History
Murmur
Most patients with small muscular ventricular septal defects (VSDs) are asymptomatic and come to medical attention due to the discovery of a systolic murmur. Most murmurs have a delayed presentation in the newborn period, occurring in the first few days to weeks following birth.
At birth, pulmonary vascular resistance (PVR) is high, which maintains an elevated right ventricular pressure equal to the left ventricular pressure. As the PVR falls, the developing pressure gradient from the left ventricle to the right ventricle allows high-velocity left-to-right shunting across the muscular VSD, producing the typical holosystolic murmur.
Progression of symptoms
Patients with an isolated, large muscular VSD are typically asymptomatic in the immediate newborn period. As PVR falls, the degree of left-to-right shunting is proportional to the size of the defect and the relative degree of PVR. The larger the VSD and the lower the PVR, the greater is the degree of left-to-right shunting.
Typically, infants with large VSDs present with signs and symptoms of congestive heart failure (CHF) at age 6-8 weeks or later as PVR continues to fall and the degree of left-to-right shunting increases. CHF signs include inadequate weight gain and growth, along with recurrent lower respiratory tract infections in patients with a large VSD without evidence of CHF but with elevated pulmonary artery pressure (>50% systemic pressure) or or a pulmonary artery–to–systemic flow ratio greater than 2:1.
Signs and symptoms of CHF also include poor feeding, tachypnea, tachycardia, sweating (especially after feeding), and lethargy.
Chromosomal anomalies
VSD is the most common congenital heart lesion (20-30%) in infants with chromosomal anomalies or syndromes. Defects may be discovered in the first days of life due to additional diagnostic evaluation to exclude multiple congenital defects.
Physical Examination
Typical physical examination findings are influenced to a significant degree by the size of the ventricular septal defect (VSD) and the degree of left-to-right shunting.
Small VSD
Symptoms of a small VSD (defined as a VSD with a dimension less than half the size of the aortic annulus diameter) include the following:
-
Vital signs and weight gain are normal
-
The precordium is quiet, with a normal apical impulse
-
The first heart sound is normal
-
The second heart sound is typically narrowly split; the pulmonary component may be accentuated
-
A third heart sound is generally not present
-
A palpable thrill may be observed at the middle to lower left sternal border
-
A grade III-VI/VI holosystolic murmur, which widely radiates throughout the precordium, is present along the left sternal border
The intensity of the murmur is inversely proportional to the size of the defect, the left ventricle–to–right ventricle pressure gradient, and the degree of left-to-right shunting. In general, smaller defects produce the loudest murmur.
Systolic murmurs are usually holosystolic but may occasionally be crescendo or crescendo-decrescendo. No diastolic murmur is typically present.
Large VSD
The symptoms of a large VSD (defined as a defect size equal to the diameter of the aortic annulus) are as follows:
-
Poor growth and poor weight gain are common
-
Signs and symptoms of congestive heart failure (CHF) may be present, including tachypnea, tachycardia, sweating, and pallor
-
Hyperdynamic precordium, with or without a precordial bulge secondary to underlying cardiomegaly
-
Abnormal apical impulse with or without right ventricular tap is present; a thrill is uncommon with large VSDs
-
A normal first heart sound and a narrowly split second heart sound with a loud pulmonary component are evident
-
A prominent third heart sound is typically present at the apex, producing a gallop rhythm
-
A II-III/VI holosystolic murmur is maximal at the left sternal border, with wide precordial radiation
-
A diastolic flow rumble may be present at the cardiac apex; this diastolic murmur is caused by a significant left-to-right shunt (at least a 2:1 left-to-right shunt), with excessive flow across a normal-sized mitral annulus
