Infants with unrestrictive ventricular septal defects (VSDs) who (1) have congestive heart failure (CHF) that is refractory to medical management and (2) are not growing should undergo surgery to close the defect, regardless of the patient’s age or size. A VSD is an abnormal opening in the interventricular septum that allows communication between the right and left ventricular cavities. (See the image below.)
VSDs are the most common congenital intracardiac defects of clinical importance. VSDs may vary in size, number, and location within the interventricular septum, and the clinical implications often depend on these factors. VSDs may occur as isolated lesions or in conjunction with other cardiac anomalies.
In 1879, Roger first characterized the clinical presentation of VSD.  VSD had been recognized prior to this date but was less well understood.  In 1897, Eisenmenger reported autopsy findings in a 32-year-old patient with a large VSD and cyanosis. He described the syndrome now referred to as progressive elevation of pulmonary vascular resistance with reversal of intracardiac shunting and cyanosis.
In 1951, at UCLA, Muller performed what current surgeons describe as a pulmonary artery band on a 5-month-old child with a presumed diagnosis of a large VSD. He reduced the size of the main pulmonary artery by removing part of the wall of the main pulmonary artery (MPA) and then placed a polyethylene strip around the stenotic area. Blalock performed 2 similar operations before 1951, but both of those patients died at surgery. In 1952, Muller and Damman reported the short-term success of this operation. 
In 1955, Lillehei and colleagues performed the first successful VSD closure under direct vision using cross-circulation from another human, at the University of Minnesota.  In 1956, Dushane and Kirklin et al performed the first successful closure of VSD using cardiopulmonary bypass at the Mayo Clinic. 
As cardiopulmonary bypass became more widely reproducible in younger children and infants, palliative surgery (to reduce pulmonary hypertension and reduce excessive pulmonary blood flow) was replaced with definitive reparative closure (to eliminate intracardiac shunting).
Complications of VSDs include the following:
Congestive heart failure (left heart failure)
Pulmonary vascular disease as a consequence of left-to-right shunting - The ultimate consequence of pulmonary vascular obstructive disease is irreversible muscular hypertrophy and, ultimately, obliteration of the pulmonary vasculature and pulmonary resistance that equals or exceeds systemic resistance; this condition is known as Eisenmenger syndrome or complex
Severe illness with viral or bacterial pneumonia
Infective endocarditis - Occurs at a rate of 2.4 cases per 1000 patients per year
Aortic regurgitation - An especially common complication in patients with subarterial VSDs
Stenosis in the right ventricular outflow tract
Discrete fibrous subaortic stenosis
Acquired left ventricular outflow tract obstruction
Aneurysm of the ventricular septum
Heart block secondary to intracardiac repair
Impaired left ventricular function in some patients
Increase in weight following VSD closure
The ventricular septum may be divided into 4 components. The inlet septum is smooth walled and lies beneath the tricuspid valve, extending from the septal attachment of the tricuspid valve to the distal attachment of the tricuspid tensor apparatus. The apical trabecular septum is covered with trabecular muscle and lies distally in the septum. The infundibular, or outlet, septum is separated from the trabecular portion. It lies anterior and superior to the septal band and makes up the portion of the outflow tracts. The membranous septum is fibrous only and lies adjacent to the anteroseptal tricuspid commissure on the right side and the right posterior aortic commissure and anterior mitral leaflet on the left side.
Lev and colleagues delineated the anatomy of the conduction system associated with septal defects, which decreased the incidence of iatrogenic atrioventricular (AV) block associated with surgical ventricular septal defect (VSD) closure. 
