Knowledge and perceptions of medical abortion among potential users

Great advances in surgical techniques, perfusion technology and cardiac anesthesia have made heart surgery safer. However, the mayor advance over the past 15 years has been in the field of myocardial protection. Much remains to be done in this field and there is not complete agreement about the different methods of myocardial protection. At the Institute of Cardiac Surgery of Parma a research is developing to concern three different cardioprotective strategies, of which preliminary results are showing. Three groups of patients with the same clinical, surgical, anesthesiological features, who underwent cardiac surgery have been selected. In patients of group A intermittent cold hyperkalemic crystalloid cardioplegia has been used, in those of group B intermittent cold blood cardioplegia and in those of group C intermittent cold blood cardiolegia associated a warm glucose blood cardioplegic reperfusion before aortic unclamping. In all patients enzyme levels (CPK; CPK-MB; LHD; SGOT; SGPT) were measured 12, 24, 72, 120 hours postoperatively; data were collected, also, on spontaneous return to sinus rhythm, perioperative myocardial infarction and the need or not for inotropic agents. All data at first and then those of patients who underwent only coronary rivascularization (75% of patients) were statistically analyzed (one-way Fischer's test). It appears that the use of antegrade cold intermittent blood cardioplegia with reperfusion is more optimal for myocardial protection, how show lower levels of CPK-MB especially in the first postoperative period. In group C remains greater spontaneous resumption of normal sinus rhythm compare to group A and this suggests a best preservation of cellula-integrity and function with use of blood cardioplegia.     

Crystalloid cardioplegia route of delivery and cardiac troponin I release

BACKGROUND: Cardiac troponin I (CTn I) has been shown to be a marker of myocardial injury. Incomplete distribution of cardioplegic solution may be responsible for injury in jeopardized myocardial areas. The aim of this study was to compare CTn I release with respect to the route of delivery of crystalloid cardioplegia, either antegrade only or initially antegrade followed by retrograde cardioplegia for the remainder of the operation, in patients undergoing elective coronary artery bypass grafting. METHODS: Sixty patients were randomly assigned to one of two cardioplegia groups. Cardiac troponin I concentrations were measured in serial venous blood samples drawn just before cardiopulmonary bypass and after aortic unclamping at 6, 9, 12, and 24 hours and daily thereafter for 5 days. Analysis of variance with repeated measures was performed to test the effect of route of delivery, coronary disease, collateral circulation, risk of cardioplegia maldistribution, and number of grafts on release of CTn I. RESULTS: Compared with the antegrade route, the combined route offered no advantage in an unselected group of patients undergoing an elective first cardiac operation and having preserved left ventricular function. The CTn I concentration did not differ between groups for any of the samples considered. In patients with major left main coronary artery stenosis, CTn I release was significantly higher at hour 9 in the antegrade group than in the group with combined delivery. CONCLUSIONS: A combined route of delivery of crystalloid cardioplegia is beneficial in patients with major stenosis of the left main coronary artery. Cardiac troponin I sensitivity is relevant in this study. Release of CTn I should be useful in determining the best form of myocardial protection for each patient.     

Warm reperfusion and myocardial protection

BACKGROUND: The aim of this study was to determine whether warm reperfusion improves myocardial protection with cardiac troponin I as the criteria for evaluating the adequacy of myocardial protection. METHODS: One hundred five patients undergoing first-time elective coronary bypass surgery were randomized to one of three cardioplegic strategies of either (1) cold crystalloid cardioplegia followed by warm reperfusion, (2) cold blood cardioplegia followed by warm reperfusion, or (3) cold blood cardioplegia with no reperfusion. RESULTS: The total amount of cardiac troponin I released tended to be higher in the cold blood cardioplegia with no reperfusion group (3.9+/-5.7 microg) than in the cold blood cardioplegia followed by warm reperfusion group (2.8+/-2.7 microg) or the cold crystalloid cardioplegia followed by warm reperfusion group (2.8+/-2.2 microg), but not significantly so. Cardiac troponin I concentration did not differ for any sample in any of the three groups. CONCLUSIONS: Our study showed that the addition of warm reperfusion to cold blood cardioplegia offers no advantage in a low-risk patient group.     

