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

Unexplained Cardiac Arrest After Near Drowning in a Young Experienced Swimmer: Insight from Cardiovascular Magnetic Resonance Imaging

Cardiac magnetic resonance imaging (cMRI) is a well-established noninvasive imaging modality in clinical cardiology. Its ability to provide tissue characterization make it well suited for the study of patients with cardiac diseases. We describe a multi-modality imaging evaluation of a 45-year-old man who experienced a near drowning event during swimming. We underline the unique capability of tissue characterization provided by cMRI, which allowed detection of subtle, clinically unrecognizable myocardial damage for understanding the causes of sudden cardiac arrest and also showed the small damages caused by cardiopulmonary resuscitation.

Distribution of biochemical markers in biologic fluids: application to the postmortem diagnosis of myocardial infarction

We evaluated the usefulness of postmortem determination of biochemical markers and the ratio of their concentrations in pericardial fluid and serum to diagnose acute myocardial necrosis. One hundred cadavers from routine necropsies were studied. Cases were allocated in diagnostic groups according to the cause of death. Myoglobin and myosin heavy chain concentrations and creatine kinase MB isoenzymes (CK-MB) activities were measured in serum and pericardial fluid. Ratios of the concentrations obtained in these fluids were calculated. Hematoxylin and eosin (H&E) and acridine orange stains were used for microscopy studies. Pericardial fluid-serum ratios of the concentrations of biochemical markers were significantly different. The ratio of the concentrations of myosin is the best indicator of wide-spread muscle damage or cardiac necrosis.

Biochemical assessment of acute myocardial ischaemia

AIMS

To evaluate the efficacy of biochemical parameters in different fluids in the diagnosis of myocardial infarction of different causes, analysed after death.

METHODS

The myoglobin concentration and total creatine kinase (CK) and creatine kinase MB isoenzyme (CK-MB) activities were measured in serum, pericardial fluid, and vitreous humour from seven diagnostic groups of cadavers classified according to the severity of myocardial ischaemia and cause of death. Lactate dehydrogenase (LDH) and myosin were measured only in serum and pericardial fluid, and cathepsin D only in pericardial fluid. Routine haematoxylin and eosin and acridine orange staining were used for microscopy studies of heart tissue.

RESULTS

In pericardial fluid there were substantial differences between the different groups with respect to CK, CK-MB, and LDH activities and myosin concentrations. The highest values were found in cases with morphological evidence of myocardial ischaemia.

CONCLUSIONS

Biochemical parameters, which reach the pericardial fluid via passive diffusion and ultrafiltration due to a pressure gradient, were thus detectable in this fluid earlier than in serum in cases with myocardial ischaemia. These biochemical parameters may be of use for ruling out myocardial ischaemia in those controversial cases in which reliable morphological findings are lacking.

Myocardial damage following coronary bypass surgery: assessment with antimyosin antibody uptake

To assess the role of 111In antimyosin antibody (AbAm) in the delineation of myocardial damage following coronary bypass surgery, we studied 51 consecutive patients who underwent coronary surgery, 27 of whom had a history of prior myocardial infarction. All patients underwent a diagnostic protocol comprising: (1) 99Tcm pyrophosphate (PYP) and AbAm injection 48 h after surgery (AbAm imaging 24 and 48 h post-injection) (myocardial/background and myocardial/lung ratios were obtained respectively from the computer image); (2) Radioimmunoassay (RIA) serum CK-B levels from samples obtained immediately before surgery, and 24 and 48 h later; (3) clinical and ECG follow-up. Twenty-five patients showed positive AbAm studies, 10 had positive PYP images, and 21 had CK-B levels above normal limits at 24 h. One patient with abnormal AbAm, PYP and CK-B studies had new Q waves on the ECG after surgery. This patient was considered to have sustained a peri-operative myocardial infarction. The large number of positive AbAm studies probably reflects myocardial damage frequently associated with coronary bypass surgery.

