The significance of multidose cardioplegia and hypothermia in myocardial preservation during ischemic arrest

A standard experimental protocol was developed to explore the optimal technique for myocardial preservation during 120 minutes of ischemic arrest followed by 30 minutes of reperfusion. Eight different experimental groups were evaluated with the use of an in vivo pig heart preparation. The parameters measured included myocardial contractility and compliance, myocardial blood flow, and endocardial/epicardial blood flow ratio. Myocardial preservation was inadequate after hypothermic arrest alone, cardioplegic arrest alone (at normothermia), and single-dose cardioplegia plus hypothermia. Adequate myocardial preservation was found only after hypothermia and multidose cardioplegia with either potassium (35 mEq. per liter) or magnesium-procaine solutions. Continuous cardioplegia and hypothermia, while providing a moderate degree of myocardial preservation, was not as satisfactory as multidose cardioplegia and hypothermia. No difference in myocardial preservation was apparent when potassium-induced cardioplegia was compared with magnesium-procaine-induced cardioplegia.     

Effect of multidose cardioplegia and cardioplegic solution buffering on myocardial tissue acidosis

Multidose administration of cardioplegic solution during cardiac operation is intended to maintain both electromechanical arrest of the heart and myocardial hypothermia as well as to remove accumulated metabolites of anaerobic glycolysis. This study was conducted to assess the effect of multidose infusion of three different types of cardioplegic solution on tissue acidosis during global myocardial ischemia. Three groups of five dogs each were placed on cardiopulmonary bypass and the aorta was cross-clamped for 3 hours. The hearts were maintained at a constant temperature (20 degrees C) and cardioplegic solution was infused at an initial dose of 500 ml and five supplementary doses of 250 ml administered every 30 minutes. Group 1 received a crystalloid solution weakly buffered with sodium bicarbonate, Group 2 received a blood-based solution, and Group 3 received a crystalloid solution strongly buffered with histidine (Bretschneider's solution). The buffering capacities of the solutions used in Groups 2 and 3 were 40 and 60 times, respectively, that of the solution used in Group 1. The average myocardial tissue pH at the end of 3 hours of ischemia was 6.54 +/- 0.07 in Group 1, 7.23 +/- 0.05 in Group 2, and 7.19 +/- 0.06 in Group 3 (Group 1 significantly lower than Groups 2 and 3). Multidose infusion of a cardioplegic solution with low buffering capacity was unable to prevent the progressive development of tissue acidosis during 3 hours of ischemia. However, the multidose infusion of either blood-based or crystalloid solutions with high buffering capacity completely prevented any further reduction of tissue pH after the first 30 minutes of ischemia.     

Antegrade crystalloid cardioplegia vs antegrade/retrograde cold and tepid blood cardioplegia in CABG.

BACKGROUND: This study evaluated the myocardial protective strategies in isolated coronary bypass surgeries. METHODS: One hundred and twenty-eight patients were prospectively randomized to 3 techniques of myocardial protection; group I (n = 47) antegrade/retrograde tepid blood cardioplegia, group II (n = 40) antegrade/retrograde cold blood cardioplegia with topical cooling, group III (n = 41) antegrade crystalloid cardioplegia with topical cooling. RESULTS: The incidence of spontaneous defibrillation was significantly higher in group I (p < 0.001) while the incidence of low cardiac output was not different between the 3 groups. The incidence of ventricular arrhythmia was higher in group III (p < 0.016 group III vs I). There was no significant statistical difference in hemodynamic recovery between the 3 groups. CK-MB levels were significantly lower in group I versus the other 2 groups, (p = 0.0013, 0.04). Acid release and oxygen extraction were higher in group II than in group I (p = 0.06) during cardioplegia and reperfusion. Lactate release was less in group I at the release of aortic cross-clamp, and reperfusion. There was no significant difference between the 3 groups in ICU stay, ventilation time, or hospital complications. CONCLUSIONS: Tepid blood cardioplegia showed superiority in metabolic and functional recovery, whereas crystalloid cardioplegia had the highest incidence of postoperative arrhythmias. There was no significant statistical difference between the 3 groups in hospital mortality and morbidity.     

