Perimembranous Ventricular Septal Defect Treatment & Management

Small perimembranous ventricular septal defects (VSDs) have a spontaneous closure rate of as high as 50% within the first 2 years of life and often do not require medical or surgical management.

Larger defects may become smaller with time. Medical therapy may be required with large membranous VSDs due to excessive left-to-right shunting and congestive heart failure (CHF). Therapy is directed at alleviating the symptoms of pulmonary overcirculation. Treatment typically includes increased-calorie feedings, diuretics, and, sometimes, an angiotensin-converting enzyme (ACE) inhibitor.

Diuretic therapy with furosemide is used to lessen volume overload. Significant potassium wasting may warrant the addition of spironolactone or potassium supplementation.

The use of afterload reduction to improve systemic-pulmonary flow ratios may be beneficial in selected cases. ACE inhibitors also inhibit the tissue-based renin-angiotensin system, preventing deleterious remodeling. Be aware that ACE inhibitors have a potassium-sparing effect. When these are used, spironolactone or supplemental potassium should be avoided or judiciously used.

Surgical indications

Failure of medical management to alleviate symptoms in the first 6 months of life requires intervention. Growth failure despite optimal medical therapy and maximized calorie intake is the most important evidence of failure of medical therapy. Intervention in VSD is either by surgery or cardiac catheterization. ^[4] Very large left-to-right shunts are usually electively repaired within the first 6 months of age.

Severe CHF requiring hospitalization indicates the need for early intervention for VSD closure. Surgical closure is also required for any size of VSD with the development of aortic valve regurgitation.

Elevated pulmonary arteriolar resistance of more than 12 Wood units/m² that does not decrease with oxygen or selective pulmonary vasodilator therapy may be regarded as inoperable.

Diet and activity

Patients with significant CHF may require caloric supplementation with fortified formula or breast milk.

Patients with small perimembranous VSDs have no activity restrictions. Patients with moderate-to-large perimembranous defects and significant symptomatology limit their own exercise activity levels until the defect is repaired. Patients with repaired VSDs and no residual cardiac sequelae have no activity restrictions.

Transfer

Patients with large or multiple VSDs may be transferred to a tertiary care center for further diagnostic evaluation or surgical intervention.

Consultations

Consultations with the following specialists may be indicated:

• Pediatric cardiologist

• Pediatric cardiothoracic surgeon, if surgery is needed

Surgical repair is the most common intervention currently performed. Surgery is indicated in patients with uncontrolled congestive heart failure symptoms, evidence of increased pulmonary vascular resistance, or the development of aortic valve insufficiency secondary to leaflet prolapse.

Gabriels et al investigated the long-term outcome of 266 patients with perimembranous VSD who were followed in the Belgian Registry on Adult Congenital Heart Disease. Of the 173 patients with isolated perimembranous VSD, 53 (31%) patients underwent VSD closure and 10 of those patients (19%) had a residual shunt. After VSD closure, complications included atrial arrhythmia, pacemaker implantation, and left ventricular outflow tract obstruction. ^[5]

In a retrospective study, Ou-Yang et al assessed the safety and effectiveness of symmetric and asymmetric occluders in 581 patients who underwent perventricular device closure of perimembranous ventricular septal defects without cardiopulmonary bypass under transesophageal echocardiography guidance from May 2011 to April 2016, as well as outpatient electrocardiography and transthoracic echocardiography assessments at 1, 3, 6, and 12 months, and annually thereafter. The success rate of device implantation was 92.6%. The investigators found a lower residual shunt disappearance rate and higher branch block incidence rate for the asymmetric occluders, thereby favoring more proactive conversion to surgical repair immediately when residual shunt is present intraoperatively. ^[6]

Surgical repair of an isolated large ventricular septal defect (VSD) involves closure of the defect with a Gore-Tex patch.

Surgical mortality is now very low (approximately 1%) in neonates and patients older than 6 months with an isolated perimembranous VSD. New surgical approaches using smaller incisions have proven effective in VSD closure. ^{[7, 8]}

Devices are being investigated (not currently FDA approved) for the transcatheter closure of perimembranous ventricular septal defects (VSDs). ^{[9, 10, 11, 12, 13, 14]} VSD closure devices typically have two asymmetrical, opposing discs (one for the right ventricular side and one for the left ventricular side), which are released during catheterization under fluoroscopic and transesophageal echocardiographic guidance to occlude the defect.

These devices can be placed percutaneously in the cardiac catheterization laboratory or in the operating room during a "hybrid procedure." These procedures are slightly more complicated than closure of muscular VSDs because of the asymmetry of the device, the proximity to the aortic valve, and the presence of conduction tissue near the defect.

Hybrid procedures may involve inserting the device through a very small incision in the free wall of the right ventricle.

Ongoing investigational trials are currently being performed to assess indications for and outcomes in VSD closure with these devices.

One report noted effective closure in children using the Amplatzer asymmetrical perimembranous occluder in 35 patients with a median age of 4.5 years. ^{[12, 15]} The defects were 3-8 mm in size, and the size of the occluder varied from 4-12 mm. After 2.5 years, the rate of complete closure was 91%. Two further studies concluded that the procedure is safe, but warrants further study and requires great skill in cases with small infants. ^{[12, 16]}

Complications in the study included residual shunting that required surgical closure of the defect subsequent to the insertion of the device and persistent regurgitation across the tricuspid or aortic valve related to the occluder. ^{[12, 15]} Conduction abnormalities, primarily heart block, related to the procedure occurred in 20% of the patients. The abnormalities were permanent in all but one of these patients. In a different study of 1046 patients with perimembranous VSD who underwent percutaneous closure using a modified double-disk occluder (MDO), postprocedure complete atrioventricular block (cAVB) occurred in only 1.63% (n=17) of patients, of whom 8 received permanent pacemaker implantation. Patients older than 18 years were more likely to develop cAVB. ^[17] The investigators noted that lifelong follow-up with periodic electrocardiography monitoring may be necessary owing to the recurrence of cAVB.

More recent findings in retrospective studies with second-generation Amplatzer vascular occluders for closure of perimembranous VSDs reported similar results regarding the safety and efficacy of these devices. ^{[18, 19]}

Another retrospective study evaluated 51 patients younger than 1 year with VSD and reported that perventricular device closure of VSDs was safe and effective in this age population as compared with conventional surgical repair with cardiopulmonary bypass. ^[20] The infants underwent minimally invasive transthoracic device closure under the guidance of transesophageal echocardiography without cardiopulmonary bypass and had a short rehabilitation period and excellent cosmetic results.

Routine inpatient monitoring of infants and children with small perimembranous ventricular septal defects (VSDs) is not necessary.

Manage patients with large VSDs and no CHF on an outpatient basis but consider early surgical closure. Mild to moderate congestive heart failure (CHF) secondary to large left-to-right shunting caused by a VSD is also managed on an outpatient basis.

Small perimembranous VSDs have a more than 50% spontaneous closure rate. Perform serial follow-up care until the VSD closes.

Manage moderately-sized VSDs on an outpatient basis by monitoring for evidence of a reduction in size or a spontaneous closure. Assess patient growth and increased pulmonary artery pressures, and evaluate the need for elective surgical closure.

For routine perimembranous VSDs, antibiotics for the prevention of bacterial endocarditis are no longer recommended by the American Heart Association. ^[21] A modest risk of endocarditis is still observed; thus, the importance of vigilant oral hygiene should be reinforced. For patients who underwent postsurgical VSD closure utilizing a gortex patch or other material, subacute bacterial endocarditis (SBE) precautions are recommended for 6 months post closure.