Homeobox genes in hematopoiesis and leukemogenesis

The effect of cold and warm intermittent antegrade blood cardioplegia, on the intracellular concentration of taurine in the ischaemic/reperfused heart of patients undergoing aortic valve surgery, was investigated. Intracellular taurine was measured in ventricular biopsies taken before institution of cardiopulmonary bypass, at the end of 30 min of ischaemic arrest and 20 min after reperfusion. There was no significant change in the intracellular concentration of taurine in ventricular biopsies taken after the period of myocardial ischaemia in the two groups of patients (from 10.1 +/- 1.0 to 9.6 +/- 0.9 mumol/g wet weight for cold and from 9.3 +/- 1.3 to 10.0 +/- 1.3 mumol/g wet weight for warm cardioplegia, respectively). Upon reperfusion however, there was a fall in taurine in both groups but was only significant (P < 0.05) in the group receiving cold blood cardioplegia (6.9 +/- 0.8 mumol/g wet weight after cold blood cardioplegia versus 8.0 +/- 0.8 mumol/g wet weight following warm blood cardioplegia). Like taurine, there were no significant changes in the intracellular concentration of ATP after ischaemia in the two groups of patients (from 3.2 +/- 0.32 to 2.95 +/- 0.43 mumol/g wet weight for cold and from 2.75 +/- 0.17 to 2.62 +/- 0.21 mumol/g wet weight for warm cardioplegia, respectively). However upon reperfusion there was a significant fall in ATP in both groups with the extent of the fall being less in the group receiving warm cardioplegia (1.79 +/- 0.19 mumol/g wet weight for cold and 1.98 +/- 0.27 mumol/g wet weight for warm cardioplegia, respectively). This work shows that reperfusion following ischaemic arrest with warm cardioplegia reduces the fall in tissue taurine seen after arrest with cold cardioplegia. Accumulation of intracellular sodium provoked by hypothermia and a fall in ATP, may be responsible for the fall in taurine by way of activating the sodium/taurine symport to efflux taurine.     

Intermittent antegrade tepid versus cold blood cardioplegia in elective myocardial revascularization

BACKGROUND: The ideal temperature for blood cardioplegia administration remains controversial. METHODS: Fifty-two patients who required elective myocardial revascularization were prospectively randomized to receive intermittent antegrade tepid (29 degrees C; group T, 25 patients) or cold (4 degrees C; group C, 27 patients) blood cardioplegia. RESULTS: The two cohorts were similar with respect to all preoperative and intraoperative variables. The mean septal temperature was higher in group T (T, 29.6 degrees +/- 1.1 degrees C versus 17.5 degrees +/- 3.0 degrees C; p < 0.0001). After reperfusion, group T exhibited significantly greater lactate and acid release despite similar levels of oxygen extraction (p < 0.05). The creatine kinase-MB isoenzyme release was significantly lower in group T (764 +/- 89 versus 1,120 +/- 141 U x h/L; p < 0.04). Hearts protected with tepid cardioplegia demonstrated significantly increased ejection fraction with volume loading, improvement in left ventricular function at 12 hours, and decreased need for postoperative inotropic support (p < 0.05). The frequency of ventricular defibrillation after cross-clamp removal was lower in this cohort (p < 0.05). There were no hospital deaths, and both groups had similar postoperative courses. CONCLUSIONS: Intermittent antegrade tepid blood cardioplegia is a safe and efficacious method of myocardial protection and demonstrates advantages when compared with cold blood cardioplegia in elective myocardial revascularization.     

