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4.8.3 Diagnostic work-up See section 3.3 for general principles. Clinical findings include a harsh systolic murmur across the obstruction and wide splitting of the second heart sound. In peripheral PS, the systolic murmur is typically heard over the lung fields. • Echocardiography: size, shape, and function of the RV can be assessed and the exact position/level of the RVOTO can be visualized, as well as pulmonary valve, main PA, and proximal PA branches. For quantification of RV sizes, volumes, and EF, CMR is a more robust and more reliable technique. Doppler ultrasound is used for measurements of flow velocities across an obstruction to assess severity. Correlation between flow velocities and pressure gradients is only good in the case of discrete stenosis, e.g. isolated valvular PS. In the presence of normal RV function and normal transvalvular flow, RVOTO is considered mild when the peak gradient across the obstruction is <36 mmHg, moderate if 3664 mmHg, and severe when the gradient is >64 mmHg. If the narrowing is elongated, or if more than one stenosis is present in series (e.g. subvalvular and valvular), application of the Bernoulli equation will lead to an overestimation of the pressure gradient. Doppler flow velocity of TR then gives a more reliable estimation of RV pressures  and with that, severity of the RVOTO  than the flow velocity across the RVOTO. Gradients only represent severity of an obstruction if a good systolic RV function is present. In a low-flow, low-gradient situation, it is very difficult to assess severity of a RVOTO.222 • CMR and CCT frequently provide additional important information identifying the level(s) of obstruction, including at the subinfundibular (DCRV), conduit, or branch PA levels, and assessment of RV volumes, pulmonary annulus, outflow tract and artery dimensions, and differential pulmonary blood flow. CMR and CCT are the methods of choice for visualization of pulmonary dilation and peripheral PS. • Cardiac catheterization may be required to confirm the extent, severity, and level of obstruction (e.g. DCRV).

4.8.4 Surgical/catheter interventional treatment Catheter-based balloon valvotomy is recommended for patients with non-dysplastic valvular PS and with peripheral PS (often with stent implantation).223 Surgery is recommended for patients with sub-infundibular or infundibular PS and hypoplastic pulmonary annulus, with dysplastic pulmonary valves, and for patients with associated lesions which need a surgical approach, such as severe pulmonary regurgitation (PR) or severe TR. Peripheral PS can rarely be addressed with surgery. Both surgical and catheter interventions should only be performed in centres specialized in CHD. In patients with subvalvular, valvular, and supravalvular PS, a markedly dilated pulmonary trunk may be present. Rupture is extremely rare in these low-pressure, highly elastic vessels and these pulmonary aneurysms generally do not require intervention.224 For RVPA conduit, see section 4.14. Indications for intervention are summarized in the Recommendations for intervention in right ventricular outflow tract obstruction table and in Figure 7. 4.8.5 Follow-up recommendations Patients with RVOTO need lifelong follow-up with regular echocardiographic imaging. The frequency of follow-up depends on the severity of the lesion, but most patients will need a yearly visit, including evaluation in specialized ACHD centres except for patients with mild or well repaired valvular stenosis. After surgical or catheter intervention, a residual PR may need reintervention later in life for patients who become symptomatic or when progressive RV dilatation or dysfunction occurs (see section 4.10). Patients with mild valvular or mild residual PS need to be seen only once in 5 years.

4.8.6 Additional considerations

• Exercise/sports: no restrictions for patients with mild (residual) PS. Patients with moderate PS should avoid high-intensity and

Recommendations for intervention in right ventricular outflow tract obstruction

Recommendations Classa Levelb

In valvular PS, balloon valvuloplasty is the intervention of choice, if anatomically suitable. I C Provided that no valve replacement is required, RVOTO intervention at any level is recommended regardless of symptoms when the stenosis is severe (Doppler peak gradient is >64 mmHgc). I C If surgical valve replacement is the only option, it is indicated in patients with severe stenosis who are symptomatic.d I C If surgical valve replacement is the only optiond in patients with severe stenosis who are asymptomatic, it is indicated in the presence of one or more of the following. • Objective decrease in exercise capacity. • Decreasing RV function and/or progression of TR to at least moderate. • RVSP >80 mmHg. • RL shunting via an ASD or VSD. I C Intervention in patients with a Doppler peak gradient <64 mmHg should be considered in the presence of one or more of the following. • Symptoms related to PS. • Decreasing RV function and/or progressive TR to at least moderate. • RL shunting via an ASD or VSD. IIa C Peripheral PS, regardless of symptoms, should be considered for catheter interventional treatment if >50% diameter narrowing, and RVSP >50 mmHg, and/or related reduced lung perfusion is present. IIa C

ASD = atrial septal defect; PS = pulmonary stenosis; RL = right-to-left; RV = right ventricle/ventricular; RVOTO = right ventricular outflow tract obstruction; RVSP = right ventricular systolic pressure; TR = tricuspid regurgitation; VSD = ventricular septal defect. aClass of recommendation. bLevel of evidence. cRVSP estimated from TR velocity should confirm severe PS. dThe threshold for intervention is higher when a valve substitute is required because long-term risks, such as endocarditis and re-intervention for prosthetic valve failure, need to be taken into account. Downloaded from academic.oup.com/eurheartj/article/42/6/563/5898606 by guest on 07 October 2026