Henry F. Mizgala

Prognostic value of exercise testing soon after myocardial infarction.

The prognostic value of a limited treadmill exercises test performed one day before hospital discharge after acute myocardial infarction was studied in 210 consecutive patients who had no over heart failure and had been free of chest pain for at least four days. No complications occurred. During a one-year follow-up period 28 of 43 patients (65 per cent) who had chest pain during the test reported angina, as compared with 60 of 167 (36 per cent) who had no chest pain during test (P less than 0.001). The one-year mortality rates were 2.1 per cent (three of 146) in patients without changes in the S-T segment during exercise and 27 per cent (17 of 64) in those with depression of the S-T segment (P less than 0.001). Sudden death occurred in one of 146 (0.7 per cent) patients who showed no change in the S-T segment and in 10 of 64 (16 per cent) with depression of the segment (P less than 0.001). Thus, a limited treadmill exercise test performed before hospital discharge after acute myocardial infarction is safe and can predict mortality in the subsequent year.

Left ventricular abnormalities in arrhythmogenic right ventricular dysplasia

Abstract Right ventricular (RV) dysplasia is a condition in which the RV myocardium is partially or totally absent and replaced with fibrous or fatty tissue. Dysplasia may be mild or there may be total absence of myocardium, with apposition of endocardium to epicardium.1–4 When associated with ventricular arrhythmias the condition has been termed arrhythmogenic RV dysplasia.4 This condition was believed to involve exclusively the right ventricle.5,6 Recently, however, left ventricular (LV) abnormalities have been described in association with RV dysplasia.7 From patients presenting over a 2-year period to the electrophysiology service at our institution, we identified 4 patients with recurrent ventricular tachycardia (VT) of RV origin and morphologic features typical of RV dysplasia. This report describes our findings (Table I).

Clinical predictors of angina following myocardial infarction

Abstract To determine if angina following myocardial infarction could be predicted before hospital discharge we prospectively evaluated 219 consecutive patients admitted to the coronary care unit with acute myocardial infarction. Of the 166 who survived to one year, angina was present before infarction in 53 per cent and after infarction in 61 per cent. Angina did not recur postinfarction in 26 per cent of the patients who had angina before infarction. However, in 47 per cent of those without previous angina it developed postinfarction. Although postinfarction angina correlated with the presence of angina before infarction (p To improve our ability to predict angina after infarction we performed exercise tests to 5 metabolic equivalents (METS), or 70 per cent of age-predicted maximal heart rate, before hospital discharge on all patients less than 70 years old who were without chest pain within four days or without overt heart failure. Of the 105 patients exercised, 31 (86 per cent) of the 36 with positive tests had angina during the subsequent year compared to only 25 (36 per cent) of the 69 with negative tests (p We conclude that the presence of angina prior to infarction and a positive limited exercise test performed before hospital discharge are predictive of angina following infarction. Myocardial infarction abolishes angina in a quarter of the patients, but angina develops postinfarction in nearly half of the patients who did not have angina previously.

Arterial expression of the plasminogen activator system early after cardiac transplantation

OBJECTIVES Recent studies suggest that alterations in tissue thrombolysis as well as the inward migration of cells may be specific events that contribute to coronary artery narrowing after cardiac transplantation. Plasminogen activators and inhibitors play a central role in governing not only tissue thrombolysis, but also vascular cell migration. The purpose of this study was to examine arterial wall expression of the plasminogen activation system in coronary arteries during graft vascular disease initiation and progression. METHODS Using in situ hybridization and immunocytochemistry, the expression patterns of uPA and PAI-1 in coronary arteries from cardiac allografts were compared to those of young individuals without disease. RESULTS Both PAI-1 and uPA were over-expressed early after transplantation and as late as 27 months post grafting. Over-expression of these molecules preceded morphological evidence of graft vascular disease. Of special note was the adventitial expression of uPA and PAI-1 in microvessels and myofibroblasts. In contrast, the expression of uPA and PAI-1 in normal coronary arteries was confined to endothelial cells of the central lumen, as well as low levels of expression in intimal and medial smooth muscle cells. CONCLUSIONS Despite morphologic similarities between normal and transplant coronary arteries, differences were noted in the vascular expression pattern of uPA and PAI-1. The exact role of these molecules in graft vascular disease requires further study; however, it is intriguing to consider that a local imbalance in the plasminogen system may contribute to arterial wall thrombosis and/or excessive cell migration and the genesis of complex vascular lesions.

Failure to Pace following High Dose Antiarrhythmic Therapy—Reversal with Isoproterenol

A patient with resistant ventricular tachycardia treated with a combination of antiarrhythmic agents is described. Sudden onset of a wide complex ventricular rhythm with periods of asystole and failure to achieve transvenous pacing were observed, presumably due to antiarrhythmic drug toxicity. Inability to pace was reversed by the infusion of isoproterenol.

The calcium channel blockers: Pharmacology and clinical applications

Summary and conclusionsThe calcium channel blockers provide an exciting and effective new therapeutic tool in the management of ischaemic cardiac syndromes and may prove popular and effective in the treatment of a variety of other disorders. They have provided a new approach to treatment and have added new insights into the pathogenesis of ischaemic cardiac syndromes. Their introduction into clinical practice has been swift and many of our concepts regarding their pharmacologic activities in man remain based on theoretic considerations. Their expanding clinical use and further comparative studies will undoubtedly provide further information in regard to indications, adverse effects, drug interaction and long-term safety. Particular caution is advised when they are combined with certain antiarrhythmic agents, digitalis and particularly beta adrenergic blocking agents. Little is known about their interaction with various general anaesthetic agents and for this reason particular vigilance is required as more patients receiving these agents are admitted for surgical procedures.

A computerized system for morphometric analysis of digitized images of histologically prepared arterial cross sections

A method is described for computerized, operator-assisted, morphometric measurement of histologically prepared arterial cross sections. The system is composed of an image cytometer equipped with a one power lens and a digitizing camera interfaced with an imaging board residing in a PC computer. Algorithms were developed for automated segmentation of the areas of interest. The method is rapid, objective, accurate and requires minimum operator intervention. It gives reliable and reproducible results in the measurement of all elements of the cross section including circumference, area of the media, circumference of the internal elastic lamina, area of the lumen and percent occlusion of the lumen by the intimal thickening. While manual measurements using computerized planimetric methods give similar results, this method is an order of magnitude faster (1-2 min vs. 10-20 min per cross section) thus facilitating the study of large numbers of specimens. A blinded re-measurement of 284 sections of artery for reproducibility yielded r values of 0.86-0.97.