History
Infundibular pulmonary stenosis (IPS) manifestations depend on the severity of obstruction and presence or absence of associated cardiac anomalies. They may include the following:
-
Most children grow well and are asymptomatic, even when stenosis is moderate or severe.
-
The murmur is discovered on routine auscultation, usually at birth, although cyanosis may lead to discovery of maximum obstruction.
-
Symptoms are rare in infants, with the notable exception of patients with critical stenosis.
-
Subjective complaints tend to increase with age.
-
Dyspnea and fatigue are the most common symptoms.
-
Exertion may provoke syncope or even death.
-
Precordial pain is common, and epigastric pain is often present.
-
Frank right-sided heart failure occasionally occurs in infancy or early childhood.
-
Squatting is extremely rare in children with isolated PS (compared with tetralogy of Fallot)
Physical Examination
Physical examination findings may include the following:
-
Growth and development are usually normal. Frank heart failure is rarely evident.
-
Chest asymmetry occasionally accompanies severe stenosis, but precordial bulge is uncommon.
-
Jugular venous pulse shows larger a waves as the degree of obstruction increases. These presystolic pulsations may be felt during palpation of the liver, even without evidence of cardiac failure.
-
Prominent left parasternal heave occurs if pulmonary stenosis is significant. [4]
-
A systolic thrill is present at the second and third left intercostal space near the sternum. Occasionally, the thrill may disappear with onset of failure.
Auscultation
The first heart sound is normal.
The pulmonic valve component (P-2) of the second heart sound is soft and delayed in moderate-to-severe stenosis. Note the following features:
-
The degree of split is proportionate to the severity of the obstruction; the greater the obstruction, the longer the right ventricle takes to empty and the wider the split.
-
P-2 decreases in intensity in proportion to the pressure in the pulmonary artery. The lower the pressure, the softer the P-2. P-2 may be inaudible with maximal obstruction.
-
In severe stenosis with unchanging cardiac output, the split may be fixed. A loud pansystolic crescendo-decrescendo murmur (ejection type), with its maximal intensity at mid systole or later (indistinguishable from that of isolated pulmonary valve stenosis [PVS]), is heard at the left sternal border and is well-conducted to the precordium, neck, and back.
A third heart sound is audible in the presence of an associated atrial septal defect (ASD) or anomalous pulmonary vein.
A fourth heart sound is heard at the lower left sternal border in severe cases. This fourth heart sound is associated with a large a wave in the right atrium and usually indicates a severe lesion.
Note the absence of the ejection click that characterizes valvar pulmonary stenosis.
A loud, long, systolic crescendo-decrescendo murmur (ejection type), with its maximal intensity at mid systole or later (indistinguishable from that of isolated PVS), is heard at the left sternal border and is well-conducted to the precordium, neck, and back. Note the following features:
-
The murmur, although louder at the second and third left intercostal space, may be heard well at the low left sternal border.
-
The later the peak intensity of the murmur occurs, the greater the obstruction.
-
Although murmur loudness does not necessarily increase with severity, murmurs of less than grade 3/6 usually occur with mild stenosis. With moderate-to-severe stenosis, murmurs are usually systolic and grade 4/6 or louder.
-
The length of the murmur depends on duration of RV systole that, in turn, depends on severity of the stenosis. Thus, mild stenosis is associated with a short murmur, with its peak earlier than mid systole. In moderate stenosis, the murmur ends at or slightly after the aortic component of the second heart sound, which remains audible. With marked-to-severe obstruction, the murmur extends beyond the aortic component, which may be obscured.
Critical stenosis
Infants with critical stenosis present with variable findings, including the following:
-
Heart failure is prominent.
-
A small infant with maximal obstruction may have minimal murmur (sometimes overlooked) and cyanosis.
-
An additional systolic murmur is heard in the lower left parasternal region from the tricuspid regurgitation.
-
Absence of P-2 along with the presence of cardiomegaly and the holosystolic murmur of tricuspid regurgitation highly suggests a critical pulmonary stenosis diagnosis.
-
Infundibular Pulmonary Stenosis. Chest radiograph of a 2-year-old boy with severe pulmonary stenosis (infundibular). Note the mild cardiomegaly, reduced pulmonary vascularity, and absence of poststenotic dilatation of pulmonary artery.
