Right Heart Anomalies

Natural History and Clinical Presentation

Progression of mild pulmonic stenosis is unusual after early childhood. The Second Natural History Study of Congenital Heart Defects demonstrated that survival was comparable to that for the general population, regardless of medical versus surgical management strategy, and most patients were asymptomatic. Those with a gradient between 25 and 49 mmHg had a 20% chance of needing an intervention, and most of those with gradients of 50 mmHg or more had progressive stenosis that required intervention.

Severe valvular pulmonic stenosis can manifest with dyspnea on exertion, fatigue, chest pain, palpitations, and syncope. Exertional chest discomfort can be attributed to relative RV ischemia or coexistent coronary atherosclerosis. Compression of the left coronary artery by an aneurysmal pulmonary artery in pulmonic valve stenosis has been reported. Patients may be cyanotic and may have clubbed fingers due to right-to-left shunting at the atrial level.

Results of the physical examination of an adult with pulmonic valve stenosis depend on the severity of the stenosis and any associated lesions. In mild pulmonic stenosis, the jugular venous waveforms are normal, and the precordium is quiet. There is a systolic ejection murmur heard in the pulmonary position that increases with inspiration and usually ends in mid-systole. There may be a pulmonic ejection click that decreases with inspiration.

In severe pulmonic stenosis, the jugular venous pressure may be elevated with a prominent a wave. There may be an RV lift and a loud, harsh ejection murmur with associated thrill that radiates to the back. The degree of second heart sound (S2) splitting is proportional to the degree of stenosis; it may be widely split and fixed. The P2 (pulmonic) component may be reduced or absent with severe stenosis, which can make S2 splitting difficult to appreciate. A right-sided S4 gallop may be auscultated.

Echocardiography for Pulmonic Valve Stenosis

Echocardiography is considered the mainstay of imaging for the assessment of pulmonic valve stenosis. The goals of the echocardiographic evaluation of pulmonic valve stenosis are summarized in Table 43.1 .

The key views for assessing the pulmonic valve are the parasternal short-axis view at the base and the parasternal long-axis RVOT view. The valve leaflets are thickened, with restricted systolic motion of the leaflet tips producing a domed appearance ( Fig. 43.1 ). A dysplastic pulmonic valve is thickened with rudimentary, immobile leaflet tissue associated with a hypoplastic annulus and often with supravalvular pulmonary artery narrowing. The high right parasternal view can image the pulmonic valve en face and provide greater detail on morphology, but it is challenging to acquire in adults.

Pulsed-wave and continuous-wave Doppler imaging are used to evaluate the degree of pulmonic stenosis and define the level of obstruction. In addition to the parasternal short-axis view at the base focused on the pulmonic valve and branch pulmonary arteries, a modified apical view with the transducer placed more medially or a subcostal view with anterior angulation can provide an another approach for assessment of gradients.

Physiologic conditions that alter flow across the pulmonic valve affect the accuracy of gradient estimation by the modified Bernoulli equation, which is most accurate when there is isolated, discrete valve stenosis. For example, if there is severe RV systolic dysfunction with RV failure, the RV cannot generate sufficient pressure to overcome significant stenosis, yielding a peak instantaneous gradient that underestimates the true severity of the stenosis. Similarly, left-to-right flow across an atrial septal defect (ASD) or concomitant pulmonic regurgitation increases flow across the pulmonic valve, thereby increasing the transpulmonic gradient and overestimating the severity of pulmonic valve stenosis. Long-segment stenosis and serial obstructions (i.e., associated subvalvular and/or supravalvular pulmonic stenosis) are other conditions in which Doppler-derived gradients are less reliable.

According to the 2014 American Heart Association and American College of Cardiology (AHA/ACC) guidelines for the management of patients with valvular heart disease and the AHA/ACC 2018 guidelines for the management of adults with CHD, the definition of severe pulmonic valve stenosis is a maximum velocity greater than 4 m/s or a peak instantaneous gradient greater than 64 mmHg ( Table 43.2 ). Echocardiography provides excellent anatomic characterization for diagnosis and for estimates of RV pressure and assessment of RV size and function.

