Long-term effects of unilateral carotid endarterectomy on arterial baroreflex function.
OBJECTIVE
Carotid endarterectomy (CE) may be complicated by the clinical syndrome of baroreflex failure. Alterations of baroreflex function may also account for the frequently observed blood pressure lability in the first hours following surgery. We investigated the long-term effects of unilateral CE on baroreflex control of function and blood pressure.


METHODS
We investigated 14 patients after unilateral CE (13 m:1 f, 64.8 +/- 6.5 years), 9 patients with a surgically untreated uni-/bilateral carotid stenosis (CS, 7 m:2 f, 57.6 +/- 10.7 years) and 12 healthy controls (HC, 11 m:1 f, 60.9 +/- 7.9 years) by means of Valsalva maneuver, active standing, forced breathing, cold face test, cold pressor test and mental arithmetic. Ambulatory blood pressure level and variability were determined from 24-hour Spacelabs and 5-hour beat-to-beat Portapres recordings.


RESULTS
Baroreflex sensitivity (derived from phase IV Valsalva maneuver) was significantly lower in CE (1.53 +/- 0.83 ms/mmHg) than in CS (4.39 +/- 2.27, p = 0.002) and HC (5.34 +/- 3.78, p = 0.003). CE patients exhibited a decreased reflex control of heart rate in response to Valsalva's maneuver and active standing without orthostatic hypotension. Office blood pressure levels before and after endarterectomy were similar, as were ambulatory blood pressure levels in the three groups. Ambulatory blood pressure variability was higher in CE and CS than in HC, but not different between CE and CS.


CONCLUSIONS
Unilateral CE causes a long-term impairment of baroreflex function, resulting in an attenuated reflex control of heart rate, but no hypertension or blood pressure lability.
Timmers
Henri J L M
HJ
Dept. of General Internal Medicine, University Medical Center Nijmegen, Geert Grooteplein Zuid 8, 6500 HB Nijmegen, The Netherlands. H.Timmers@aig.umcn.nl
Buskens
Frans G M
FG
Wieling
Wouter
W
Karemaker
John M
JM
Lenders
Jacques W M
JW
D000328:Adult; D000368:Aged; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure; D016893:Carotid Stenosis / Q000601:surgery*; D016894:Endarterectomy, Carotid / Q000009:adverse effects*; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D013997:Time Factors