Fumiki Mori

Clinical trial of nicardipine cardioplegia in pediatric cardiac surgery

To clarify the effectiveness of nicardipine, one of the dihydropyridine calcium-channel blockers, for myocardial protection during cold potassium cardioplegic arrest in pediatric cardiac surgery, a clinical trial of nicardipine (0.25 mg/L) added to potassium cardioplegic solution was performed in children undergoing surgical repair of congenital heart diseases. Twenty patients were selected to receive nicardipine cardioplegia and 13 patients received a standard potassium cardioplegia, serving as a control group. Nicardipine cardioplegia provided better cardiac performance in the early postoperative period and reduced release of the MB isozyme of creatine kinase, as determined during a 48-hour postoperative period. These results suggest that nicardipine added to cold potassium cardioplegic solution offers additional protection for the myocardium during ischemia and postischemic reperfusion in pediatric cardiac surgery.

Effects of Coenzyme Q10 Added to a Potassium Cardioplegic Solution for Myocardial Protection during Ischemic Cardiac Arrest

To evaluate effects of coenzyme Q10 added to a potassium cardioplegic solution for myocardial protection, 17 mongrel dogs underwent 60 minutes of ischemic cardiac arrest under cardiopulmonary bypass. Cardiac arrest was induced by infusing the cardioplegic solution into the aortic root every 20 minutes. Experimental animals were divided into three groups according to the cardioplegic solution used. In Group 1, we used our clinical potassium cardioplegic solution (K+, 22.31 mEq/L); in Group 2, potassium cardioplegic solution with coenzyme Q10 added (coenzyme Q10, 30 mg/500 ml of solution); and in Group 3, cardioplegic solution with coenzyme Q10 solvent. Exogenous coenzyme Q10 in the cardioplegic solution provided significantly high myocardial stores of adenosine triphosphate and creatine phosphate and a low level of lactate during induced ischemia and reperfusion. Furthermore, percent recovery of the aortic flow in Group 2 was significantly higher than that in the other two groups. Ultrastructures of the ischemic myocardium in Group 2 were better preserved than those in Group 1. Addition of coenzyme Q10 to potassium cardioplegia resulted in improved myocardial oxygen utilization and accelerated recovery of myocardial energy metabolism after reestablishment of circulation.

Myocardial protection by a left ventricular assist device during reperfusion following acute coronary occlusion

To evaluate the effects of a left ventricular assist device (LVAD) during the reperfusion period following acute coronary occlusion, sixteen mongrel dog hearts were subjected to 1 hour’s occlusion of the circumflex coronary artery and then reperfused for 6 hours. In seven control dogs (control group), the hearts were reperfused without any support. In nine LVAD dogs (LVAD group), however, the left ventricles were supported by the application of a pneumatic driven diaphragm-type pump for 5 hours and then reperfused for another hour without any device. Triphenyltetrazolium chloride was used to determine the extent of infarction. The results showed a significant reduction in the area of infarct (AI) as a percentage of the area at risk (AR) in the LVAD group compared with the control group, the AI/AR being 22.3 per cent for the control groupversus 4.8 per cent for the LVAD group (p<0.05). The cardiac output was also significantly higher in the LVAD group compared with the control group. The per cent systolic shortening in the ischemic region of the LVAD group showed a significantly better recovery, being 75.8 per cent for the LVAD groupversus 24.4 per cent for the control group (p<0.01). It was concluded that the application of a LVAD during reperfusion after 1 hour’s coronary occlusion results in a significant reduction of infarct size and provides improvement in both regional and global cardiac function.

Malignant duodenocolic fistula--a case report.

A 63 year-old woman with a malignant duodenocolic fistula of colonic origin was so diagnosed following radiological examination. She had symptoms of feculant vomitus, persistent diarrhea and emaciation. Following preoperative treatment of the nutritional and electrolyte disorders with intravenous hyperalimentation, a one-staged right hemicolectomy and pancreatoduodenectomy was performed successfully. We emphasized that an en-bloc removal of all the possibly involved structures is the most successful procedure for malignant duodenocolic fistula of colonic origin.

Evaluation of a new calcium containing cardioplegic solution in the isolated rabbit heart in comparison to a calcium-free, low sodium solution

Isolated perfused rabbit hearts were studied to compare the effects of 3 hour ischemic arrest following either calcium-free or calcium-containing cardioplegia, on the recovery of isovolumic function of the left ventricle, coronary flow, release of creatine phosphokinase and myocardial water content. The hearts perfused with the calcium-containing solution (Ca 0.5 mmol/L) showed better recovery of the developed pressure in the left ventricle, and its first derivative and compliance. Coronary flow at a constant perfusion pressure was better restored during reperfusion in the hearts with calcium-containing solution. The release of less CPK and a lower water content were also observed in the hearts reperfused with calcium-containing solution. We concluded that calcium-containing cardioplegic solution with a high concentration of magnesium (10 mmol/L) was superior to calcium-free solution for myocardial protection.

Depression of host-defence mechanisms following cardiac surgery

The purpose of the present study was to determine the effects of open-heart surgery on host-defence mechanisms, by studying serial changes in serum immunoglobulins, circulating lymphocyte function in patients undergoing open-heart surgery. Serum proteins and immunoglobulins were significantly depressed immediately after operation and these depressions were correlated to the degree of the durations of cardiopulmonary bypass and associated hypothermia. White cell counts in peripheral blood increased significantly after operation. In contrast, total circulating lymphocytes were depressed postoperatively. The depression of circulating lymphocytes was mainly due to a marked decrease in the number of T-cells. Mitogen responses of lymphocytes stimulated by phytohemagglutinin were also depressed postoperatively. The quantitative and qualitative depression of cell-mediated immunity following open-heart surgery was observed. However, these depressions returned to preoperative levels in one week and had no clinical significance.