Comparison of myocardial temperatures with multidose cardioplegia versus single-dose cardioplegia and myocardial surface cooling during coronary artery bypass grafting

Myocardial hypothermia with multidose cardioplegia has not been compared with single-dose cardioplegia and myocardial surface cooling with a cooling jacket in patients having coronary artery bypass grafting. In this study, 20 patients with three-vessel disease undergoing coronary bypass at 28 degrees C with bicaval cannulation, caval tapes, and pulmonary artery venting (4.9 +/- 0.7 grafts per patient) were prospectively randomized equally into group I (multidose cardioplegia) and group II (single-dose cardioplegia with a cooling jacket). The initial dose of cardioplegic solution was 1000 ml. Group I then received 500 ml of cardioplegic solution every 20 minutes, delivered into the aortic root and available grafts. In group II, after the cardioplegic solution had been administered, a cooling jacket covering the right and left ventricles was applied. In both groups temperatures were recorded every 30 seconds at five ventricular sites: (1) right ventricular epicardium; (2) right ventricular myocardium or cavity, 7 mm; (3) left ventricular epicardium; (4) left ventricular myocardium or cavity, 15 mm; and (5) septum, 20 mm. Group mean temperatures at each site at various times were compared within each group and between the two groups by analysis of variance. Aortic crossclamp time was 60.3 +/- 12.1 minutes in group I and 52.8 +/- 7.3 minutes in group II (p = 0.12); cardiopulmonary bypass time was 103.7 +/- 11.1 minutes in group I versus 87.7 +/- 12.7 minutes in group II (p less than 0.01). One minute after the cardioplegic solution was initially given, temperatures between groups at each site were not statistically different, but left ventricular epicardial temperatures within both groups were significantly higher than in the other four sites. Nineteen minutes after administration of the cardioplegic solution, temperatures in group I at all sites were higher than in group II. Similarly, throughout the entire period of aortic crossclamping, mean temperatures (except left ventricular myocardial site), maximum temperatures, and percentage of time all temperatures were 15 degrees C or higher were greater in group I than in group II. The following conclusions can be reached: 1. Initial myocardial cooling with 1000 ml of cardioplegic solution is not significantly limited by coronary artery disease but is suboptimal (16 degrees or 17 degrees C) in the inferior left ventricular epicardium because of continual warming from the aorta and subdiaphragmatic viscera. 2. Without myocardial surface cooling, excessive external myocardial rewarming to 18 degrees to 22 degrees C occurs within 20 minutes at all sites after delivery of the cardioplegic solution.(ABSTRACT TRUNCATED AT 400 WORDS)     

Clinical evaluation of normothermic cardiopulmonary bypass and cold cardioplegia.

BACKGROUND: To evaluate the validity of normothermic cardiopulmonary bypass (CPB) associated with topical hypothermia and cold cardioplegia technique. METHODS: In a clinical prospective trial, a consecutive series of 100 patients, homogeneous for demographics, clinical and operative data, undergoing coronary artery bypass surgery were randomized for hypothermic CPB (rectal temperature 28-32 degrees C group A, 50 patients) and normothermic CPB (rectal temperature 35-37 degrees C, group B, 50 patients). In both groups of patients cold crystalloid cardioplegic solution and topical hypothermia was used. RESULTS: During CPB group B patients had lower systemic vascular resistance (p=0.0001); they needed a significant (p=0.0001) increase in vasocostrictive. At the removal of aortic cross-clamp, a spontaneous sinus rhythm resumed in 48% of patients in group A and in 95% of group B patients (p=0.001). To disconnect CPB, vasoconstrictive drugs were used in 10% of patients in group B and in none of patients in group A (p=0.0001); vasodilating drugs were infused in 96% of patients in group A and in 40% of patients in group B (p=0.0001). In the immediate postoperative period, positive inotropic agents were used in 67% of patients in group A and in 22% of patients in group B (p= 0.0003); group B patients showed a more physiological rewarming, reduced periods of mechanical ventilation and an easier regulation of the volemia. CONCLUSIONS: In our clinical experience the technique of cold heart and warm body proved to be safe and effective in simplifying surgical procedures and facilitating postoperative management.     