How to protect hypertrophied myocardium? A prospective clinical trial of three preservation techniques

Protection of the hypertrophied myocardium during heart surgery is still a controversial matter. We prospectively studied 3 currently available preservation techniques in 60 patients operated on for isolated aortic stenosis. Patients were randomly assigned to one of the following groups: CWB: continuous warm blood cardioplegia ICB: intermittent cold blood with warm blood controlled reperfusion Cryst: intermittent cold crystalloid cardioplegia (SLF11, Biosédra Laboratory, Vernon, France). All groups were matched for age, ejection fraction, NYHA class, aortic valve surface, and operative risk score. There were no deaths. No statistically significant difference was found among the groups in terms of ventilatory support time, ICU stay time, hospitalization or atrial fibrillation occurrence. Blood gases in the coronary sinus at the time of clamp release showed deep acidosis with crystalloid cardioplegia (pH = 7.11 vs 7.39 for CWB and 7.38 for UCB, p < 0.0001) associated with a higher lactate production than in the other groups (1.3 mmol vs 0.5 for CWB and 0.58 for ICB, p < 0.0001). Acidosis was corrected at the end of bypass with no significant differences among groups. CK-MB samples were taken on arrival in ICU, then 6 and 24 hours later. These samples showed much higher levels with cold blood (H6: 70 mcg/l vs 33 for CWB and 45 for Cryst, p = 0.0019). Although the 3 types of cardioplegia may be safely used for isolated aortic stenosis surgery, continuous warm blood cardioplegia appears to be the best choice.     

A study of the 30 minutes following reperfusion after crystalloid and cold blood cardioplegia by enzymatic and metabolic analysis of coronary blood flow

Post-ischemic reperfusion phenomena were studied in two methods of myocardial protection: crystalloid cardioplegia (St Thomas n(o) 2) and cold blood cardioplegia (Buckherg) during cardiopulmonary bypass for human myocardial revascularisation. Myocardial protection was assessed on the course of hemodynamic parameters, reperfusion arrhythmias and biochemical analysis of the coronary flow after cross-clamp removal: creatine phosphokinase (CPK-MB) and nucleotide adenine metabolites (adenosine, inosine, hypoxanthine, xanthine and uric acid). The study was performed in two groups of 14 patients. Hemodynamic conditions were similar in both groups during reperfusion in order to avoid different coronary flow. Under these conditions, myocardial protection by cold blood cardioplegia reduced reperfusion arrhythmias, and resulted in a loss of CPK-MB release. Furthermore, cold blood cardioplegia provided protection of myocardial energy metabolism by reducing the loss of metabolites, purine bases and oxypurine bases into the coronary sinus. Our results also show that hypoxanthine is probably the final product of ATP degradation in human myocardial tissue.     

Lidocaine cardioplegia for prevention of reperfusion ventricular fibrillation

Lidocaine addition to crystalloid cardioplegic solution for prevention of reperfusion ventricular fibrillation after the release of the aortic cross-clamp was studied in 50 patients undergoing coronary artery bypass grafting and in 30 patients undergoing mitral or aortic valve replacement. Twenty-six of the patients undergoing coronary artery bypass grafting received lidocaine, 100 mg/L of cardioplegia, whereas a control group of 24 patients received cardioplegia without lidocaine. In the group undergoing valve replacement, 14 patients received lidocaine cardioplegia and 16 patients served as control. In the coronary artery bypass grafting group, lidocaine cardioplegia reduced significantly the incidence of reperfusion ventricular fibrillation from 100% to 42%. In the valve group, lidocaine cardioplegia also reduced significantly the incidence of reperfusion ventricular fibrillation from 93% to 42%. In both groups, lidocaine cardioplegia decreased the number of direct-current countershocks required to defibrillate the heart, with no significant increase in the incidence of high-grade atrioventricular block.     