The effect of the left ventricular assist device on the myocardium during reperfusion after coronary artery occlusion

The effect of the left ventricular assist device (LVAD) during reperfusion after acute coronary occlusion was evaluated in a canine experimental model. The left circumflex artery was occluded for one hour, then reperfused for six hours immediately after removal of the occluder. Sixteen mongrel dogs were divided into the following two groups; a control group comprised of 7 dogs not given the LVAD support and another group comprised of 9 dogs (the LVAD group) assisted by LVAD for five hours during reperfusion. Throughout the study period, there was no significant difference in heart rate, aortic pressure or PA pressure between the two groups. However, LA pressure was significantly lower, while cardiac output, LV dp/dt, and LVSW were significantly higher in the LVAD group compared to the control group. Regional myocardial blood flow in the LCx area was significantly decreased after LCx occlusion in both groups but in the LVAD group, it recovered to the same level as before LCx occlusion after the beginning of reperfusion, while in the control group it remained significantly low throughout reperfusion. The LVAD group showed a positive myocardial lactate extraction in the early reperfusion period however, there was persistent lactate production in the control group. Thus, the unloading effect of LVAD during reperfusion after acute coronary artery occlusion improved regional myocardial blood flow and myocardial lactate metabolism and consequently, left ventricular function showed better recovery even after weaning from the LVAD support.

The effect of fluorocarbon emulsion on 24-hour canine heart preservation by coronary perfusion

This study was designed to evaluate the effects of fluorocarbon emulsion as an oxygen carrier in myocardial preservation. The hearts were preserved for 24 hours by coronary perfusion with either oxygenated crystalloid cardioplegic solution (group C) or crystalloid cardioplegic solution with fluorocarbon added (group FC). The perfusion pressure was kept at 20 mm Hg, and myocardial temperature was maintained at 4 degrees C. Group FC demonstrated better recovery in developed pressure and maximum rate of rise of left ventricular pressure compared with group C. The postpreservation end-diastolic pressure in group C increased significantly compared with the baseline value (value obtained before preservation). On the other hand, group FC showed no significant increase of end-diastolic pressure after preservation. Group FC released a significantly lower level of creatine kinase into its perfusate than did group C. Ultrastructural changes after preservation in group C showed severe ischemic injury, but there was no evidence of ischemic injury in group FC. The use of fluorocarbon emulsion proved beneficial to myocardial protection in long-term preservation of canine hearts.

Aneurysms of the descending aorta: Surgical experience with three methods of adjunct procedures

Thirteen patients were surgically treated for the repair of aneurysms of the descending aorta, using three different types of adjunct procedures—an external temporary bypass with a vascular prosthesis, a tridodecylmethylammonium chloride (TDMAC) or a partial cardiopulmonary bypass. There was no operative death, though one patient died 73 days following surgery. Significant intraoperative morbidity occurred in 3 patients: one had ventricular fibrillation and the other two massive hemorrhages. There was no instance of paraplegia or renal failure. The only significant complication that developed was pulmonary insufficiency in two patients with a pump bypass. The mean operative time and the mean aortic occlusion time in patients with the TDMAC shunt were shorter than the times in patients with the vascular prosthetic shunt or the pump bypass. TDMAC shunt required no special equipment and cannulation was simpler and safer.

Effect of combined dopamine and bunazosin on the ischemic heart after occlusion of the coronary artery

In order to investigate whether dopamine combined with bunazosin improves cardiac function, the global and regional cardiac function and regional blood flow of 7 anesthetized dogs were analyzed before and after occlusion of the left anterior descending coronary artery (LAD), then after 10 μg/kg/min dopamine infusion following the LAD occlusion, and again after a bolus infusion of bunazosin 250 μg/kg. Dopamine with bunazosin reduced left atrial pressure from 4.9±0.9 to 3.1 ±0.5 mmHg (p<0.05) and improved cardiac output from 1.22±0.15 to 1.50 ±0.14 L/min (p<0.05), maximum positive left ventricular dp/dt from 1721 ±202 to 3600±663 mmHg/sec (p<0.05) and the time constant from 45.2±5.0 to 27.5±4.6 msec (p<0.01). Bunazosin added to the dopamine reduced the elevated left ventricular peak systolic pressure caused by dopamine from 130±7 to 113±8 mmHg (p<0.01). With regard to the regional wall motion, the impaired LAD-ΔL (the segment systolic shortening) and LAD-Elmax (the slope of peak systolic pressure—endsystolic length relation) following the LAD occlusion improved from 0.5±2.5 per cent to 5.9±2.6 per cent (p<0.01) and from 50±9 to 82±14 mmHg/mm (p<0.01) after the infusion of dopamine with bunazosin. Dopamine greatly increased the Rate Pressure Product (RPP) from 12610±1120 after LAD occlusion to 16950±1420, whereas dopamine in combination with bunazosin did not increase the RPP due to a drop of LV-PSP with little change in regional myocardial blood flow. It was concluded that combining dopamine with bunazosin was useful for improving both the global and regional cardiac functions of the ischemic heart.