In 1956, Becu used numbers to describe the location, but that nomenclature has since fallen into disuse.  VSDs are generally classified into 1 of 4 groups depending upon their location in the interventricular septum. The 4 groups are as follows:
Inlet muscular VSD (Becu type III)
Supracristal VSDs make up approximately 5-7% of VSDs in the Western Hemisphere, but they are the most common VSD in some Asian populations, making up 25% of all VSDs in patients in the Eastern Hemisphere. Alternate nomenclature systems refer to this VSD as conal, outlet, subarterial, or infundibular. Supracristal VSDs lie just beneath the pulmonary and aortic valve annuli. Because of the anatomic location and Venturi effect from VSD flow, prolapse of the right coronary cusp of the aortic valve into the defect may result in significant aortic insufficiency. If significant extension into other portions of the septum is absent, the conduction system is distant to this type of defect.
Perimembranous VSDs make up most VSDs that require surgery. In some series, perimembranous VSDs account for 80% of the surgical VSD volume. Perimembranous VSDs lie in the region of the membranous septum (posterior and inferior to type I VSD). Alternate nomenclature systems have termed these VSDs paramembranous, membranous, conoventricular, or infracristal.
In the right ventricle, perimembranous defects lie between the inlet and outlet portions of the septum. In the left ventricle, perimembranous defects lie in the outlet portion beneath the aortic valve commissure between the noncoronary and right coronary cusps. Aortic valve cusp prolapse with or without aortic valve insufficiency is possible. The conduction tissue passes along the posteroinferior margin of the VSD.
Inlet muscular VSDs
Approximately 5% of VSDs are inlet muscular VSDs. These lie posteriorly in the inlet septum, immediately beneath the septal leaflet of the tricuspid valve. Many surgeons separate this type of VSD and consider it a type of AV septal defect or AV canal defect. The AV node and conduction bundles pass along the leftward aspect of the inferior margin of the defect.
Trabecular muscular VSDs
Approximately 5% of VSDs that require surgery are trabecular muscular VSDs. These VSDs lie within the trabecular septum and may be isolated or multiple. Because pectinate muscles cover them, muscular VSDs often have multiple openings on different planes on the right ventricular side, complicating visual definition and repair of the entirety of the defect(s). In early infancy, trabecular muscular VSDs are as common as perimembranous VSDs. Most of these defects undergo spontaneous closure.
Indications for Surgery
As previously stated, infants with unrestrictive ventricular septal defects (VSDs) who (1) have congestive heart failure (CHF) that is refractory to medical management and (2) are not growing should undergo surgical closure, regardless of age or size. Even if the VSD is large, for babies to stop growing in the first 3 months of life is unusual.
Infants with unrestrictive, large VSDs who are growing should be observed for signs that the VSD is becoming pressure restrictive and decreasing. If the VSD remains large and unrestrictive, most infants should undergo surgical closure at age 4-6 months. However, this is somewhat controversial, and although a repair later in the first year of life is acceptable, a progressive risk of pulmonary vascular disease after age 6 months is observed.
Infants with a moderate-sized, pressure-restrictive VSD should undergo repair if their growth is abnormal or if evidence is seen of progressive or persistent left-sided heart enlargement after age 6 months. After infancy, a child with a moderate-sized VSD who develops left-sided heart dilation should undergo surgical closure.
Pulmonary vascular resistance
Most children who undergo surgical VSD closure no longer require cardiac catheterization. Beyond infancy, if a child has a large VSD with no pressure restriction, cardiac catheterization may be helpful. The most important piece of information obtained at catheterization is the degree of elevation in pulmonary vascular resistance (PVR). Typically, children without VSD have a PVR of 2 Wood units (2 resistance units or 2 units), indexed for body surface area. The body size adjustment is in the numerator, not the denominator. If the PVR is greater than 2 units but less than 4 units, pulmonary vascular disease is not present.
Patients with a large VSD and a PVR greater than 4 units but less than 8 units have some degree of PVR. If the PVR drops with administration of supplemental oxygen, surgery should be performed. Most of these children do not have elevated pulmonary artery pressure at rest after surgery. However, they do have an increased risk of elevated pulmonary artery pressure during exercise, suggesting an abnormal pulmonary vascular bed.