A case of post-traumatic coronary occlusion

Several cases of transmural myocardial infarction and ventricular aneurysm caused by a blunt trauma of the chest have been reported. Nevertheless, the cases documented with coronary and ventricular angiography are very few. There has always been a debate over the etiological mechanism of such lesions. Since in some cases there was no evidence of coronary lesions, it was postulated that they were produced by direct myocardial contusion, but in other instances the evidence of coronary occlusion was angiographically and pathologically proved. We experienced a case of acute myocardial infarction with ventricular aneurysm secondary to nonpenetrating chest trauma by an umbrella tip and wish to report this unusual case, along with a review of the literature.

Usefulness of different myocardial sampling zones for the postmortem diagnosis of myocardial infarction

The diagnosis of myocardial infarction requires the use of a group of tests that are very efficient, quick and inexpensive. Another important consideration is the choice of myocardial sampling zones, especially in cases of differential diagnosis between a cardiac injury secondary to a trauma or violent asphyxia and others, secondary to myocardial infarction. The aim of this work was to choose, through discriminant analysis, the most useful zones of cardiac tissue for the quantification of free fatty acids and free carnitine and for the performance of the K/Na quotient, as biochemical parameters for the postmortem diagnosis of myocardial infarction. According to the discriminant analysis performed, seven zones of cardiac tissue are necessary to achieve a differential diagnosis among "myocardial infarction," "other natural deaths," and "violent deaths" with a 71.9% efficacy. Greater diagnostic efficacy was found (78.1%) for differentiating between "natural deaths" and "violent deaths."

Comparison of different techniques for the postmortem diagnosis of myocardial infarction

A study was performed on 74 medicolegal autopsy cases for the purpose of comparing the reliability of four different techniques (haematoxylin-eosin stain, acridine orange method, formazan test and K/Na ratio) used for the postmortem diagnosis of myocardial infarction. Although the results showed that the formazan test and K/Na ratio give a good reliability to rule out a myocardial infarction, the most specific technique for the diagnosis of infarct is the formazan test.

Serum enzyme determinations in the diagnosis of acute myocardial infarction: an update

Serum CK-MB and LD-1 have proved extremely useful in the diagnosis and differential diagnosis of acute myocardial infarction. However, CK-MB is present in skeletal muscle and can be released during ischemic attacks; thus, abnormal serum CK-MB activities cannot be equated with myocardial injury. Even wider is the distribution of LD-1, which is found particularly in erythrocytes and renal cortex; hence, an abnormal LD-1 level also cannot be equated with myocardial injury. The method of choice and the final arbiter for the CK and LD isoenzymes is electrophoresis. The possibility of interpreting the results visually fulfills, in part, quality-control needs, and makes the technique suitable for small and large laboratories. Extreme analytic sensitivity is not needed, and electrophoresis provides clinically useful and acceptable results.

The postmortem determination of CK isozymes in the pericardial fluid in various causes of death

The authors have studied the CK isozyme pattern in the pericardial fluid of 100 cadavers autopsied in the Anatomic Forensic Institute of Granada. The samples were classified into several groups according to the cause of death: --Multiple trauma with thoracic contusion --Pneumonia and pulmonary embolism --Mechanical asphyxia --Cranio-cerebral trauma --Acute haemorrhage --Myocardial infarction --Others. The results showed that the CK isozyme pattern of pericardial fluid provides useful postmortem information of cardiac "status", adding to the diagnostic potential of CK isozymes.

Radionuclide assessment of left ventricular function in patients requiring intraoperative balloon pump assistance

