Right Ventricular Function in Retrograde Cardioplegia for Myocardial Protection : An Experimental Study

Mongrel dogs were subjected to this study and were placed on cardiopulmonary bypass using a conventional heart-lung machine。Total aortic cross-clamping time was60minutes in all dogs.In group I 4°C St.Thomas‘Hospital solution was injected into the aortic root by the use of a syringe.Cardioplegic solution was replenished every20minutes with a half of the initial dose.Group II were the dogs with the retrograde cardioplegia in which the same solution was given retrogradely from the coronary sinus by the drip method at the hight of 60厘米，and the replenishing dose and interval of cardioplegia were the same as Group I.Group III was the dogs treated with retrograde cardioplegia identical to Group II and the combined use of topical cooling with ice-slush.The hearts were resuscitated after 60 minutes aortic of crosing.Right ventricular functions such as cardiac output，right atrial pressure，right ventricular enddiastolic pressure，right ventricular max dp/dt，and shortening fraction of the right ventricle were measured 15，30，45，and 60 minutes after cardiac resuscitation respectively。In group II，right atrial pressure was significantly elevated from the control value 15 and 30 minutes after cardiac resuscitation。On the other hand，all indices of right ventricular function in Group III showed insignificant change.The present experimental study demonstrated the retrograde cardioplegic method could produce poor right ventricular perfusion resulting in right ventricular dystunction early after cardiac resuscitation。This deleterious effect however could be prevented by the combined sue of topical cooling of the right ventricle with ice-slush.

Mongrel dogs were subjected to this study and were placed on cardiopulmonary bypass using a conventional heart-lung machine. Total aortic cross-clamping time was 60 minutes in all dogs. In group I 4゜C St. Thomas' Hospital solution was injected into the aortic root by the use of a syringe. Cardioplegic solution was replenished every 20 minutes with a half of the initial dose. Group II were the dogs with the retrograde cardioplegia in which the same solution was given retrogradely from the coronary sinus by the drip method at the hight of 60cm, and the replenishing dose and interval of cardioplegia were the same as Group I. Group III was the dogs treated with retrograde cardioplegia identical to Group II and the combined use of topical cooling with ice-slush.The hearts were resuscitated after 60 minutes of aortic cross-clamping. Right ventricular functions such as cardiac output, right atrial pressure, right ventricular enddiastolic pressure, right ventricular max dp/dt, and shortening fraction of the right ventricle were measured 15, 30, 45, and 60 minutes after cardiac resuscitation respectively. In group II, right atrial pressure was significantly elevated from the control value 15 and 30 minutes after cardiac resuscitation. On the other hand, all indices of right ventricular function in Group III showed insignificant change. The present experimental study demonstrated the retrograde cardioplegic method could produce poor right ventricular perfusion resulting in right ventricular dystunction early after cardiac resuscitation. This deleterious effect however could be prevented by the combined sue of topical cooling of the right ventricle with ice-slush.