A technique of recording electrocardiographic maps after exercise is described. This technique allows a measurement to be made of the area of ST segment changes that are projected onto the front of the chest after exercise. A comparison of the sensitivity and specificity of this technique with the orthogonal lead system and a single chest lead showed that praecordial exercise mapping was significantly superior to the other two lead systems in the diagnosis of ischaemic heart disease and may help in identifying patients with extensive disease. In addition information obtained from praecordial exercise mapping can be used to increase the data that are obtained from Holter monitoring of ST segments. The place of the technique in the management of medical and surgical treatment remains to be evaluated.

Coronary Disease↗

PubMed1979

Relation between the precordial projection of S-T segment changes after exercise and coronary angiographic findings.

The recent introduction of electrocardiographic mapping permits measurement of the precordial area and severity of exercise-induced S-T segment changes. This study was designed to compare this technique with a modified 12 lead electrocardiogram in defining the degree and site of coronary artery disease. One hundred patients, who later had diagnostic coronary arteriography, underwent an exercise test using both 16 point precordial mapping and a modified 12 lead electrocardiogram. The sensitivity of electrocardiographic mapping (96 percent) for the diagnosis of coronary artery disease was significantly greater than that of the modified 12 lead electrocardiogram (80 percent). However, the specificity of the two lead systems was similar. Typical precordial projections of S-T segment change were found when the left main stem or proximal left anterior descending coronary artery were narrowed or when there was isolated disease of the left anterior descending or right coronary artery. Widespread precordial changes were found in patients with three vessel disease. Although there was no significant difference in the sensitivity (66 percent) and specificity (100 percent) of electrocardiographic mapping and of the 12 lead system in identifying three vessel disease, there was a significant difference in sensitivity (electrocardiographic mapping 74 percent, 12 lead system 42 percent) in identifying isolated single vessel disease. In addition, information regarding the presence of left main stem or proximal left anterior descending coronary arterial narrowing was obtained only with electrocardiographic mapping. The superiority of electrocardiographic mapping over the modified 12 lead electrocardiogram has been shown, and clinical application of this technique should be useful in the management of patients presenting with chest pain.

Adult↗

PubMed1979

Projection of electrocardiographic signs in praecordial maps after exercise in patients with ischaemic heart disease.

Praecordial surface maps of the electrocardiogram were recorded before and after exercise using 16 electrodes covering the left hemithorax. The ST segment and R and S wave changes were measured in the praecordial maps from 20 individuals with no detectable cardiovascular disease. These showed no significant alteration in ST segments of R/S. In contrast in 40 patients with angiocardiographically proven coronary artery disease it was possible clearly to outline the distribution, severity, and time course of praecordial areas of ST segment depression (36 patients) and ST segment elevation (10 patients). In addition these praecordial areas of ST segment changes were accompanied by a regional and significant fall in the R/S. The praecordial electrocardiogram with exercise complements the anatomical information obtained from the coronary arteriogram by clearly outlining electrocardiographic projections of regional myocardial ischaemia or cell death.

Adult↗

PubMed1979

Precordial mapping of ST-segment elevation and Q waves following anterior myocardial infarction. The effects of established beta-blocking drugs.

The electrocardiographic (ECG) signs of ST-segment elevation and the development of Q was using 72-lead precordial surface mapping, and the release of creatine kinase (CK) activity has been studied in 47 patients with uncomplicated anterior myocardial infarction. These findings were compared with a further nine patients who had acute myocardial infarction but were receiving long-term beta-blocking drugs. It was found that ST-segment elevation and Q waves had rapidly changing and different natural histories and that beta-blocking drugs altered the natural history of ST-segment changes but had no effect on the pattern and time course for the loss of electrically active myocardium. There was a close relationship between the precordial area of ST-segment elevation at 2--3 h and the final development of Q waves in the patients with uncomplicated anterior myocardial infarction. No similar relationship could be found in those on beta-blocking drugs. The pattern of changes in plasma CK and its MB isoenzymes activity were similar for both groups. The relationship between early ST-segment elevation and the final area of Q waves may prove useful in clinical practice. This may not apply where beta-blocking drugs are commenced before the initial recording of ST-segment elevation.

Acute Disease↗

PubMed1978

Myocardial imaging with extractable cations and inert tracers: the effects of flow and metabolism.

The physical and biological properties of 201thallium (Tl) have been investigated and are discussed in this review. A new technique using the ultra-short lived 81mkrypton (81mKr) as a continuous infusion into the aortic root in dogs and man is described. This provides a dynamic assessment of changes in regional myocardial perfusion. Experiments using 201Tl and 81mKr in dogs have shown that regional decreases in myocardial perfusion alone cannot be detected in images of the heart using 201Tl. The effects of perfusion and a variety of factors on the energy dependent cellular uptake of 201Tl are discussed as being of primary importance in changing the regional myocardial distribution of this tracer. The constant infusion of 81mKr in patients with anginal chest pain provides continuous measurement of regional myocardial perfusion in high spatial resolution images. This dynamic method provides a physiological assessment of stenosed coronary arteries at rest and during stress.

Animals↗

PubMed1978

A method for praecordial surface mapping of the exercise electrocardiogram.

A technique for praecordial surface mapping of the exercise electrocardiogram is described. This showed the area, time course, and severity of ST segment depression as projected onto the front of the chest after exercise. Twenty normal volunteers and 20 patients with coronary artery disease have been studied. No changes were seen after exercise in the normal subjects but areas of ST segment depression appeared in all 20 patients with angina pectoris. In 5 of the 20 patients with coronary artery disease, the exercise test was repeated on a later date. There were no significant differences in the area of severity of electrocardiographic abnormalities recorded during the two tests. This technique may prove to be useful for diagnosis and assessing medical and surgical treatments in patients with ischaemic heart disease.

