Evaluation of calcium-mediated vasoconstriction in chronic congestive heart failure.
Intercellular vascular smooth muscle calcium results in vasoconstriction and is therefore a potentially adverse mechanism of increased afterload in chronic congestive heart failure. Therefore, an evaluation was made of supine and tilt hemodynamic data, sympathetic reflexes, and the hormonal response to calcium channel antagonism after administration of nifedipine in nine patients with severe chronic congestive heart failure. After a 10 mg oral dose, the peak hemodynamic response occurred at 30 minutes and was characterized primarily by afterload reduction, improvement of systemic flow, and reduction of pulmonary hypertension. Despite reduction of supine blood pressure, there was no orthostatic hypotension during head-up tilt at the same time of peak response. Reflex responses to sympathetic stimulation (cold pressor test) were improved but still attenuated when compared with normal responses. Plasma renin activity increased significantly, but a dissociation of the aldosterone response was observed. Plasma catecholamine levels were not significantly altered. In summary, calcium antagonism resulted in significant afterload reduction and hemodynamic improvement in chronic congestive heart failure. This was associated with improved reflex responsiveness and, potentially, altered other vasoconstrictor hormones independently of the hemodynamic response. Calcium antagonism may provide a means to further understand vasoconstrictor mechanisms in heart failure and enhance therapy in appropriate patient subsets.
D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D002118:Calcium / Q000502:physiology; D006333:Heart Failure / Q000188:drug therapy*; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009543:Nifedipine / Q000494:pharmacology / Q000627:therapeutic use*; D011187:Posture; D012018:Reflex / Q000187:drug effects; D012084:Renin-Angiotensin System / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects
D009543:Nifedipine; D002118:Calcium