Twenty-three surviving patients who were weaned from cardiopulmonary bypass with intraaortic balloon pump assistance returned for follow-up radionuclide left ventricular (LV) function and thallium 201 perfusion studies at a mean of 23 +/- 3 months following operation. It was found tat despite profound intraoperative myocardial depression requiring intraaortic balloon assistance, 13 patients had no change (within 10%) in the resting LV ejection fraction compared with the preoperative measurement. Among all 23 patients, there was no difference between mean (+/- standard error of the mean) preoperative and postoperative resting LV ejection fraction (48 +/- 4 vs 46 +/- 4%, p = not significant [NS]). Only 11 patients had perioperative myocardial infarction documented by new Q waves in the electrocardiogram, by elevation of creatine kinase-MB fraction, or by defects on thallium 201 imaging not explained by documented myocardial infarction before operation. Overall, postoperative resting LV ejection fraction was not different from the preoperative value in patients with perioperative myocardial infarction (44 +/- 7 vs 47 +/- 5%, p = NS). Postoperative resting LV ejection fraction rose by greater than 10% compared with preoperative values in 4 patients (3 with aortic valve replacement), remained within the 10% limit in 9 patients, and fell by greater than 10% in 10 patients (7 with perioperative myocardial infarction). Only 4 out of 16 patients studied at follow-up with exercise radionuclide studies demonstrated a normal LV response to exercise (greater than 5% increase in LV ejection fraction). Thus, among survivors requiring intraaortic balloon pump assistance for weaning from cardiopulmonary bypass, LV performance at rest is frequently preserved. In addition, 11 of the 23 patients had evidence of perioperative myocardial infarction, indicating a component of reversible intraoperative LV dysfunction.

Myocardial protection during aortocoronary bypass operations. Comparison of two different operative procedures: cold chemical cardioplegia versus intermittent cross-clamping of the aorta

Myocardial injury was studied in 40 randomized coronary patients operated on electively with coronary bypass grafting using two different techniques, (A) cardioplegic arrest and continuous cross-clamping of aorta, and (B) ischaemic arrest and intermittent cross-clamping of aorta. The released quantity of the MB isoenzyme of creatine kinase was used as an indicator of myocardial injury. Of the whole group, 3 patients (8%) suffered a myocardial infarction as judged by ECG. The CK-MB release was not significantly different in the two groups. The total period of aortic cross-clamping was markedly longer in the cardioplegic group than in the intermittent clamping group. A significant correlation between the duration of aortic clamping and the amount of CK-MB release was found in the cardioplegic group. Our results indicate that the beneficial effects of cardioplegic arrest are outweighed by an unavoidable longer period of total aortic clamping as compared with the intermittent clamping technique.

CPK-MB isoenzyme determinations: diagnostic and prognostic value in evaluation of blunt chest trauma

The incidence of myocardial contusion in patients with blunt chest trauma was examined. The criterion used for diagnosing contusion--actual cellular injury--was based on detection of the MB-isoenzyme of creatine phosphokinase, a sensitive and specific marker for cardiac cellular injury. Forty-nine patients with blunt chest trauma were evaluated using this diagnostic approach. Twenty-six demonstrated measurable serum levels of MB-CPK. Electrocardiographic (ECG) evaluation of this subgroup revealed that 85% exhibited anatomically localized ST-T wave abnormalities while 15% showed nonlocalized and nonspecific changes. Sixty-eight percent of those with localized abnormalities demonstrated ST segment changes depicting injury, most of which were localized to the anterior septal leads. The remaining 23 patients demonstrated non-detectable serum levels of MB-CPK and were classified as cardiac concussion on the basis of other clinical criteria. Twenty-six percent with concussion exhibited anatomically localized ECG changes. The remaining 74% had nonlocalized and nonspecific ECG changes.

Perioperative myocardial infarction: a diagnostic dilemma

Patients undergoing coronary bypass grafting were studied for incidence of perioperative myocardial infarction (MI) using three modalities: serial electrocardiograms (ECG), serial creatine phosphokinase isoenzymes (MB-CPK), and serial technetium 99m-labeled pyrophosphate scans. A definite perioperative MI was diagnosed if the results were positive in two of the three variables studied. The perioperative infarction rate for the entire group was 8%. The operative mortality was 2.9%. Seven of 8 perioperative MIs were diagnosed by the use of scanning alone. The combination of isoenzyme and ECG analysis diagnosed 5 of 8 perioperative MIs. The MB-CPK and ECG studies were associated with a higher incidence of false-positive diagnoses than myocardial scanning. Patients with perioperative MI had a benign clinical course. Justification for performing three routine 99mTc-pyrophosphate scans on all patients undergoing aortocoronary bypass operation is still to be determined.