Comparison of washed blood and oxygenator whole blood as vehicles for sanguinous multidose cardioplegia

The effects of washed blood or oxygenator-traumatized whole blood as vehicles for sanguinous cardioplegia were studied utilizing the isolated blood-perfused dog heart preparation. Hearts were subjected to 2 hr of potassium-induced arrest at 27 degrees C followed by 90 min of normothermic reperfusion. Washed blood cardioplegia (n = 7) contained blood washed thrice with saline while oxygenator blood cardioplegia (n = 6) contained whole blood which had been exposed to an extracorporeal circuit for 30 to 45 min. Cardioplegic solutions were administered at a perfusion pressure of 100 mm Hg every 15 min during arrest. While the arrest-reperfusion sequence caused minor variations in the mechanical, metabolic, and biochemical parameters tested, generally insignificant differences were found to exist between groups. Differences in coronary washout PCO2 appeared to be due to inherent differences between the two cardioplegic solutions. Thus, while washing blood may be thought to be beneficial and whole blood from the extracorporeal circuit may be theorized to have a deleterious effect on the myocardium, excellent recovery of mechanical function was observed with both cardioplegic solutions. The present study suggests that it is unnecessary to wash the sanguinous cardioplegic solution obtained from the cardiopulmonary circuit.     

Functional and metabolic effects of nicardipine on ischemic rat hearts with multidose potassium cardioplegia

This study was undertaken to assess the effect of a calcium antagonist, nicardipine (N), added in a cardioplegic solution on the ischemic myocardium. Isolated rat hearts were perfused with oxygenated Krebs Ringer Bicarbonate (KRB) solution by Langendorff's perfusion method and were subjected to 2 hours of ischemic arrest at 30 degrees C with multidose cardioplegia (every 30 min, for 5 min) and a subsequent 60 min of reperfusion. HR, LVP, coronary flow and oxygen tension of coronary effluent were monitored. Oxygen saturation of intracellular myoglobin and redox state of mitochondrial cytochrome aa3 in the myocardial cell were continuously measured throughout studies by a spectrophotometer. Oxygenated crystalloid cardioplegic solution (KRB) containing 25 mM of potassium was used. 40 rats were divided into 4 groups (10 rats each) according to the concentration of N (none, 0.5, 1 and 2 mg/L) in fully oxygenated potassium cardioplegic solution (PO2: 601 +/- 31 mmHg). The percent recovery of pressure-rate product after reperfusion was compared in each group and the optimal concentration of N was found to be 1 mg per liter of cardioplegic solution. No significant difference was found between Group Ia (N = 0 mg/L) and Group Ib (N = 1 mg/L) in metabolic or hemodynamic recovery after reperfusion. In other experiments, 40 rats in Group IIa (N = 0 mg/L, n = 20) and Group IIb (N = 1 mg/L, n = 20) received 10 ml of poorly oxygenated cardioplegic solution (PO2: 215 +/- 10 mmHg) on each reinfusion followed by a 25 min interval of ischemic arrest. The index of oxygen utilization, MVO2/pressure-rate product after reperfusion was significantly lower in Group IIb than in Group IIa (p less than 0.05). The results show that the addition of N (1 mg/L) to the cardioplegic solution preserved a more aerobic state (higher intracellular oxygen level) in the myocardium by further suppressing myocardial oxygen demand during the ischemic period which resulted in better myocardial protection. Therefore, it is concluded that the addition of N to the cardioplegic solution enhances myocardial preservation during myocardial ischemia.     

Myocardial oxygen tension during surgical revascularization. A clinical comparison between blood cardioplegia and crystalloid cardioplegia.

