Novick R J, Stefaniszyn H J, Malcolm I D, Burdon F D, Salerno T A
Ann Thorac Surg. 1984 Feb;37(2):154-8. doi: 10.1016/s0003-4975(10)60305-0.
To elucidate the electrical interrelationship of the atria during cardioplegic arrest, simultaneous bipolar right atrial (RA) and left atrial (LA) electrograms and myocardial temperatures of all four chambers of the heart were recorded in 10 pigs during an hour of aortic clamping. Five pigs (Group 1) underwent single venous cannulation; in 5 others (Group 2), snared double caval cannulation, RA venting, and intracavitary RA irrigation with cold saline solution were employed. Myocardial protection was provided by systemic hypothermia (28 degrees C) and intermittent intraaortic administration of cold (4 degrees C) hyperkalemic (20 mEq/L) crystalloid cardioplegic solution. Single RA cannulation was associated with sustained RA activity during cardioplegic arrest and with the warmest mean myocardial temperatures. Electrical activity was infrequent in the left atrium, which was often silent while RA impulses continued to be observed. Four Group 1 pigs exhibited high-grade RA-LA block, whereas in 2 animals completely asynchronous RA-LA electrical activity occurred. Isolated LA activity was not encountered. The combined methods used in Group 2 pigs significantly reduced mean myocardial temperatures. Both RA and LA impulses were practically abolished, and their mean durations decreased 96% and 85%, respectively. It is concluded that the pattern of electrical activity differs in the two atria during cardioplegic arrest when a single venous cannula is employed. Intracavitary RA irrigation with cold saline solution in the presence of snared caval cannulas provides improved myocardial hypothermia and effectively eliminates both RA and LA activity in the course of cold crystalloid cardioplegia.
为阐明心脏停搏期间心房的电相互关系，在10头猪主动脉阻断1小时期间，记录了心脏四个腔室的同步双极右心房（RA）和左心房（LA）电图以及心肌温度。5头猪（第1组）进行单静脉插管；另外5头猪（第2组）采用圈套双腔静脉插管、RA排气和冷盐水溶液腔内RA灌注。通过全身低温（28℃）和间歇性主动脉内给予冷（4℃）高钾（20 mEq/L）晶体心脏停搏液来提供心肌保护。单RA插管与心脏停搏期间RA的持续活动以及最高的平均心肌温度相关。左心房电活动不常见，在持续观察到RA冲动时左心房通常无电活动。第1组的4头猪表现出高度RA-LA阻滞，而2头动物出现完全不同步的RA-LA电活动。未发现孤立的LA活动。第2组猪使用的联合方法显著降低了平均心肌温度。RA和LA冲动实际上均被消除，其平均持续时间分别减少了96%和85%。结论是，在使用单静脉插管时，心脏停搏期间两个心房的电活动模式不同。在圈套腔静脉插管的情况下，用冷盐水溶液进行腔内RA灌注可改善心肌低温，并在冷晶体心脏停搏过程中有效消除RA和LA活动。