There are mixed data on the accuracy of peak instantaneous gradients derived by echocardiography compared with invasive gradients measured by cardiac catheterization for assessment of pulmonic stenosis. Some studies have demonstrated excellent correlation with peak-to-peak gradients, ^, whereas others have determined that peak instantaneous gradients overestimate peak-to-peak gradients but are comparable with catheter-derived maximal instantaneous gradients. ^, Mean Doppler gradients have the best correlation with peak-to-peak gradients in isolated and complex pulmonic valve stenosis.

In our experience, peak instantaneous gradients obtained by echocardiography overestimate peak-to-peak gradients in the catheterization laboratory and may be exaggerated by effects of sedation. Other echocardiographic methods can indirectly assess the degree of pulmonic stenosis. Tricuspid regurgitation peak velocity, or v, can be used to measure RV systolic pressure (as opposed to pulmonary artery systolic pressure) by using the modified Bernoulli equation 4 v ² and adding RA pressure estimates. The latter is estimated by assessing IVC size and inspiratory collapse. Although the exact gradient across the pulmonic valve is not calculated, the pressure load to the RV relative to the left ventricular (LV) systolic pressure assessed by blood pressure cuff measurement can be compared. Qualitative assessment of septal position and degree of RV hypertrophy can provide additional information on relative pulmonic stenosis severity. Correlation between the Doppler gradient derived by echocardiography and clinical findings is recommended.

Indications for Intervention and Assessment After Intervention

Indications for intervention in pulmonic valve stenosis are summarized in Table 43.3 . Successful percutaneous balloon valvuloplasty was initially reported in 1982, and it is the treatment of choice for classic domed pulmonic valve stenosis ( Fig. 43.2 ). The mechanism for relief of stenosis is commissural splitting, and outcomes are typically excellent. ^, Although outcomes are not optimal compared with those for classic domed pulmonic valve stenosis, balloon valvuloplasty may provide some degree of relief for dysplastic pulmonic valves and is a reasonable first-line option.

A large, multicenter registry of 533 patients followed for a median of 33 months (range, 1 month to 8.7 years) after balloon valvuloplasty showed that 23% had suboptimal results, defined as a residual gradient of 36 mmHg or more or repeat balloon valvuloplasty or surgical valvotomy. Predictors of suboptimal outcome included earlier study year of intervention, higher residual postprocedural gradient, and valvular anatomy. In 2012, long-term outcomes were reported for 139 patients with a median follow-up of 6 years (range, 0–21 years) and showed that reintervention was required in only 9.4% of patients, mostly for restenosis. In the same study, 79 patients who had undergone surgical valvotomy were identified; after a median follow-up of 22.5 years (range, 0–45 years), 20.3% required reintervention, mostly for pulmonic regurgitation. Other studies showed a significant incidence of pulmonic regurgitation after surgical valvotomy, necessitating repeat surgical intervention (e.g., pulmonic valve replacement) later in life. Balloon valvuloplasty was supported as the treatment of choice in patients with anatomically suitable substrates.

The severity of residual obstruction and location and severity of pulmonic regurgitation should be documented during echocardiographic evaluation of patients after percutaneous balloon valvuloplasty or surgical valvotomy. Worsening of infundibular obstruction after relief of pulmonic valve stenosis is a well-documented phenomenon of surgical valvotomy and balloon valvuloplasty, but it improves over time with regression of RV hypertrophy. ^,

Pulmonic regurgitation is not uncommon, especially after surgical intervention in cases of pulmonic valve stenosis. Indications for valve replacement for severe regurgitation after pulmonic valvotomy are not well established. Data suggest that despite the comparable extent of RV remodeling in response to chronic pulmonic regurgitation, reverse remodeling may be different, and guidelines used to determine the timing for pulmonic valve replacement in TOF should not be extrapolated to patients with pulmonic valve stenosis. ^, Pulmonary valve replacement may be reasonable in the asymptomatic patient with moderate or greater pulmonic regurgitation if there is evidence of progressive RV dilation and/or dysfunction.