Effects of nicardipine and urapidil on length-dependent regulation of myocardial function in coronary artery surgery patients.
OBJECTIVE
To assess effects of a decrease in left ventricular (LV) afterload (pharmacologically induced by nicardipine and urapidil) on myocardial contraction and relaxation, with emphasis on the effects on load dependence of myocardial function.


METHODS
Prospective, blinded study.


METHODS
University hospital.


METHODS
Coronary artery surgery patients.


METHODS
Alterations of systolic load were effected by leg elevation in control conditions and after administration of either nicardipine or urapidil before and after cardiopulmonary bypass.


RESULTS
High-fidelity LV pressure tracings were obtained at end-expiration while hearts were paced at a fixed rate of 90 beats/min. Hemodynamic effects of leg elevation were compared before and after nicardipine, 7 microg/kg (n = 15), and before and after urapidil, 0.4 mg/kg (n = 15). The effects of leg elevation on parameters of contraction and relaxation were coupled. Both nicardipine and urapidil similarly decreased systolic pressures and peripheral resistance. Nicardipine decreased rate of pressure development (dP/dtmax) and slowed LV pressure fall, whereas load dependence of LV relaxation was not altered. Urapidil did not alter dP/dtmax, rate of LV pressure fall, or load dependence of relaxation. Similar results were observed after cardiopulmonary bypass.


CONCLUSIONS
The results of the present study indicate that a pharmacologically induced moderate reduction in LV afterload with nicardipine or urapidil did not alter the length-dependent regulation of myocardial function.
De Hert
S G
SG
Department of Anesthesiology, University Hospital Antwerp, Belgium.
Van der Linden
P J
PJ
Ten Broecke
P W
PW
Sermeus
L A
LA
Gillebert
T C
TC
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002315:Cardiopulmonary Bypass; D001026:Coronary Artery Bypass / Q000379:methods; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply; D008297:Male; D009200:Myocardial Contraction / Q000187:drug effects*; D009529:Nicardipine / Q000494:pharmacology*; D010879:Piperazines / Q000494:pharmacology*; D011446:Prospective Studies; D014655:Vascular Resistance / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology*
D000317:Adrenergic alpha-Antagonists; D002121:Calcium Channel Blockers; D010879:Piperazines; D014665:Vasodilator Agents; C015568:urapidil; D009529:Nicardipine