Subject(s)
Bucladesine/pharmacology , Coronary Circulation/drug effects , Coronary Disease/physiopathology , Myocardium/metabolism , Adult , Aged , Bucladesine/therapeutic use , Coronary Disease/drug therapy , Female , Hemodynamics/drug effects , Humans , Male , Middle Aged , Oxygen Consumption/drug effectsABSTRACT
The purpose of this study is to record continuously electrocardiograms of alpinists during different activities practiced in mountaineering, compare heart rate and QT interval at high altitude with those at sea level, and compare alpinists with nonalpinists. Analysis was attempted on 14 alpinists (9 male, 5 female, ages 26-45) to determine changes in heart rate and QT interval using continuous ambulatory electrocardiograms recorded at sea level and high altitude. Between 1983 and 1984, 9 of 14 alpinists (6 male, 3 female) were subjected to the study at high altitude, that is, at Mt. Kangchenjunga (Himalaya), Mt. Satopanth (Himalaya), and Mt. Jitudake (Butan), 4400 to 7800 m (mean 5710 m). The following were noted: Heart rate at high altitude was significantly higher both in daytime and nighttime. The circadian rhythm of the heart rate disappeared at extremely high altitude in several alpinists. A high correlation was noted between measured QT interval (QTm) and RR interval (r = 0.81, p = 0.005). Nighttime QTm at high altitude was prolonged in comparison with that of daytime so far as the RR interval remained the same. At high altitude, the nighttime corrected QT interval (QTc) was also significantly prolonged in spite of shortened RR interval. The mechanism of QTc prolongation is not clear. Many factors may impact on the QT interval during mountaineering.
Subject(s)
Altitude , Electrocardiography , Heart Rate , Monitoring, Physiologic , Mountaineering , Circadian Rhythm , HumansABSTRACT
Effects of nicorandil (NC), a newly synthesized nicotinamide derivative (2 mg i.v.), nitroglycerin (TNG, 0.3 mg sublingual), nifedipine (NF, 10 mg sublingual), and propranolol (PR, 0.1 mg/kg i.v.) on coronary hemodynamics were evaluated in 41 patients with ischemic heart disease. Coronary sinus flow (CSF) was measured using a continuous thermodilution method. NC decreased arterial pressure, cardiac output (CO), and pulmonary artery pressure without changing heart rate. Rate-pressure product tended to decrease. Resting CSF was increased by NC (117-148 ml/min, p less than 0.01) and NF. TNG and PR caused no significant changes. Furthermore, NC revealed the highest CSF/CO ratio among four agents and decreased coronary resistance. During rapid atrial pacing, CSF was slightly increased by TNG, but remained unchanged after NC and NF. Myocardial norepinephrine release was markedly increased by TNG (1.5-6.2 ng/min, p less than 0.01) and slightly increased by NF. No changes were noted after NC and PR. Myocardial lactate extraction varied insignificantly in all agents. NC is a potent coronary vasodilator and seems to reduce both preload and afterload; however, in contrast to TNG and NF, NC did not cause reflex tachycardia or an increase of myocardial sympathetic tone.
Subject(s)
Coronary Disease/physiopathology , Hemodynamics/drug effects , Niacinamide/analogs & derivatives , Vasodilator Agents/pharmacology , Adult , Aged , Cardiac Pacing, Artificial , Coronary Circulation/drug effects , Humans , Lactates/metabolism , Lactic Acid , Middle Aged , Myocardium/metabolism , Niacinamide/pharmacology , Nicorandil , Nifedipine/pharmacology , Nitroglycerin/pharmacology , Norepinephrine/metabolism , Oxygen Consumption/drug effects , Propranolol/pharmacologyABSTRACT
Plasma levels of histamine (HI) were determined by fluorescence photometry in 12 patients with old myocardial infarction, 10 patients with stable effort angina pectoris and 10 control subjects without coronary arterial lesion. Resting HI were 57.6 +/- 7.5 ng/ml for control subjects and 68.6 +/- 3.9 ng/ml for patients with coronary artery disease (CAD) (N.S.). HI were 62.6 +/- 4.7 ng/ml for patients with one vessel disease, 68.0 +/- 10.6 ng/ml for patients with two vessel disease and 79.1 +/- 4.9 ng/ml for patients with three vessel disease (one vessel disease: three vessel disease, p less than 0.05). HI for all subjects decreased from 65.6 +/- 3.5 ng/ml before treadmill exercise test to 63.4 +/- 3.8 ng/ml after exercise (N.S.), and the rate of change did not differ from control subjects to diseased patients. HI increased significantly from 63.5 +/- 3.7 ng/ml to 70.7 +/- 3.7 ng/ml after hyperventilation (p less than 0.05), but the rate of change did not differ from control to CAD patients. In the present study a tendency was observed that the severe the coronary arterial lesions, the higher were HI. In old myocardial infarction and stable effort angina pectoris, however, the changes in HI produced by exercise and hyperventilation do not seem to be deeply involved in the onset of acute myocardial ischemia.
