Chapter 83 Ventricular Septal Defect and Repair
PATHOPHYSIOLOGY
A ventricular septal defect (VSD) is a communication or abnormal opening between the right and left ventricles of the heart. VSDs are classified according to location in the ventricular septum as either membranous or muscular. The size of the communication varies widely. Many small, muscular VSDs close spontaneously. The defect is frequently associated with other cardiac defects such as transposition of the great arteries, pulmonary stenosis, atrial septal defect, and coarctation of the aorta. The altered physiology can be described as follows:
1. Pressure is higher in the left ventricle, and thus oxygenated blood shunts from the left ventricle to the right ventricle.
2. Increased blood volume is pumped into the lungs, which eventually may become congested with blood. Over time, this may lead to increased pulmonary vascular resistance.
3. If the pulmonary resistance is high, right ventricular pressure may increase, causing a reversal of the shunt. The unoxygenated blood then flows from the right ventricle to the left, which produces cyanosis (Eisenmenger’s syndrome).
INCIDENCE
1. VSD is the most common congenital heart defect, occurring at a rate of 2 per 1000 live births and accounting for 20% of all congenital heart defects.
2. VSD is also the most common congenital heart defect in children with chromosomal abnormalities such as Down syndrome.
4. Congenital heart defects are more common in the offspring of those who had a VSD.
CLINICAL MANIFESTATIONS
1. Loud systolic murmur generally heard best at left lower sternal border; the size of the defect does not correlate with intensity of the murmur, since louder murmurs may be associated with smaller defects.
2. Thrill may be palpable at left lower sternal border.
3. Signs and symptoms vary with size of the defect and pressure differences between the right and left ventricle.
COMPLICATIONS
1. Cardiac: CHF, development of aortic insufficiency or pulmonary stenosis, progressive pulmonary vascular disease, damage to ventricular conduction system
Postoperative Complications
1. Cardiac: aortic insufficiency, tricuspid insufficiency, electrocardiogram (ECG) changes such as right bundle branch block, arrhythmias including heart block, ventricular dysfunction with potential for low cardiac output (especially if pulmonary hypertension and/or ventriculotomy), residual VSD
3. Growth and development: neurodevelopmental sequelae of cardiopulmonary bypass
LABORATORY AND DIAGNOSTIC TESTS
Refer to Appendix D for normal values and ranges of laboratory and diagnostic tests.
1. Chest radiograph—varying degrees of cardiomegaly, with increased pulmonary vascular markings
2. ECG—normal with a small VSD; may have left ventricular hypertrophy (LVH) with larger defects
3. Echocardiogram—to identify size and location of defect, identify associated defects, and estimate the magnitude of the left to right shunt
4. Cardiac catheterization—may not be required unless there are other associated defects or concerns regarding elevated pulmonary vascular resistance
5. Preoperative laboratory data
Medical and Surgical Management
Management strategies vary according to the child’s symptoms. Digoxin, diuretics, and afterload-reducing agents are prescribed for children with CHF. For children with associated growth delay, calorically dense formula (greater than 20 kcal/ounce) may be prescribed to maximize growth, and oral feedings may be supplemented with nasogastric tube feedings. No exercise restriction is necessary unless the child has Eisenmenger’s syndrome.
1. Cardiac glycosides—improve myocardial contractility, modulate the autonomic nervous system, and decrease elevated ventricular filling pressures (e.g., digoxin)
2. Diuretics—decrease circulatory congestion (e.g., furosemide)
3. Angiotensin-converting enzyme (ACE) inhibitors—reduce afterload (e.g., captopril)
Ventricular Septal Defect Repair
Early surgical repair (in the first 3 months of life) is preferable if the defect is large, particularly if there is CHF and growth failure that does not improve with maximal medical management. Because many VSDs resolve spontaneously or decrease in size, asymptomatic infants and infants whose symptoms can be adequately managed medically are followed clinically. The size of the defect and magnitude of the left-to-right shunt are evaluated at around 6 to 12 months of age. Significant left-to-right shunts are repaired in that time frame. Those with small, insignificant left-to-right shunts may not require repair. Pulmonary artery banding is rarely performed in lieu of complete repair unless there are additional lesions or complications that make complete repair difficult.
Repair is accomplished through a median sternotomy, and cardiopulmonary bypass is required. Hypothermia is used for some infants. For many defects, a right atrial incision allows the surgeon to repair the defect by working through the tricuspid valve. Otherwise, a right or left ventriculotomy is necessary. Generally, a Dacron or pericardial patch is placed over the lesion, although direct suturing may be used if the defect is minimal. Surgery should produce a hemodynamically normal heart, although any damage caused by pulmonary hypertension is irreversible.
NURSING DIAGNOSES
NURSING INTERVENTIONS
Preoperative Care
Postoperative Care
1. Monitor child’s postoperative status per institutional policy.
2. Monitor and maintain child’s respiratory status.
4. Monitor child’s hydration status.
5. Maintain skin temperature at 36.0° to 36.5° C (96.8° to 97.7° F) and rectal temperature at 37° C (98.6° F).
6. Provide pain medications as needed (see Appendix I).
7. Provide opportunities for child to express feelings through age-appropriate means (see the relevant section in Appendix F).
8. Encourage parental presence and appropriate involvement with care.
9. Perform wound care according to institutional policy.
10. Monitor for signs and symptoms of infection.
11. Provide education and emotional support to parents (see the Supportive Care section in Appendix F).
12. Monitor for complications (see the Complications section in this chapter).
Discharge Planning and Home Care
1. Instruct parents on home care management.
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