Clinical trial of retrograde warm blood reperfusion versus standard cold topical irrigation of transplanted hearts

BACKGROUND: A prospective, randomized clinical study involving 34 patients undergoing heart transplantation compared myocardial preservation of donor hearts maintained with continuous reperfusion with retrograde warm blood cardioplegia during surgical implantation versus the standard cold topical irrigation. METHODS: Hearts in both groups were arrested with a standard crystalloid solution and maintained in a cold saline solution during transportation. In the retrograde group, cardioplegia was administered through a catheter in the coronary sinus during surgical implantation. An average of 471 +/- 30 mL of hyperkalemic crystalloid solution diluted 1:4 in warm blood from the oxygenator was infused. In the standard group, the heart was kept cold by topical irrigation of cold saline solution and was reperfused only when the ascending aorta was unclamped. RESULTS: Preoperative characteristics of donors and recipients were similar in the two cohorts. Ischemic time average 139 +/- 12 minutes in the retrograde group compared with 130 +/- 11 minutes in the standard group (p = 0.57). Cardiopulmonary bypass time averaged 89 +/- 4 minutes in the retrograde group and 110 +/- 12 minutes in the standard group (p = 0.12). Defibrillation at reperfusion was performed in 4 patients (4/17, 24%) in the retrograde group and 12 patients (12/18, 67%) in the standard group (p = 0.01). There were no deaths in the retrograde group (0/17), whereas in the standard group, 3 patients (3/17) died of early graft failure (p = 0.11). Four early graft failures occurred in the standard group (p = 0.06). Two patients (2/17, 12%) were weaned from bypass with ventricular assist devices in the standard group. The number of subendocardial necrotic cells in the first two weekly endomyocardial biopsy specimens averaged 2.7 +/- 0.8 cells/mm2 in the retrograde group and 5.9 +/- 2.4 cells/mm2 in the standard group (p = 0.12). CONCLUSIONS: Retrograde warm blood reperfusion appears to improve the initial recovery of transplanted hearts. The technique is easy to use and may be a useful approach to graft protection during surgical implantation.     

The effects of using a leukocyte removal filter during cold blood cardioplegia

During myocardial ischemia, neutrophils and platelets exert negative effects on the myocardium. In this study, we used a leukocyte removal filter during cardioplegia, and investigated its effect on myocardial damage during reperfusion by measuring the plasma levels of granulocyte components, platelet components, and cardiac enzymes [creatinine phosphokinase (CK) and creatinine phosphokinase myocardial band (CK-MB)] in 24 patients who underwent cardiopulmonary bypass. The patients were divided into two groups of 12 according to whether or not a filter was placed in the cardioplegic route. Blood samples were drawn directly from the coronary sinus before aortic cross clamping, and at 1, 5, and 15 min after declamping. Group F, which had the filter, showed better cardiac enzyme and lipid peroxidation results than group N, which did not. The results of this study suggest that the application of a filter during cold blood cardioplegia may reduce myocardial damage.     

Ischemic preconditioning prior to myocardial protection with cold blood cardioplegia in coronary surgery

OBJECTIVE: Encouraging results on myocardial preconditioning in experimental models of infarction, stunning or prolonged ischemia raise the question whether preconditioning techniques may enhance conventional cardioplegic protection used for routine coronary surgery. METHODS: A prospective clinical trial was conducted to investigate the effect of additional ischemic normothermic preconditioning prior to cardioplegic arrest applying cold blood cardioplegia in patients scheduled for routine coronary surgery (3 vessel disease, left ventricular ejection fraction > 50%). Two cross clamp periods of 5 min with the hearts beating in sinus rhythm were applied followed by 10 min of reperfusion, each (n = 7, group I). Inducing moderate hypothermia cold blood cardioplegia was delivered antegradely. In control groups, cold intermittent blood cardioplegia (n = 7, group II) was used alone. Coronary sinus effluents were analyzed for release of creatine kinase (CK), CK-MB, lactate, and troponin T at 1, 3, 6, 9, and 12 h. In addition, postoperative catecholamine requirements were monitored. RESULTS: The procedure was tolerated well, and no perioperative myocardial infarction in any of the groups studied occurred. Concentrations of lactate tended to be higher in group I, but this difference was not significant. In addition, no significant differences for concentrations of CK, CK-MB, and troponin T were found. Following ischemic preconditioning an increased dosage of dopamine was required within the first 12 h postoperatively (group I: 2.63 +/- 1.44 microg/kg/min, group II: 0.89 +/- 1.06 microg/kg/min). CONCLUSIONS: Combining ischemic preconditioning and cardioplegic protection with cold blood cardioplegia does not appear to ameliorate myocardial protection when compared to cardioplegic protection applying cold blood cardioplegia alone. Inversely, contractile function seemed to be impaired when applying this protocol of ischemic preconditioning.     

