What is a ventricular septal defect?
Ventricular septal defect is the most common congenital heart defect and accounts for 20-30% of children seen in large pediatric cardiology clinics. The exact incidence is not known with estimates ranging from 2 to 5 out of every 1000 babies born. The cause of the problem is not well understood.
A ventricular septal defect (VSD) is a defect or hole(1) in the wall that separates the lower two chambers of the heart. These chambers are called the ventricles (2) and the wall separating them is called the ventricular septum. A child can have single or multiple ventricular septal defects. Ventricular septal defects also occur in association with more complex heart defects such as Tetralogy of Fallot and transposition of the great vessels. The information on this page applies to patients with a ventricular septal defect and an otherwise normal heart.
Ventricular septal defects can be further described by 1) size of the defect, 2) location of the defect, 3) whether there is more than one defect present, and 4) the presence or absence of a ventricular septal aneurysm. The size of the defect is usually described as small, moderate, or large. In general, small defects cause no symptoms during infancy or childhood and often close spontaneously. Moderate and large defects are less likely to close spontaneously, may result in congestive heart failure, and more often require surgical closure. Sometimes, the term restrictive or non-restrictive are used to describe the size of the defect. The term restrictive describes small defects that allow little or no blood to flow from the left side of the heart to the right side of the heart. Non-restrictive defects are large defects that allow a significant amount of blood to flow from the left side to the right of the heart. This results in excessive blood flow to the lungs, high pulmonary artery pressures, extra work for the heart, and congestive heart failure.
Different systems for describing the location of ventricular septal defects are used. Some are located in the lower portion of the septum called the muscular septum. Defects in this location are called muscular ventricular septal defects. Perimembranous ventricular septal defects (also called membranous VSD'S) are located in the membranous septum, a relatively small portion of the septum located near the heart valves. Ventricular septal defects may also be described as inlet or outlet VSDs. These terms further describe where the defect is located. Inlet VSDs are located close to where the blood enters the ventricular chamber and outlet VSDs are located close to where the blood exits the ventricular chamber.
Sometimes a ventricular septal aneurysm is seen when the echocardiogram is done. This is a thin flap of tissue that causes no harm and may increase the chances that the defect will close spontaneously.
What are the effects of this defect on my child's health?
In general, the effects of a ventricular septal defect are related to the size of the defect. As described previously, small ventricular septal defects do not cause symptoms in infancy or childhood and rarely require surgical or medical treatment. The majority of muscular VSDs close spontaneously during early childhood. Membranous VSDs can close at any time if a ventricular septal aneurysm is present. Small ventricular septal defects are not expected to affect the child's growth or development.
Usually, the primary significance of a small ventricular septal defect is a slightly increased risk for subacute bacterial endocarditis (SBE). This is an infection of the heart caused by bacteria in the blood stream. It most commonly occurs after a dental or other medical procedure and can usually be prevented by a dose of antibiotic prior to the procedure.
The effects of larger ventricular septal defects result from the shunting of blood across the defect causing excessive blood flow to the lungs. Ordinarily, the resistance or pressure on the heart's left side is much higher than the pressure on the heart's right side. When there is a large defect, the blood takes the "path of least resistance" and goes back to the right ventricle instead of out to the body. This results in pulmonary overcirculation and extra work for the heart. When the heart is unable to meet this extra work load, symptoms of congestive heart failure develop including excessive sweating (a cold, clammy sweat often noted during feeding), poor feeding, slow weight gain, irritability or lethargy, and/or rapid breathing. If this occurs medicines will usually be started (see treatment options). If the medicines aren't effective, surgery is usually recommended.
A very small number of ventricular septal defects located near the pulmonary valve can result in damage to the aortic valve. When this occurs the aortic valve starts to leak. Since the leakage usually progresses over time, surgical closure of the defect is often recommended even if the defect is small.
Participation in physical activities and sports: Exercise recommendations are best made by the patient's doctor so all so that all relevant factors can be included in the decision. If otherwise healthy, children with small ventricular defects and those with repaired ventricular defects can participate fully in physical activities including vigorous and competitive athletics.
