digitoxin and Arterial-Occlusive-Diseases

Topics: Acetyldigitoxins; Aged; Arterial Occlusive Diseases; Digitoxin; Humans; Male; Spasm

The effects of digitalis (ouabain infusion, priming dose of 10 micrograms/kg/min followed by 2.0 micrograms/kg/min) on subepicardial and subendocardial ischemic dysfunction during partial occlusion (59.4% reduction in coronary flow) and total coronary occlusion were evaluated in 14 dogs using pairs of ultrasonic crystals implanted in the epicardial and endocardial layers. After 30 minutes of partial coronary occlusion, systolic shortening in the ischemic zone decreased from 12.4 +/- 2.9% to -0.4 +/- 0.9% (p less than 0.001) in the epicardium and from 18.9 +/- 3.1% to -1.0 +/- 1.1% (p less than 0.001) in the endocardium. Ouabain infusion increased the systolic shortening from -0.4 +/- 0.9% to 10.6 +/- 3.1% (p less than 0.001) in the epicardium and from -1.0 +/- 1.1% to 17.2 +/- 3.4% (p less than 0.001) in the endocardium. The end-diastolic length did not change. In contrast, after 30 minutes of total coronary occlusion, systolic shortening in both epicardial and endocardial layers was replaced by systolic lengthening and remained unaffected by ouabain infusion in both layers. Systolic shortening in the nonischemic epicardial and endocardial layers increased consistently. We conclude that ouabain improves the contractile function of both ischemic epicardial and endocardial layers layers after partial coronary occlusion and does not worsen subendocardial ischemic dysfunction. After total coronary occlusion, however, the contraction of the ischemic zone is unaffected by ouabain.

Topics: Animals; Arterial Occlusive Diseases; Coronary Circulation; Coronary Disease; Digitalis; Dogs; Myocardial Contraction; Ouabain; Plants, Medicinal; Plants, Toxic; Ultrasonography

This study examined nonuniform postganglionic cardiac sympathetic neural discharge as a possible mechanism involved in the production of coronary occlusion or ouabain-induced arrhythmias. After acute occlusion of the left anterior descending coronary artery in 12 cats, anesthetized with alpha-chloralose and pretreated with atropine, arrhythmia occurred within 3 min in eight animals; three of these died in ventricular fibrillation. In recordings from 15 nerves in the eight animals with arrhythmia, spontaneous discharge increased in nine nerves, decreased in five nerves, and showed no change in one nerve. This nonuniform neural discharge was associated with the development of arrhythmia after occlusion. In four of the cats, neural discharge did not change within the first 3 min after coronary artery occlusion and arrhythmia did not occur. Development of ouabain-induced arrhythmia was accompanied by a nonuniform pattern in the neural discharge (13 cats). This discharge may alter ventricular excitation and conduction to produce arrhythmia.

Topics: Action Potentials; Animals; Arrhythmias, Cardiac; Arterial Occlusive Diseases; Blood Pressure; Cats; Coronary Vessels; Digitalis; Heart; Heart Conduction System; Heart Rate; Ouabain; Plants, Medicinal; Plants, Toxic; Sympathetic Nervous System; Time Factors

Topics: Adult; Aged; Arterial Occlusive Diseases; Coronary Disease; Digitalis; Electrocardiography; Ethylamines; Female; Furans; Humans; Injections, Intravenous; Male; Middle Aged; Myocardial Infarction; Naphthalenes; Pacemaker, Artificial; Phytotherapy; Plants, Medicinal; Plants, Toxic; Propionates; Vasodilator Agents

Topics: Adult; Aged; Arterial Occlusive Diseases; Atrial Flutter; Cardiac Output; Digitoxin; Female; Humans; Hyperemia; Intermittent Claudication; Leg; Male; Middle Aged; Plethysmography; Quinidine