Studies on cardiac lymph during extracorporeal circulation.

Cardiac lymph in dogs was used to study the metabolism and state of the myocardium during extracorporeal circulation and various additional procedures. Changes in the flow characteristics, cdor and pH of lymph were noted, and corresponding samples of cardiac lymph and coronary sinus blood were analyzed for lactate concenlmtion. Ventricular fibrillation led to higher lactate levek when compared to analyses of lymph and blood from a heart beating with sinus rhythm. Aortic occlusion at normothernia caused a pronounced and long-lasting elevation of lactates in the lymph, which also became blood stained, indicating capillary damage. Moderate hypothermia conferred a distinct but not complete protection against these effects. Coronary perfusion at normothermia appeared to be the preferable technique among those tested. We suggest that cardiac lymph reflects the state of the myocardium more accurately than do venous and arterial blood samples, and that lymph is a valuable medium for further studies on cardiac function and metabolism.