Acute effects of ketanserin on left ventricular function, metabolism and coronary blood flow.

An acute intravenous bolus of 10 mg ketanserin (a specific 5-HT antagonist) caused an abrupt fall in left ventricular systolic pressure of 17 +/- 9.2 mm Hg (P less than 0.025) in ten patients undergoing cardiac catheterisation for chest pains. A fall in pulmonary artery diastolic pressure of 2.1 +/- 0.74 mm Hg (P less than 0.02) was also observed. No changes in resting heart rate occurred and the response to pacing was largely unmodified by ketanserin, except for a reduction in pulmonary vascular resistance (3.70 +/- 1.27 units to 2.97 +/- 1.44 units, P less than 0.05), at the fastest rate (136 +/- 3 beats/min). At the highest pacing rate coronary sinus blood flow fell (83 +/- 12 ml 100 g-1 min-1 to 68 +/- 8 ml 100 g-1 min-1, P less than 0.05), as did myocardial oxygen consumption (18 +/- 2 ml-1 min to 14 +/- 1 ml min-1, P less than 0.05) after the drug. No changes in the parameters of left ventricular contractile function could be attributed to ketanserin, save for a modest increase in the ejection fraction (48 +/- 6% to 57 +/- 6%, P less than 0.05) in seven patients. There were no alterations in myocardial metabolism of lactate, pyruvate, hydroxybutyrate, glycerol nor free fatty acids after ketanserin. The findings are consistent with a peripheral site of action of this drug and its blood pressure lowering effect in the subjects suggest a non-specific hypotensive action rather than an anti-hypertensive effect.