Evaluation of myocardial damage in patients undergoing coronary-artery bypass procedures with halothane-N2O anesthesia and ajuvants

During a 6-month period in 1975, 102 patients undergoing scheduled coronary-artery bypass grafting were studied by both conventional ECG and heart-specific enzymatic methods to evaluate the incidence and estimate the extent of myocardial damage associated with an anesthetic management protocol using halothane as a primary agent with adjuvant agents. Anesthetic interventions were made to maintain heart rate and systolic pressure at resting levels or below the heart rate systolic pressure product documented during exercise-induced angina. These interventions included adjustment of halothane concentration in all patients, the use of adjuvant agents in 88.2 percent, vasodilators in 26.5 percent, and the precardiopulmonary bypass use of vasoconstrictor or cardiostimulants in 9.8 percent. There were 2 early postoperative deaths. ECG evidence of infarction was observed in 4 surviving patients. Sustained release of heart-specific CPK-MB isoenzyme occurred in 78 percent of surviving patients. Isoenzyme activity was detected in only 1 patients prior to cardiopulmonary bypass (CPB), in 1 patient during CPB, and in all others after termination of CPB. The extent of myocardial damage as estimated by integrating CPK-MB values over time was directly related to number of vessels grafted and to aortic cross-clamp and CPB times. The ECG and enzymatic data both document a low level of myocardial damage associated with this anesthetic management protocol.

Lactate dehydrogenase isoenzyme in detecting carriers of Duchenne muscular dystrophy

Thirty mothers of patients with Duchenne muscular dystrophy were studied with serum enzyme tests, including serum glutamic-oxaloacetic transminase, creatine kinase, and lactate dehydrogenase isoenzymes. In addition, females from the mothers' pedigrees were studied. Lactate dehydrogenase isoenzyme 5 determinations were as senitive an indicator of carrier status as creatine kinase and also identified several mothers who had normal dehydrogenase isoenzyme 5 determinations, as well as extensive pedigree testing, identified 28 to 30 mothers as probable heterozygotes. These data independently support the suggestion that cases of Duchenne muscular dystrophy as a result of spontaneous mutation are more uncommon than currently accepted.

Diagnosis of myocardial infarction by serum isoenzyme analysis

Serial monitoring of the serum isoenzyme patterns of creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) in patients suspected of acute myocardial infarction has become a highly sensitive and specific diagnostic method. The predictable evolution of isoenzyme patterns following infarction permits diagnosis and recognition of early stages, recovery stages and extension of infarction in the individual. Usual therapeutic and resuscitative manipulations do not interfere with evaluation of patients with angina or following cardiopulmonary arrest without infarction. Despite significant elevations of serum enzyme levels following general and cardiac operative procedures, the occurrence of myocardial necrosis in the surgical population can be recognized by detection of the specific CPK-MB isoenzyme.

The relationship between enzymatic and histologic estimates of the extent of myocardial infarction in conscious dogs with permanent coronary occlusion

Relationships between enzyme estimates (EE) and histologic measurements of infarct size (HIS) were analyzed in 14 conscious dogs with permanent occlusion of the circumflex coronary artery. EE were derived from serial CPK, CPK-MM, CPK-MB, and CPK-BB. Estimates were obtained using methods of Shell et al., Norris et al., and Roberts et al. HIS was determined from multiple histologic sections 5-6 days after infarction. In 14 animals, HIS ranged from 0.1-26.6 grams. Regression analysis demonstrated poor correlation (r2 less than 0.06) between EE by each method and HIS. Using the Shell method and restricting the analysis to HIS of less than 13 grams, improved the correlation (r2 = 0.42). Correlation in this subgroup could be further improved by using CPK-MM and MB data, elimination of animals with high background values, or limiting analysis to the portion of the curve where LDH isoenzymes indicated a cardiac zone. When the analysis was restricted to animals with HIS of less than 13 grams, Norris and Roberts modifications as compared to Shell's method improved correlation with CPK-MB but reduced correlation using CPK and CPK-MM data. In this subgroup, each method overestimated extent of HIS; Shell greater than Norris greater than Roberts. In this study it was not possible to distinguish small from large HIS by serum enzyme measurements.

