HEART DEFECTS
Congenital heart defects are the most common type of birth defect. Defects that involve the wall or vessels of the heart include atrial septal defect (ASD), ventricular septal defect (VSD), and patent ductus arteriosus (PDA). In certain situations, guidelines recommend surgery or transcatheter device closure to repair the defect and prevent complications.1
VENTRICULAR SEPTAL DEFECTS (VSD)
A VSD is common in both children and adults second only to bicuspid aortic valves as the most common congenital heart defect. Spontaneous closure occurs most often in muscular defects; it also occurs in 35%-40% of patients with perimembranous defects. Spontaneous closure frequently occurs in children, usually by age 2 years; it is uncommon after age 4.2
Data show that spontaneous closure is decreased in patients who have VSD in addition to patent ductus arteriosus (PDA), likely because PDA further increases left-to-right shunt and leads to more severe hemodynamic effects.3
There are 4 types of VSDs:
- Perimembranous VSDs—the most common, composing 80% of VSDs—are located in the membranous septum, adjacent to the septal leaflet of the tricuspid valve. On the left ventricular (LV) side, the defect is adjacent to the aortic valve.
- Muscular VSDs can be located centrally, at the apex, or at the margin of the septum and right ventricular free wall. Although muscular VSDs account for up to 20% of VSDs in infants, spontaneous closure reduces their incidence in adults.
- Conal or subpulmonary VSDs, found just beneath the pulmonary and aortic valves, occur in about 6% of defects in non-Asian populations and up to 33% in Asian populations. Spontaneous closure is uncommon.
- Inlet VSDs, which occur in the lower right ventricle and adjacent to the tricuspid valve, typically occur in patients with Down syndrome.
A left-to-right shunt resulting from the VSD can result in:
- Increased LV volume load
- Excessive pulmonary blood flow
- Reduced systemic cardiac output
- Elevated pulmonary artery pressures
- Patients with a moderate left-to-right shunt may remain asymptomatic for years. However, historical series have shown that chronic volume overload may ultimately lead to severe complications:
- Congestive heart failure
- Atrial arrhythmias
- Irreversible hypertensive pulmonary vascular disease
- Endarteritis
- In rare cases: ductus aneurysm or acute aortic dissection
Among the contributing factors are:
- A congenital cardiovascular defect in a parent or sibling
- Maternal diabetes
- Maternal alcohol consumption (for muscular VSD)
VSDs are the most common lesion in many chromosomal syndromes, including trisomy 13, trisomy 18, trisomy 21, and other more rare syndromes. However, for more than 95% of patients with VSDs, there is no association with a chromosomal abnormality.2
Defect size as noted below is presented as a percentage of the aortic annulus diameter. A small VSD of ≤ 25% has small left-to-right shunts and no LV volume overload. These VSDs usually have a very good prognosis but the defect can:
- Present as a systolic murmur
- Put the patient at risk for infective endocarditis
- For perimembranous VSDs, present an increased risk for aortic cusp prolapse
A moderate VSD of > 25% but < 75% has moderate LV volume overload, and mild or no PAH. Patients may present with:
- No symptoms of mild congestive heart failure
A large VSD of ≥ 75% has a moderate to large shunt, LV volume overload, and PAH. Infants with a large VSD have symptoms including:
- Dyspnea Tachypnea Perspiration Fatigue while feeding Poor weight gain
An adult with a VSD may present with:
- A systolic murmur previously thought to be an innocent murmur
- Fever and bacteremia from infective endocarditis
- A new diastolic murmur indicating aortic regurgitation due to aortic valve prolapse
- Cyanosis and exercise intolerance due to the progressive development of pulmonary vascular disease
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- Stout KK, Daniels CJ, Aboulhosn JA, et al. 2018 AHA/ACC Guideline for the Management of Adults with Congenital Heart Disease: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Circulation. 2018;000:e000-e000. doi: 10.1161/CIR.0000000000000603
- Ramaswamy P. Ventricular septal defects. Medscape. emedicine.medscape.com/article/892980-overview. Accessed August 28, 2018.
- Xu Y, et al. Factors influencing the spontaneous closure of ventricular septal defect in infants. Int J Clin Exp Pathol. 2015;8(5):5614-5623.