Adult↗

PubMed1978

Natural history and evaluation of Q waves during acute myocardial infarction.

Serial 72 point praecordial electrocardiographic maps were recorded in 45 patients with uncomplicated acute anterior myocardial infarction. These were analysed and the serial changes in Q waves and ST segments were recorded. Cardiospecific enzyme release curves were constructed from repeated measurements of the plasma activity of the myocardial isoenzyme of creatine kinase (MB CK) during 4 days after the onset of chest pain. The praecordial maps showed that Q waves appeared in the second hour after the onset of chest pain and the development of this electrocardiographic sign was completed within 12 hours. There were complex relations between the development of Q waves, the natural history of ST segment elevation, and the release of MB CK activity. The praecordial area of ST segment elevation at 2 hours was directly related to the fully developed Q wave area at 24 hours after the onset of chest pain. The electrical activity of affected myocardium was lost before peak plasma MB CK activity.

Acute Disease↗

PubMed1978

Loss of electrically active myocardium during inferior infarction in man.

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Adult↗

PubMed1978

Electrocardiographic precordial mapping in anterior myocardial infarction. The critical period for interventions as exemplified by methylprednisolone.

Serial 72-point precordial mapping of ECG has been recorded to describe the natural history of changes in the precordial areas of ST segment elevation and the development of Q waves in 51 patients with acute uncomplicated anterior myocardial infarction. Eight patients have been studied in the same way but received 25 mg/kg of methylprednisolone sodium succinate as a single intravenous injection within 6 hours from the onset of chest pain. There was a linear relationship between the stable precordial area of Q waves at 24 hours and the rapidly changing precordial areas of ST segment elevation at 2--3 hours, 5--6 hours and 12 hours after the onset of pain in the untreated patients. When methylprednisolone was given, the treated patients developed a smaller precordial area of Q waves at 24 hours than was predicted from the precordial area of ST elevation recorded before the drug was given. This study has introduced a technique that can provide a qualitative assessment of the relationship between ECG evidence of ischemia and infarction in each patient.

Adult↗

PubMed1978

The relationship between myocardial ischaemia and cell death during acute myocardial infarction.

Praecordial mapping of the electrocardiogram (ECG) demonstrated the natural history of ST segment elevation, loss of R and appearance of Q waves in 50 patients suffering uncomplicated anterior myocardial infarction. The results showed that ST segment elevation has a complicated natural history. The loss of R wave electromotive force and development of Q waves were complete by 12 h following the onset of chest pain. This evidence for the loss of viable myocardium was complete before the MB-isoenzyme of creatine kinase (MBCK) was detected in the plasma. Regression analysis of these results showed a direct relationship between the praecordial area of ST segment elevation at 2 h (myocardial ischaemia) and the praecordial area of Q waves at 24 h after the onset of symptoms (cell death). The efficacy of interventions on the natural history of myocardial infarction might be assessed by their effects on the relationship between myocardial ischaemia and cell death.

Acute Disease↗

PubMed1978

The loss of electrically active myocardium in cardiogenic shock.

A method of precordial mapping of RS ratio changes and the appearance of Q waves that occur in acute myocardial infarction has been developed. The serial changes of R and Q waves in 40 patients suffering uncomplicated anterior infarction shows that the loss of electrically active myocardium occurs within 6 h from the onset of chest pain. The total precordial ECG changes of R and Q waves in 5 patients suffering anterior infarction and cardiogenic shock showed that the loss of electrically active myocardium continues after 6 h from the onset of chest pain, and is significantly different from the uncomplicated group. This was supported by the serial plasma MBCK activity determinations which suggest more than one episode of necrosis.

Adult↗

PubMed1978

The effect of drugs on enzyme release from the hypoxic myocardium.

The leakage of enzymes from the myocardial cell can be used as an index of the onset and severity of tissue damage. A study has been carried out using the isolated perfused hypoxic rat heart in which the ability of various doses of isoprenaline, dobutamine, propranolol, glucose, insulin, mannitol, adenosine triphosphate and hydrocortisone to increase or decrease myocardial enzyme leakage has been evaluated.

Adenosine Triphosphate↗

PubMed1977

Praecordial mapping of Q waves and RS ratio changes in acute myocardial infarction.

The theory related to the loss of R waves and appearance of Q waves in acute myocardial infarction is discussed. A method of praecordial mapping of RS ratio changes and the appearance of Q waves that occur in acute myocardial infarction is described. The serial changes in these electrocardiographic signs in 17 patients during acute infarction are recorded. The potential value of these serial measurements in delineating the extent of myocardial injury in patients with acute infarction, and evaluating the effects of any treatment aimed at limiting infarct size is discussed.

Adult↗

PubMed1977

Creatine kinase isoenzymes: their separation and quantitation.

The cardiospecificity of the MB isoenzyme of creatine kinase, EC 2.7.3.2, (CK) with its associated diagnostic and research value has resulted in the development of a number of procedures for the separation and quantitation of the three isoenzymes of CK. In our experience methods involving cellulose acetate electrophoresis, apposition incubation, and fluoroscanning for quantitation are of limited linearity, insensitive, and irreproducible. We have, therefore, developed a method which overcomes these difficulties. Our method is based on agarose gel electrophoresis, gel overlay incubation with optimisation of all substrates and elution of the NADPH into solution for isoenzyme quantitation. We have: (1) characterised this technique; (2) used it to verify the extent to which the MB isoenzyme of CK is cardiospyocardial; (3) studied its application to the diagnosis of acute myocardial infarction; and (4) compared it with existing methods involving dithiothreitol activation and ion exchange chromatography.

Animals↗