tetracycline and Coronary-Disease

Static radionuclide imaging procedures are now available for evaluating regional myocardial perfusion and for detecting acute myocardial infarction. Thallium-201, a radiopharmaceutical that possesses many of the characteristics of potassium analogues, at present is receiving the greatest attention as a regional blood flow indicator. Ischemic lesions appear as areas of decreased tracer uptake. Unfortunately, this agent is expensive, is in limited supply, and has a photopeak that is low for optimum imaging. Positive infarct images can be obtained with various Technetium-99m chelates. Pyrophosphate appears to be the best of the technetium compounds studied to date, although the mechanism of uptake of the chelates has not yet been fully elucidated. Therefore, quantitative measurements of infract size are not justified. As perfusion imaging and infarct imaging provide useful, complementary data, a dual tracer approach to evaluating patients with suspected coronary artery disease and/or myocardial infarction, is probably justifiable.

Topics: Ammonia; Animals; Carbon Radioisotopes; Cesium Radioisotopes; Coronary Circulation; Coronary Disease; Diphosphates; Dogs; Fatty Acids; Heart Rate; Humans; Microspheres; Nitrogen Radioisotopes; Potassium Radioisotopes; Radioisotopes; Radionuclide Imaging; Rubidium; Sugar Acids; Technetium; Tetracycline; Thallium

This paper represents a review of the recent literature on techniques to measure myocardial blood flow in man. A short discussion on flow meters in followed by a more detailed discussion of the radionuclide techniques used to measure myocardial blood flow. The radionuclide techniques are discussed in two groups: (1) qualitative measurement of blood flow using static images; and (2) quantitative measurements of blood flow using diffusible substances that actively enter the cell, radioactive labeled particles, and radioactive diffusible gases.

Topics: Absorptiometry, Photon; Cesium Radioisotopes; Coronary Circulation; Coronary Disease; Fatty Acids; Humans; Indicator Dilution Techniques; Iodine Radioisotopes; Krypton; Microspheres; Nitrogen Radioisotopes; Phosphates; Physical Exertion; Potassium Radioisotopes; Radioisotope Dilution Technique; Radioisotopes; Radionuclide Imaging; Rheology; Rubidium; Serum Albumin, Radio-Iodinated; Technetium; Tetracycline; Thallium; Ultrasonography; Xenon Radioisotopes

Topics: Acute Disease; Anti-Bacterial Agents; Chlamydia Infections; Chlamydophila pneumoniae; Coronary Disease; Humans; Macrophage Activation; Potassium Channels; Roxithromycin; Tetracycline

Topics: Chest Pain; Coronary Disease; Electrocardiography; Female; Humans; Middle Aged; Rocky Mountain Spotted Fever; Splenomegaly; Tetracycline

The effects of the dimethyl quarternary analog of propranolol, UM-272, on myocardial infarct volume were studied in the canine heart. Myocardial infarction was produced by occlusion of the left circumflex coronary artery for 60 minutes followed by reperfusion and quantitation of infarct volume 24 hours later. Groups of dogs were either untreated or pretreated with UM-272 with an initial loading dose of 5.0 mg/kg (group A) or 2.5 mg/kg (group B) 30 minutes before occlusion of the left circumflex coronary artery. Both group A and group B animals received additional doses of 2.5 mg/kg of UM-272 every 90 minutes for a period of 6 hours so that the total respective doses were 15 and 12.5 mg/kg. Control animals received comparable volumes of 0.9% sodium chloride solution. All animals were followed throughout the 6-hour procedure with continuous electrocardiographic recordings which were used to assess the effects of acute myocardial ischemia upon disturbances in cardiac rhythm and the effects of drug treatment. Dogs which survived the procedure were given tetracycline i.v. the next day and sacrificed 1 hour later by an overdose of pentobarbital sodium. The hearts were removed and the left ventricle was sliced and examined first under ultraviolet light to localize the ischemic zone by noting the tetracycline fluorescence. The ventricular slices were next incubated in nitro blue tetrazolium which stains normal myocardial tissue, thus allowing one to quantitate the volume of infarcted myocardium by excising and weighing the nonstained and stained muscle separately. The untreated control group had an infarct volume of 23.8 +/- 3.2 g/100 g of left ventricle. The treated animals in groups A and B had respective infarct volumes of 2.3 +/- 0.8 g/100 g (P less than .001) and 7.0 +/- 3.3 g/100 g (P less than .025) of left ventricle. During the acute phase of ischemia and reperfusion, arrhythmias and alterations in the ST-segment, R-wave amplituted and development of pathologic Q-waves were more prominent in the untreated animals and almost totally absent in the treated animals. UM-272 produced a dose-dependent decrease in heart rate as well as a decrease in developed isometric tension. Pretreatment with UM-272 did not prevent the derangement of function in the ischemic zone nor did it permit a return of function upon reperfusion, even though it reduced the degree of cellular damage resulting from 60 minutes of regional ischemia. A possible mechanism for the protective ef

