CLINICAL UPDATE
Congenital“ holey” hearts: Ventricular septal defect
By Dr Luigi D’ Orsogna, Paediatric Cardiologist.
Western Cardiology. Tel 9346 9300
Ventricular septal defect( VSD) is the commonest congenital heart disease of childhood( 55 % of cardiac defects in WA). Single or multiple defects of the interventricular septum can be simply classified as membranous or muscular, and they can be isolated or associated with other defects like coarctation of the aorta or more complex malformations such as Tetralogy of Fallot. The pathophysiology and clinical manifestation of a VSD after birth is dependent on its size, the pulmonary vascular resistance( PVR) and the differential pressure between right and left ventricles.
Pathophysiology
Immediately after birth the PVR is high, hence there will be little flow across the VSD, which will be clinically“ silent”. As the PVR diminishes over the ensuing days, flow increases across the defect. Small defects are not associated with symptoms but a typical pansystolic murmur at the lower left sternal border is audible; smaller defects tend to produce louder murmurs as greater turbulence is created by the larger pressure difference between ventricles.
Conversely, excessive pulmonary blood flow from a large defect increases pulmonary artery pressure, which in turn raises the right ventricle pressure and diminishes the pressure difference across the VSD, thereby making the murmur less prominent.
� Fig 1: 2-dimensional echocardiogram( apical 4 chamber view) showing a large mid-muscular VSD( arrow).
� Fig2: with AmplatzerTM VSD occlusive device in situ.
However, the newborn or young infant manifests symptoms and signs of excessive pulmonary blood flow: dyspnea and tachypnea that cause difficulty with feeding, tachycardia and hyperdynamic praecordial activity with or without a thrill, and an accentuated second heart sound with the pansystolic murmur. There may be an ejection systolic murmur at the left upper sternal border( excessive flow across the pulmonary valve) and a mid-diastolic murmur at the apex( increased flow across the mitral valve). If congestive cardiac failure develops, hepatomegaly is the best indicator at this age.
Investigation and treatment
Echocardiography is most accurate and informative. A small VSD requires no treatment as the defect may diminish or even close spontaneously; most small muscular
VSDs close before school age and even moderate or large defects diminish enough in infancy so that no treatment will be needed.
However, if the infant with moderate or large VSD shows signs of not thriving or develops heart failure, then surgery will be required early, usually before six months of age. An asymptomatic moderate to large VSD requires elective closure later in infancy or early childhood to avoid the long-term complications of either pulmonary hypertension or volume overloaded left heart. Surgery is now relatively low risk with mortality < 1 %.
Transcatheter VSD device closure has limited application as it can only be used safely with muscular defects in older infants; perimembranous defects are close to the cardiac valves and the conduction system, thereby risking their damage from an occlusive device.
Infective endocarditis prophylaxis is not required for VSD unless there has been previous endocarditis( but it is required for six months after cardiac surgery / device closure).
Declaration: Western Cardiology has contributed to the production costs of this clinical update. No author competing interests.
Conference Corner
Rural Health West Aboriginal
Health Conference Dates: July 6-7 Venue: Pan Pacific, Perth Website: www. ruralhealthwest. com. au or www. ruralhealthwest. com. au WA ANZCA Winter Scientific Meeting Date: July 20 Venue: University Club, UWA Website: www. anzca. edu. au / events General Practitioner Conference & Exhibition Dates July 20-21 Venue: Perth Convention Exhibition Centre Website: www. gpce. com. au / en / visit / perth / Rural Health West Remote Coastal Emergency Medicine Conference Dates: September 6-8 Venue: Gnaraloo Station Website: www. ruralhealthwest. com. au
GPET Convention 2013 Dates: September 11-12 Venue: Crown Perth Website: www. agpt. com. au / NewEvents / GPETConvention2 2013 Rural and Remote Mental Health Conference Dates: September 17-19 Venue: Bridgeley Community Centre, Northam Website: www. wacountry. health. wa. gov. au National Environmental Health Conference Dates: September 24-26 Venue: Parmelia Hilton Website: www. eh. org. au / events
WA ANZCA Meeting Bunker Bay Dates: October 11-13 Website: www. anzca. edu. au / events
Rural Health West
Fremantle Conference Date: October 19 Venue: Fremantle Website: www. ruralhealthwest. com. au WA Transcultural Mental Health and Australasian Refugee Health Conference 2013 Dates: October 31-November 1 Venue: Duxton Hotel, Perth Website: www. transrefugee2013. com. au Australasian Injury Prevention & Safety Promotion Conference Dates: November 11-13 Venue: The Esplanade Hotel, Fremantle Website: www. injuryprevention2013. com. au
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