RISK FACTORS : FAMILY H/O CONGENITAL HEART DISEASE. ASSOCIATION WITH CHROMOSOMAL ANOMALIES. EXPOSURE TO TERATOGENS DURING GESTATION
Medical therapy:
" The medical treatment of infants with ventricular septal defect (VSD) is directed at the control of congestive heart failure. The goals of therapy are to relieve symptoms, to minimize frequency and severity of respiratory infections, and to facilitate normal growth.
" Restricting the activities of a child with an isolated VSD is rarely necessary.
" Patients with small VSDs do not require treatment because approximately 80% of such lesions heal spontaneously. A VSD that either decreases in size or closes completely during the first year of life presents no problems to the practicing physician.
" Older children with VSDs are seldom symptomatic and require little in the way of medical therapy.
" Medical management includes endocarditis antibiotic prophylaxis for all patients with VSDs.
" Respiratory infections require prompt evaluation and treatment.
" Evaluate children with VSD at least once or twice yearly to detect changes in the clinical picture that suggest the development of pulmonary vascular obliterative changes.
" Patients with VSD and pulmonary vascular obstructive disease who are deemed inoperable because of irreversibly elevated resistance require more intensive support and symptomatic therapy as cyanosis progresses and activity becomes more limited. Improvement in the symptoms associated with the polycythemia of Eisenmenger complex (headache, extreme fatigue, and extreme dyspnea) may be provided by partial exchange transfusion for RBC volume reduction.
Surgical therapy:
" Small and moderate VSDs with normal PVR have a natural tendency to become smaller and eventually close. Surgery is not indicated for these defects.
" For symptomatic patients or patients with larger 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 is 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 PAP is known to be near normal.
" 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 AV valves.
" 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.
o 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.
o In the presence of moderate or severe aortic regurgitation, valvuloplasty is preferred to valve replacement.
o Operation should probably be deferred in asymptomatic patients with a subcristal VSD and an insignificant left-to-right shunt when aortic regurgitation is not severe.
Preoperative details:
" Management of patients with 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 PAPs with small shunts (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 development of fixed obliterative changes in the pulmonary vessels.
" For patients who develop Eisenmenger complex, surgical therapy is ineffective and thus not recommended. These patients are managed medically and may be considered for lung or heart-lung transplantation.
Intraoperative details:
" Pulmonary artery banding as a palliative procedure is occasionally useful in certain high-risk patients such as those with multiple VSDs, VSDs with coarctation of the aorta, or VSDs with straddling and/or overriding of one AV valve. Banding is also sometimes useful in extremely small patients or those with concomitant lung disease. However, for most patients with simple VSD who require operative intervention, primary intracardiac repair is the procedure of choice.
" Operations for intracardiac repair of VSDs are performed through midline sternotomy incision. The procedure aims to obtain a secure and complete closure of the defect without damaging any important structure, particularly the conduction tissue of the heart, which is responsible for maintaining atrioventricular synchrony.
" Most centers use conventional hypothermic cardiopulmonary bypass with cold cardioplegia for older infants and children. 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.
" Depending on their location in the interventricular septum and the presence or absence of associated cardiac anomalies, VSDs are closed through the right atrium, the right ventricle, the left ventricle, or one of the great arteries.
o Closure through the right atrium is chosen to close most isolated VSDs of the perimembranous or inlet muscular types.
o Trabecular muscular defects and infundibular muscular defects are often accessible through the right atrium.
o Defects of the lower part of the muscular trabecular septum, particularly when multiple, are often best approached through a left ventriculotomy.
o Closure through the right ventricle can be used for the perimembranous outlet, infundibular defects, and some trabecular defects.
o Defects of the outlet septum are best approached through the pulmonary artery.
o Subarterial defects are approached through the pulmonary valve.
" Many small defects associated with low PAP are closed by suture; larger VSDs and VSDs with accompanying pulmonary hypertension are closed using a patch. Patches are made of Dacron velour, Teflon, Gore-Tex, or xenograft pericardium.
" 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.
" 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.
Postoperative details:
" Postoperatively, monitoring the left atrial and PAP simplifies management in patients with large defects, preexisting heart failure, and known pulmonary hypertension.
" Precautions are taken to limit the responsiveness of the pulmonary vascular bed, and ventilatory management becomes an important tool. Hyperventilation (low carbon dioxide) and hyperoxia (elevated fraction of inspired oxygen) tend to increase pulmonary blood flow and decrease PVR. The opposite is also true. With persistent, severe pulmonary hypertension, nitric oxide is available in many centers.
" Standard bacterial endocarditis prophylaxis is recommended for patients with repaired VSD with residual defect. For operated VSDs without residual defects, prophylactic antibiotics are indicated for only the first 6 postoperative months.
" Complete heart block is the most significant surgically induced conduction system abnormality, occurring immediately after surgery in fewer than 1% of patients. Late-onset complete heart block is occasionally a problem, especially in the 10-25% of patients whose postoperative ECG findings show complete right bundle branch block with left anterior hemiblock.
Follow-up care: Medical follow-up care in the older age groups consists of periodic evaluation, encouragement of full activity, and education about the use of antibiotic prophylaxis for bacterial endocarditis.
COMPLICATIONS :
COMLICATIONS of ventricular septal defects (VSDs) include the following:
" Growth failure
" 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 RV outflow tract
" Discrete fibrous subaortic stenosis
" Acquired LV outflow tract obstruction
" Aneurysm of the ventricular septum
" Paradoxical emboli
" Sudden death
" Heart block secondary to intracardiac repair
OUTCOME & PROGNOSIS :
" The course is variable depending on the size of the VSD.
" Of all VSDs noted at age 1 month, 80% close spontaneously. Spontaneous closure of VSDs occurs as a function of native defect size, anatomy, and patient age. The highest closure rates are observed in the first year of life and in patients with small defects.
" Studies on the mortality rate associated with the natural history of VSD indicate that 27% of patients die by age 20 years, 53% by age 40 years, and 69% by age 60 years.
" For uncomplicated VSD repair, the operative mortality rate should approach 0%. The overall risk for VSD repair is less than 5%. Mortality and morbidity rates increase with multiple VSDs, pulmonary hypertension, and complex associated anomalies.
" When surgical repair is performed before age 2 years, the long-term outlook is excellent, and patients ultimately have a normal-sized left ventricle and normal ventricular function. The patient who undergoes VSD closure in childhood is usually asymptomatic and leads a normal life.
" The overall 25-year survival rate for all patients managed with medical or surgical therapy is 87%; mortality rates increase with the severity of the VSD.