A 31-year-old man is referred for evaluation of severe pulmonary regurgitation. He has a history of tetralogy of Fallot with AV canal defect, initially repaired at the age of 9 months, with transannular patch enlargement of the right ventricular outflow tract (RVOT) and main pulmonary artery. He subsequently developed severe RVOT obstruction and underwent a total of 4 redo surgical patch repairs of the RVOT by the age of 8 years. At the age of 29, he was medically treated for Staphylococcus endocarditis of the pulmonary valve. Now at the age of 31, routine surveillance transthoracic ­echocardiography demonstrates severe pulmonary regurgitation (Figures 25-1 and 25-2), moderate pulmonary stenosis (­Figure 25-2), and a moderately enlarged but normally functioning right ventricle in the setting of decreasing exercise tolerance. He is referred for consideration of transcatheter pulmonary valve implantation.

It is estimated that nearly 1 million adults in the United States are living with congenital heart disease (CHD).¹ Although many of these patients have undergone corrective or palliative ­surgical ­procedures early in life, they often have the sequelae of their disease and require repeat cardiac procedures over their lifetime. Lesions causing RVOT dysfunction are an important subset of CHD and include primary pulmonary valve dysfunction, supravalvular stenosis, and subvalvular stenosis mainly due to infundibular or subinfundibular stenosis. RVOT obstruction is a hallmark of ­tetralogy of Fallot (TOF), the most common form of cyanotic heart disease after the age of 1 year, with an incidence of approximately 10% of all CHD.² Treatment for RVOT obstruction and TOF has advanced dramatically over the past 7 decades. Prior to the first ­palliative systemic-pulmonary shunt operation by Blalock and Tausig in 1945, TOF was nearly universally fatal. In the mid 1950s, the first successful intracardiac repair of TOF took place at the University of Minnesota, reducing the mortality rate from 50% to <2%.³ Complete intracardiac repair is currently accomplished by (1) widening of the RVOT with preservation of the native pulmonic valve or replacing the RVOT using a surgical valved conduit with a homograft or bioprosthetic pulmonary valve, and (2) ­placing a patch over the ventricular septal defect to eliminate shunting at the ventricular level and redirect the aortic override. With modern operative repair, most patients with TOF live well into adulthood, but the majority will continue to experience residual hemodynamic and arrhythmic sequelae. Over time, the right ventricle (RV)–­pulmonary artery (PA) conduit fails, resulting in severe pulmonary insufficiency and RV volume overload or significant pulmonary stenosis and RV pressure overload or, often, as a mixture of both lesions. As the condition progresses, RV failure ensues and patients often develop arrhythmias or symptomatic heart failure. Traditionally, RVOT conduit failure has been treated with surgical pulmonary valve replacement (PVR) using a bioprosthesis. The procedural mortality is generally low (<1%) but is not negligible. The early results of valve replacement are excellent, and PVR often results in improvement of functional and hemodynamic parameters and a possible decrease in arrhythmic burden. However, surgically implanted bioprostheses degrade over time and typically require replacement within 10 years.³ Transcatheter pulmonary valve implantation was first reported in 2000⁴ and has emerged as a novel technology to treat RVOT dysfunction and reduce the total ­number of open-heart surgeries patients may require over their lifetime.

HISTORY

Patients with history of TOF should be seen and examined by a provider with experience in managing complex CHD. Initial history should focus on symptoms of RVOT dysfunction and RV failure. In particular, the provider should assess the patient’s functional capacity and symptoms to determine whether there have been any decrements over time. Specific topics and symptoms to address should include the following:

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  Exercise capacity

  
  
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  Symptoms with exertion, including dyspnea or chest pain

  
  
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  Rest symptoms

  
  
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  Palpitations

  
  
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  Presyncope/syncope

PHYSICAL EXAM

Physical examination findings may demonstrate signs of pulmonary valve/conduit dysfunction, RV failure, or volume overload, including the following:

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  Crescendo-decrescendo systolic murmur of pulmonary stenosis

  
  
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  High-pitched diastolic murmur of pulmonary regurgitation

  
  
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  RV heave

  
  
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  Elevated jugular venous pressure +/– hepatojugular reflux

  
  
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  Ascites

  
  
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  Lower extremity edema

IMAGING STUDIES

Additional workup should include the following cardiac testing, as appropriate:

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  Electrocardiogram (ECG): A right bundle branch block is common among patients with TOF and prior repair. ­Attention should be paid to evidence of new atrial or ventricular arrhythmias.

  
  
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  Transthoracic echocardiogram (TTE): A complete 2-­dimensional and Doppler echocardiographic assessment should be conducted as a first-line assessment. ­Particular ­attention should be given to assessment of the conduit/­pulmonary valve function, degree of pulmonary regurgitation, degree of pulmonary stenosis, evidence of distal PA branch stenosis, RV size and function, and RV filling pressures. Color Doppler images obtained in the short axis at the base best demonstrate severe pulmonary regurgitation (see Figure 25-1). ­Continuous-wave color Doppler across the ­pulmonary valve reveals severe pulmonary insufficiency and moderate pulmonary stenosis (see Figure 25-2). Frequently, ­tricuspid regurgitation is the result of RV volume or pressure overload (Figure 25-3). Severe RV and right atrial enlargement can often be seen in the 4-chamber view (Figure 25-4).

  
  
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  Cardiac magnetic resonance imaging (MRI) with gadolinium enhancement: Cardiac MRI can be very useful to demonstrate the degree of conduit/valvular regurgitation, quantitate chamber sizes and RV function, and provide measurements for the RVOT and PA diameters. Cardiac MRI can be used to both follow the patient and assess the need and timing of valve replacement and can serve as an important preprocedural planning tool. Representative MRI views demonstrating enlarged RV and atrial ­chambers are shown in Figure 25-5, A-C.

  
  
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  Cardiopulmonary exercise testing (CPET): CPET can be a useful adjunct to determine a patient’s exercise tolerance and to compare a quantitative measure of exercise ability over time.

  
  
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  Cardiac catheterization: Cardiac catheterization is generally reserved for patients undergoing planned catheter-based or ­surgical interventions.