9. What are the three main complications of cardiopulmonary bypass?
Correct answer: (1) Emboli. (2) Haemorrhage. (3) Hypothermic injury and ischaemia.
8. How does ‘cardioplegic’ solution work?
Correct answer: This cold solution is infused via the coronary arteries. It contains potassium so produces a rapid cardiac arrest in diastole.
7. What is ‘cardioplegic’ solution used for?
Correct answer: The heart may be stopped once on cardiopulmonary bypass and can be cooled by infusion via the coronary arteries of cold ‘cardioplegic’ solution containing potassium, to produce rapid cardiac arrest in diastole.
6. What is the technique of cardiopulmonary bypass? What is the role of ‘cardioplegic’ solution?
Correct answer: After full heparinization, cannulae are inserted into the venae cavae via the right atrium to siphon off the venous return from the systemic circulation. The blood is then pumped through an oxygenator and a heat exchanger before returning…
5. What has been possible with the development of cardiopulmonary bypass?
Correct answer: It is now possible to stop the heart for prolonged periods while a machine is used to take over the pumping and oxygenation of the blood. Generally, a combination of hypothermia and cardiopulmonary bypass is used.
3. How long can the heart muscle survive ischaemic conditions before it is irreversibly damaged? (At body temperature)
Correct answer: Between 3 and 6 minutes.
2. What happens to the body when the circulation is temporarily stopped at body temperature? Which tissues are the least tolerant to ischaemia?
Correct answer: If the circulation is temporarily stopped at normal body temperature, organs suffer ischaemic damage owing to lack of oxygen, the extent varying according to the metabolic demand of the organ. The brain is the most sensitive tissue in…
How important was the development of cardiopulmonary bypass? What type of operations on the heart were possible before this?
Correct answer: Prior to the development of cardiopulmonary bypass, surgery on the heart was limited to procedures that could be performed rapidly on a beating heart, such as mitral valvotomy to relieve mitral stenosis, where a finger is passed blindly…
13. What is a haemothorax?
Correct answer: A haemothorax often accompanies a chest injury and may be associated with a pneumothorax (haemopneumothorax). The bleeding is usually from an intercostal artery in the lacerated chest wall or from underlying contused lung, but on occasions may result…
