The Relationship Between Carotid Sinus Hypersensitivity, Orthostatic Hypotension, and Vasovagal Syncope: A Case-Control Study

Maw Pin Tan; Julia L. Newton; Tom J. Chadwick; Steve W. Parry

Disclosures

Europace. 2008;10(12):1400-1405. 

In This Article

Abstract and Introduction

Abstract

Aims: Previous uncontrolled studies reported an overlap between carotid sinus hypersensitivity (CSH), vasovagal syncope (VVS), and orthostatic hypotension (OH). We conducted a case-control study evaluating this relationship in a large patient cohort.
Methods and Results: The electronically stored continuous electrocardiograph and blood pressure (BP) measurements for active stand and head-up tilt-table (HUT) tests of 302 consecutive patients investigated with carotid sinus massage (CSM) were analysed. Carotid sinus hypersensitivity was defined as ≥3 s asystole and/or systolic BP (SBP) drop of ≥50 mmHg during CSM. Orthostatic hypotension was defined as BP reductions of ≥20 mmHg systolic or of ≥10 mmHg diastolic, whereas VVS was diagnosed with a positive HUT test. There was no significant difference in the number of subjects with OH (57 vs. 55%; P = 0.778) or HUT-positive VVS (45 vs. 47%; P = 0.828) between cases with CSH and controls without CSH. Carotid sinus hypersensitivity subjects had significantly larger SBP reduction (P = 0.039) and longer time to nadir (P = 0.007) during active stand, and trends to vasodepressor (P = 0.071) and dysautonomic responses to HUT (P = 0.151).
Conclusion: Carotid sinus hypersensitivity, OH, and VVS are common conditions affecting patients with syncope and falls which are likely to co-exist in such individuals. The differences in haemodynamic response patterns to active stand and HUT in CSH subjects could be the result of an age-associated delay in sympathetic responses.

Introduction

Syncope accounts for 1-3% of admissions to the emergency room[1,2,3] and up to 6% of acute hospital admissions.[4] Vasovagal syncope (VVS) is most common in the younger age group, whereas arrhythmias, cardiac structural causes, orthostatic hypotension (OH), and carotid sinus hypersensitivity (CSH) become more common in the older age group. However, VVS is now being diagnosed with increasing frequency in older patients since the use of head-up tilt-table (HUT) test in 1986.[5,6]

An overlap is said to occur for VVS, CSH, and OH. McIntosh et al.[7] reported that 14 of 26 (60%) patients with vasodepressor carotid sinus syndrome had OH or vasodepressor VVS, now classified as type 3 response according to the Vasovagal Syncope International Study (VASIS) classification.[7,8] Alboni et al.[9] described a 'complex neurally mediated syncope (NMS)' in a group of subjects with a positive HUT and a positive response to carotid sinus massage (CSM). Subjects with complex NMS comprised 31 of 280 (11%) patients diagnosed with NMS or reflex syncope following a systematic evaluation for unexplained syncope.[9]

The above studies were uncontrolled observational studies. The relationship between VVS, OH, and CSH has never been evaluated in a case-control fashion. We conducted a retrospective case-control study to investigate the overlap between VVS, OH, and CSH in patients investigated with CSM for syncope, drop attacks, and unexplained falls.

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