Ventricular septal defect

Published on 02/04/2015 by admin

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Last modified 22/04/2025

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21 Ventricular septal defect

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 (p. 122).

Examination

• There is a normal pulse.

• There are 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 (VSD) undermines the aortic valve annulus.

• Small, muscular VSDs may produce high-frequency systolic ejection murmurs that terminate before the end of systole (when the defect is occluded by contracting heart muscle) (Fig. 21.1).

• 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 P indicates pulmonary hypertension.

• Look for signs of cardiac failure.

image

Fig. 21.1 Phonocardiogram showing the holosystolic murmur of isolated ventricular septal defect.

Note: VSD is the most common congenital cardiac anomaly, occurring in 2 per 1000 births. It is a feature of Down syndrome (p. 806).

Diagnosis

This patient has a ventricular septal defect (lesion) of congenital origin (aetiology) and has pulmonary hypertension (functional status).

Questions

Is the loudness of the murmur related to the size of the defect?

No; in fact, very small defects (maladie de Roger) cause loud murmurs (Bull Acad Med, 1879;VIII:1074–94).

What are causes of a ventricular septal defect?

• Congenital

• Rupture of the interventricular septum as a complication of myocardial infarction.

Where is the defect usually situated?

In the membranous portion of the interventricular septum.

Can such defects close spontaneously?

Spontaneous closure usually occurs in a small defect, during early childhood in about 50% of the patients.

What are complications of a ventricular septal defect?

• Congestive cardiac failure

• Right ventricular outflow tract obstruction (muscular infundibular obstruction develops in about of 5% of VSDs)

• Aortic regurgitation

• Infective endocarditis

• Pulmonary hypertension and reversal of shunt (Eisenmenger complex).

How would you investigate this patient?

• ECG 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’ is evident on the chest radiograph (Fig. 21.2).
• If pulmonary hypertension occurs, the QRS axis shifts to the right, and right atrial and ventricular enlargement are noted on the ECG; the chest radiograph 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 ventricular septal defect, and Doppler colour-flow mapping can identify the magnitude and direction of shunting.

• Magnetic resonance imaging (MRI).

• 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.

image

Fig. 21.2 (A) Radiograph of a moderately restrictive perimembranous ventricular septal defect with left-to-right shunt. Pulmonary arterial vascularity is increased, the pulmonary trunk and its proximal branches are markedly dilated, and a moderately enlarged convex LV occupies the apex. (B) Radiograph of a non-restrictive perimembranous ventricular septal defect and a bidirectional shunt. Pulmonary arterial vascularity is increased, the pulmonary trunk and its proximal branches are markedly dilated, an enlarged convex LV occupies the apex, and a prominent right atrium forms the right lower cardiac border.

(With permission from Perloff 2003.)

Advanced-level questions

What types of ventricular septal defect do you know?

• The supracristal type (above the crista supraventricularis, a muscular ridge that separates the main portion of the right ventricular cavity from the infundibular or outflow portion) 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 Fallot’s tetralogy, this defect is associated with a rightward shift of the interventricular septum, and in double-outlet LV 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 (<5% of the defects):

• Small defects (maladie de Roger)
• Swiss cheese appearance (multiple small defects)
• Large defects
• Gerbode defect (defect opening into the right atrium) (Ann Surg 1958;148:433).

Mention other cardiac lesions that may be associated with a ventricular septal defect

• Conditions in which VSD is an essential part of the syndrome:

• Fallot’s tetralogy
• Truncus arteriosus
• Double-outlet RV
• Atrioventricular 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 a ventricular septal defect?

• Small defects should present with no problems.

• Moderate-sized defects and moderate pulmonary hypertension are at the risk of developing acute right ventricular failure and rapidly worsening pulmonary hypertension in pregnancy.

• Pregnancy should be avoided in pulmonary hypertension and pregnancy.

What is the management of patients with a ventricular septal defect?

• The natural history of ventricular septal defect depends on:

• the size of the defect
• 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 VSDs 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 these patients may benefit from surgery:

• Recurrent endocarditis

• Development of aortic regurgitation caused by prolapse of the right coronary cusp through the septal defect

• Progressive left ventricular dilatation caused by volume overload imposed by the shunt (pulmonary to systemic ratio is 3:1)

• When the defect is caused by 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 life.

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’: ‘A developmental defect of the heart occurs from which cyanosis does not ensue in spite of the fact that a communication exists between the cavities of the two ventricles and in spite of the fact that admixture of venous blood and arterial blood occurs. This congenital defect, which is even compatible with a long life, is a simple one. It comprises a defect in the interventricular septum’.

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