James H. Thomsen

Changes in tissue levels of carnitine and other metabolites during myocardial ischemia and anoxia

Abstract The induction of ischemia in the open chest dog, or anoxia in the perfused rat heart, causes dramatic changes in the tissue levels of free acyl carnitine and related metabolites. During the early phase of ischemia or anoxia the tissue levels of free carnitine decline, while acetyl carnitine rapidly increases. These changes are accompanied by elevation in long-chain acyl carnitine, long-chain acyl CoA, and lactate and by decreases in acetyl CoA, CoA, ATP, and creatine phosphate. As the degree of ischemia becomes more severe, carnitine appears to be lost from the myocardium. A scheme is presented which relates carnitine-linked mitochondrial metabolism to the activity of carnitine acyl transferase, ANT, carnitine/acyl carnitine translocase, creatine phosphokinase, and pyruvate dehydrogenase. It is suggested that the conversion of carnitine to acyl carnitine during the onset of ischemia may play an important role, by virtue of its effect on these enzymes, in the regulation of metabolism during the early or reversible phase of ischemia.

A Study of Hemodynamics and Coronary Blood Flow in Man with Coronary Artery Disease

Coronary blood flow was measured by the nitrous oxide method, and cardiac output was measured by the Fick principle, in a series of 31 human subjects with the clinical diagnosis of angina pectoris. Coronary arteriography was carried out on the same subjects as a part of the same procedure, and the extent and severity of the coronary artery lesions was determined. A numerical value was assigned to the severity of the coronary artery disease, an attempt was made to correlate the severity of coronary artery disease with the measured coronary blood flow and with various hemodynamic parameters which traditionally describe the systemic and pulmonary circulation. There was no correlation between any of the parameters measured and the severity of coronary artery disease demonstrated by angiography. It is concluded, therefore, that the nitrous oxide method for measuring coronary blood flow is not helpful in separating subjects with normal coronary arteries from those with coronary artery disease, nor are resting hemodynamic observations helpful.Maximum flow through the coronary arteries of the dog heart was measured by postmortem perfusion. This flow rate is sufficient to provide a considerable factor of safety as far as constriction of the major coronary arteries is concerned. If these data are extrapolated to the coronary vessels of man, it would seem that a very large “safety factor” exists, and this may explain why severe coronary disease is not revealed by studies of coronary blood flow.

Pulsed doppler echocardiography in diagnosis of pulmonary regurgitation: Its value and limitations☆

Abstract Ninety-eight patients were studied with two dimensional echocardiography combined with pulsed Doppler echocardiography to assess the usefulness and limitations of the Doppler technique in the diagnosis of pulmonary regurgitation. The diagnosis of pulmonary regurgitation by pulsed Doppler echocardiography depended on subjective interpretation of the audio signal and objective interpretation of the time interval histogram for the presence of wide frequency dispersion. During cardiac catheterization in 53 of the 98 patients, indocyanine green was injected into the pulmonary artery, and simultaneous sampling was performed from the right ventricle and femoral artery to diagnose pulmonary regurgitation. Pulmonary regurgitation was confirmed by pulmonary arteriogram in one patient. Among 62 patients with adequate pulsed Doppler echocardiographic studies, diastolic turbulence was noted in 21. When diastolic turbulence was less than 50 percent of the period of diastole, no pulmonary regurgitation was demonstrated in patients studied by indicator-dilution technique. However, three of the four patients with diastolic turbulence greater than 50 percent had positive evidence of pulmonary regurgitation. Audio output was more sensitive than the time interval histogram, and only five patients findings suggested pulmonary regurgitation. Three of these patients underwent dye-dilution studies; two studies were positive for pulmonary regurgitation and one was negative. Thus, interpretation of pulmonary regurgitation based on the time interval histogram alone produces a large number of false positive results. When diastolic turbulence is greater than 50 percent of the period of diastole, both the sensitivity and specificity of diagnosis of pulmonary regurgitation are increased. Combining audio output and the time interval histogram results in improved diagnostic capability.

Coronary and Systemic Hemodynamic Effects of Cardiac Pacing in Man with Complete Heart Block

Twelve subjects with an average age of 65.9 years who had complete heart block had cardiac output and coronary blood flow measured at three different rates of pacing. Cardiac output and calculated external work increased with rate from the slow to the intermediate rate, but declined at the fast rate. Even at the intermediate rate, cardiac output remained low as compared to standards for normal younger subjects. Coronary blood flow and left ventricular oxygen usage increased with cardiac rate. Cardiac efficiency, expressed as left ventricular work divided by left ventricular oxygen consumption, tended to decrease as cardiac rate rose; however, these changes were not statistically significant. Lactate consumption increased with rate, but changes in glucose and pyruvate consumption were not significant. Considering the circulatory system as a whole, the intermediate or normal resting rate was more efficient. At this rate the cardiac output and cardiac work were greatest, and the mixed venous oxygen content (which must reflect body tissue oxygenation) was highest, while the cardiac oxygen consumption and coronary blood flow were intermediate.