OBJECTIVE: The aim of this study was to assess the effect of cardioplegic solutions on myocardial oxygenation during surgical revascularization. METHODS: In 30 patients, randomized to receive crystalloid (CC) or blood (BC) cardioplegia, myocardial oxygen tension was measured continuously by polarography. RESULTS: The two groups were comparable in terms of patients' age, sex, pre-operative ejection fraction, coronary disease, perfusion time, and aorta cross-clamping time. However, the BC group required 22% more of cardioplegic solution to stop electrical activity of the heart. Throughout the pre- and post-cardiac arrest periods, oxygen tension between the two groups was similar. At the end of the observation (4th day), myocardial oxygenation increased over 200% in relation to the values before revascularization. During the first infusion of cardioplegia, oxygen tension in the CC group was lower compared to the BC group (0.1 mmHg vs 1.3 mmHg; P<0.05) being the only significant difference between the two groups during cardiac arrest. Throughout the cardiac arrest, myocardial oxygen tension was close to zero regardless of the type of cardioplegia used. Post-operatively, addition of oxygen to the respiratory air increased myocardial oxygenation by over 17% resulting in a positive correlation (r=0.94; P<0.05) between myocardial oxygen tension and peripheral saturation. CONCLUSIONS: In conclusion, the differences in myocardial oxygen tension between the CC and BC groups are trivial. Thus, any potential beneficial effect of blood cardioplegia compared to crystalloid cardioplegia must be due to other circumstances than its oxygen carrying capacity. An important observation is a significant increase in myocardial oxygenation during oxygen supplement to the respiratory air.     

Preservation of myocardial high-energy phosphates in open-heart surgery with deep general hypothermia and multidose crystalloid cardioplegia

Myocardial energy metabolism during deep general hypothermia (20 degrees C) and multidose crystalloid cardioplegia, and also during subsequent reperfusion, was studied in eight patients undergoing isolated aortic valve replacement. Six serial transmural biopsy samples from the left ventricular apex were analyzed for high-energy phosphates and their degradation products. Reductions in ATP, total adenine nucleotide content and energy charge were insignificant during cardioplegia, as were changes in adenosine and uric acid concentrations. During reperfusion, however, there was slight but significant reduction in total adenine nucleotide content, despite adequate oxygenation as indicated by reversal of lactate accumulation. These observations suggest that the reperfusion phase is accompanied by metabolic aberrations which are not overcome by good oxygenation in relation to the metabolic rate.     

Nicorandil pretreatment and improved myocardial protection during cold blood cardioplegia.

OBJECTIVE: The present study was designed to assess whether pretreatment with nicorandil enhanced myocardial protection provided by cold (15 degrees C) high-potassium (25 mmol/l) blood cardioplegia during open heart surgery. METHODS: Subjects were 40 patients with a variety of acquired heart diseases undergoing cardiac surgery involved cardiopulmonary bypass. They were randomly divided into two groups, 25 pretreated nicorandil (0.3 mg/kg) 30 minutes before aortic cross clamping, 15 not pretreated. After aortic cross clamping, the initial dose of cardioplegic solution (10 ml/kg) was administered through the ascending aorta and supplemental doses of cardioplegia (5 ml/kg) given each 30 minutes thereafter. Preoperative and postoperative cardiac troponin-T, myosin light chain 1 and cardiac enzymes were measured and hemodynamic data recorded. RESULTS: Postoperative serum creatine kinase and myosin light chain 1 were significantly lower in the nicorandil pretreatment group than in controls. Serum glutamic oxalacetic transaminase and troponin-T were lower and cardiac output was higher after surgery in the nicorandil group, although not statistically significant. CONCLUSION: This data suggests that pretreatment with nicorandil enhances the myocardial protection achieved by cold blood cardioplegia.     