Molecular cloning of cDNA for pro-phenol-oxidase-activating factor I, a serine protease is induced by lipopolysaccharide or 1,3-beta-glucan in coleopteran insect, Holotrichia diomphalia larvae

BACKGROUND: To evaluate the effects of minimally diluted tepid blood cardioplegia, a prospective, randomized study was undertaken. METHODS: Thirty-seven patients undergoing isolated primary coronary artery bypass grafting were randomized to receive standard 4:1 diluted tepid blood cardioplegia (4:1 group, n = 18) or minimally diluted tepid blood cardioplegia (Mini group, n = 19). Cardioplegic solution was delivered in an intermittent antegrade fashion in both groups. Myocardial oxygen and lactate metabolism, release of the MB isoenzyme of creatine kinase and thiobarbituric acid reactive substances, and cardiac function were measured during and after the operation. RESULTS: Myocardial oxygen consumption was significantly greater and lactate release was significantly lower in the Mini group than in the 4:1 group during cardioplegia. Minimally diluted blood cardioplegia resulted in more prompt resumption of lactate extraction, lower levels of release of the myocardial-specific isoenzyme of creatine kinase and thiobarbituric acid reactive substances during reperfusion, and better postoperative left ventricular function compared with the standard 4:1 cardioplegia. CONCLUSIONS: Minimally diluted tepid blood cardioplegia may provide superior myocardial protection than the standard 4:1 dilution technique by optimizing the aerobic environment through an increase in oxygen supply during intermittent cardioplegia.     

The versatility of anterograde/retrograde cardioplegia in heart surgery

Eighty patients underwent open-heart surgery from March 1990 to March 1993. We used combined aortic root (antegrade)/coronary sinus (retrograde) perfusion for cardioplegia delivery as a means of myocardial protection. The special retroplegia cannula was introduced to the coronary sinus (CS) in 67 patients by the transatrial (blind intubation) after one cannula cava insertion; the CS was cannulated under direct vision by right atriotomy after bicaval cannulation in 13 patients. Varied and prolonged cardiac procedures were done using cooled crystalloid cardioplegia (4 centigrades + potassium) except in one patient with severe ventricular damage in whom warm blood cardioplegia was infused. There was no CS or cardiac vein damage or disruption. There was no A-V blockade. The CS was intubated easily in all cases and cardioplegia solution readily infused. Coronary sinus pressure never exceeded 40 mm Hg. Overall hospital mortality (30 days postoperative) was 3.75% (3 cases). Sepsis was the cause of death in 2 patients and stroke in one. Inotropes were used in few cases as a means of renal protection. We conclude that the combined antegrade/retrograde cardioplegia delivery can be used routinely in most patients undergoing open-heart surgery.     

Clinical experience with continuous warm blood cardioplegia

We applied the Continuous Warm Blood Cardioplegia (CWBC) as an approach to improve myocardial preservation. From March to June in 1992, we used the CWBC in six patients and the conventional cold crystalloid cardioplegia (CCCP) in seven patients. All of them underwent isolated coronary artery bypass grafting. There was no marked difference between the CWBC and CCCP in post operative serum level of creatine kinase (MB type), cardiac output and dose of dopamine during they weaned from cardiopulmonary bypass. All patients treated with CWBC spontaneously restored the normal sinus rhythm shortly after removal of the aortic crossclamp, which was distinct from the fact that the CCCP group showed no such recovery. This result suggest that CWBC kept high-energy phosphate level without disturbing production of ATP in myocardium. Furthermore, reperfusion injury was also likely to be prevented by CWBC.     