How is this problem diagnosed?
Clinical findings: Most newborns with VSD do not have heart related symptoms. If the defect is moderate to large in size, symptoms of congestive heart failure usually develop during the first 1 to 2 months of life.
Physical findings: A heart murmur is often the first clue that a child has a VSD. In many children, the murmur is heard right after birth but it may not be heard until the child is 6 to 8 weeks of age. If the child is in congestive heart failure, there will be poor weight gain, the heart rate and breathing rate will be higher than normal, and the liver will be enlarged.
Medical tests: Medical tests that provide helpful information include an electrocardiogram, oxygen saturation test, and chest x-ray. The diagnosis is confirmed by an echocardiogram. If there are questions about the child's heart anatomy that can't be answered by the echocardiogram or if the child's symptoms seem out of proportion to the size of the defect, a heart catheterization may be done.
How is the defect treated?
As described earlier, small ventricular septal defects do not cause symptoms so generally treatment (other than SBE prophylaxis) is not needed. Usually, ventricular septal defects diagnosed in infancy get smaller with time and even large defects can close completely. If the child develops congestive heart failure, treatment is needed. This involves the use of medications to decrease the work of the heart and increase the strength of the heart beat. Medications that may be used include digoxin, diuretics, and afterload reducers. These medications often control the symptoms until the child gets bigger and the defect gets smaller or closes altogether.
If the child's symptoms cannot be controlled by medications, surgical repair will be considered. Often the need for surgery is demonstrated most convincingly by the child's inability to gain weight. Even if the symptoms are minimal, surgical closure is recommended for any defect that is big enough after the first year or two of life to allow excessive pulmonary blood flow. This is to prevent a very serious long term complication called pulmonary vascular obstructive disease.
Surgical repair of a ventricular septal defect involves open heart surgery and placement of a prosthetic patch, sutured in placed, that covers the defect. The heart tissue grows over the patch so the heart never "outgrows" it.
Clinics
Care and services for patients with this problem are provided in the Congenital Heart and Cardiovascular Surgery clinics at the University of Michigan Medical Center in Ann Arbor.
What is the outlook for children with ventricular septal defects?
Overall, the outlook for a child with a ventricular septal defect is excellent. As previously described the majority of defects close on their own or are small so that treatment is not needed. Surgical results are also excellent. If the child has only a ventricular septal defect and an otherwise normal heart, the operative mortality approaches 0%. Major complications are rare and include heart block and incomplete closure of the defect. The incidence of major complications is less than 1%.
References
Gumbiner CH & Takao A. Ventricular septal defect. In Garson A, Bricker J, Fisher D & Neish S (Eds), The science and practice of pediatric cardiology, Vol I. Williams & Wilkins: Baltimore, MD, 1997,1119-1140.
Mavroudis C, Backer Cl, & Idriss FS. Ventricular septal defect. In C Mavroudis & C Backer (Eds) Pediatric Cardiac Surgery. Mosby, St. Louis, MO,1994,201-224.
Onat T, Ahunbay G, Batmaz G & Celebi A. The natural course of isolated ventricular septal defects during adolesence. Pediatr Cardiol 19:230-234, 1999.
The natural history of isolated VSD was studied in 106 patients from infancy through puberty. There was a 22 % closure rate during adolescence which was higher than anticipated. Stature was normal with a significantly lower weight which increased to normal by the end of adolescence. Using Kaplan-Meier curves, 61% of muscular defects and 50% of perimembranous defects closed spontaneously prior to adolescence. Spontaneous closure during adolescence was much higher than anticipated with implications when considering surgical closure. The majority of muscular VSDs close during the first year of life and perimembranous defects could close in any period of life with the development of VSA. Higher rate of closure in infancy and adolescence when growth is rapid suggests a role in spontaneous closure.
Written by: S. LeRoy RN, MSN
Reviewed September, 2012