Percutaneous cardiopulmonary bypass limits myocardial injury from ischemic fibrillation and reperfusion.

Percutaneous implementation of cardiopulmonary bypass (PCPB) with a synchronous pulsatile pump has been shown to be an efficient means of unloading the heart. Therefore, this technique may provide a practical and effective method for treating patients undergoing a major cardiac catastrophe who are unresponsive to the usual resuscitative efforts. We tested whether PCPB could effectively unload the heart and provide myocardial salvage during left anterior descending (LAD) coronary artery occlusion complicated by ventricular fibrillation in the canine model (n = 13). All 13 dogs fibrillated within 20 minutes of LAD occlusion, and none could be successfully resuscitated by manual cardiac compression, sodium bicarbonate administration, antiarrhythmic agent administration, and electrical defibrillation. All 13 dogs were then placed on PCPB by way of the right jugular vein and right femoral artery; in seven, we used a synchronous pulsatile pump and in six a standard roller pump. No vent was placed in the left ventricle. All animals returned to normal sinus rhythm within 20 minutes of institution of PCPB. The LAD snare was released after 2 hours, and all animals were maintained on PCPB during 3 hours of reperfusion. At sacrifice, the area of infarction was determined by staining with triphenyltetrazolium chloride and was expressed as a percentage of the left ventricular area-at-risk for infarction. The tension time index was also measured and expressed as percent change from baseline. The left ventricular area-at-risk for infarction was similar in both groups (31.5% for roller pump vs. 29.2% for pulsatile pump; p greater than 0.05), but the area of infarction as a percentage of the area at risk was significantly smaller in the pulsatile-pump group (22.0%) than in the roller-pump group (35.4%; p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of methods for limiting myocardial infarct expansion during acute reperfusion--primary role of unloading.

Current use of angioplasty, thrombolysis, and surgical techniques for prompt reperfusion of an acute myocardial infarction raises questions concerning the optimum reperfusion technique for maximum myocardial salvage. Alterations in the conditions of reperfusion and/or the composition of the initial reperfusate can exert a significant effect on the extent of myocardial salvage. In an effort to define an optimum reperfusion technique, we used 40 dogs in a series of experiments in which the left anterior descending coronary artery (LAD) was snared for 2 hr followed by reperfusion by one of five methods for 4 hr. In addition, in a control group(group I, n = 6) the LAD was occluded for 6 hr without any reperfusion. In group 2 (n = 12), simulating medical reperfusion, reperfusion was achieved by simply releasing the snare for 4 hr. Group 3 dogs (n = 6) were placed on pulsatile left atrial-femoral bypass throughout 4 hr of reperfusion. Group 4 dogs (n = 9) were placed on percutaneous, synchronized pulsatile cardiopulmonary bypass during reperfusion. The procedure in group 5 (n = 7) dogs simulated coronary artery bypass grafting with cardiopulmonary bypass and cold blood, low-Ca++ cardioplegia during reperfusion. Group 6 (n = 6) was treated similarly except that during reperfusion amino acid-enriched cardioplegia was administered by warm induction techniques. At the end of 4 hr of reperfusion, the left ventricular area of infarction was determined by triphenyltetrazolium chloride staining and expressed as a percentage of the left ventricular area at risk for infarction (area of infarction [AI]/area at risk [AR]).(ABSTRACT TRUNCATED AT 250 WORDS)

Percutaneous cardiopulmonary bypass with a synchronous pulsatile pump combines effective unloading with ease of application.

Percutaneous total cardiopulmonary bypass offers the advantage of rapid, simple implementation without the need for thoracic incision and provides the ability to support both left and right ventricular failure as well as pulmonary insufficiency. Previous studies using roller pump percutaneous bypass were only partially successful because of the inability to effectively unload the left ventricle. In the present experiment we attempted to determine in a normal canine model whether use of synchronous pulsatile pumping for percutaneous bypass could overcome this problem. Fourteen dogs were placed on percutaneous bypass for 1 hour. A roller pump was used in seven and a synchronous pulsatile pump with an electrocardiogram triggering mechanism in the other seven. All animals were maintained on percutaneous bypass for 1 hour. In the pulsatile pump group there was a significantly greater percent decrease from baseline in tension-time index (-56.3% versus -19.1%, p less than 0.01) and in myocardial oxygen consumption (-45.8% versus +2.1%, p less than 0.05) and a significantly greater percent increase in the endocardial/epicardial blood flow ratio (27.6% versus -6.5%, p less than 0.01) than in the roller pump group. These results show that superior unloading can be achieved by percutaneous pulsatile bypass compared with percutaneous roller pump bypass. The findings suggest that percutaneous total cardiopulmonary bypass with a synchronous pulsatile pump offers a relatively simple but effective method for providing appropriate patients with temporary hemodynamic stability before cardiac catheterization or medical or surgical revascularization.