Diagnostic and prognostic significance of electrocardiographic and CPK isoenzyme changes following coronary bypass surgery: correlation with findings at one year

The incidence of ECG (14 per cent) indication of acute myocardial infarction complicating coronary artery bypass surgery is documented, corroborating the findings of prior series. An additional 32 per cent of patients had appearance of myocardial specific CPK-MB in serum during the immediate postoperative period. All patients surviving to 1 year following surgery (93 of 103) were asked to return for repeat cardiac catheterization to determine the presence and extent of interim ventricular contraction abnormalities. Sixty-five (70 per cent) of the group returned for evaluation. Preoperative and 1 year postoperative left ventriculograms were compared to determine if new contraction abnormalities would confirm the specificity of perioperative QRS and isoenzyme changes, and if the absence of new abnormalities would confirm their sensitivity. The majority of patients (65 per cent) had new areas of asynergy. However, 73 per cent of these were confined to the apex and thus could have been produced by the vent employed during cardiopulmonary bypass. QRS changes were 100 per cent specific and CPK-MB appearance was 78 per cent specific but they were only 20 and 54 per cent sensitive, respectively. Indeed, 46 per cent of those with new asynergy which was non apical had neither QRS change nor CPK-MB appearance. Thus QRS changes were always--and CPK-MB appearance was usually--associated with new asynergy but, in addition, many patients with no perioperative indication of infarction developed new areas of left ventricular contraction abnormality within the first postoperative year.

Diagnosis of acute myocardial infarction in a community hospital: significance of CPK-MB determination

Twice-daily CPK-MB determinations were performed but not made availabe to the physicians of 179 consecutive patients with precordial pain admitted to a community hospital to evaluate the diagnostic importance of this isoenzyme. Physician decision was based upon history and once-daily ECG and total enzymes (CPK, SGOT, LDH). Following hospital discharge, each patient's clinical record was reviewed to determine the physician diagnostic decision. The patients were subdivided into three groups. The first group consisted of 46 patients with diagnostic QRS changes and elevated total enzymes. All 46 had physician diagnosis of acute myocardial infarction and CPK-MB was present in 44 (96%). The second group included 55 patients with nondiagnostic QRS but elevated total enzymes. Physician diagnosis was acute myocardial infarction in 28 (51%) but 16 (57%) of these had no CPK-MB. The third group contained 50 patients with nondiagnostic QRS and normal enzyme levels. Six (12%) had physician diagnosis of acute myocardial infarction but none had CPK-MB. Thus, absence of CPK-MB failed to confirm physician diagnosis of acute myocardial infarction when based upon history and total enzymes in the absence of QRS changes in 22 of 34 (65%) patients.

Persistence of MB isoenzyme of creatine phosphokinase in the serum after minor iatrogenic cardiac trauma. Absence of postmortem evidence of myocardial infarction

The specificity of serum CPK-MB for acute myocardial infarction was examined by retrospective analysis of 401 consecutive patients admitted to Coronary Care Unit over a three and one-half year period with suspected infarction in whom the isoenzyme was subsequently detected. Four patients (1 per cent) who died during the hospital admission had no autopsy evidence of acute myocardial infarction. All four had experienced mild iatrogenic cardiac trauma, following which serum CPK-MG persisted for at least 24 hours. In one patient, a permanent pacemaker had been inserted by the transmediastinal approach. Two patients had been subjected to closed chest cardiac massage and intracardiac puncture, and one to external cardiac massage alone. The findings suggest that persistent identification of serum CPK-MB, although specific for myocardial necrosis, cannot be regarded as diagnostic of myocardial infarction. The implications of this are important to treatment of patients after cardiopulmonary resuscitation and operative trauma to the heart.

