A ventricular septal defect (VSD) is a hole in the wall that separates the heart’s left and right ventricles, the lower pumping chambers. The hole provides an opening for blood to cross the wall, or septum, from the left side to the right side of the heart. When this occurs, some of the blood in the left ventricle, which has just come back to the heart from picking up oxygen in the lungs, may go into the right ventricle and immediately back to the lungs.
These holes can exist in various parts of the wall between the bottom pumping chambers of the heart (septum). They can occur near the valves that let blood into the pumping chambers (inlet), the thick section of the septum (muscular), in the thinner fibrous area of the wall (perimembranous), or toward the valve that lets blood out to the lungs (outlet)."
An increase in blood flow to the right ventricle causes it to enlarge as it works harder to handle the blood, and an increase in blood flow to the lungs causes the lungs to become congested. Congestion of the lungs interferes with their job of transferring oxygen from the air to the blood and carbon dioxide from blood to air. When the heart is overburdened and cannot pump enough blood to the body and the lungs become congested, a condition called congestive heart failure (CHF) occurs.
Because the heart and lungs have to work harder, the child will become short of breath, particularly with the exertion of feeding (which is the most exercise an infant does). This could limit the amount of exertion the child can endure and thus lead to poor feeding and eventually to poor weight gain and growth.
Birth defects of the heart occur in one percent of all born children. Half of all patients with congenital heart disease have ventricular septal defects. Premature infants have a much higher incidence of ventricular septal defect: 10 times that of full term babies.
Symptoms
If the VSD is small, the amount of increased blood flow into the right ventricle and lungs will not significantly increase and the child will not be noticeably affected. If it is larger and allows much more blood than normal to flow to the right ventricle, serious problems may result, including:
- Fatigue of the heart, because it has to work harder to deal with the inefficient circulation of blood.
- Congestion of the lungs, leading to difficulty in breathing.
- Poor weight gain of the child because of an inability to tolerate the exertion needed to feed properly.
Progression
Ventricular septal defects may close without treatment, but the larger the defect, the less likely it is to do so. The location of the VSD in the ventricular septum also influences whether it closes on its own.
If a moderate or large VSD is not treated, the result may be irreversible damage to the blood vessels of the lungs. If the damage progresses, death can result, typically in the fourth or fifth decade of life.
Treatment
Some VSDs, particularly muscular and perimembranous ones, may close by themselves over time and cardiologists may wait to see if this happens. However, surgery is often necessary if there is too much blood passing through the holes or if there is increasing leakage found of the aortic valve over time. Some VSDs can be successfully closed in the catheterization lab using special devices, thus avoiding open heart surgery.
Medications
If the VSD does not close on its own, the cardiologist may recommend anti-congestive heart failure medications. These may include:
- Diuretics: The most commonly prescribed diuretics are furosemide (Lasix) and thiazides (Diuril and Hydrodiuril). Diuretics act to cause the child to pass more urine, leading to a smaller blood volume – and a smaller burden on the heart to pump. Another commonly used diuretic is spiranolactone (Aldactone). It has a weak diuretic effect and is mainly used because it helps the kidneys retain potassium. Other diuretics tend to waste potassium excessively.
- Inotropes: These medications, which include digoxin, help the heart pump more efficiently (stronger while using less energy).
- Afterload reducing agents: These drugs, which include captopril, are infrequently used in the treatment of VSD. However, when used, they act to reduce the resistance of blood flow to the body. The leads to less blood crossing the ventricular septal defect – and reduction in congestive heart failure.
Surgical Closure of VSD
Open heart surgery may be recommended if the VSD is too large, medications are not helping or the child is beyond an age when the VSD may close. During surgery, the surgeon opens the heart and closes the defect by using a patch or sutures only. The child who undergoes surgery may stay in the hospital three to five days.
Occasionally, surgery may be recommended if the VSD is not large but is causing damage to the nearby aortic valve, the structure that keeps blood flowing out in one direction from the heart’s left ventricle and the aorta, the vessel that carries blood from the heart to the rest of the body.