If catheterization reveals a PVR greater than 8 units, vasodilator testing is indicated. If the PVR drops to less than 8 units in response to oxygen or inhaled nitric oxide, surgery should be performed. Most of these patients also have normal or mildly elevated pulmonary artery pressure at birth, and most are healthy after surgery. Some children from this group develop progressive pulmonary vascular obstructive disease. These children should be closely monitored for postsurgery pulmonary hypertension. If pulmonary hypertension persists or develops, appropriate pulmonary vasodilator therapy lessens symptoms and prolongs life.
In most cases, if the PVR remains above 8 units, even with vasodilator testing, pulmonary vascular disease is severe and progressive. Surgery does not prolong life or improve health in this group and is therefore not indicated.
Aortic insufficiency and other indications
Other indications for surgical closure include the following:
Progressive aortic insufficiency
Progressive left ventricular enlargement or decreased left ventricular function
Progressive aortic insufficiency occurs in a small minority of patients with perimembranous VSD and more than half of patients with supracristal VSD. Development of aortic insufficiency with prolapse of an aortic valve leaflet also warrants surgery.
Prolapse of an aortic valve leaflet into a perimembranous VSD without aortic insufficiency is a controversial indication. Some cardiologists advocate for surgery and others advocate for no intervention. No definitive data exist to guide the approach to aortic valve prolapse without insufficiency. In patients with supracristal VSD, the likelihood of progressive aortic valve insufficiency is higher, and aortic prolapse warrants surgical repair.
Pulmonary artery banding
Pulmonary artery banding is reserved for patients with unique circumstances. A small infant with multiple trabecular muscular VSDs may have a better result from definitive surgery after he or she has grown. In addition, some VSDs disappear with time and growth. Certain surgeons have advocated pulmonary artery banding for low birth-weight infants. Others have recommended the same approach as that used for term newborns.
Contraindications to Surgery
Small and moderate VSDs with normal PVR have a natural tendency to become smaller and eventually close. Surgery is not indicated for these defects.
Fixed pulmonary vascular obstructive disease resulting in diminution of left-to-right shunting or even right-to-left shunting is an absolute contraindication to ventricular septal defect (VSD) closure. In this situation, the VSD acts as a "pop-off valve," allowing right-to-left flow to bypass the lungs and maintain systemic cardiac output. In this situation, closure of this defect results in right-sided ventricular failure and low cardiac output.
Timing and Types of Surgical Treatment
For symptomatic patients or patients with larger ventricular septal defects (VSDs) or elevated PVR, surgical closure is indicated. However, the timing of surgery varies. The ideal time to intervene is when the likelihood of spontaneous VSD closure is lowest and the risk of irreversible pulmonary vascular disease and ventricular dysfunction will be minimized.
In subarterial VSDs, the risk of irreversible aortic valve damage caused by cusp prolapse leads to earlier intervention. With perimembranous and muscular defects, surgery may be reasonably delayed up to 1 year or more if the infant is thriving and the pulmonary artery pressure is known to be near normal.
Pulmonary artery banding
Multiple VSDs present a different problem. If a large shunt is present and persists longer than 6-8 weeks, pulmonary artery banding and removal after age 2 years with an attempt at septation is reasonable. Banding is also reasonable in VSDs complicated by straddling or overriding of the atrioventricular (AV) valves.
Dilatable main pulmonary artery bands allow for progressive dilation with postponement of surgery. Bilateral dilatable branch pulmonary bands offer palliative benefit, especially in hybrid cases in which pulmonary blood flow may be limited by the bands before the ideal conditions for a stage II procedure exist. Progressive dilation can facilitate postponing surgery or can result in spontaneous constriction of the VSD. The bands can be percutaneously released and can decrease the gradient across the VSD. Bilateral branch pulmonary artery bands can also be used and may increase oxygen saturations. 