Enzymatic alterations in Reye's syndrome: prognostic implications

Serial studies on serum enzyme and isoenzyme abnormalities in seven cases of Reye's syndrome were found to segregate patients into three categories of organ involvement. The patients with both extensive hepatic and previously unrecognized skeletal muscle involvement died despite therapeutic measures. The other two groups were characterized by enzyme and isoenzyme changes consistent with either predominantly muscular or hepatic involvement. The prognostic value of these abnormalities has been substantiated in subsequent cases of this syndrome. These findings suggest that those patients at greatest risk may be identified early, thus improving evaluation of the efficacy of specific therapeutic interventions in this disease.

Coronary perfusion versus cold ischemic arrest during aortic valve surgery. A randomized study

Sixty-four randomized patients undergoing primary, isolated, scheduled, prosthetic aortic valve replacement were studied to determine the safety of coronary perfusion and mild hypothermia (31 patients) and of cold ischemic arrest (33 patients). Cardiac performance, metabolism, and isoenzyme release and the electrocardiogram were studied early postoperatively. No differences greater than expected by chance were found between the two groups; however, the difference between group means of several hemodynamic variables was significantly larger than experimental error. Combined abnormalities of creatine phosphokinase (CPK) and lactic dehydrogenase (LDH) heart-specific isoenzymes, indicative of myocardial necrosis, were found in 33 of 48 patients (68.7%) so studied. The incidence was similar in both study groups. In 14 of 52 (27%) patients with electrocardiographic studies, changes indicative of new infarction or ischemia were demonstrated, but no differences in incidence between the two groups of patients were found. In both groups the transmyocardial excess lactate immediately postoperatively was elevated, falling to near normal over the next 24 hours. Aortic crossclamp and cardiopulmonary bypass times were less by 27% and 21% respectively when cold ischemic arrest was used.

Recognition of postoperative acute myocardial infarction. Application of isoenzyme techniques

Routine enzymatic and electrocardiographic diagnosis of postoperative acute myocardial infarction (AMI) is frequently inconclusive. The detection and quantitation of isoenzymes of lactate dehydrogenase (LDH) and creatine phosphokinase (CPK), especially the cardiac-specific CPK-MB isoenzyme, have allowed earlier recognition of AMI in nonsurgical patients. Serial monitoring with these methods has been utilized during the postoperative period in 20 noncardiac surgical patients and 100 patients undergoing coronary artery bypass grafting (CABG).

In the noncardiac surgery group, both isoenzymes were accurate in diagnosing AMI in the early postoperative period. Of the 100 patients in the CABG group, CPK-MB appearance in 21 correlated with AMI by electrocardiogram. The absence of CPK-MB postoperatively in 49 patients permitted a 73% incidence of new ECG abnormalities to be effectively resolved. Autopsy confirmation of AMI was obtained in two patients with nondiagnostic ECG, but with elevated CPK-MB. The elevated CPK-MB without ECG evidence of AMI in the remaining patients could possibly be explained by varying degrees of myocardial damage produced by intraoperative cardiac manipulation. These data demonstrate the value and sensitivity of CPK-MB isoenzyme determinations in the early recognition of postoperative acute myocardial infarction.

The importance of identification of the myocardial-specific isoenzyme of creatine phosphokinase (MB form) in the diagnosis of acute myocardial infarction

Serial plasma determinations of the isoenzymes of CPK were performed in all patients (376) admitted to a coronary care unit during a 12-month period with diagnosis of possible acute myocardial infarction. Results were compared with data from other enzyme studies and from the electrocardiogram. An attempt was made to determine the incidence of falsely positive CPK-MB (myocardial-specific form). "No acute infarction" was diagnosed in all patients in whom neither total CPK nor the isoenzymes of LDH indicated myocardial necrosis, and in whom there were no QRS changes on ECG. Incidence of falsely negative CPK isoenzyme data was also determined. All patients, in whom total CPK was transiently elevated, and LDH 1 exceeded LDH 2 , and new QRS changes occurred, were termed "definite" acute infarction. CPK-MB form was present in all 55 of these (0% false negative). Therefore, determination of the isoenzymes of CPK by this method provides both a sensitive and specific indication of acute myocardial infarction.