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.
(See also Overview of Cardiac Valvular Disorders.)
Etiology of Pulmonic Stenosis
Pulmonic stenosis 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)
Carcinoid syndrome (in adults)
Symptoms and Signs of Pulmonic Stenosis
Many children with pulmonic stenosis remain asymptomatic for years and do not develop symptoms until adulthood. Even in adulthood, many patients remain asymptomatic. When symptoms of pulmonic stenosis 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 second intercostal space.
Auscultation
Widened second heart sound (S2) and delayed pulmonic component of S2 (P2)
Harsh crescendo-decrescendo ejection murmur
On auscultation, the first heart sound (S1) is normal and the normal splitting of the S2 is widened because of prolonged pulmonic ejection (P2 is delayed). In RV failure and hypertrophy, the third and fourth heart sounds (S3 and S4) are rarely audible at the left parasternal fourth 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 second (valvular stenosis) or fourth (infundibular stenosis) intercostal space with the diaphragm of the stethoscope when the patient leans forward.
Unlike the aortic stenosis murmur, a pulmonic stenosis 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 of Pulmonic Stenosis
Echocardiography
Diagnosis of pulmonic stenosis is confirmed by Doppler echocardiography, which can characterize the severity as
Mild: Peak gradient < 36 mm Hg or peak velocity < 3 m/second
Moderate: Peak gradient 36 to 64 mm Hg or peak velocity 3 to 4 m/second
Severe: Peak gradient > 64 mm Hg or peak velocity > 4 m/second
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.
Treatment of Pulmonic Stenosis
Sometimes balloon valvuloplasty
Prognosis of pulmonic stenosis without treatment is generally good and improves with appropriate intervention.
Treatment of pulmonic stenosis is balloon valvuloplasty, which is indicated for patients with symptoms and moderate or severe valvular stenosis and for asymptomatic patients with severe stenosis.
Percutaneous valve replacement may be offered at highly selected congenital heart centers, especially for younger patients or those who have had multiple previous procedures, in order to reduce the number of open heart procedures.
When surgical valve replacement is necessary, bioprosthetic valves are preferred due to the high rates of thrombosis of right-sided mechanical heart valves; anticoagulation is temporarily required (see Anticoagulation for patients with a prosthetic cardiac valve).
Key Points
Pulmonic stenosis is usually congenital, but symptoms (eg, syncope, angina, dyspnea) usually do not appear until adulthood.
Heart sounds include increased splitting of the second heart sound and a harsh crescendo-decrescendo ejection murmur heard best at the left parasternal second or fourth intercostal space when the patient leans forward; the murmur grows louder immediately with Valsalva release and with inspiration.
Balloon valvuloplasty is done for symptomatic patients and for asymptomatic patients with normal systolic function and a peak gradient > 40 to 50 mm Hg.