Application of multivariate analysis to the enzyme patterns in the serum of patients undergoing coronary artery operation

Serial determinations of serum glutamic oxaloacetic transaminase, lactic dehydrogenase, and creatine phosphokinase were performed in 50 consecutive patients undergoing cardiac operation for coronary artery bypass or combined valve replacement and coronary artery bypass. Thirty-seven patients (74%) who demonstrated minimal or no changes on the electrocardiogram manifested a recognizable pattern of distribution of the enzyme sequences. The pattern of these patients served as controls for the detection of abnormal patterns. All other patients were grouped together, regardless of clinical behavior. Perioperative myocardial infarction was established in 5 patients (10%) and resulted in 1 death. The purpose of this study was to apply discriminant analysis to two clinically determined patient groups in order to ascertain whether the three enzyme readings can be used to classify patients into their respective groups. The results suggest that enzyme profiles reflect degrees of myocardial damage that can serve to identify clinical infarction.

Creatine kinase MB isoenzyme in the evaluation of myocardial infarction

The measurement of serum CK-MB isoenzyme is a very sensitive and specific indication of myocardial injury since only myocardium has substantial amounts of CK-MB. Serum CK-MB levels are most helpful clinically when the total creatine kinase is nonspecifically elevated, as with intramuscular injections, cardiac catheterization, stroke, noncardiac surgery and electric cardioversion. Elevations of serum CK-MB occurring in Duchenne's muscular dystrophy and other neuromuscular disorders may be due to the presence of abnormal regenerative skeletal muscle fibers, which are known to contain large amounts of CK-MB isoenzyme. These examples emphasize that under normal, nonregenerative conditions, elevations of serum CK-MB are rare in the absence of myocardial injury.

The significance of the MB isoenzyme in patients with acute cardiovascular disease with a normal or borderline total CPK activity

CPK MB isoenzymes were qualitatively identified using an electrophoresis method in 166 patients with acute cardiovascular disease during a six month period. Forty-three had total CPK activity in the normal or borderline range (0--75 U/Liter at the time the MB isoenzyme was first identified. Fifteen of these patients were diagnosed as having had a new acute myocardinal infarction (Group I) and another 15 as having had an old myocardial infarction (Group II). Diagnosis was based on electrocardiographic changes or autopsy findings. The remaining 13 patients were classified as "ischemic heart disease" (Group III) in the absence of strict electrocardiographic criteria or autopsy evidence of myocardial infarction. Nine of the 15 patients in Group I subsequently had elevations of their total CPK activity above 75 U/L. In contrast the total CPK activity of only one patient from Group II and Group III subsequently exceeded 75 U/liter. All 43 patients had evidence of cardiovascular disease. Our findings suggest that the detection of MB isoenzyme in the presence of a normal total CPK activity is a significant laboratory finding and is indicative of cardiac myofiber injury.

Transient elevation of serum activity of MB isoenzyme of creatine phosphokinase in drivers involved in automobile accidents

Drivers involved in automobile accidents were screened for the presence of occult cardiac injury without regard for apparent severity of the accident or injury. An electrocardiogram was recorded, and serum levels of total creatine phosphokinase and the MB isoenzyme of creatine phosphokinase (myocardial form) were measured as soon as possible after the accident and subsequently during admission (or on the following day in patients treated and discharged from the emergency room). Electrocardiographic abnormalities were observed in 18 of 82 patients but correlated poorly with other evidence of the severity or location of injury. Of the 22 drivers admitted to the hospital (for any cause), nine demonstrated significant early elevations of the activity of the MB isoenzyme of creatine phosphokinase. We conclude that blunt cardiac trauma is a clinical subtlety; to be found, it must be sought. The ECG is of limited value. Measurement of the serum activity of the MB isoenzyme of creatine phosphokinase early after injury would appear to offer the best evidence of cardiac trauma.