Percutaneous transcatheter device occlusion
Another surgical approach is percutaneous transcatheter device occlusion of membranous VSDs. This technique may be associated with further complications, including conduction anomalies and valve dysfunction.
A multicenter study of 430 patients demonstrated successful percutaneous VSD closure in 410 (95%) of cases. Complete heart block occurred in 16 patients (4%), aortic regurgitation in 14 patients (2 required surgery), and tricuspid regurgitation in 27 patients (none required surgery). The authors recommended careful monitoring of rhythm and AV conduction, especially with perimembranous VSDs. 
A complete heart block rate of 22% was found in a retrospective review of 20 pediatric patients who underwent perimembranous VSD device closure of large perimembranous VSDs with the Amplatzer Membranous VSD Occluder. 
Minimally invasive transthoracic device closure of perimembranous VSDs has been performed with an inferior sternotomy. A single per–right ventricular U-like suture is established, and a delivery system is introduced, with a 16-gauge trocar, guidewire, sheath, and loading sheath being employed under transesophageal echocardiographic guidance without cardiopulmonary bypass. Long-term results have not been established for this procedure. [11, 12]
Several centers have investigated transcatheter closure of VSD using a clamshell double umbrella device. The device is inserted via a venous catheter through a long sheath; ultimately, the device is placed across the ventricular septum from the RV side. The devices do not appear to be useful for perimembranous defects, which are readily approachable by the surgeon, but they can be successfully used to close defects of the trabecular septum, well distanced from the semilunar and AV valves.
Treatment of double-outlet right ventricle with subpulmonary VSD
Procedures have been proposed for patients who have double-outlet right ventricle (DORV) with subpulmonary VSD or Taussig-Bing anomaly [13, 14] . Intraventricular repair with rerouting has fewer complications and conserves the indigenous aortic valve. The disadvantage of this operation is that obstruction in the aorta or right ventricle results. Correction with arterial switch operation and closure of the VSD has emerged as the criterion standard because it is applicable in most patients.
Treatment of VSD and transposition of the great arteries
Treatment of patients with VSD and transposition of the great arteries (TGA) is controversial. The Rastelli procedure was once the first choice in many cases. Difficult anatomic morphologies, such as restrictive VSD or straddling AV valves, may complicate this operation. Left ventricular dysfunction and arrhythmia may also lead to mortality.
Nikaidoh described a new surgical approach that consisted of an aortic translocation without coronary transfer with biventricular outflow tract reconstruction. Rather than harvesting the aortic root, together with the coronary arteries, which could lead to coronary ischemia, Nikaidoh proposed a complete transfer of the aortic root. The procedure avoids any postoperative ischemic events.
Treatment of VSD-associated aortic arch obstruction
Treatment of patients with aortic arch obstruction associated with VSD is also achieved with good results. Aortic arch reconstruction is accomplished by direct anastomosis using continuous, absorbable sutures. Mortality and morbidity are primarily related to noncardiac causes rather than to the procedure itself. Residual VSD shunting requiring reoperation is not a major consideration.
Treatment of VSD with aortic regurgitation
Treatment of patients with VSD and aortic regurgitation is controversial. In patients with a large, hemodynamically significant left-to-right shunt, repair of the VSD is indicated, but aortic regurgitation is repaired only if at least moderate aortic regurgitation exists.
If a supracristal VSD without aortic regurgitation is identified at cardiac catheterization in early childhood, a sensible argument for prophylactic closure of the VSD can be put forth to prevent the potential complication of aortic valve incompetence. In the presence of moderate or severe aortic regurgitation, valvuloplasty is preferred to valve replacement.
All imaging studies should be reviewed preoperatively to clearly visualize the defect(s) and to assess for the presence of other intracardiac anomalies. These studies delineate the anatomic substrate and allow appropriate planning for the operation.
All attempts should be made to control CHF and improve the overall condition of the child prior to surgery.
Management of patients with ventricular septal defects (VSDs) depends upon the size of the VSD, the age and symptoms of the patient, the PVR, and the presence of other associated cardiac defects.
