title: Lack of effect of low levels of carboxyhemoglobin on cardiovascular function in patients with ischemic heart disease.
abstract: We studied 30 patients 38-75 yr of age who had ischemic heart disease to assess the effect of acute elevation of carboxyhemoglobin (COHb) concentration. Patients were nonsmokers with ischemia defined by exercise-induced ST depression (ST decreases)--25/30, angina--23/30, or abnormal ejection fraction (EF) response--18/30. After an initial familiarization and exercise session patients were exposed to air (carboxyhemoglobin [COHb] = 1.5 +/- 0.05%) and to carbon monoxide (CO) (100 ppm-COHb-average = 3.8 +/- 0.1%) on successive days in a double blind, randomized fashion. There was no significant difference in time to onset of angina (air = 312 sec, CO = 306 sec), maximal exercise time (air = 711 sec, CO = 702 sec), maximal ST decreases (1.5 mm for both), or time to significant ST decreases (air = 474 sec, CO = 475 sec). Double product at ST decreases and maximal double products were similar for both conditions. Resting ejection fraction was slightly but nonsignificantly higher after CO exposure (air = 53.9%, CO = 55.2%). Maximal ejection fraction was similar for both conditions (air = 57.4%, CO = 57.1%). Change in ejection fraction was slightly lower for CO exposure (air = 3.5%, CO = 2%), p = .049. In conclusion, there is no clinically significant effect of 3.8% COHb (representing a 2.2% increase from resting values) on the cardiovascular system in this study.
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000368:Aged; D002248:Carbon Monoxide / Q000633:toxicity*; D002263:Carboxyhemoglobin / Q000502:physiology*; D003327:Coronary Disease / Q000097:blood* / Q000503:physiopathology; D004311:Double-Blind Method; D005080:Exercise Test; D005260:Female; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011875:Radionuclide Angiography; D011897:Random Allocation; D013318:Stroke Volume / Q000187:drug effects
chemical_list: D002248:Carbon Monoxide; D002263:Carboxyhemoglobin