Continuous warm blood cardioplegia: a new technique for myocardial protection

Hypothermia is used to prolong the safe period of ischemic arrest by reducing the heart's oxygen demands. Due to this effect, hypothermia has been the fundamental component of most methods of myocardial protection during cardiac surgery. However, hypothermia has a number of unwanted side effects, such as detrimental effects on enzyme function, energy generation, and cell membranes. Since electromechanical arrest accounts for 90% of myocardial oxygen consumption, arresting the heart with chemical cardioplegia will reduce O2 consumption dramatically. Therefore, if the resting (arrested) heart is continuously perfused with oxygenated blood cardioplegia, one can easily provide the remaining 10% of O2 that it requires. Under these conditions, the need for hypothermia becomes questionable. In this paper, we describe the perfusionist's experience using the antegrade and retrograde technique of continuous warm blood cardioplegia.