Small and moderate VSDs with normal PVR have a natural tendency to become smaller and eventually close. Patients with such defects can be observed because surgery is not indicated.
When clinical findings suggest a moderate shunt but no pulmonary hypertension, elective hemodynamic evaluation should be undertaken before age 3 years. Of prime importance in the hemodynamic evaluation is determination of pressure and blood flow in the pulmonary artery. Surgical treatment is not recommended for children who have normal pulmonary artery pressure with a small shunt (pulmonary-systemic flow ratios of < 1.5-2:1).
Identifying patients who may develop irreversible pulmonary vascular obstructive disease (Eisenmenger complex) is crucial. If early primary closure is not recommended, perform recatheterization before age 18 months and make a second determination of PVR in these patients to decide whether surgical intervention is obligatory to prevent the development of fixed obliterative changes in the pulmonary vessels.
For patients who develop Eisenmenger complex, surgical therapy is ineffective and is therefore not recommended. These patients are managed medically and may be considered for lung or heart-lung transplantation.
Ventricular septal defects (VSDs) are closed through a median sternotomy approach. Cardiopulmonary bypass using dual caval cannulation (inferior vena cava [IVC] and superior vena cava [SVC]) and cardioplegic diastolic arrest provides a bloodless, motionless field for intracardiac closure. Alternatively, the technique of profound hypothermia and low-flow bypass, or even total circulatory arrest, is used by some centers for VSD repair in infants younger than 1 year.
Most VSDs may be closed working through an incision in the right atrium (transatrial approach). The surgeon inspects and repairs the VSD looking through the right atrium, across the tricuspid valve, and into the right ventricle. To visualize defects of the inlet septum, detachment of the septal leaflet of the tricuspid valve may be required.
Conal VSDs may be approached through an incision in the main pulmonary artery, working across the pulmonary valve (transpulmonary approach). Conal VSDs with associated aortic valve insufficiency may be approached through an incision in the ascending aorta, allowing VSD closure and aortic valve repair (transaortic approach). Muscular VSDs may be approached through the ventricular apex (transventricular approach).
Most surgeons close the defect using a synthetic patch (Dacron or polytetrafluoroethylene [PTFE]) sewn to the rightward aspect of the VSD with a running, nonabsorbable, monofilament suture. Take care to avoid placing deep sutures in the area of conduction tissue, to prevent postoperative heart block. Primary closure of VSDs through direct suturing of the defect without using a patch is of historic interest only. Double patch repair through a single ventriculotomy has been reported. 
In some centers, the use of intraoperative transesophageal echocardiography has provided accurate assessment of patch integrity and revealed the presence of additional muscular defects after termination of cardiopulmonary bypass. The image below depicts a patch repair.
When aortic valve leaflet prolapse with valvular incompetence accompanies conal or perimembranous defects, aortic valve repair (valvuloplasty) is performed. The elongated free edge of the distorted leaflet is shortened, and the leaflet is resuspended against the aortic wall with sutures. Repair of the aortic valve is almost always possible, and aortic valve replacement should be reserved only for extremely damaged valves.
Pulmonary artery pressure is often directly measured to assess for postclosure pulmonary hypertension. If pulmonary artery pressure is significantly elevated (>50% of systemic arterial pressure), a pressure monitoring line may be left in the pulmonary artery for postoperative monitoring, if desired.
Associated lesions, such as patent ductus arteriosus or atrial septal defect, should be concomitantly repaired during VSD closure.
Most children rapidly recover from ventricular septal defect (VSD) closure. Extubation usually occurs in the ICU in the hours following surgery. Children requiring postoperative inotropic support, pressor support, or both are weaned within 24 hours postsurgery. Postoperative diuretic therapy is generally needed to return intravascular volume to normal levels.
