Early Detection Of Myocardial Ischemia Research Articles

Early detection of myocardial ischemia in hypertensive patients using exercise esophageal electrocardiography

Effects of submaximal exercise were studied on the unipolar esophageal electrocardiogram recorded at ventricular level in 15 patients with essential hypertension who complained of chest discomfort on effort but had negative exercise stress tests using standard leads and lead CM 5. Six patients developed horizontal or downsloping depression of the ST segment in the esophageal lead. The ischemic response might result from subcritical coronary stenosis in face of the increased myocardial oxygen demand of hypertrophied myocardium.

Early detection of myocardial ischemia by myocardial free fatty acid extraction in patients with exercise-induced angina pectoris

This study investigated whether the measurement of plasma free fatty acids (FFAs) could assist in the early detection of exercise-induced myocardial ischemia. Fifteen subjects with effort angina pectoris underwent angina-limited supine bicycle ergometer exercise testing. Myocardial FFA extraction decreased significantly from 22.8 ± 3.1% at rest to 7.7 ± 1.5% at peak exercise (p < 0.05). Myocardial lactate extraction showed no significant change between rest and peak exercise. After control exercise testing, 8 subjects were given a single oral dose of nilvadipine (6 mg) and then again underwent exercise testing for the same duration. Nilvadipine lessened or abolished chest pain and there was less depression of the ST segment at peak exercise. Furthermore, myocardial FFA extraction showed no significant change between rest and peak exercise after nilvadipine administration. These results suggest that myocardial FFA extraction can be used to assess the presence of exercise-induced myocardial ischemia at an earlier stage than myocardial lactate extraction.

Histochemical and Fluorescent Techniques for Detection of Early Myocardial Ischemia Following Experimental Coronary Artery Occlusion: A Comparative and Quantitative Study

Several workers have used histochemical, enzymatic, and fluorescent methods to diagnose early myocardial ischemia, but the problem of unequivocal detection of early ischemia still remains an enigma to pathologists. In the present study, the left coronary artery was ligated in an animal model, rat, in order to produce myocardial ischemia at different time intervals, from five minutes to six hours. Fluorescent techniques and tetrazolium staining of myocardial succinic dehydrogenases have been used to detect onset of ischemia with the purpose of identifying a sensitive technique for use in routine pathologic specimens. Nitroso-blue tetrazolium and triphenyl tetrazolium chloride staining of myocardium showed loss of dehydrogenases within five to twenty minutes of ligation of the coronary artery. This loss was consistent and progressively increased at longer time intervals, the mean ischemic area mapped being 25.74 mm2 and 66.87 mm2 at five to twenty minutes and six hours respectively. Such comparison of ischemic area of myocardium at different time intervals has not been reported earlier. Autofluorescence in formalin-fixed, hematoxylin and eosin-stained sections showed positive fluorescence only after fifty to seventy-five minutes of ischemia and was patchy in distribution in the left ventricular wall even up to six hours of ligation. Examination of myocardium under fluorescent light after acridine orange staining proved to be more sensitive than autofluorescence for detecting ischemia. At five to twenty minutes, the mean ischemic area was 18.67 mm2 and by six hours it increased to 27.48 mm2.(ABSTRACT TRUNCATED AT 250 WORDS)

Pulmonary arterial catheterization before anesthesia in patients undergoing cardiac surgery. Placement of the pulmonary arterial catheter before anesthesia for cardiac surgery: safe, intelligent, and appropriate use of invasive hemodynamic monitoring.

Should one catheterize the pulmonary artery (PA) for cardiac surgery before or after induction of anesthesia? Issues of central importance to this question include (1) the patient's preexisting hemodynamic abnormalities, (2) cardiovascular effects of anesthetic induction drugs, and (3) hemodynamic stress caused by laryngoscopy, endotracheal intubation, and PA catheter insertion. Some clinicians use the PA catheter immediately before anesthetic induction to detect and correct acute abnormalities in preload and ventricular function. This approach has been described as being partially responsible for decreased morbidity and mortality in patients with cardiovascular disease. Hemodynamic instability during induction has been reported with many of the common anesthetic induction agents, especially in patients with poor ventricular function. Since blood pressure is the product of cardiac output and systemic vascular resistance, accurate interpretation and treatment of hypotension are possible only when these variables are provided by vigorous use of the PA catheter. Early detection of myocardial ischemia is possible with examination of acute changes in the pulmonary capillary wedge pressure tracing. However, the lack of such information can restrict even the best anesthetist. Insertion of the PA catheter in the awake patient can be accomplished effectively and with minimal risk, so long as good patient rapport, adequate premedication, and continuation of antianginal medication until the time of surgery are assured. Preinduction placement of the PA catheter provides valuable, objective information for the cardiac anesthesiologist without incurring significant risk to the patient.

Myocardial ischemia after maximal exercise in healthy men: A method for detecting potential coronary heart disease?

A study of 433 asymptomatic men emphasizes the value of strenuous exercise testing in the early detection of myocardial ischemia. The sensitivity of the maximal exercise capacity test was nine times greater than that of the double Master's two-step test in eliciting electrocardiographic evidence of myocardial ischemia in 201 “normal” men who were over 34 years of age. Improved detection of potential coronary heart disease by this method is illustrated by comparison with several epidemiologic studies. If the reliability and specificity of this electrocardiographic abnormality in predicting clinical coronary heart disease is confirmed by future follow-up examinations, a method of detection and study of potential coronary heart disease and factors influencing its course will be available.