心肌保护

<正> 自从体外循环于1951年开始应用于临床以来,许多心脏病能在心内直视手术下得到矫治,但是由于心脏较长时间的缺血,缺氧引起了一系列不良后果,如心脏复苏困难,低排综合症,“石样心”等严重并发症,甚至导致病人死亡。因此近20多年来,对此进行了广泛的研究,使心肌保护技术一再得到改讲。

MYOCARDIAL PROTECTION

Twenty mongrel dogs of either sex,11 to 22kg of body weight,were divided into five groups.In Group 1(n=6) the animals were perfused with cold myocardial protective solution of K~+ 15mEq/L,osmolarity 347mOsm/L; in Group 2(n=5)K~+ 15mEq/L,osmolarity 592 mOsm/L,and in Group 3(n=3)K~+ 30mEq/L,osmolarity 614 mOsm/L.The animals of Group 4(n=3) were per- fused with cold blood by intermittent release of aortic cross-clamp and Group 5(n=3) with cold Ringer's solution(4℃).The body temperature fell to 19～ 24℃ during cardiopulmonary bypass.Mean arterial pressure and flow rate were maintained between 60 to 100mmHg and 100～130ml/kg/min respective- ly.In Groups 1,2,3,5,hearts were perfused every 30′ during 90 minutes of aortic cross-clamp.In Group 4 intermittent releases of aortic cross-clamp were perfused every 30′ and lack with a 3′ duration.Temperature of the outer and inner surfaces of right ventricle and that of the ventricular septum were measured respectively at immediate,30′,60′,90′ after aortic cross- clamp.After measuring temperature myocardial specimens were taken on the outflow tract of right ventricle for electron microscopic,histochemical and histological examinations.Long-term survival dogs (2～12 weeks) were killed and fult thick specimens of left ventricle were taken for pathologic observation. By means of comparative observation of temperature,arrest states,ele- ctron microscopic,histochemical and histological examinations and long-term pathologic observation,the results suggested that the myocardial protective solution employed in Group 1(K~+ 15mEq/L,osmolarity 347 mOsm/L) achieved the best myocardial protective effects.Our experimental results showed cold myocardial protective solution seems better than the cold Ringer's solution and the cold blood perfusion by intermittent aortic cross-clamp.As for the components of myocardial protective solution,15mEq/L of K~+ and 340～400 mOsm/L of osmolarity showed a better result.