Myocardial Protection

Myocardial protection was a key part of these developments that allowed safe cardiac surgery to
be performed. The term myocardial protection encompasses more than just cardioplegia, and can be
said to include things such as the perioperative management of patients with medical treatment (such
as beta-blockers, etc.), or support devices (such as intraaortic balloon pumps), better anesthetic agents,and better hemodynamic management. All of these treatments contribute to making cardiac surgery safer, and to get a sick patient through a major operation.
However, for the purposes of our discussion we will focus more on the development of cardioplegia.
This is a very large field of research and has been reviewed in several books and review articles. In one chapter we will only be able to go over some of the important highlights, and give a general
outline of the work that has brought us to where we are today.

Cardioplegia

The first use of "elective cardiac arrest" was by Melrose in 1955, who also coined the term "cardioplegia" for the technique . Melrose used a solution containing potassium to remove the transmembrane electrical potential and hence to stop the cardiac impulse and arrest the heart in diastole. However, once again, the paper by Melrose makes it clear that his initial impetus to devise the technique was to reduce the foaming that occurred with the cardiopulmonary machines he was using, in order to reduce air emboli,and not to protect the heart.

Summary

One could consider that the whole field of myocardial protection has gone almost full circle as the emphasis has returned to the avoidance of ischemia. The other chapters in this book will address each topic more fully, but one might view the return of beating heart surgery as the best way to avoid ischemia altogether.
This is certainly a promising area for research, both with regards to myocardial protection and neurological functioning. We may see a change in emphasis as we adopt the new paradigm of "off-pump" surgery, but we will still need the basic concepts of myocardial protection, even in that setting. We will also need touse methods of circulatory support and myocardial protection for "open" procedures, such as valve surgery or intracardiac repairs of congenital defects,for the foreseeable future. There will still be a need for myocardial protection.
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