Ischemic Area Of Left Ventricle Research Articles

Antiarrhythmic effects of aspirin during nonthrombotic coronary occlusion.

To study the action of aspirin upon the myocardium per se, independent of thrombosis, coronary occlusion with a balloon catheter was induced in 53 anesthetized dogs divided into two groups. One group (N = 20) was treated daily with aspirin (600 mg/dog) for seven days and another (N = 33) was untreated. Left ventricular hemodynamics and precordial ECG mapping were used to assess the influence of myocardial ischemia over a four hour period. There were no significant differences in left ventricular function or extent of injury as judged by ECG mapping between the two groups. However, there was a significant decrease in the incidence of ventricular fibrillation in the treated dogs (5% vs 39%). Serial plasma samples for free fatty acid determination showed a significant rise in the untreated group. Aspirin blocked the FFA increment in the treated animals. Tissue samples from the ischemic area of left ventricle exhibited a significant reduction of the sodium and water increments, as well as a lesser potassium loss in the treated animals compared to the controls and may have been the basis for the lower incidence of arrhythmias. Since infusion of 51Cr labelled platelets showed no myocardial accumulation of platelets in either group, microthrombi did not appear to contribute to the observed differences.

Digoxin distribution in the dog's left ventricle in the presence of coronary artery ligation

Tritiated digoxin was administered intravenously to open-chest dogs 1 h after the left anterior descending coronary artery had been ligated. Myocardium was sampled 1 h later in eight animals and 4 h later in two. Themost severely ischemic area of left ventricle contained 3% to 67% of the digoxin concentration of distant left ventricular muscle, a finding which helps explain the poor clinical and hemo-dynamic response to digitalis when a significant portion of the ventricle is infarcted. No zone of increased digoxin uptake was demonstrated in muscle contiguous with the ischemic area, the concentration residing between that of the maximally ischemic and distant areas. The significant uptake in this boundary zone which is often the site of ectopic impulse formation may, however, explain the additive effects of digitalis and ischemia or infarction in producing ventricular arrhythmias.

Identification of ischemic area of left ventricle by visualization of 43 K myocardial deposition.

A new method to determine myocardial blood distribution was used to study a patient with a recent large transmural anterior myocardial infarct. The method consisted of injecting 43 potassium into a peripheral arm vein and recording the radioactivity over the chest with a scintillation (Anger) camera. Elimination of noncardiac radioactivity in the analysis of data was accomplished by recording the rapid passage of injected 99m technetium through the heart. The cardiac deposition of the potassium was visualized by identifying the contour of the heart from the technetium scan. In this patient deposition of 43 potassium was markedly reduced in the septal region of the myocardium. This correlated well with the ischemic area suggested by coronary angiography, which demonstrated proximal occlusion of the left anterior descending coronary artery and absence of obstructive disease in the other coronary arteries. Intracoronary artery injection of 43 K gave confirmation of decreased deposition in the same area. This method should prove helpful in the study of certain clinical problems, such as the evaluation of the patency of coronary artery bypass grafts.