EXPLANATION


Isolated ventricular septal defect (VSD) is the most common form of congenital heart disease (CHD). VSDs allow the shunting of blood between the systemic and pulmonary circulations, increasing the volume load of the left heart. The magnitude and direction of the intracardiac shunt depends on the pressure gradient between the ventricular chambers and the resistance to flow, which is largely determined by the size of the shunt. Over time, patients with untreated VSD suffer from decreased exercise tolerance, heart failure, and pulmonary arterial hypertension (PAH). The onset and progression of symptoms are associated with the degree of the intracardiac shunt. Patients with moderate and large VSDs exhibit symptoms of heart failure during early infancy. Volume and pressure overload from intracardiac shunting leads to the development of left atrial and ventricular dilatation with eventual heart failure. Without treatment, the effective systemic cardiac output progressively decreases as a larger proportion of the left ventricular output is circulated through the intracardiac shunt to the pulmonary circulation (Qp) rather than the systemic circulation (Qs), resulting in a Qp:Qs of greater than one. Over time, this increase in pulmonary blood flow may also result in pulmonary vascular disease and pulmonary arterial hypertension (PAH). With long standing, unrestricted left to right intracardiac shunt, pulmonary arterial pressure may exceed systemic arterial pressure, leading to the shunt reversal and Eisenmenger syndrome.


A long-term follow-up study by Corone et al. of 790 patients with unrepaired VSDs provides interesting insights into the natural history of unrepaired defects. The study showed that the overall survival rate of patients at 25 years of age with small, moderate, and large unrepaired VSDs was 96%, 86%, and 61%, respectively. Patients with Eisenmenger syndrome had the lowest survival rate of 42%. Small restrictive VSDs are usually associated with small intracardiac shunts, a Qp:Qs < 1.5, and near normal pulmonary vascular resistance. Patients with moderately restrictive VSDs and a Qp:Qs ≥ 1.5:1 and < 2:1 often have mild to moderate PAH. Patients with large, nonrestrictive defects are at high risk for early development of PAH and Eisenmenger syndrome. A 2023 Danish study by Eckerstrom et al. examining survival of patients with repaired and unrepaired VSDs demonstrated that the causes of death were cardiac-related in approximately a third of patients with unrepaired defects and approximately two thirds of patients with surgically repaired VSDs. Interestingly, although repaired VSDs have a higher survival than unrepaired patients, their survival is still lower compared with the general population, after excluding operative mortality. The reasons for these differences in mortality are unclear but the authors speculate that the delayed effects of surgery such as intraoperative myocardial injury, residual intraventricular conduction defects, and ventricular dyssynchrony may be contributing factors. Approximately 6% of patients with isolated VSDs develop aortic valve prolapse, which can lead to aortic valve insufficiency (AI). The most affected cusp of the aortic valve is the right cusp. The Venturi effect is hypothesized to be a predominant factor in the development of AI associated with VSD.


The 2018 American Heart Association (AHA) guidelines for management of adults with congenital heart disease recommend conservative, watchful management of small restrictive VSDs in the absence of aortic valve prolapse or more than trivial aortic valve insufficiency. Once aortic valve prolapse develops, there is a likelihood of progression and development of AI. Since the likelihood of spontaneous closure of a perimembranous VSD is low, closure may prevent further progression of AI and later need for aortic valve replacement. At the time of the VSD closure, the aortic valve can be inspected and repaired if indicated.


Patients with unrepaired VSD have an increased risk of infective endocarditis, usually affecting the tricuspid and pulmonary valves. Those patients with restrictive VSDs and a history of infective endocarditis warrant VSD closure per AHA guidelines.


In summary, the patient in the stem has a restrictive VSD with a high-pressure gradient across the defect (>90 mmHg), lack of left heart enlargement, and lack of cardiac symptoms. Both aortic cusp prolapse and mild AI were newly demonstrated on a yearly echocardiogram, which fall into the AHA criteria for VSD closure.


REFERENCES


Tweddell JS, Pelech AN, Frommelt PC. Ventricular septal defect and aortic valve regurgitation: pathophysiology and indications for surgery. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2006:147-52. doi: 10.1053/j.pcsu.2006.02.020.


Eckerström F, Nyboe C, Maagaard M, Redington A, Hjortdal VE. Survival of patients with congenital ventricular septal defect. Eur Heart J. 2023 Jan 1;44(1):54-61. doi: 10.1093/eurheartj/ehac618.


Stout KK, Daniels CJ, Aboulhosn JA, et al. 2018 AHA/ACC Guideline for the Management of Adults with Congenital Heart Disease: Executive Summary: A report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines [published correction appears in J Am Coll Cardiol. 2019 May 14;73(18):2361]. J Am Coll Cardiol. 2019;73(12):1494-1563. doi: 10.1016/j.jacc.2018.08.1028


Bukhari SM, Desai M, Zurakowski D, et al. Fate of aortic regurgitation after isolated repair of ventricular septal defect with concomitant aortic regurgitation in children. JTCVS Open. 2023; 13:271-277. Published 2023 Jan 28. doi: 10.1016/j.xjon.2022.12.015


Corone P, Doyon F, Gaudeau S et al. Natural history of ventricular septal defect. A study involving 790 cases. Circulation. 1977; 55:908-15.