VSD

Most common form of CHD (15-20%) in peds

• 4 types: perimembranous (70%), muscular, inlet and outlet
• Small lesions are asymptomatic with normal growth
• Larger lesions present with CHF and FTT at 2-3 mos of life
• Early systolic or holosystolic murmur at LLSB; diastolic rumble present with large lesions

Pathophysiology

• Left to right shunting across VSD
• Increased pulmonary blood flow
• Increased pulmonary venous return to the left heart
• Left sided volume overload
• Large, uncorrected shunts result in Eisenmenger’s syndrome

EKG findings

• Small VSD: normal
• Moderate VSD: LVH +/-LAE
• Large VSD: CVH +/-LAE
• Eisenmenger’s: RVH

CXR

• Cardiomegaly
• Increased pulmonary vascular markings

Management

• Spontaneous closure in 30-40% of perimembranousand muscular VSD’s
• Medical management of CHF and FTT
• Surgical correction - while repair of a ventricular septal defect is indicated beyond 12 months of age, it is usually not due to the congestive failure symptoms. Chronic progressive left ventricular enlargement, the development of aortic sinus prolapse into the ventricular defect, or the development of subaortic turbulence with a subaortic ridge all may be indications for the late repair of a ventricular septal defect.
• Babies at risk for Eisenmenger syndrome should have surgery before sx occur
• SBE prophylaxis may be d/c’d 6 mos after surgery unless there is residual shunt

CHLA Board Review 2005
Park MK. Pediatric Cardiology for Practictioners, 3rded. St. Louis,
 Mosby, 1996.

Discussion from Prep Exam Question

The ages at which congestive heart failure typically develops vary with the causes of heart failure.

Congestive heart failure due to a large ventricular septal defect might better be termed the "pulmonary vascular overcirculation syndrome." As pulmonary vascular resistance falls in the first months of life, a significantly higher portion of left ventricular output is shunted through the ventricular defect to the lungs where it returns to the left ventricle. According to Starling's law of the heart, increased preload is associated with increased systolic ejection performance and enhanced stroke volume. Indeed, the left ventricle systolic performance often appears excellent on echocardiographic evaluation when these infants are experiencing classic signs and symptoms of congestive heart failure. Even in the presence of diminished left ventricular performance, many of the hallmark signs of heart failure are caused by the secondary neurohumoral milieu of congestive failure. Examples include increased activation of the renin-  angiotensin system, increased aldosterone levels, and increased circulating norepinephrine. These changes are found in infants who have large left-to-right shunts and enhanced ventricular performance (but with "steal" of the systemic output to the pulmonary circuit) as well as in the rare children who have systemic ventricular pump failure. Most infants who have large ventricular defects exhibit tachypnea, tachycardia, gallop rhythm, sweating with feedings, diminished volumes of feedings, hepatomegaly, and failure to thrive at about the second to third month of life. At this time, the pulmonary vascular resistance has fallen sufficiently to allow for a large shunt through the ventricular defect. It is rare for heart failure to occur in the newborn nursery. Neonatal severe myocardial dysfunction from myocarditis or cardiomyopathy may present at this time, but more frequently it presents as hydrops fetalis from intrauterine congestive heart failure. Ventricular defects do not present with congestive heart failure in the first days of life.

One of the congenital obstructive left heart lesions (click for link) should be suspected in an infant who presents with congestive failure outside of the newborn nursery but within the first month of life. Such lesions include the hypoplastic left heart syndrome, critical neonatal aortic coarctation, and critical aortic valve stenosis. When the ductus arteriosus closes, the right ventricular contribution to the systemic blood flow is lost. Shock and metabolic acidosis quickly follow the development of more typical heart failure signs such as tachypnea and poor feeding.

A moderate-sized ventricular defect may have enough pulmonary overcirculation to result in failure to thrive in the second half of the first year of life (age 6-12 mos). However, the development of signs of congestive heart failure would be expected earlier in an infant who has a large and unrestricted defect, typically from 2 to 4 months of life. The systolic murmur of left-to-right shunting across a large ventricular defect may be present in the first weeks of life. However, because of elevated pulmonary vascular resistance, this finding may be subtle or occasionally absent.

When surgical repair of a ventricular septal defect is indicated beyond 12 months of age, it is usually not due to the congestive failure symptoms. Chronic progressive left ventricular enlargement, the development of aortic sinus prolapse into the ventricular defect, or the development of subaortic turbulence with a subaortic ridge all may be indications for the late repair of a ventricular septal defect. Generally, the affected child has not exhibited classic signs or symptoms of congestive heart failure because the defect is small and is associated with less pulmonary blood flow. Occasionally an infant who has a very large and unrestricted ventricular defect will not have any signs of congestive heart failure in the first 6 months of life because of persistent elevation of the pulmonary vascular resistance, which prevents the occurrence of a large shunt. These babies are at risk for Eisenmenger syndrome with irreversible pulmonary vascular changes and should undergo cardiac surgery before symptoms occur.

References:
Driscoll DJ. Left-to-right shunt lesions. Pediatr Clin North Am.
1999;46:355-368
O'Laughlin MP. Congestive heart failure in children. Pediatr Clin North
Am. 1999;46:263-273