Cardiac Troponin T to evaluate myocardial protection via intermittent cold blood or continuous warm blood cardioplegia in coronary artery bypass grafting.

BACKGROUND: The aim of our study was to evaluate the efficacy of myocardial protection during coronary artery bypass grafting (CABG) in cold blood intermittent (CBIC) and warm continuous blood cardioplegia (WCBC). To assess myocardial necrosis, Troponin T, a structural protein belonging to the troponin complex, was measured. Troponin T is released in the blood stream 4 hours after myocardial damage, and it does not cross-react with the isomeric form of the skeletal muscle. METHODS: Our study involved 20 consecutive patients, scheduled for isolated CABG. They were divided into two groups: the first group (10 patients; 8 m, 2 f) underwent surgery with the use of CBIC, the second group (10 patients; 9 m, 1 f) with WCBC. The serum levels of cardiac Troponin T (cTn-T) were all <0.2 microg/l before operation. RESULTS: In the CBIC the mean cTn-T peaked on the 1st day after CABG, in the WCBC group the first peak occurred in the 2nd hour after arrival in the intensive care unit, and the second peak occurred on the 4th day postoperatively. The mean serum cTn-T was lower in the WCBC vs CBIC group from the 1st to the 5th day postoperatively, with a statistical difference on the 1st day (p<0.05). In the CBIC group either the cTn-T peak values (r=0.77; p<0.02) or area under the concentration curve of cTn-T release (r=0.85; p<0.004), were directly correlated with the aortic cross-clamping time. This was not demonstrated in the WCBC. CPK and CK-MB peaked in both groups 6 hours after arrival in the intensive care unit and on the 1st day postoperatively, with higher values at 6 hours in the WCBC group (p<0.05). The CK-MB/CPK ratio was significantly lower in the WCBC group at the six hours (p<0.05). CONCLUSIONS: The results of this preliminary study suggest that fewer necrosis markers are released during CABG in the WCBC group; in the CBIC group the release of cTn-T whether measured by peak serum level or by area under the curve, shows a statistically significant correlation with cross-clamping time. Warm blood cardioplegia is safe and supplies adequate myocardial protection during CABG; the more prolonged cross-clamping is, the more myocardial protection is afforded by WCBC.

Hemodynamic, respiratory, and metabolic effects of medium-chain triglyceride-enriched lipid emulsions following valvular heart surgery.

STUDY: A lipid emulsion containing 10 percent medium-chain triglycerides (MCT) and 10 percent long-chain triglycerides (LCT) was infused at a rate of 1 ml/kg/h (3.3 mg/kg/min) for 2 h, in 12 patients (2 males, 10 females; mean age, 54 +/- 3 (SEM) years; range, 34 to 67 years) 24 h after open-heart surgery (mitral valve replacement). METHODS: Hemodynamic factors (pulmonary and radial artery indwelling catheters), oxygen and carbon dioxide partial pressures, oxygen saturation, oxygen delivery and consumption, and intrapulmonary shunt fraction were obtained before, during, and after lipid infusion (for 2 h), at 30-s intervals, along with some metabolic indexes (triglycerides, free fatty acids, glucose, insulin, lactate, acetoacetate). RESULTS: No statistically significant changes in heart rate, cardiac index, systemic and pulmonary pressures and resistances, central venous and pulmonary capillary pressures, or arterial oxygen partial pressure were observed during infusion. Arterial carbon dioxide partial pressure values were constantly reduced throughout and after the end of lipid infusion, as compared with baseline values, while oxygen consumption was increased significantly without any change in oxygen delivery. No adverse effects on intrapulmonary shunt fraction were observed. Statistically significant increases of triglycerides, free fatty acids, acetoacetate and insulin (peak values at end of the lipid infusion) were found in comparison with baseline values. Plasma glucose increased significantly during lipid infusion and remained higher than baseline values until the end of the study. Lactate levels were unchanged except for a slight decrease at the end of the study, without any derangement of acid-base equilibrium. Neither arrhythmias nor adverse clinical reactions were observed as a consequence of lipid infusion. CONCLUSIONS: Fat emulsions containing both MCT and LCT, when given at 3.3 mg/kg/min for 120 min following valvular heart surgery, do not exert negative cardiopulmonary effects, and could represent a source of rapidly metabolized substrates.

Incidence of anti-hepatitis C virus antibodies in non-A, non-B post-transfusion hepatitis in an area of northern Italy.

A total of 210 patients consecutively submitted to heart surgery at the Parma University Hospital and transfused with 1,898 units of blood were followed after transfusion in order to evaluate both the incidence of anti-hepatitis C virus (HCV) seroconversion in non-A, non-B post-transfusion hepatitis (PTH-NANB) cases and the usefulness of the screening for anti-HCV in comparison with that for serum glutamic pyruvic transaminase (SGPT) values in preventing PTH-NANB transmission. Fifteen recipients developed PTH-NANB (group A); ten of them (66.6%) showed anti-HCV seroconversion within 3-12 months. Eight of the ten anti-HCV positive patients developed chronic hepatitis, but none of the five PTH-NANB anti-HCV negative did. None of the 15 controls (group B) randomly chosen among the patient population showed anti-HCV seroconversion. A close correlation with the transmission of PTH was showed by anti-HCV positivity but not by SGPT elevation in blood donors. Eleven of 172 blood products transfused to group A but none of 139 products transfused to group B were anti-HCV positive. The incidence of elevated SGPT values was similar between the two groups of the transfused blood products. Nevertheless, the correlation observed between anti-HCV positivity and SGPT levels in the blood products involved in PTH confirms the need to exclude blood donors with abnormal SGPT values. On the whole, anti-HCV screening of donors showed a predictive value higher than that of SGPT (100% vs. 53.3%), allowing a minor blood donation exclusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell metabolism in patients undergoing major valvular heart surgery: relationship with intra and postoperative hemodynamics, oxygen transport, and oxygen utilization patterns.

The relationships between cell metabolism and both hemodynamics and oxygen transport/utilization (VO2/DO2) pattern were evaluated intra and postoperatively in eight patients undergoing major valvular heart surgery with the aid of moderately hypothermic cardiopulmonary bypass (CPB). Quadriceps femoris specimens were obtained by the needle biopsy technique for muscle ATP, ADP, AMP, phosphocreatine (PCr), creatine and lactate determination at anesthesia induction, after CPB, as well as in the ICU 18 h after surgery. Moreover, hemodynamic variables, oxygen transport and utilization indices, and plasma lactate were measured at the same intervals and throughout the CPB period. After CPB, muscle ATP and PCr contents were reduced (p less than .05) as compared to those of both pre-CPB patients and healthy control subjects; muscle and plasma lactate levels were increased (p less than .05). Mean VO2 and DO2 values measured during CPB significantly decreased (p less than .05), but VO2 reduction was proportionally greater than that of DO2 (-62% vs. -41%). No correlation was found between VO2 and DO2 at that time, but a significant relationship (p less than .05) was found at the end of CPB. A further decrease in muscle ATP and PCr levels was measured in the ICU, as muscle and plasma lactate levels were still elevated. At that time, VO2 and DO2 were not significantly different from pre-CPB values, but were significantly (p less than .05) correlated with each other.(ABSTRACT TRUNCATED AT 250 WORDS)