Topics: Animals; Blood Pressure; Cardiac Output; Coronary Circulation; Coronary Disease; Disease Models, Animal; Dogs; Electrocardiography; Heart Rate; Myocardial Contraction; Myocardial Infarction; Myocardium; Nitroblue Tetrazolium; Oxidoreductases; Propranolol; Tetracycline; Time Factors

After acute coronary occlusion in primates, the time period during which reperfusion results in significant salvage of reversibly injured myocardium was investigated. In 23 monkeys, the left anterior descending coronary artery was occluded from 1 to 6 h; and in 5 others, occlusion was maintained for the 1-wk study. Unipolar epicardial electrocardiograms were monitored from mapping points on the anterior and lateral left venticle. S-T segment elevation (S-T upward arrow) and R + S wave amplitude (RS) were measured before occlusion and at regular intervals during occlusion and reperfusion. Summated S-T upward arrow (SigmaS-T upward arrow) and summated RS (SigmaRS), computed for mapping points demonstrating greater than 2 mV S-T upward arrow, were used as serial measures of electrical injury. SigmaS-T upward arrow peaked within 2-h postocclusion and then gradually declined throughout the period of occlusion suggesting the progress of infarction within the area of injury. After reperfusion SigmaS-T upward arrow rapidly declined to near cnotrol values indicating the extent of reversible injury. During the period of occlusion, the magnitude of voltage loss in SigmaS-T upward arrow as a percent of maximum SigmaS-T upward arrow was proportional to the duration of occlusion, though the rate of loss decreased with increasing time of occlusion. Reperfusion after 6 h of occlusion resulted in reversal of only a small remaining component of the maximum current of injury. The voltage decrease in SigmaRS (from control values) was proportional to the duration of occlusion, though the decrease was accelerated during the first 2-h postocclusion. Whereas reperfusion interrupted the decline in SigmaRS, a consistent increase in SigmaRS postreperfusion was observed only after occlusion of 1 h. With respect to reperfusion groups, significance in SigmaS-T upward arrow voltage loss as a percent of maximum SigmaS-T upward arrow was demonstrated between 2-h and 4-h, 4- and 6-h, and 6-h and chronically ligated animals. Significance in SigmaRS voltage loss as a percent of control SigmaRS was demonstrated between 2- and 4-h, and 4- and 6-h reperfusion groups. Hearts were excised at 7 days for histological assessment of infarct size. Planimetric determination of left ventricular areas and areas of necrosis using slides made from 10 serial cross sections were used in estimating the percent of left ventricle infarcted. A significant reduction in infarct size was demonstrated between reper

Topics: Animals; Coronary Circulation; Coronary Disease; Coronary Vessels; Electric Injuries; Electrocardiography; Fluorescence; Heart Ventricles; Ligation; Macaca fascicularis; Models, Biological; Myocardial Infarction; Necrosis; Tetracycline; Time Factors; Tourniquets

Topics: Adrenal Cortex Hormones; Bronchial Spasm; Bronchodilator Agents; Central Nervous System Stimulants; Coronary Disease; Digitalis Glycosides; Guaiacol; Haemophilus Infections; Humans; Hypercapnia; Hypoxia; Injections, Intramuscular; Injections, Intravenous; Metaproterenol; Oxygen Inhalation Therapy; Phenethylamines; Physical Therapy Modalities; Resorcinols; Respiratory Insufficiency; Tetracycline; Time Factors

Topics: Adolescent; Antibodies; Arrhythmias, Cardiac; Arteritis; Cardiovascular Diseases; Cerebrovascular Disorders; Child; Chlortetracycline; Coronary Disease; Geriatrics; Heart Defects, Congenital; Heart Diseases; Humans; Infant; Raynaud Disease; Rickettsia Infections; Rolitetracycline; Tetracycline; Thrombophlebitis; Thrombosis