Definition and Overview
A ventricular septal defect (VSD) is the most common congenital heart disease, occurring in 2 per 1000 live births. It is a hole in the ventricular septum, which separates the left and right ventricles. A VSD may be an isolated defect or it may be associated with more complex lesions, such as tetralogy of Fallot and atrioventricular canal defects. In most patients, a VSD spontaneously closes. However, some patients will require ventricular septal defect closure surgery to alleviate the symptoms and prevent the development of irreversible heart failure.
VSDs may also develop in adult patients and are usually caused by a traumatic or an ischemic (heart attack) etiology. These VSDs must be closed surgically.
Who Should Undergo and Expected Results
A ventricular septal defect is a left-to-right shunt, which means that oxygenated blood coming from the left ventricle is pumped to the right side and re-circulated to the pulmonary bed. This causes an increase in pulmonary flow, which results in increased workload for both ventricles, as well as an increased risk of recurrent infections of the respiratory tract.
Patients with VSDs typically present with symptoms of congestive heart failure, such as difficulty of breathing and failure to thrive. A harsh murmur is heard upon auscultation, and further examination may reveal the enlargement of the left ventricle and left atrium. Approximately 30% of patients with ventricular septal defects develop failure symptoms within the first year of life, necessitating ventricular septal defect closure.
Persistent shunting across the VSD also results in changes in the pulmonary vasculature. Through time, this can lead to pulmonary hypertension, a serious complication of an unrepaired VSD. This condition requires surgical intervention before changes become irreversible.
There are several kinds of VSD, depending on the location of the defect on the septum. The perimembranous kind is the most common. Inlet type and outlet type VSDs are not likely to spontaneously close, and should be repaired once diagnosed. Aortic regurgitation or insufficiency can accompany VSDs, especially the outlet type, due to prolapse of the aortic valve into the defect. Surgery is likewise indicated in VSD patients with progressive aortic insufficiency.
The closure of an isolated VSD is generally associated with good outcomes. The mortality rate is very low, approaching 0% in most institutions, even in extremely small infants. Good candidates who undergo the procedure within the first two years of life are generally able to achieve full functionality, and life expectancy is normal or near normal.
How is the Procedure Performed?
Ventricular septal defect closure is performed under cardiopulmonary bypass. The majority of isolated VSDs are approached via an incision in the right atrium. The tricuspid valve, located between the right atrium and the right ventricle, is retracted to access the ventricular septum. A patch, which may be made of polytetrafluoroethylene (PTFE or Gore-Tex), Dacron or pericardium, is fashioned to the size of the defect. The patch is then sutured to the ventricular septum and the tricuspid annulus. Caution should be exercised when suturing the patch, making sure that vital structures, such as the conduction system and the aortic valve, are not injured or affected. If there are other associated conditions, such as a patent ductus arteriosus or aortic insufficiency, they are also addressed during the same procedure. Other kinds of VSDs (outlet type) and associated defects may have to be approached through additional incisions.
Patients are typically extubated within the first 24 hours after surgery. Temporary pacing wires may be inserted during the procedure and are useful in cases of postoperative arrhythmias.
Possible Risks and Complications
Patients undergoing VSD closure are at risk of developing complications associated with the use of cardiopulmonary bypass. These include bleeding, kidney failure and pneumonia, among others.
Aside from these, there are also complications associated with the procedure itself. Injury to vital structures near the defect, such as the tricuspid valve and aortic valve, may occur during the placement of sutures.
Since the conduction system of the heart travels through the ventricular septum, there is a risk for the development of rhythm abnormalities. Right bundle branch blocks occur commonly but are usually tolerated well by the patient. Complete heart block occurs in approximately 1-3% of patients and this may necessitate the insertion of a permanent pacemaker.
Very young patients subjected to VSD closure are at risk for residual VSDs. This usually occurs because of suture dehiscence through the friable cardiac muscle in small infants. In most patients, these can be observed and will eventually close spontaneously. However, if the leak is large and causes hemodynamic problems, reoperation should be done.
In older patients, pulmonary hypertension is a dreaded complication after VSD closure. Sedation, hyperventilation, and the administration of nitric oxide are useful techniques in the management of postoperative pulmonary hypertensive crisis. These patients usually have decreased exercise tolerance and are at risk of premature death in the long-term.
Muller WH, Damman JF. The treatment of certain congenital malformations of the heart by the creation of pulmonic stenosis to reduce pulmonary hypertension and excessive pulmonary blood flow; a preliminary report. Surg Gynecol Obstet. 1952 Aug. 95(2):213-9.
Quansheng X, Silin P, Zhongyun Z, Youbao R, Shengde L, Qian C, et al. Minimally invasive perventricular device closure of an isolated perimembranous ventricular septal defect with a newly designed delivery system: preliminary experience. J Thorac Cardiovasc Surg. 2009 Mar. 137(3):556-9.