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............................................................................................................................................................................. 4.8 Right ventricular outflow tract obstruction 4.8.1 Introduction and background RVOTO can occur at the sub-infundibular, infundibular, valvular, or supravalvular levels.

• Sub-infundibular stenosis, or DCRV, is commonly associated with a VSD. It is caused by narrowing between prominent and hypertrophied muscle bands or ridges that separate the hypertrophied, high-pressure inlet and apical portions from a lowpressure, non-hypertrophied and non-obstructive infundibular portion of the RV.219 • Infundibular stenosis usually occurs in combination with other lesions, particularly VSD, TOF, and secondary to valvular pulmonary stenosis (PS) (reactive myocardial hypertrophy). At the infundibular level, and to some extent the sub-infundibular level, the obstruction tends to be dynamic, meaning that the orifice narrows during systole. • Valvular PS is usually an isolated lesion. Mainly due to intrinsic wall abnormalities, and independent of haemodynamics, dilation of the PA may occur. Most often, there is a typical dome-shaped pulmonary valve with a narrow central opening but a preserved mobile valve base. A dysplastic pulmonary valve, with poorly mobile cusps and myxomatous thickening, is less common (1520%; even less in untreated adults) and frequently part of Noonan syndrome. In adults, a stenotic pulmonary valve may calcify late in life. • Supravalvular PS, or pulmonary arterial stenosis, is caused by narrowing of the main pulmonary trunk, pulmonary arterial bifurcation, or pulmonary branches. It seldom occurs in isolation, and may occur in WilliamsBeuren syndrome, Noonan syndrome, congenital rubella syndrome, or Alagille syndrome. The stenosis may be located in the main branches or more peripherally; it may be discrete or diffuse (hypoplastic) or there may be frank occlusion, and it may occur as single or multiple stenoses. Stenosis may be secondary to previous placement of a PA band or at a previous shunt site. A diameter narrowing >_50% is usually considered to be significant and would be expected to have a pressure gradient and result in hypertension in the proximal PA.

4.8.2 Clinical presentation and natural history

• Sub-infundibular/infundibular: adult patients with DCRV may be asymptomatic or they may present with dyspnoea, chest discomfort, dizziness, or syncope during exertion. The degree of obstruction is progressive over time.220 • Valvular: patients with mild-to-moderate valvular PS are usually asymptomatic. Mild valvular PS in unoperated adults is usually not progressive.221 Moderate PS can progress at the valvular level (calcification) or at the subvalvular level due to reactive myocardial hypertrophy. Patients with severe stenosis may present with dyspnoea and reduced exercise capacity and have a worse prognosis. • Supravalvular: patients may be asymptomatic or have symptoms of dyspnoea and reduced exercise capacity. They are usually recognized in the context of certain syndromes or in patients referred for suspicion of PH. Peripheral PA stenosis may progress in severity.

Recommendations for aortic surgery in aortopathies

Recommendations Classa Levelb

Marfan syndrome and HTAD Aortic valve repair, using the reimplantation or remodelling with aortic annuloplasty technique, is recommended in young patients with Marfan syndrome or related HTAD with aortic root dilation and tricuspid aortic valves, when performed by experienced surgeons. I C Surgery is indicated in patients with Marfan syndrome who have aortic root disease with a maximal aortic sinus diameter >_50 mm.c I C Surgery should be considered in patients with Marfan syndrome who have aortic root disease with maximal aortic sinus diameter >_45 mmc and additional risk factors.d IIa C Surgery should be considered in patients with a TGFBR1 or TGFBR2 mutation (including LoeysDietz syndrome) who have aortic root disease with maximal aortic sinus diameter >_45mm.c IIa C Bicuspid aortic disease Aortic surgery should be considered if the

ascending aorta is: • >_50 mm in the presence of a bicuspid valve

with additional risk factorse or coarctation. • >_55 mm for all other patients. IIa C Turner syndrome Elective surgery for aneurysms of the aortic root and/or ascending aorta should be considered for women with Turner syndrome who are >16 years of age, have an ascending aortic size index >25 mm/m2, and have associated risk factors for aortic dissection.f IIa C Elective surgery for aneurysms of the aortic root and/or ascending aorta may be considered for women with Turner syndrome who are >16 years of age, have an ascending aortic size index >25 mm/m2, and do not have associated risk factors for aortic dissection.f IIb C

AR = aortic regurgitation; BAV = bicuspid aortic valve; ECG = electrocardiogram; BSA = body surface area; CoA = coarctation of the aorta; HTAD = heritable thoracic aortic disease. aClass of recommendation. bLevel of evidence. cAt the extreme ends of the BSA range, recommended cut-offs may require appropriate adjustment. dFamily history of aortic dissection at a low diameter (or personal history of spontaneous vascular dissection), progressive AR, desire for pregnancy, uncontrolled hypertension, and/or aortic size increase >3 mm/year (on repeated measurements using the same ECG-gated imaging technique measured at the same level of the aorta with side-by-side comparison and confirmed by another technique). eFamily history of dissection at a low diameter, desire for pregnancy, systemic hypertension, and/or size increase >3 mm/year (on repeated measurements using the same ECG-gated imaging technique, measured at the same level of the aorta with side-by-side comparison and confirmed by another technique). fBAV, elongation of the transverse aorta, CoA, and/or hypertension. Downloaded from academic.oup.com/eurheartj/article/42/6/563/5898606 by guest on 07 October 2026