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August 1, 2017 Circulation. 2017;136:e60–e122. DOI: 10.1161/CIR.0000000000000499 e86

5.3 Carotid Sinus Syndrome: Recommendations

Carotid sinus syndrome is associated with mechanical manipulation of the carotid sinus, either spontaneously or with carotid sinus massage. It is diagnosed by the reproduction of clinical syncope during carotid sinus massage, with a cardioinhibitory response if asystole is >3 seconds or if there is AV block, or a significant vasodepressor response if there is ≥50 mm Hg drop in systolic blood pressure, or a mixed cardioinhibitory and vasodepressor response. It occurs more commonly in men >40 years of age413,414 and is due to an abnormal reflex attributed to baroreceptor and possibly medulla dysfunction.415,416 Carotid sinus massage should be performed sequentially over the right and left carotid artery sinus in both the supine and upright positions for 5 seconds each, with continuous beat-to-beat heart rate monitoring and blood pressure measurement.417 Contraindications to performing carotid sinus massage include auscultation of carotid bruit and transient ischemic attack, stroke, or myocardial infarction within the prior 3 months, except if carotid Doppler excludes significant stenosis.418

Recommendations for Carotid Sinus Syndrome

COR LOE Recommendations IIa B-R Permanent cardiac pacing is reasonable in patients with carotid sinus syndrome that is cardioinhibitory or mixed.413,419–426

See Online Data Supplements 29–32. Syncope recurred in fewer patients treated with pacing than in untreated patients, with observation periods up to 5 years.420,423 In 3 controlled, open-label trials, the relative risk reduction of syncope recurrence with pacemaker implantation was 76%.409,427–429 There are no large RCTs.

IIb B-R It may be reasonable to implant a dual-chamber pacemaker in patients with carotid sinus syndrome who require permanent pacing.427–430

See Online Data Supplements 29–32. Evidence for dual-chamber pacing versus single-chamber pacing in carotid sinus hypersensitivity is limited to a few small RCTs and limited observational data.409,418,427–429 Although mixed, the data suggest dual-chamber pacing may prevent hemodynamic compromise and improve symptom recurrence in older adults who may have concomitant sinus node dysfunction or conduction system disease.

5.4 Other Reflex Conditions

Situational syncope is defined as syncope occurring only in certain distinct and usually memorable circumstances, including micturition syncope, defecation syncope, cough syncope, laugh syncope, and swallow syncope.431–437 Appropriate investigations should be undertaken to determine an underlying etiology, including causes that may be reversible.431,433–436 Evidence for treatment is limited mainly to case reports, small case series, and small observational studies.431,433–436 Treatment of most types of situational syncope relies heavily on avoidance or elimination of a triggering event. This may not always be possible, so increased fluid and salt consumption and reduction or removal of hypotensive drugs and diuretics are encouraged where appropriate and safe.436

6. ORTHOSTATIC HYPOTENSION: RECOMMENDATIONS 6.1. Neurogenic Orthostatic Hypotension: Recommendations

OH involves excessive pooling of blood volume in the splanchnic and leg circulations. With standing, venous

Figure 4. Vasovagal Syncope. Colors correspond to Class of Recommendation in Table 1. V VS indicates vasovagal syncope.

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