Multiple calcified thrombi (rocks) in the right ventricle.

Large, organized right ventricular thrombi are rare. This report describes a 51 year old man with a history of recurrent pulmonary emboli treated with inferior vena cava ligation who subsequently developed multiple mobile calcified thrombi in the right ventricle. He was treated successfully by surgical resection. Unusual clinical presentation on admission consisted of a two component friction rub secondary to calcified masses rubbing against each other in systole and diastole. Cardiac catheterization showed a constrictive-restrictive pattern that persisted after surgery. The role of noninvasive studies in the diagnosis and long-term follow-up of the patient is emphasized.

Severe atherosclerosis in the “single coronary artery”: Report of a previously undescribed pattern

Abstract A case is presented in which a true single coronary artery of a previously unreported type was found to arise from an unusual position high in the ascending aorta. Atherosclerotic involvement of this vessel was extremely heavy, and there was extensive development of coronary arterial collateral circulation. The problems inherent in attempting to diagnose this type of anomaly are discussed, and the potential impact of abnormal origin and distribution on the development of atherosclerosis in the single coronary vessel is reviewed.

Effect of Hyperventilation on Precordial T Waves of Children and Adolescents

Following the taking of 12-lead routine electrocardiograms, three precordial leads were recorded before, during, and after 10 to 15 seconds of voluntary hyperventilation in 296 students, ranging in age from 8 to 17 years.Fifteen per cent of the total group, comprising 212 Caucasians and 84 Negroes, inverted one or more previously upright precordial T waves following hyperventilation. The incidence of T-wave inversion in children 12 years of age and under was nearly four times greater in Caucasians than in Negroes. There was no significant difference when the older Negro and Caucasian students were similarly compared. Sinus tachycardia, T-wave flattening, and “tucking,” short of frank inversion, as well as junctional depression of the ST segment, were commonly seen following hyperventilation.The similarity of the hyperventilation-induced T-wave inversion in children to those previously documented in adults is noted, and the clinical implication of this study requires continued cognizance of the occurrence of “nonpathological” T-wave inversion in adults, so as to avoid iatrogenic heart disease.

Potassium-loading test in the differentiation of T wave abnormalities

Abstract This report summarizes our experience with the oral potassium-loading test in a group of patients who presented with abnormal T wave inversion on routine resting electrocardiograms. The test empirically normalizes most T wave abnormalities that are unassociated with clinically demonstrable heart disease, particularly the T wave changes induced by brief hyperventilation or by anxiety reactions. The response to the test procedure is dosage-dependent and is not related to a nonspecific osmolar load. It is recommended that the oral potassium-loading test not be utilized as a clinical testing procedure. Although the results frequently clarify the significance of T wave abnormalities in asymptomatic patients, false positives and false negatives will occur. At best, awareness of this study will recall to the clinicians mind that anxiety, hyperventilation and standing may result in T wave abnormalities entirely similar to those of an acute myocardial ischemic episode, pericarditis or myocarditis.

A model for teaching coronary artery anatomy.

We present a simple model for teaching coronary artery anatomy and distribution. The thumb and first two fingers of the left hand can be formed into a baseball pitchers grip that can be used to portray the commonly used arteriographic positions.

The standard 12-lead scalar electrocardiogram, an assessment of left ventricular performance

Summary The results of standard 12 lead scalar electrocardiograms were correlated with left ventricular performance as reflected in the determinations of left ventricular end diastolic pressure at rest, ejection fraction and in the qualitative evaluation of left ventricular systolic wall motion. The study group included 55 patients who had at least 50% obstruction of one or more of the three major coronary arteries. The cardiothoracic ratio and a coronary artery index, expressing the residual patency of the three major coronary arteries, were also determined for each patient. The results indicate that normal left ventricular systolic wall motion can only be expected when the electrocardiogram is normal or reveals only minor repolarization abnormalities. Such an electrocardiogram favors but does not guarantee normal wall motion. Corresponding areas of abnormal left ventricular wall motion were observed in all cases with electrocardiographic evidence of a transmural anterior wall infarction and in the great majority of cases with an inferior wall infarction. Electrocardiographic evidence of a single transmural myocardial infarction was associated with a mean ejection fraction of 52% which was 10% less than that observed with a normal electrocardiogram and with only repolarization abnormalities. The reduction in ejection fraction was most marked in those with transmural anterior wall infarctions and in those with multiple transmural infarctions. The left ventricular end diastolic pressure was similar in those patients with and without electrocardiographic evidence of a transmural myocardial infarction. However, the mean left ventricular end diastolic pressure was significantly lower in those with inferior wall infarctions (13 mmHg) than in those with anterior wall infarctions (18mm Hg.). The total coronary artery index was not significantly different in patients with and without electrocardiographic evidence of a transmural myocardial infarction.