Pulmonic stenosis (PS) is narrowing of the pulmonary outflow tract causing obstruction of blood flow from the right ventricle to the pulmonary artery during systole. Most cases are congenital; many remain asymptomatic until adulthood. Signs include a crescendo-decrescendo ejection murmur. Diagnosis is by echocardiography. Symptomatic patients and those with large gradients require balloon valvuloplasty.
PS is most often congenital and affects predominantly children; stenosis may be valvular or just below the valve in the outflow tract (infundibular). It commonly is a component of tetralogy of Fallot. Less common causes are Noonan syndrome (a familial syndrome similar to Turner syndrome but with no chromosomal defect) and carcinoid syndrome in adults.
Symptoms and Signs
Many children remain asymptomatic for years and do not present to a physician until adulthood. Even then many patients remain asymptomatic. When symptoms develop, they resemble those of aortic stenosis (syncope, angina, dyspnea). Visible and palpable signs reflect the effects of right ventricular (RV) hypertrophy and include a prominent jugular venous a wave (due to forceful atrial contraction against a hypertrophied RV), an RV precordial lift or heave, and a left parasternal systolic thrill at the 2nd intercostal space.
On auscultation, the 1st heart sound (S1) is normal and the normal splitting of the 2nd heart sound (S2) is widened because of prolonged pulmonic ejection (P2, the pulmonic component of S2, is delayed). In RV failure and hypertrophy, the 3rd and 4th heart sounds (S3 and S4) are rarely audible at the left parasternal 4th intercostal space. A click in congenital PS is thought to result from abnormal ventricular wall tension. The click occurs early in systole (very near S1) and is not affected by hemodynamic changes. A harsh crescendo-decrescendo ejection murmur is audible and is heard best at the left parasternal 2nd (valvular stenosis) or 4th (infundibular stenosis) intercostal space with the diaphragm of the stethoscope when the patient leans forward. Unlike the aortic stenosis murmur, a PS murmur does not radiate, and the crescendo component lengthens as stenosis progresses. The murmur grows louder immediately with Valsalva release and with inspiration; the patient may need to be standing for this effect to be heard.
Diagnosis is confirmed by Doppler echocardiography, which can characterize the stenosis as mild (< 36 mm Hg peak gradient), moderate (36 to 64 mm Hg), or severe (> 64 mm Hg). ECG may be normal or show RV hypertrophy or right bundle branch block. Right heart catheterization is indicated only when 2 levels of obstruction are suspected (valvular and infundibular), when clinical and echocardiographic findings differ, or before intervention is done.
Prognosis without treatment is generally good and improves with appropriate intervention. Treatment is balloon valvuloplasty, indicated for symptomatic patients and asymptomatic patients with normal systolic function and a peak gradient > 40 to 50 mm Hg.
Last full review/revision November 2012 by Guy P. Armstrong
Content last modified September 2013