Calcium paradox in an in vivo model of multidose cardioplegia and moderate hypothermia. Prevention with diltiazem or trace calcium levels

The production and prevention of calcium paradox injury in myocardium was studied in a canine model of cardiopulmonary bypass with multidose, moderately hypothermic, crystalloid cardioplegic solution. During 4 1/2 hours of global ischemia, three groups of six dogs each received one of three histidine-buffered cardioplegic solutions (500 ml initially and 250 ml every 30 minutes) at 27 degrees C. Group 1 cardioplegic solution was calcium free, group 2 solution contained a trace amount of calcium chloride (70 mumols /L), and group 3 cardioplegic solution was calcium free but contained diltiazem (150 micrograms/kg body weight). Left ventricular function measured as percent control of developed pressure revealed significantly greater (p less than 0.05) recovery in groups 2 and 3. Triphenyltetrazolium chloride staining showed 35% +/- 9% (mean +/- standard error) of heart mass necrosis in group 1 versus 0% and 0.5% +/- 0.4% in groups 2 and 3, respectively (p less than 0.001). Electron microscopy revealed ultrastructural changes characteristic of calcium paradox injury in group 1 myocardium. Calcium paradox injury was produced in an in vivo model of global myocardial ischemia and multidose cardioplegia despite moderate hypothermia and non-coronary collateral flow. The addition of either trace levels of calcium or diltiazem to the cardioplegic solution was effective in preventing this injury.     

冷温血停搏液联合灌注对瓣膜置换术中炎性细胞因子和自由基的影响

目的　评价冷温血停搏液联合灌注在瓣膜置换术中对血浆促炎性细胞因子和自由基代谢水平的影响 ,探讨更有效的心肌保护方法。方法　将 30例瓣膜病病人随机分为两组 :温血组 (A组 ,n =15 ) ,采用温血诱导心脏停搏、冷血维持与终末温血灌注心肌保护方法 ;冷血组 (B组 ,n =15 ) ,采用冷氧合血停搏液进行心肌保护。分别于心肺转流 (CPB)前 (T1)、CPB 30min(T2 )、CPB结束后30min(T3 )、4h(T4)、2 4h(T5)测定血浆白细胞介素 6 (IL 6 )、IL 8和MDA浓度及SOD活性。结果B组IL 6于T2 即升高 ,持续至T5;A组无明显变化 ,于T3 明显低于B组 (P <0 0 5 )。B组IL 8于T2升高 (P <0 0 1) ,至T3 达峰值 (P <0 0 1) ,于T5下降至基础值水平 ;A组在T3 ～T4较基础值明显升高 (P <0 0 5 ) ,于T2 ～T4均显著低于B组 (P <0 0 5 )。两组MDA均在T2 升高 ,持续至T4,但A组于T3 、T4显著低于B组 (P <0 0 5 )。B组SOD活性自T2 开始降低 ,持续至T4(P <0 0 1) ;A组无明显变化 ,且在T3 与B组比较有显著性差异 (P <0 0 5 )。结论　冷温血停搏液联合灌注对瓣膜病病人的心肌再灌注损伤的抑制效应优于冷血心脏停搏液。     

Protection of the immature heart. Temperature-dependent beneficial or detrimental effects of multidose crystalloid cardioplegia in the neonatal rabbit heart