Antimicrobial activity in the skin of the channel catfish Ictalurus punctatus: characterization of broad-spectrum histone-like antimicrobial proteins

BACKGROUND: A major reduction in the energy demand of the myocardium results from the electromechanical arrest, and cooling contributes to a lesser degree to this reduction. It is from this assumption that strategies of myocardial protection, utilizing warm blood cardioplegic induction, followed by cold cardioplegia with terminal warm reperfusion before removal of the aortic cross clamp, became established as optimal myocardial protection. Continuous normothermic perfusion 'closed the loop' by avoiding myocardial ischemia and linking warm induction and terminal reperfusion. A series of laboratory and clinical data confirmed the benefits of warm heart surgery on myocardial function and metabolism. The disadvantages of continuous warm blood cardioplegia including disturbance of the operative field, led surgeons to administer warm hyperkalaemic blood intermittently as a new cardioplegic strategy. METHODS: This review examines the laboratory and clinical data with reference to the intermittent warm blood cardioplegia, to establish its experimental basis and place in clinical practice. CONCLUSIONS: Experimental observation and clinical application have established intermittent warm blood cardioplegia as a practical, effective and cheap myocardial protection technique, particularly with reference to coronary artery surgery.     

Prospective, randomized trial comparing blood and oxygenated crystalloid cardioplegia in reoperative coronary artery bypass grafting

OBJECTIVES: Reoperative coronary artery bypass grafting presents unique challenges for myocardial preservation. The purpose of this study was to compare oxygenated blood cardioplegia with oxygenated crystalloid cardioplegia during reoperative coronary artery bypass grafting using transesophageal echocardiography to assess regional wall motion of the left ventricle before and after cardiopulmonary bypass. METHODS: Sixty-one patients undergoing reoperative coronary artery bypass grafting were prospectively randomized to receive oxygenated blood cardioplegia or oxygenated crystalloid cardioplegia delivered with a combined antegrade-retrograde technique. Transgastric short axis views of the left ventricle were made with transesophageal echocardiography during the operation before cardiopulmonary bypass and immediately after cardiopulmonary bypass. Regional wall motion was graded by a blinded observer, and before cardiopulmonary bypass scores were compared with after cardiopulmonary bypass scores. RESULTS: No significant differences were found in the change in regional wall motion score from before cardiopulmonary bypass to after cardiopulmonary bypass between the blood and crystalloid cardioplegia groups. CONCLUSIONS: This study found blood and crystalloid cardioplegia to be equally efficacious for myocardial preservation during reoperative coronary artery bypass grafting.     

Evaluation of myocardial protection with DBcAMP in crystalloid cardioplegic solutions

The potential for myocardial protection during cardiac operation was evaluated by adding Dibutyryl cyclic AMP (DBcAMP) to the crystalloid cardioplegic solutions. We have compared the cold crystalloid cardioplegia with DBcAMP (Group D n = 15) and without DBcAMP (Group n = 20) in patients undergoing cardiac operation. In hemodynamics, both groups were no difference before and after operation. CPK and CPK-MB was significantly (p < 0.01) high level after cardiopulmonary bypass (CPB) in group C. Myoglobin was also high value after CBP in group C, but not significant. Myocardial oxygen extraction rate and coronary blood PCO2 release were similar change in both groups. Insulin/glucose ratio was high level during and after CBP in group D. Myocardial lactate/pyruvate ratio was very high level after CBP in group C without significant difference. We consider that the cardioplegic solution with DBcAMP is effectual for the myocardial metabolism and preservation of myocardial damage during cardiac arrest.     

Aspartate kinase from the cyanobacteriium Plectonema boryanum infected with the cyanophage LPP-3

