Chronic AT1-receptor blockade does not alter cerebral oxygen supply/demand ratio during cardiopulmonary bypass in hypertensive patients.
BACKGROUND
The angiotensin II receptor type 1 antagonist candesartan has been hypothesized to alter vasopressor requirements and brain-blood flow by changing cerebrovascular autoregulation. Therefore, we assessed the effects of a pre-anaesthetic treatment course with candesartan on cerebral arterial-jugular bulb oxygen content difference, middle cerebral artery blood velocity, and vasopressor requirements in hypertensive patients undergoing elective on-pump coronary artery bypass graft surgery.


METHODS
In a randomized, double-blind, placebo-controlled study, we evaluated the effects of candesartan (8 mg po/d, given for 6-8 days before surgery) in 35 hypertensive patients. The mean arterial pressure was maintained above 60 mmHg by bolus administration of phenylephrine, if required, and dosages were recorded.


RESULTS
Candesartan did not significantly alter oxygen content difference across the cerebral circulation, mean middle cerebral artery blood velocity during cardiopulmonary bypass, or phenylephrine requirements either before (0.0067 microg/kg/min+/-0.0042 vs. 0.0056 microg/kg/min+/-0.0049, P=0.48) or during cardiopulmonary bypass (0.0240 microg/kg/min+/-0.0240 vs. 0.0250 microg/kg/min+/-0.0190, P=0.97) compared with placebo.


CONCLUSIONS
Thus, a 6-8-day treatment course with candesartan does not alter global cerebral perfusion and oxygen supply/demand ratio during cardiopulmonary bypass, or vasopressor requirements in hypertensive patients undergoing on-pump coronary artery bypass graft surgery, and no deleterious consequences of AT1-receptor blockade were detected.
Kottenberg-Assenmacher
E
E
Klinik für Anästhesiologie und Intensivmedizin, Universitätsklinikum Essen, Essen, Germany. eva.kottenberg-assenmacher@uni-duisburg-essen.de
Massoudy
P
P
Jakob
H
H
Philipp
T
T
Peters
J
J
D000368:Aged; D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology* / Q000627:therapeutic use; D000959:Antihypertensive Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001562:Benzimidazoles / Q000494:pharmacology* / Q000627:therapeutic use; D001713:Biphenyl Compounds; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000378:metabolism*; D002315:Cardiopulmonary Bypass / Q000009:adverse effects; D002536:Cerebral Arteries; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000188:drug therapy*; D002534:Hypoxia, Brain / Q000209:etiology / Q000517:prevention & control*; D007431:Intraoperative Complications / Q000209:etiology / Q000517:prevention & control*; D007601:Jugular Veins; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery; D010100:Oxygen / Q000378:metabolism*; D010656:Phenylephrine / Q000008:administration & dosage / Q000627:therapeutic use; D011292:Premedication; D013777:Tetrazoles / Q000494:pharmacology* / Q000627:therapeutic use; D017211:Treatment Failure
D047228:Angiotensin II Type 1 Receptor Blockers; D000959:Antihypertensive Agents; D001562:Benzimidazoles; D001713:Biphenyl Compounds; D013777:Tetrazoles; D010656:Phenylephrine; D010100:Oxygen; C081643:candesartan