Postoperative monitoring of the left atrial and pulmonary artery pressure simplifies management in patients with large defects, preexisting heart failure, and known pulmonary hypertension.
For the small proportion of children with hemodynamically significant pulmonary hypertension (pulmonary artery pressure >50-75% of systemic arterial pressure), continued sedation with mechanical ventilation (to maintain normal arterial oxygen and carbon dioxide tensions) and pulmonary vasodilators (eg, nitric oxide, sildenafil) may be used until pulmonary vasculature relaxes within several days after surgery.
Most children are transferred from the intensive care unit (ICU) on the first or second postoperative day. Within 48 hours, mediastinal drainage tubes are removed. Many patients are ready for discharge within 4-7 days of surgery.
Residual VSDs after surgery occur in 5-25% of cases. There are increased risks associated with redo surgery. An alternative option is percutaneous VSD closure with the Amplatzer VSD device, This is an option when echocardiographic signs of left ventricle volume overload (Q(p)/Q(s) >/= 1.5) are present. Transcatheter VSD closure is a safe and effective option and avoids a redo surgery and bypass. 
Patients who have undergone VSD repair should be observed routinely to ensure a return to normal function. Depending on the severity of the preoperative condition and postoperative complications encountered, follow-up care is tailored to the relief of residual CHF and the promotion of normal growth and development. As symptoms of heart failure subside, the patient may be weaned off digitalis and diuretic therapy.
Potential complications of surgical ventricular septal defect (VSD) closure include infection, postoperative bleeding requiring reexploration, valve injury (tricuspid, pulmonary, or aortic), pulmonary hypertension with poor cardiac output, AV heart block, residual VSD with continued left-to-right shunting, and death.
Permanent AV heart block occurs in 1% or fewer of children undergoing VSD closure. Care must be taken to correctly identify the position of the defect, since this determines the location of conduction tissue and directs the repair to avoid conduction injury. Transient AV block is treated expectantly with temporary cardiac pacing. When AV conduction does not return (in < 1% of patients in the best centers), a permanent pacemaker is needed.
Residual left-to-right shunt from incomplete VSD closure may result from insufficient intraoperative exposure or suture disruption with patch dehiscence. Significant residual shunting is most commonly observed in muscular defects (particularly multiple defects) in which trabeculations decrease visualization of the full extent of the VSD(s). Residual shunting with Qp:Qs greater than 1.5:1 occurs in 2% of patients or fewer and should prompt reoperation. 
The mortality rate associated with surgical VSD closure has decreased dramatically with improvements in perfusion, myocardial protection, and postoperative care. The overall surgical mortality rate for patients with isolated VSD is less than 1%, and the mortality rate for low-risk candidates is miniscule. Risk factors for mortality include severe associated noncardiac anomalies, multiple VSDs, and major associated cardiac anomalies.
American Heart Association guidelines consider a repaired VSD a negligible risk lesion for bacterial endocarditis (no greater than the general population). Therefore, prophylactic antibiotics are recommended for patients for no more than 6 months after their surgical VSD repair. 
Long-term results of ventricular septal defect (VSD) repair are favorable. In the absence of pulmonary vascular disease, infants who undergo VSD repair within the first 1-2 years of life are considered cured and demonstrate improved physical development (growth and weight gain), as well as normal long-term ventricular function. Most long-term survivors are asymptomatic and lead normal lives. Vasoactive-inotropic score (VIS) after surgery may be useful as a predictor of outcomes. One prospective study of 70 infants undergoing cardiothoracic surgery found that a higher VIS is associated with increased length of ventilation, and prolonged ICU and total hospital stay. 
Exercise tolerance may be diminished. If congestive heart failure and cardiomegaly are well established and repair has been undertaken late in life, postoperative symptoms, including exercise intolerance, are more common. Premature late death is rare (< 2.5%) in patients with low preoperative pulmonary vascular resistance. Patients with preoperative pulmonary vascular disease may develop severe, life-threatening pulmonary hypertension.