ESC Guidelines for Carotid Sinus Hypersensitivity (CSH)

Carotid Sinus Hypersensitivity (CSH)

Definition

Carotid sinus hypersensitivity (CSH) is an exaggerated response to carotid sinus stimulation leading to:

• Excessive bradycardia (cardioinhibitory response)

• Hypotension (vasodepressor response)

• Or a combination of both

It is an important cause of unexplained syncope, especially in elderly patients.

---

Anatomy and Physiology of the Carotid Sinus

• Located at the bifurcation of the common carotid artery

• Contains baroreceptors sensitive to stretch

• Afferent pathway: Glossopharyngeal nerve (Hering’s nerve)

• Central integration: Medulla

• Efferent pathway: Vagus nerve → SA/AV node

Normal function: Maintains blood pressure homeostasis

In CSH: Minor stimulation → exaggerated reflex

---

Epidemiology

• More common in age > 60 years

• Male predominance

• Frequently associated with hypertension

• Seen in patients with recurrent unexplained falls

CSH may be present in asymptomatic elderly individuals, so clinical correlation is essential.

---

Pathophysiology

Exaggerated baroreceptor reflex leads to:

1. Increased vagal tone → sinus arrest / AV block

2. Sympathetic withdrawal → vasodilation → hypotension

Even mild external pressure (tight collar, shaving, neck turning) can trigger symptoms.

---

Types of Carotid Sinus Hypersensitivity

1. Cardioinhibitory Type

• Asystole ≥ 3 seconds during carotid sinus massage

• Predominantly bradycardia-mediated syncope

• Most common type

2. Vasodepressor Type

• Drop in systolic BP ≥ 50 mmHg

• Minimal heart rate change

• Syncope due to hypotension

3. Mixed Type

• Both significant asystole and hypotension

---

Clinical Presentation

• Recurrent syncope

• Presyncope

• Unexplained falls in elderly

• Syncope triggered by: – Shaving

– Tight collars

– Neck rotation

– Carotid sinus pressure

Often abrupt, with rapid recovery.

---

Diagnosis

Carotid Sinus Massage (CSM)

Performed under continuous ECG and BP monitoring.

Technique: • Supine position

• Massage one side at a time

• 5–10 seconds duration

• Repeat in upright position if negative

Diagnostic Criteria: • Asystole ≥ 3 sec

OR

• SBP drop ≥ 50 mmHg

With reproduction of symptoms

Contraindications: • Recent TIA or stroke (<3 months)

• Significant carotid stenosis

• Carotid bruit (relative)

---

Differential Diagnosis

• Vasovagal syncope

• Orthostatic hypotension

• AV block

• Sick sinus syndrome

• Arrhythmias

• Structural heart disease

---

Management

1. Conservative Measures

• Avoid tight collars

• Avoid neck pressure

• Treat hypertension carefully

• Patient education

2. Permanent Pacemaker

Indicated in:

• Symptomatic cardioinhibitory CSH

• Recurrent syncope with documented asystole

Preferred mode: • Dual chamber pacing (DDD)

Pacemaker is less effective in pure vasodepressor type.

---

Prognosis

• Generally benign in terms of mortality

• Morbidity due to falls and trauma

• Pacemaker significantly reduces recurrence in cardioinhibitory type

---

Important Clinical Pearls

• Always perform CSM in unexplained syncope in elderly (if no contraindications)

• Asymptomatic CSH does not require treatment

• Mixed type may still benefit from pacing

• Reproduction of symptoms during CSM is crucial for diagnosis

---

Quick Exam Revision Table

Feature Cardioinhibitory Vasodepressor Mixed

Asystole ≥ 3 sec Yes No Yes

SBP drop ≥ 50 mmHg May Yes Yes

Pacemaker benefit High Low Moderate

---

Carotid sinus hypersensitivity is an important, often under-recognized cause of syncope in elderly patients. Proper bedside testing and correct phenotyping guide management, particularly when considering permanent pacing.