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Heart. 2006 Jun;92(6):792-7. Epub 2006 Jan 31.

Cerebral autoregulation is impaired in cardioinhibitory carotid sinus syndrome.

Author information

1
Cardiovascular Investigation Unit, Royal Victoria Infirmary, Newcastle upon Tyne, UK. steve.parry@nuth.northy.nhs.uk

Abstract

OBJECTIVES:

To compare changes in cerebral autoregulation in response to controlled, lower body negative pressure-induced hypotension in patients with carotid sinus syndrome (CSS) and case controls.

DESIGN:

Prospective case controlled study.

SETTING:

Secondary and tertiary referral falls and syncope service.

PATIENTS:

17 consecutive patients with CSS and 11 asymptomatic controls.

INTERVENTIONS:

Hypotension insufficient to cause syncope induced by lower body negative pressure (minimum 30 mm Hg fall in systolic blood pressure (SBP)) during concomitant transcranial Doppler ultrasonography.

MAIN OUTCOME MEASURES:

Cerebral autoregulation (systolic, diastolic and mean middle cerebral arterial blood flow velocities and cerebrovascular resistance) with continuous end-tidal carbon dioxide and haemodynamic monitoring.

RESULTS:

Cerebral autoregulatory indices differed significantly between patients with CSS and controls. Systolic, diastolic and middle cerebral arterial blood flow velocities were, respectively, 9.2 m/s (95% confidence interval (CI) 2.9 to 15.4 m/s), 4.7 m/s (95% CI 1.5 to 7.9 m/s) and 6.9 m/s (95% CI 2.5 to 11.4 m/s) slower in patients with CSS. Cerebrovascular resistance was significantly greater in patients with CSS than in controls at SBP nadir and suction release; differences were 0.9 mm Hg/m/s (95% CI 0.0 to 1.7 mm Hg/m/s) and 0.8 mm Hg/m/s (95% CI 0.0 to 1.7 mm Hg/m/s), respectively. End-tidal carbon dioxide and systemic haemodynamic variables were similar for patients and controls at baseline and during lower body negative pressure.

CONCLUSIONS:

Cerebral autoregulation is altered in patients with CSS. This difference may have aetiological implications in the differential presentation with falls and drop attacks rather than syncope.

PMID:
16449521
PMCID:
PMC1860657
DOI:
10.1136/hrt.2004.053348
[Indexed for MEDLINE]
Free PMC Article
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