title: Paradox of improved exercise but not resting hemodynamics with short-term prazosin in chronic heart failure.
abstract: In patients with chronic heart failure exercise allows the simultaneous observation of the cardiovascular pathophysiology and the symptoms of these patients. We administered short-term, oral prazosin to 10 patients with severe chronic heart failure. Prazosin increased cardiac output and stroke volume significantly during exercise (both P less than 0.05) but not at rest (both P greater than 0.10). Prazosin decreased the arteriovenous oxygen difference and left ventricular filling pressure significantly during exercise (both  P less than 0.05) but not at rest (both P greater than 0.10). There was no significant correlation between prazosin-induced changes at rest and during exercise in cardiac output (r = 0.12), stroke volume (r = 0.02), arteriovenous oxygen difference (r = 0.33) or left ventricular filling  pressure (r = 0.43). Prazosin predominantly affects hemodynamics during exercise because its pharmacologic activity as an alpha-adrenergic blocking agent is most prominent during exercise. The full evaluation of prazosin-induced changes in the hemodynamics of patients of patients with chronic heart failure requires evaluation during exercise.
mesh_terms: D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D005080:Exercise Test; D005260:Female; D006333:Heart Failure / Q000188:drug therapy*; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000187:drug effects; D011224:Prazosin / Q000627:therapeutic use*; D011799:Quinazolines / Q000627:therapeutic use*; D013997:Time Factors; D014655:Vascular Resistance / Q000187:drug effects
chemical_list: D011799:Quinazolines; D010100:Oxygen; D011224:Prazosin