Pulmonary valve stenosis is one of the most common types of congenital heart disease and is predominantly asymptomatic throughout childhood and adulthood. In the case of severe stenosis, the effort of the right ventricle is increased due to reduced blood flow into the pulmonary trunk, causing fatigue and dyspnea. The anomaly is visible with echocardiography and the diagnosis is often incidental.
Pulmonary valve stenosis is responsible for approximately 1-5% of all congenital heart diseases (CHDs)  , and appears either as an isolated defect or as a constitutive feature of Noonan syndrome, an autosomal dominant genetic disease characterised by hypertrophic cardiomyopathy, atrial septal defect (ASD) and stenosis of the pulmonary valve  . The clinical presentation is usually asymptomatic, as stenosis causes minimal obstruction of the pulmonary outflow tract in the majority of patients throughout childhood and adulthood  . However, significant obstruction and consequent hypertrophy of the right ventricle can result in volume overload and the development of fatigue, dyspnea, and syncope   . Pregnancy is one of the conditions that exerts a higher load on the right ventricle and is associated with a risk of atrial arrhythmias with many women being diagnosed with pulmonary valve stenosis during pregnancy  . On the other hand, individuals suffering from Noonan syndrome exhibit numerous congenital abnormalities in addition to CHD, most prominent being short stature, feeding difficulties, failure to thrive, cryptorchidism (either unilateral or bilateral), and a delayed onset of puberty .
The diagnosis of a pulmonary valve stenosis can be made by performing a thorough clinical examination, with an emphasis on cardiac auscultation. Common findings are widening of the second heart sound (S2), the presence of a fourth heart sound (S4), a harsh mid-systolic ejection murmur (also known as crescendo-decrescendo) heard at the 2nd left parasternal intercostal space that may be accompanied by a thrill, as well as increased jugular venous pressure   . Patient history is also an integral part of the workup, as information regarding the onset and course of symptoms are highly useful for further evaluation. Electrocardiography (ECG) is usually the first method used in assessment of cardiac disease, but the cornerstone in diagnosing pulmonary valve stenosis is cardiac ultrasonography and Doppler echocardiography, which directly determines the severity of obstruction by measuring the peak gradient flow (< 36 mmHg is considered as mild obstruction, 36-64 mmHg as moderate and > 64 mmHg as severe)   . Where available and when necessary, cardiac magnetic resonance (CMR) imaging is recommended in order to obtain a better view of the right ventricle and measure its size and function, while cardiac catheterization is indicated when inconclusive results are obtained, or when both supravalvular and subvalvular obstruction is concomitantly present  . Plain radiography usually reveals a normal heart shadow, but a reduced visibility of the pulmonary vasculature is often seen in severe stenosis .