There are conflicting reports of the detrimental or beneficial effects of hypothermic cardioplegia in the immature heart. We therefore investigated the temperature-dependence of myocardial protection and the ability of single-dose and multidose infusions of cardioplegic solution to protect the immature heart during hypothermic ischemia. Isolated, working hearts (n = 6 per group) from neonatal rabbits (aged 7 to 10 days) were perfused aerobically (37.0 degrees C) for 20 minutes before infusion (2 minutes) with either perfusion fluid (noncardioplegia control) or St. Thomas' Hospital cardioplegic solution and ischemic arrest (for 4, 6, and 18 hours) at various temperatures between 10.0 degrees and 30.0 degrees C. Hearts arrested with cardioplegic solution received either one preischemic infusion only (single-dose cardioplegia) or repeated infusions at intervals of 60 or 180 minutes (multidose cardioplegia). Ischemic arrest with single-dose cardioplegia for 4 hours at 10.0 degrees, 20.0 degrees, 22.5 degrees, 25.0 degrees, 27.5 degrees, and 30.0 degrees C resulted in 96.0% +/- 4.3%, 96.6 +/- 2.5%, 87.0% +/- 3.8%, 71.8% +/- 10.0% (p less than 0.05 versus 10.0 degrees C group), 35.1% +/- 10.3% (p less than 0.01 versus 10.0 degrees C group), and 3.0% +/- 1.9% (p less than 0.04 versus 10.0 degrees C group) recovery of preischemic cardiac output, respectively. With 6 hours of ischemia at 20.0 degrees C, single-dose cardioplegia significantly (p less than 0.01) increased the recovery of cardiac output from 20.9% +/- 13.1% (control) to 76.4% +/- 4.4%, whereas multidose cardioplegia (infusion every 60 minutes) further increased recovery to 97.8% +/- 3.8% (p less than 0.01 versus control and single-dose cardioplegia). In contrast, after 6 hours of ischemia at 10.0 degrees C, cardiac output recovered to 93.4% +/- 1.2% (control) and 92.3% +/- 3.1% (single-dose cardioplegia), whereas multidose cardioplegia reduced recovery to 76.9% +/- 2.2% (p less than 0.01 versus both groups). This effect was confirmed after 18 hours of ischemia at 10.0 degrees C; single-dose cardioplegia significantly increased the recovery of cardiac output from 24.5% +/- 10.9% (control) to 62.9% +/- 13.3% (p less than 0.05), whereas multidose cardioplegia reduced recovery to 0.8% +/- 0.4% (p less than 0.01 versus single-dose cardioplegia) and elevated coronary vascular resistance from 8.90 +/- 0.56 mm Hg.min/ml (control) to 47.83 +/- 9.85 mm Hg.min/ml (p less than 0.01). This effect was not reduced by lowering the infusion frequency (from every 60 to every 180 minutes).(ABSTRACT TRUNCATED AT 400 WORDS)     

Comparison of isothermic and cold cardioplegia in paediatric cardiac surgery

Background Use of isothermic blood cardioplegia is not widely reported in paediatric cardiac surgical practice. It is a prospective comparative study of isothermic versus cold cardioplegia done from July 2005 to October 2005. Methods Fifty patients were selected and divided into two equal groups. Group I, Isothermic blood cardioplegia, patients were cooled to 30° C, and cardioplegia given at the same temperature as circulating blood in cardiopulmonary bypass and repeated at 20 minutes. Cardioplegic heat exchanger was not utilized in cardiopulmonary bypass circuit. In group II, conventional cold cardioplegia, patients were cooled to 28–30° C. Cardioplegia was given at 7–10° C and was repeated every 30 minutes. To assess myocardial metabolic activity, myocardial oxygen consumption (MVO₂), myocardial glucose uptake, myocardial lactate and acidosis were measured, using arterial and coronary venous blood samples. Results Mean cardiopulmonary bypass time was significantly shorter in children receiving isothermic blood cardioplegia(69 v/s 96 minutes). Serum lactate after cardiopulmonary bypass in isothermic blood cardioplegia were lower (1.9 v/s2.9). There was less metabolic acidosis in isothermic group (pH 7.37 v/s 7.34). Glucose uptake was higher in isothermic group. Myocardial contractile function was slightly better in the isothermic group (Ejection Fraction −62 v/s 60 %). Conclusion Myocardium utilizes more oxygen and glucose after isothermic cardioplegia, but lactate and acid production were less. However they are not statistically significant and operative outcome was not different. Isothermic blood cardioplegia is a safe and cost effective alternative to conventional cold cardioplegia for children undergoing open heart surgery.     

Paradoxical effects of cardiac arrest by multidose potassium cardioplegia on myocardial lysosome integrity and phospholipid content