During normothermic cardiopulmonary bypass (CPB), the body temperature is maintained at 37 degrees C. Since 1987, it has been our standard practice to use normothermic CPB in our patients undergoing a cardiac operation, and our experience now consists of more than 3,000 consecutive patients. Myocardial protection is achieved through the combination of cold intermittent antegrade blood cardioplegia, no topical cooling, and a terminal "hot shot" of blood cardioplegia. We disagree with the stance of the Toronto group that normothermic CPB requires the administration of large volumes of cardioplegic and crystalloid solutions and the frequent use of phenylephrine hydrochloride to ensure a low systemic vascular resistance. To establish a routine technique of cold heartwarm body bypass, we conducted a clinical study in 100 consecutive patients with coronary artery disease. We found that the total cardioplegia volume needed in our patients was 1,946 +/- 257 mL, versus 4,700 +/- 1,900 mL in the Toronto study, and an additional crystalloid volume loading of 400 +/- 141 mL during CPB was needed in 26% of our patients, versus a total volume of 3,650 +/- 800 mL in the Toronto series. Phenylephrine (250 micrograms) was used in 16% of our patients, versus 88% of the patients in the Toronto study (mean dose, 1.3 mg). During normothermic CPB, the mean radial arterial pressure was 57.3 +/- 9.4 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)     

The use of cluster analysis for cell typing

BACKGROUND: Experiments were designed to evaluate the effect of warm blood cardioplegia on endothelium-dependent contraction of the coronary endothelium after cardiac global ischemia and reperfusion. METHOD: Dogs (n = 12 in each group) were exposed to extracorporeal circulation with the body temperature at 37 degrees C (group 1) or 28 degrees C (groups 2 and 3). The ascending aorta was crossclamped for 120 minutes while continuous infusion of warm blood cardioplegec solution (group 1) or intermittent infusion of cold (4 degrees C) crystalloid cardioplegic solution (group 2) was performed via the coronary arteries through the aortic root. Cardioplegic solution was not used in group 3 animals. The heart was then allowed to function for 60 minutes of reperfusion. Reperfused (groups 1, 2, and 3) and control (group 4) coronary arteries were then harvested for study. RESULTS: Perfusate hypoxia caused endothelium-dependent contraction in the arteries of all four groups that could be attenuated by NG-monomethyl-L-arginine (L-NMMA) or L-NMMA plus D-arginine, but not by L-NMMA plus L-arginine or endothelin receptor A and B antagonist PD 145065. The endothelium-dependent contraction results in groups 2 and 3 (75% +/- 4% and 80% +/- 5%, respectively) were significantly greater than those in groups 1 and 4 (15% +/- 3% and 18% +/- 5%, respectively). Scanning electron microscope studies showed that platelet adhesion and aggregation, areas of microthrombi, disruption of endothelial cells, and separation of the intercellular junction could be found in coronary segments from groups 2 and 3, but not in vessels from groups 1 and 4. CONCLUSION: These experiments suggest that global ischemia and reperfusion enhances hypoxia-mediated endothelium-dependent contraction of the coronary endothelium and damages the ultrastructure. These kinds of changes can be prevented by continuous antegrade infusion of warm blood cardioplegic solution during global ischemia.     

A clinical application of histidine buffered cardioplegia

Blood cardioplegia has been widely accepted due to better oxygen delivery, pH buffering and free radical scavenge. We have found that a crystalloid cardioplegia solution formulated to accelerate anaerobic glycolysis with high buffering capacity. To conserve blood cardioplegia, we formulated a crystalloid cardiopletia containing 100 mM histidine for buffering. This cardioplegia (HBS) was compared to cold blood cardioplegia in patients requiring open heart surgery. Eighty patients including HBS (n = 28), and CBC (n = 40) were involved in this study. Left ventricular end-systolic elastance (Emax; mmHg/cm3) was evaluated pre- and postoperatively. Cardiac index and inotropic requirement were also monitored at 1, 3, and 12 hours after cardiopulmonary bypass. There was no death in either group. All hearts returned to previous rhythm in HBS group, whereas total 12 DC cardioversions were requested in 6 patients. Emax was significantly higher in HBS group (5.2 +/- 0.6 mmHg/cm3) than in CBC group (3.4 +/- 0.4 mmHg/cm3). Cardiac index was also significantly higher in HBS group postoperatively than in CBC group with lower inotropic requirements. We conclude that histidine containing crystalloid cardioplegia provides excellent recovery of cardiac performance with lower inotropic requirements in open heart surgery. The ease of use, and lack of blood are other important advantages of this crystalloid cardioplegia.