The management of acute coronary insufficiency

1. Coronary insufficiency is a pathophysiologic state that can initiate lethal cardiac arrhythmias in the absence of myocardial necrosis. Patients with suspected coronary insufficiency should be monitored until they are stabilized and a diagnosis is confirmed. 2. Early and adequate intravenous antiarrhythmic prophylaxis with lidocaine to raise the fibrillation threshold in the setting of coronary insufficiency can prevent primary ventricular fibrillation. Classic "warning arrhythmias" are not predictive of ventricular fibrillation. Their persistence during adequate antifibrillatory prophylaxis does not indicate therapeutic failure. 3. The isoenzyme of creatine phosphokinase, CPK-MB, is an extremely sensitive and specific indicator of myocardial necrosis if measured serially during the 24 hours following the onset of symptoms suggesting coronary insufficiency. It may prove most useful in eliminating the false positive diagnosis of myocardial infarction in difficult clinical cases. 4. The management of heart failure in myocardial infarction requires an understanding of the relationship between ventricular preload and the cardiac output. The treatment of clinical manifestations of an elevated ventricular preload in asymptomatic patients is not justified and may be detrimental. In symptomatic patients, however, judicious manipulation of ventricular preload should be the first therapeutic consideration, and an optimal filling pressure should be achieved and maintained when other determinants of the cardiac output are manipulated. 5. Indications for the prophylactic insertion of a temporary transvenous pacing electrode for heart block associated with myocardial infarction must be individualized. Most authorities agree that prophylactic pacing may be justified in patients with evidence of new infranodal block involving two of the three fascicles. Patients with bifascicular block who progress to complete heart block transiently may benefit from permanent transvenous pacemaker insertion before discharge. 6. Hospitalized patients with persistent pain of suspected cardiac origin but without evidence of myocardial infarction can be studied safely with coronary angiography. A small percentage will be normal or have diffuse disease that is inoperable. Of those with operable disease, short-term mortality appears to be similar for medical and surgical therapy. 7. Patients with an uncomplicated myocardial infarction may be safely discharged from thehospital by day 7-10. 8. Experimental evidence indicates that modification of infarct size is possible. Application of these concepts to human subjects presently is limited by the absence of a proved method of measuring infarct size in vivo in humans.

Usefulness of preoperative and postoperative Tc-99m (Sn)-pyrophosphate scans in patients with ischemic and valvular heart disease

To assess the usefulness of myocardial imaging with technetium-99m-stannous pyrophosphate for detecting acute myocardial necrosis in patients undergoind cardiac surgery, 66 such patients were stldied. Tc-99m (Sn)-pyrophosphate scans were obtained in all patients 3 to 6 days postoperatively and in 45 preoperatively. Electrocardiograms and serum samples for measuring myocardial isoenzyme of creatine kinase (MB CK) levels were obtained before and serially after cardiac surgery. Seven of the 46 patients undergoing myocardial revascularization had a definite new myocardial infarction as indicated by electrocardiogram and MB CK isoenzyme concentrations, and postoperative pyrophosphate scans were abnormal in all but one. In addition, six of the eight patients with possible myocardial infarction (elevated MB CK levels and persistent ST-T wave depressions) had an abnormal scan postoperatively. Seven of the 20 patients undergoing aortic or mitral valve replacement, or both, had a possible postoperative myocardial infarction by electrocardiogram and MB CK criteria and the myocardial scan was positive in two. All the patients with a normal electrocardiogram and normal MB CK levels had a normal pyrophosphate scan. Preoperative scans were obtained in 22 patients wit; valvular heart disease and were positive in two with a heavy calcified mitral valve on fluoroscopy and in one with a calcified aortic valve. After valve replacement, the pyrophosphate scan became normal in two patients and remained abnormal in the third patient with electrocardiograms and MB CK levels suggesting acute myocardial infarction. We conclude that the Tc-99m (Sn)-pyrophosphate scan is useful for analyzing the occurrence of acute myocardial infarction in patients undergoing cardiac surgery and that, in conjunction with the electrocardiogram, it permits confirmation or exclusion of that diagnosis. Furthermore, false positive pyrophosphate scans may occur in patients with heavy valve calcifications.