Multidose potassium cardioplegia is known to result in greater preservation of myocardial ATP content and better recovery of function as compared to cardiac arrest induced by aortic clamping. The present study was undertaken to assess the effects of this procedure on biochemical markers of tissue damage. Rat hearts undergoing either multidose cardioplegia or ischemic cardiac arrest were maintained at 18 degrees C for 1 or 2 hr and processed without reperfusion. Control hearts were processed at time zero. The activity of two lysosomal enzymes (beta-glucuronidase and acid phosphatase), as well as membrane phospholipid content, was measured in cardiac homogenates. One hour of arrest by either technique did not induce significant changes in these parameters. Two hours of arrest affected lysosomal integrity, as indicated by release of lysosomal enzymes into the cytosol. Soluble acid phosphatase activity averaged 44.7 +/- 1.3 mU/mg of protein in the hearts processed after 2 hr of cardioplegic arrest, and was significantly higher than that of control hearts (12.3 +/- 3.8 mU/mg of protein; P less than 0.01) and that of hearts subjected to 2 hr of ischemic arrest (29.2 +/- 4.5 mU/mg of protein; P less than 0.01 vs cardioplegic arrest; P less than 0.01 vs controls). Phospholipid content in hearts subjected to 2 hr of cardioplegic arrest was lower than in controls (0.49 +/- 0.06 micrograms Pi/mg of protein vs 0.76 +/- 0.03 micrograms Pi/mg of protein; P less than 0.01). In conclusion, 2 hr of hypothermic cardiac arrest was associated with biochemical indices of tissue damage.(ABSTRACT TRUNCATED AT 250 WORDS)     

Release of cardiac troponin I in antegrade crystalloid versus cold blood cardioplegia.

OBJECTIVE: The purpose of this study was to assess the efficacy of myocardial protection, comparing antegrade crystalloid cardioplegia with cold blood cardioplegia, in patients with preserved left ventricular function who were undergoing elective first coronary artery bypass grafting. Release of cardiac troponin I was used as a marker for the effectiveness of myocardial protection. METHODS: A consecutive series of 62 patients were randomly assigned to receive crystalloid or blood cardioplegia. Cardiac troponin I concentrations were determined in venous blood samples before the operation, immediately after unclamping, at 6, 9, 12, and 24 hours, and daily thereafter for 5 days. RESULTS: Rising levels of troponin I were found in all patients. The time course and peak release were similar in the crystalloid cardioplegia and the blood cardioplegia groups. No patients in either group had electrocardiographic evidence of perioperative myocardial infarction. Cardiac troponin I was able to detect small areas of myocardial damage, not revealed by electrocardiography or creatine kinase MB release. Aprotinin administration was associated with lower cardiac troponin I release in both groups. Cardiac troponin I was lower in patients whose conditions did not require electrical defibrillation after aortic unclamping, irrespective of cardioplegia type. The presence of a main stem lesion was associated with higher cardiac troponin I release only in the crystalloid cardioplegia group. CONCLUSIONS: Antegrade cold blood cardioplegia is equally effective as antegrade crystalloid cardioplegia in a randomized group of patients with preserved left ventricular function who were undergoing elective first coronary artery bypass grafting. Aprotinin administration resulted in lower cardiac troponin I release, whereas electrical defibrillation was related to a higher release irrespective of cardioplegia type. The presence of a main stem lesion resulted in higher cardiac troponin I release in the crystalloid cardioplegia group.     

Warm or cold continuous blood cardioplegia provides similar myocardial protection.

BACKGROUND: This study was performed to investigate the effect of temperature of blood cardioplegia on the recovery of postischemic cardiac function. METHODS: Pigs on cardiopulmonary bypass were subjected to global ischemia (30 minutes), followed by cold (n = 10) or warm (n = 11) continuous antegrade blood cardioplegia (45 minutes) delivered at 55-60 mm Hg. RESULTS: Global left ventricular function, evaluated by preload recruitable stroke work, decreased with cold cardioplegia from 91 (85-103) [mean (quartile interval)], at baseline, to 73 (55-87) erg x 10(3)/mL postbypass (p = 0.03), but was unchanged after warm cardioplegia; 110 (80-132) to 109 (71-175) erg x 10(3)/mL (p > 0.5). However, the difference between treatment effects was not significant (p = 0.25). Diastolic function, evaluated by end-diastolic pressure-volume relation, deteriorated without any difference between groups. Mean cardioplegic flow was similar between groups. Coronary vascular resistance increased at constant rate during warm cardioplegic delivery, but remained unchanged with cold cardioplegia (p = 0.001 between regression coefficients). CONCLUSIONS: No significant difference was found in postischemic functional recovery comparing cold and warm continuous blood cardioplegia. Cold cardioplegia is therefore preferred due to added safety of hypothermia.