Ventricular septal defect تشوه الحاجز البطيني
INSTRUCTION Listen to this patient's heart. SALIENT FEATURES History · Small defects are usually asymptomatic. · Large defects with shunts: repeated respiratory tract infections, debilitating dyspnoea and exercise intolerance. · Symptoms of infective endocarditis or past history of endocarditis. · Symptoms of Eisenmenger syndrome (see pp 88-90). Examination · Normal pulse. · Normal findings on palpation (there may be either left or right ventricular enlargement). · With substantial left-to-right shunting and little or no pulmonary hypertension, the left ventricular impulse is dynamic and laterally displaced, and the right ventricular impulse may not be felt. The murmur of a moderate or large defect is pansystolic, loudest at the lower left sternal border, and usually accompanied by a palpable thrill. · A short mid-diastolic apical rumble (caused by increased flow through the mitral valve) may be heard. · A decrescendo diastolic murmur of aortic regurgitation may be present if the ventricular septal defect undermines the aortic valve annulus. · Small, muscular ventricular septal defects may produce high-frequency systolic ejection murmurs that terminate before the end of systole (when the defect is occluded by contracting heart muscle). · If pulmonary hypertension develops, a right ventricular heave and a pulsation over the pulmonary trunk may be palpated. The pansystolic murmur and thrill diminish and eventually disappear as flow through the defect decreases, and a murmur of pulmonary regurgitation (Graham Steell's murmur) may appear. Finally, cyanosis and clubbing are present. · The second sound may be normal when the defect is small. A2 is obscured by the pansystolic murmur of large defects. A single second sound indicates that the ventricular pressures are equal and a loud P2 indicates pulmonary hypertension. · Look for signs of cardiac failure. Note. VSD is the most common congenital cardiac anomaly, occurring in 2 per 1000 births. VSD is a feature of Dawn's syndrome (see pp 600-2). DIAGNOSIS This patient has a ventricular septal detect (lesion) of congenital origin (aetiology) and has pulmonary hypertension (functional status). QUESTIONS Is the loudness of the murmur related to the size of the VSD? No' in fact, very small detects (maladie de Roger) cause loud murmurs (Bulletin de I'Aca&;mie de Mddicine1879; 2 (VIII): 1074 94). What are the causes of a VSD? · Congenital. · Rupture of the interventricular septum as a complication of myocardial infarction. Where is the defect usually situated? In the membranous portkm of the interventricular septum. Can such defects close spontaneously? Spontaneous closure usually occurs in a small defect, in early childhood in about 50% of the patients. What are the complications of a VSD? · Congestive cardiac failure. · Right ventricular outflow tract obstruction (muscular infundibular obstruction develops in about 5% of VSDs). · Aortic regurgitation. · Infective endocarditis. · Pulmonary hypertension and reversal of shunt (Eisenmenger complex). How would you investigate this patient? · Electrocardiography and chest radiography provide insight into the magnitude of the haemodynamic impairment: -With a small ventricular septal defect, both ECG and chest radiograph are normal. -With a large defect, there is ECG evidence of left atrial and ventricular enlargement and left ventricular enlargement and 'shunt vascularity' are evident on the chest radiograph. -If pulmonary hypertension occurs, the QRS axis shills to the right, and righ atrial and ventricular enlargement are noted on the ECG. The chest radiograph of a patient with pulmonary hypertension shows marked enlargement of the proximal pulmonary arteries, rapid tapering of the peripheral pulmonary arteries, and oligaemic lung fields. · Doppler echocardiography can identify the presence and location of the ven-tricular septal defect, and Doppler colour-flow mapping can identify the magnitude and direction of shunting. · Cardiac catheterization and angiography can confirm the presence and location of the ventricular septal defect, as well as determine the magnitude of shunting and the pulmonary vascular resistance. ADVANCED-LEVEL QUESTIONS What types of VSD do you know of? The supracristal type (above the crista supraventricularis) is a high defect just below the pulmonary valve and the right coronary cusp of the aortic valve. The latter may not be adequately supported, resulting in aortic regurgitation. In Failer's tetralogy this defect is associated with a rightward shill of the interventricular sepmm, and in double-outlet left ventricle with subaortic stenosis the supracristal defect is associated with a leftward shift of the septum. The infracristal defect, which may be in either the upper membranous portion of the interventricular septum, or the lower muscular part (less than 5% of the defects): · Small detects (maladie de Roger). · Swiss cheese appearance (multiple small defects). · Large defects. · Gerbode detect (defect opening into the right atrium; Ann Sttqg 1958; 148: 433). Note. The crista supraventricularis is a muscular ridge that separates the main portion of the right ventricular cavity from the infundibular or outflow portion. Mention other cardiac lesions that may be associated with a VSD. Conditions in which VSD is an essential part of the syndrome: · Fallot's tetralogy. · Truncus arteriosus. · Double-outlet right ventricle. · AV canal defects. Conditions frequently associated with a VSD but not an essential part of the syndrome: · Patent ductus arteriosus. · Pulmonary stenosis. · Secundum atrial septal defects. · Coarctation of aorta. · Tricuspid atresia. · Transposition of the great arteries. · Pulmonary atresia. What is the effect of pregnancy in women with VSO? Small defects should present no problems. · Patients with moderate sized defects and moderate pulmonary hypertension are at risk of developing acute right ventricular failure and rapidly worsening pul-monary hypertension in pregnancy. · Pregnancy should be avoided in patients with pulmonary hypertension. What is the management of patients with VSD? The natural history of ventricular septal defect depends on: (a) the size of the defect and (b) the pulmonary vascular resistance: · Adults with small defects and normal pulmonary arterial pressure are usually asymptomatic, and pulmonary vascular disease is unlikely to develop. Such patients do not require surgical closure of their defect, but they are at risk for infective endocarditis and should therefore receive antibiotic prophylaxis. · Patients with large ventricular septal defects who survive to adulthood usually have left ventricular failure or pulmonary hypertension with associated right ventricular failure. Surgical closure of such defects is recommended, if the magnitude of pulmonary vascular obstructive disease is not prohibitive. Once the ratio of pulmonary to systemic vascular resistance exceeds 0.7, the risk associated with surgery is excessive. Which patients merit surgical attention? Usually, in an adult, VSD is small enough to be safely ignored, or the patient has Eisenmenger syndrome. However, there are exceptions to this and patients with the following conditions may benefit from surgery: § · Recurrent endocarditis. § · Development of aortic regurgitation due to prolapse of the right coronary cusp through the septal defect. § · Progressive left ventricular dilatation due to volume overload imposed by the shunt (pulmonary to systemic ratio is 3:1). § · When the defect is due to an acute rupture of the ventricular septum. Note. If the VSD is large enough to cause heart failure or pulmonary hypertension, it usually manifests in the first few years of lite. Henri Roger (1809-1891), a French paediatrician, described maladie de Roger in 1879 in a paper entitled Clinical researches on the congenital communication of the two sides of the hearts, but failure of occlusion of the interventricular septum.