[Increase in tolerance to physical effort in patients with X syndrome after acute administration of aminophylline].
Myocardial flow maldistribution and transmural steal phenomena, due to excessive arteriolar dilation elicited by elevated adenosine release during exercise, might be the mechanism of myocardial ischemia in patients with syndrome X. The effect of the adenosine receptor blocker aminophylline (AM) on effort ischemia in patients with syndrome X was tested: following double blind, randomized intravenous infusion of aminophylline (6 mg/kg over 15 minutes) or placebo, 8 patients with syndrome X underwent exercise stress test. After AM administration there was an increase in work tolerance (AM = 7.7 +/- 1.2 minutes of exercise vs placebo = 5.6 +/- 0.9, p less than 0.01) paralleled by an increase of the ischemic threshold, evaluated through the rate pressure product (mmHg x beats/min x 1/100) at 0.1 mV of ST-segment depression or at peak exercise (AM = 278 +/- 55 vs placebo = 230 +/- 24, p less than 0.05). AM prevented the occurrence of ischemic ECG signs in all 8 patients. Thus, at a dosage which effectively inhibits adenosine receptors, aminophylline infusion exerts beneficial effect on exercise induced ischemia in syndrome X, possibly through the prevention of transmural steal phenomena, elicited by inappropriate adenosine release during effort.
Emdin
M
M
Lattanzi
F
F
Picano
E
E
D000328:Adult; D000628:Aminophylline / Q000008:administration & dosage / Q000627:therapeutic use*; D000787:Angina Pectoris / Q000503:physiopathology*; D003327:Coronary Disease / Q000188:drug therapy* / Q000503:physiopathology; D004311:Double-Blind Method; D005080:Exercise Test; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D008875:Middle Aged; D005082:Physical Exertion / Q000187:drug effects*; D016032:Randomized Controlled Trials as Topic; D013577:Syndrome
D000628:Aminophylline
Aumento della tolleranza allo sforzo fisico in pazienti con sindrome X indotto dalla somministrazione acuta di aminofillina.