Simultaneous antegrade/retrograde cardioplegia protects myocardium distal to a coronary occlusion: a study in isolated pig hearts

A simple method of placing a coronary sinus catheter through the femoral vein in miniature swine

The aim of the present study was to evaluate the feasibility of placing a coronary sinus (CS) catheter through the femoral veins of miniature swine. A total of 16 male domestic pigs (3-4 months old, 25±2 kg) were used. Firstly, the anatomic structure of the CS ostium of swine heart was observed at different angles under X-ray. The guide wire and Cobara catheter were subsequently advanced into the right atrium through the femoral vein. Subsequently, the guide wire was retracted behind the fix curve of the Cobara catheter and the catheter bent spontaneously in the absence of supporting guide wire following retraction. The catheter was then gently rotated clockwise to direct the catheter tip to the left allowing the catheter to easily be placed in the CS ostium. This method was associated with a short procedure time: The time on separation of the blood vessels was 15.5±5.8 min and the time of radiation exposure was 112±20 sec. The success rate of placing the catheter to CS ostium was 100%. Only one pig experienced a hematoma after the sheath was pulled out. All swine recovered without serious complications, such as perforation of coronary vein and pericardial tamponade. Therefore, this method of placing CS catheter is simple, safe and reliable, which may offer help for related research.

Effect of antegrade graft cardioplegia combined with passive graft perfusion in on-pump coronary artery bypass grafting

Patients undergoing on-pump coronary artery bypass graft (CABG) with proximal graft anastomosis were randomly divided into groups that received antegrade cardioplegic infusion only via the aortic root (group A) or antegrade cardioplegic infusion via the aortic root and additional cardioplegia via vein or free arterial grafts after completion of each distal anastomosis (group B). The group B patients also received bypass graft perfusion with warm arterial blood just after removal of the cross-clamp until the proximal graft anastomosis was completed. The need for defibrillation and inotropic support during separation from cardiopulmonary bypass (CPB), and total CPB time were significantly lower in group B than in group A. Group B also had significantly lower peak cardiac troponin I levels 12 h after operation compared with group A and this was more pronounced in subgroups with severe right coronary artery stenosis and poor left ventricular ejection fraction than in the whole population. It is concluded that antegrade graft cardioplegia and graft perfusion with warm blood during proximal graft anastomosis may improve myocardial protection.

Does normothermic normokalemic simultaneous antegrade/retrograde perfusion improve myocardial oxygenation and energy metabolism for hypertrophied hearts?

BACKGROUND

Beating-heart valve surgery appears to be a promising technique for protection of hypertrophied hearts. Normothermic normokalemic simultaneous antegrade/retrograde perfusion (NNSP) may improve myocardial perfusion. However, its effects on myocardial oxygenation and energy metabolism remain unclear. The present study was to determine whether NNSP improved myocardial oxygenation and energy metabolism of hypertrophied hearts relative to normothermic normokalemic antegrade perfusion (NNAP).

METHODS

Twelve hypertrophied pig hearts underwent a protocol consisting of three 20-minute perfusion episodes (10 minutes NNAP and 10 minutes NNSP in a random order) with each conducted at a different blood flow in the left anterior descending coronary artery (LAD [100%, 50%, and 20% of its initial control]). Myocardial oxygenation was assessed using near-infrared spectroscopic imaging. Myocardial energy metabolism was monitored using localized phosphorus-31 magnetic resonance spectroscopy.

RESULTS

With 100% LAD flow, both NNAP and NNSP maintained myocardial oxygenation, adenosine triphosphate, phosphocreatine, and inorganic phosphate at normal levels. When LAD flow was reduced to 50% of its control level, NNSP resulted in a small but significant decrease in myocardial oxygenation and phosphocreatine, whereas those measurements did not change significantly during NNAP. With LAD flow further reduced to 20% of its control level, both NNAP and NNSP caused a substantial decrease in myocardial oxygenation, adenosine triphosphate, and phosphocreatine with an increase in inorganic phosphate. However, the changes were significantly greater during NNSP than during NNAP.

CONCLUSIONS

Normothermic normokalemic simultaneous antegrade/retrograde perfusion did not improve, but slightly impaired myocardial oxygenation and energy metabolism of beating hypertrophied hearts relative to NNAP. Therefore, NNSP for protection of beating hypertrophied hearts during valve surgery should be used with extra caution.

Minimally-Diluted Blood Cardioplegia Supplemented With Potassium and Magnesium for Combination of 'Initial, Continuous and Intermittent Bolus' Administration

BACKGROUND

The present study was designed to examine the hypothesis that minimally-diluted blood cardioplegia (BCP) supplemented with potassium and magnesium provides superior myocardial protection in comparison with the standard-diluted BCP for a combination of 'initial, continuous, and intermittent bolus' BCP administration.

METHODS AND RESULTS

Seventy patients undergoing elective coronary revascularization between 1997 and 2001 (M : F =55:15, mean age 67.6+/-7.5 years) were randomly divided into 2 groups: Group C (n=35) was given the standard 4:1-diluted blood-crystalloid BCP, and Group M (n=35) was given minimally-diluted BCP supplemented with potassium-chloride and magnesium-sulfate. The BCP temperature was maintained at 30 degrees C. Cardioplegic arrest was induced with 2 min of initial antegrade BCP infusion, followed by continuous retrograde BCP infusion. Intermittent antegrade BCP was infused every 30 min for 2 min. The time required for achieving cardioplegic arrest was significantly shorter in Group M (47.5+/-16.3 vs 62.5+/-17.6 s, p<0.0001). The number of patients showing spontaneous heart beat recovery after reperfusion was significantly larger in Group M (28 vs 15, p=0.0029), and the number of patients suffering from atrial fibrillation during the postoperative period was significantly smaller in Group M (n=3 vs 11, p=0.034). Both the postoperative maximum dopamine dose (3.57+/-2.46 vs 5.44+/-2.23 microg/kg per min, p=0.0014) and peak creatine kinase-MB (19.5+/-8.5 vs 25.8+/-11.9 IU/L, p=0.0128) were significantly less in Group M. The number of patients showing paradoxical movement of the ventricular septum in the early postoperative echocardiography was significantly smaller in Group M (9 vs 24, p=0.0007).

CONCLUSIONS

These results suggest that 'initial, continuous and intermittent bolus' administration of minimally-diluted BCP supplemented with potassium and magnesium is a reliable and effective technique for intraoperative myocardial protection.