Ventricular Septal Defect (VSD)

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Ventricular Septal Defect (VSD) is a disease of the heart, namely the septum (or division) between the two ventricles (or main chambers of the heart). 3-4 per 1000 live births. VSD is the most common congenital cardiac malformation. The aetiology (origins) of congenital heart defects is not understood but several factors are known to be associated with this condition:1) Maternal drug abuse, alcohol abuse and radiation exposure.2) Maternal infection during pregnancy, particularly rubella.3) Genetic abnormalities.4) Chromosomal abnormalities (septal defects common with Trisomy 21- Down's syndrome). VSDs may occur in isolation or may be associated with other malformations. Small VSDs usually close spontaneously.Moderate to large VSDs often become smaller but remain patent and allow shunting of blood from one side of the circulation to the other. Because the left (systemic) blood pressure is higher than the right (pulmonary), the shunt is left to right and increased blood is circulated through the lungs. Eventually, the increased flow rates through the pulmonary circulation lead to obliteration of the lung tissue and pulmonary hypertension. When the pulmonary circulatory pressure is equal to or greater than the systemic, the shunt reverses and becomes right to left. This is called "Eisenmenger's syndrome." When this occurs, less blood flows through the pulmonary circulation and the patient may become cyanosed (skin and mucous membranes turn blue) as a result of poor blood oxygenation. Ventricular septal defects are rarely "acquired," as in myocardial infarction involving the ventricular septum. Chest x-ray: small VSDs may show nothing. Moderate may show cardiomegaly and enlarged pulmonary arteries due to increased pulmonary vascular flow rates. ECG: features of right ventricular enlargement may be seen. Approximately 24% of small defects close spontaneously by 18 months. Up to 75% are closed by the age of 10. Large septal defects threaten life early on through congestive failure. The risk of death is 11%. If large defects are not corrected before pulmonary hypertension develops the outlook is poor. Patients with the Eisenmenger's syndrome have an average life expectancy of 33 years. Fortunately surgical techniques may provide a better outcome. For small defects medical treatment may be tried (eg. treating heart failure) if the defect is expected to improve spontaneously. Frequent measurement of pulmonary pressure should be performed to monitor this condition.Moderate to large defects should be corrected surgically. [1] Anderson et al. Paediatric Cardiology. Churchill Livingstone 1987.[2] Behrman, Kliegman, Jenson. Nelson Textbook of Paediatrics 17th Ed. Saunders 2004.[3] Hurst's The Heart 8th Edition, McGraw-Hill 1994.[4] Kumar and Clark, Clinical Medicine 4th Edition, W.B SAUNDERS 1998.[5] Rudolph et al. Rudolphs's Paediatrics (21st edition). McGraw-Hill 2003.