. Intracranial aneurysms, typically small and of unclear clinical significance, may be present in approximately 10% of people with aortic coarctation. There is a high prevalence of aortic coarctation in patients with Turner syndrome.

    Hemodynamically, the increased afterload due to obstruction of flow from the left ventricle may be accompanied by significant hypertension in the aorta and branch vessels proximal to the coarctation site and may be associated with systemic ventricular dysfunction, vessel aneurysm formation, and effects of premature atherosclerosis. Distal to the coarctation, there is diminished flow, and collaterals may develop to supplement areas of relative hypoperfusion. Clinical presentation, physical examination findings, and laboratory features are summarized in table 84.4.

Table 84.4 AORTIC COARCTATION

    In normals, the aortic pulse should be transmitted at equal speed and intensity from the left ventricle to the radial and femoral pulses that are approximately equidistant from the left ventricle. In patients with significant aortic coarctation, pulse wave propagation is both slowed and diminished distal to the coarctation, thereby delaying and diminishing femoral pulse relative to radial pulse. Standard practice dictates that all pulses should be checked at least once in the evaluation of all patients with systemic hypertension to rule out significant aortic coarctation.

    Significant coarctation has previously been defined as a peak-to-peak gradient of 20 mm Hg across the stenosis as determined in the catheterization laboratory, although few data support this relatively arbitrary cut point that has been used to signify risk of sequelae. Several factors need to be considered in selecting the most appropriate method for repair including age, anatomy of the transverse and descending aorta, history of prior repair, and institutional expertise. Stent implantation became a treatment option in the early 1990s and may be appropriate in adults and adult-size adolescents. Balloon angioplasty with or without stent implantation is the accepted treatment approach in recurrent coarctation with good acute and intermediate outcomes.

    In a past era of few medical therapies for systemic hypertension or heart failure, untreated patients with aortic coarctation had poor survival with an estimated mortality of 75% by 46 years of age and median age of death of only 31 years. Causes of death were related to uncontrolled hypertension, congestive heart failure, infective endocarditis, aortic rupture or dissection, and cerebral hemorrhage. Today, adult survivors after aortic coarctation intervention remain at risk for increased prevalence of atherosclerotic risks factors, premature coronary and cerebrovascular disease, persistent hypertension, heart failure, aortic aneurysm, and recoarctation. ACHD care guidelines recommend lifelong surveillance for adults after coarctation repair, and therapy of atherosclerotic risks, with monitoring of blood pressure control to help reduce sequelae. Currently adults who have undergone surgical repair have a 20-year survival rate of 84%.

TETRALOGY OF FALLOT

Tetralogy of Fallot (TOF) is the most common cyanotic congenital cardiac defect in adults. This conotruncal anomaly results from anterior deviation of the infundibular septum and is characterized by (1) right ventricular tract outflow obstruction; (2) VSD; (3) overriding aorta; and (4) right ventricular hypertrophy.

    The clinical presentation of unrepaired patients with TOF depends largely on the amount of right ventricular outflow tract obstruction, which is a major determinant of the amount of right-to-left shunting across the VSD. Thus, patients with TOF and minimal obstruction may on occasion have little, if any, cyanosis and can remain unrecognized until later in life. The surgical strategies for TOF repair have evolved over time. Adults who were operated on in the late 1950s and 1960s may have first undergone palliation with a systemic-to-pulmonary artery shunt (examples including central Waterston and Pott’s shunts, and the more controlled classic and modified Blalock-Taussig shunts) to augment pulmonary flow prior to a complete repair. More recently, primary repair has been established that involves a right ventricular outflow tract patch or conduit with removal of infundibular-level obstruction and any additional muscle bundles, and VSD closure. Clinical presentation, physical examination findings, and laboratory features are summarized in table 84.5.

Table 84.5 TETRALOGY OF FALLOT

    For adults with TOF who survive either unrepaired or are status-post palliative shunt only, a relatively well-balanced situation must be present. These patients need to be monitored for progressive right ventricular outflow tract obstruction, right heart failure, cyanosis, paradoxical emboli, and arrhythmias. In the post-repair patient, management is focused on residual lesions, their location, and severity— including pulmonary regurgitation, branch or more distal pulmonary artery stenosis, presence of aortopulmonary collaterals, aortic dilatation, aortic regurgitation, VSD patch leak, recurrent right ventricular outflow tract obstruction, and right ventricular outflow tract aneurysm.

    Despite repair, adults with TOF require lifelong follow-up due to potential for right-sided heart failure, aortic dilatation with resultant aortic insufficiency, left-sided heart dysfunction, and atrial and ventricular arrhythmias. Sudden cardiac death in adults with TOF has been well studied, with identification of several electrical, hemodynamic, and mechanical markers of increased risk.

EBSTEIN ANOMALY

Ebstein anomaly is an abnormality of the tricuspid valve and right ventricular sinus. Failure of delamination of the septal and posterior leaflets of the tricuspid valve results in apical displacement of the tricuspid valve annulus. An associated ASD or patent foramen ovale is found in 80–94% of cases, with less frequent association of concomitant mitral regurgitation, left ventricular myocardial, and right ventricular outflow abnormalities. The hemodynamic consequences of the Ebstein anomaly are right ventricular dysfunction and tricuspid valve regurgitation. The right atrium acts as a passive reservoir for this regurgitant flow and progressively dilates. Clinical presentation, physical examination findings, and laboratory features are summarized in table 84.6. The natural history of this lesion varies from early presentation with profound cyanosis and shock to adult survival, depending on the degree of tricuspid valve involvement, right ventricular dysfunction, degree of shunting across the interatrial septum, and the presence and type of arrhythmias.

Table 84.6 EBSTEIN ANOMALY

    Patients with Ebstein anomaly are at risk for arrhythmias and sudden cardiac death. The dilated right atrium creates a substrate for supraventricular tachyarrhythmias, and accessory pathways are common in these patients with Wolff-Parkinson-White syndrome found in 10–25%. As survival trends improve for these adults, the profile of noted arrhythmias increasingly includes potential for atrial fibrillation and flutter, as well as ventricular tachycardia and fibrillation.

    Medical management consists of congestive heart failure treatment as appropriate. Catheter ablation of accessory pathways or supraventricular arrhythmias should be performed in these patients or at the time of surgical repair. Surgical correction should be considered for patients with decreased exercise tolerance, worsening heart failure symptoms despite medical therapy, intractable arrhythmias, progressive right ventricular dysfunction, and/or cyanosis. Surgical goals include optimization of right ventricular function, elimination of tricuspid regurgitation, and relief from cyanosis. The tricuspid valve may be repaired or replaced in addition to closure of an interatrial communication.

SEVERE LESIONS

TRANSPOSITION OF THE GREAT ARTERIES

Transposition of the great arteries (TGA) is a form of atrioventricular concordance with ventriculoarterial discordance (each great artery arises from the incorrect ventricle). The most common form of TGA is referred to as D (dextro) loop TGA, in which all of the deoxygenated blood returns to the right atrium, right ventricle, and then back to the body through the aorta (Figure 84.3). This creates systemic and pulmonary circulations that run “in parallel” (rather than in series) and is incompatible with life unless there is some type of communication between the two vascular circuits (ASD, VSD, or ductus arteriosus). Immediately after this physiology is recognized, if there is not an adequate mixing lesion, an emergent atrial septostomy or definitive repair may be performed.

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