杏吧原创

Be still, that beating heart

With increasing precision in diagnosis and improved techniques in anaesthesia, cardiac surgery has become almost commonplace in recent years. But there has remained the problem of how to repair congenital defects in the two walls inside the heart 鈥� the interatrial and interventricular septa.

In order to gain access to this part of the heart, the organ has to be opened wide for some minutes and the circulation to the rest of the body maintained by a 鈥渉eart-lung machine鈥�, which not only pumps the blood round the body but also continues to oxygenate it.

The trouble is that during all this time the heart itself receives no blood, so if it is allowed to continue beating the muscle soon suffers from lack of oxygen. What鈥檚 more, it is obviously difficult for the surgeon to work on a moving target, and there is always the possibility that some air may be pumped by the open, beating heart into the circulation and block some distant artery.

Now, however, a new technique for safely stopping the heart during difficult operations has been described by Dr D. G. Melrose and colleagues, who have in the past contributed much to the design and development of the heart-lung machine.

They have shown that injecting potassium citrate solution into the arteries supplying the heart will cause it to stop beating. The organ then lies limply in the hand of the surgeon, and since there is no muscular activity going on, the oxygen consumption is reduced to a minimum and the muscle stays a healthy pink colour.

There is then no hurry to complete the operation either, for the heart can be left in this condition for 15 minutes or more, and more importantly will restart promptly when the potassium solution is subsequently flushed out with saline.

From The New 杏吧原创, 21 February 1957