Cardiac Surgery
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Closed Heart SurgeryThis is undertaken via a thoracotomy whilst the heart is still beating. It is used for extra cardiac procedures eg. PDA ligation, Blalock Taussig Shunt, Coarctation repair, PA banding or Thoracic procedures. The first elective closed cardiac surgical procedure was ligation of a PDA by Gross in Boston in 1938 |
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Open Heart SurgeryMost corrective procedures are undertaken with the open heart surgery and the heart and lung function taken over by the bypass machine. This machine was developed in the early 1950's by Gibson. A median sternotomy incision is made through which access is gained to the heart. Sometimes in females for ASD repair a submammary incision is preferred. The whole procedure is team dependent with the best results achieved when the surgeon, anaesthetist, pump technician and nurse are working in harmony. |
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Cardiopulmonary BypassThe patient is anaesthetised, monitoring lines inserted and the chest opened. Cannulae are placed in the SVC & IVC to draw off blood returning to the heart into the bypass machine under gentle suction. The blood is passed through a membrane oxygenator (which also removes CO2) & and a heat exchanger before it is pumped (roller or centrifugal) into the ascending aorta. The heart is stopped by injecting a cardioplegia solution into the coronary arteries via the aortic root. |
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The length of time the heart is not beating is described as the cross clamp time. Using the heat exchanger the body cooled to approximately 20º C to reduce metabolic rate. When the repair is undertaken the body is rewarmed and as it does so the heart fibrillates. It is restored to sinus rhythm with a DC shock. Temporary pacemaker wires are inserted to allow pacing in the postoperative period (if required) and a PD cannula in infants to enable PD to be instituted if renal impairment occurs. |
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Circulatory ArrestEven with cardiopulmonary bypass the field is not bloodless as there is a constant return to the right side of the heart via the coronary sinus and to the left side of the heart via the pulmonary veins filled through the bronchial circulation. In addition to this the cannulae required to remove and return blood to the circulation restrict access to the thoracic cavity especially in neonates. When these difficulties occur the surgeon may elect to reduce the body temperature to 15 - 18 ºC, stop the bypass machine and remove the cannulae. This period of total circulatory arrest may past up to an hour in most patients without clinical sequelae. Times much beyond this result in an increased risk of major organ damage. |
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This page was last edited 14/2/2004 |
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