Ventricular Septal Defect

According to the Professional Guide to Diseases, In ventricular septal defect (VSD), the most common congenital heart disorder, an opening in the septum between the ven­tricles allows blood to flow between the left and right ventricles. This disease ac­counts for up to 30% of all congenital heart defects. The prognosis is good for de­fects that close spontaneously or are cor­rectable surgically but poor for untreated defects, which are sometimes fatal by age one, usually from secondary complications.

Causes and incidence

In infants with VSD, the ventricular septum fails to close completely by the eighth week of gestation, as it would normally. VSD occurs in some infants with fetal al­cohol syndrome, but a causal relationship hasn't been established. Although most children with congenital heart defects are otherwise normal, in some, VSD coexists with additional birth defects, especially Down syndrome and other autosomal tri­somies, renal anomalies, and such cardiac defects as patent ductus arteriosus and coarctation of the aorta. VSDs are located in the membranous or muscular portion of the ventricular septum and vary in size. Some defects close spontaneously; in other defects, the entire septum is absent. VSD isn't readily apparent at birth, be­cause right and left ventricular pressures are about equal, so blood doesn't shunt through the defect. As the pulmonary vasculature gradually relaxes, 4 to 8 weeks af­ter birth, right ventricular pressure de­creases, allowing blood to shift from the left to the right ventricle. Less than 1% of infants are born with VSD. In 80% to 90% of infants who are born with this disorder, the hole is small and will usually close spontaneously. In the remaining 10% to 20% of infants, sur­gery is needed to close the hole.

Complications

■ Right arterial and ventricular hyper­ trophy

■ Heart failure

■ Pulmonary hypertension

Signs and symptoms

Features of VSD vary with the de­fect's size, the shifting effect on the pulmonary vasculature, and the infant's age. In a small VSD, shunting is minimal, and pulmonary artery pressure and heart size remain normal. Such defects may eventual­ly close spontaneously without ever caus­ing symptoms.

Initially, large VSD shunts cause left atri­ al and left ventricular hypertrophy. Later, an uncorrected VSD will cause right ven­tricular hypertrophy due to increasing pul­monary vascular resistance. Eventually, biventricular heart failure and cyanosis (from reversal of shunt direction) occur. Resulting cardiac hypertrophy may make the anterior chest wall prominent. A large VSD increases the risk of pneumonia.

Infants with large VSDs are thin and small and gain weight slowly. They may de­velop heart failure with dusky skin; liver, heart, and spleen enlargement because of systemic venous congestion; diaphoresis; feeding difficulties; rapid, grunting respirations; and increased heart rate. They may also develop severe pulmonary hypertension. Fixed pulmonary hypertension may occur much later in life with right-to-left shunt (Eisenmenger's syndrome), causing cyanosis and clubbing of the nail beds. The typical murmur associated with a VSD is blowing or rumbling and varies in frequency.

TREATMENT

Based on The Professional Guide to Diseases, for mild ventricular septal defect (VSD), no treatment is needed, al­though the infant should be closely fol­lowed to make sure that the hole closes properly as he grows. Large defects usually require early surgical correction before heart failure and irreversible pulmonary vascular disease develop. For small defects, surgery consists of simple suture closure. In peoples with heart failure, digoxin and diuretics may be prescribed to control symptoms. In people who develop increased pulmonary resistance and irreversible pulmonary vas­cular changes that produce a reversible right-to-left shunt (Eisenmenger's syn­drome), a heart-lung transplant may be re­quired.

If the child has other defects and will benefit from delaying surgery allow post­ponement of surgery. A rare complication of VSD repair is complete heart block from interference with the bundle during surgery. Although the parents of an infant with VSD often suspect something is wrong with their child before diagnosis, they need psychological support to help them accept the reality of a serious cardiac disorder. Instruct parents to watch for signs of heart failure, such as poor feeding, sweat­ing, and heavy breathing. If the child is receiving digoxin or other medications, tell the parents how to give it and how to recognize adverse effects. Caution them to keep medications out of the reach of all children.Teach parents to recognize and report early signs of infection and to avoid expos­ing the child to people with obvious infec­tions. Encourage parents to let the child engage in normal activities. Tell parents to follow-up with their pedi­atrician. Also tell them that child life thera­py may be appropriate if their child dis­plays delayed growth and development or failure to thrive.