Adams–Stokes syndrome

Overview

Adams–Stokes syndrome, also known as a Stokes–Adams attack, is a medical condition characterized by sudden, brief episodes of loss of consciousness (syncope) due to a temporary lack of blood flow to the brain. It results from abnormal heart rhythms, most commonly caused by a transient heart block or severe bradyarrhythmia. These episodes typically last less than a minute and resolve spontaneously, though they may be life-threatening if not properly managed.

Causes

Adams–Stokes syndrome is caused by transient disturbances in the heart’s electrical conduction system, leading to pauses in effective heartbeats and reduced cardiac output. Common causes include:

• Complete (third-degree) heart block – the most frequent cause

• High-grade second-degree AV block

• Sick sinus syndrome

• Severe bradycardia (slow heart rate)

• Ventricular tachycardia or asystole

These conduction disturbances can occur spontaneously or may result from underlying heart disease, medications, or age-related degeneration of the cardiac conduction system.

Symptoms

The hallmark symptom of Adams–Stokes syndrome is sudden, recurrent syncope (fainting), often without warning. Associated symptoms may include:

• Abrupt loss of consciousness (typically lasting 10–30 seconds)

• Slow or absent pulse during the episode

• Pallor followed by facial flushing

• Seizure-like movements (in prolonged episodes, due to cerebral hypoxia)

• Rapid recovery without confusion once normal rhythm resumes

Episodes may be sporadic or frequent, and can result in injury due to falls or loss of motor control.

Diagnosis

Diagnosing Adams–Stokes syndrome involves confirming a correlation between syncope and transient cardiac arrhythmia. Key diagnostic steps include:

• Electrocardiogram (ECG): To detect heart block, bradycardia, or pauses

• Holter monitor or event recorder: Continuous ECG recording to capture intermittent events

• Electrophysiological studies: In select cases to assess conduction system function

• Blood tests: To rule out electrolyte abnormalities or drug-induced causes

• Physical examination and history: Including prior cardiac disease, medications, and syncope episodes

Treatment

Treatment of Adams–Stokes syndrome aims to prevent further episodes by addressing the underlying arrhythmia. Common treatment approaches include:

1. Permanent Pacemaker:

• The mainstay treatment for heart block or severe bradycardia

• Provides continuous electrical pacing to maintain a stable heart rate

2. Temporary Pacing:

• Used in acute settings until a permanent device is implanted

3. Medications:

• May be used in some tachyarrhythmias (e.g., beta-blockers or antiarrhythmics)

• Avoid drugs that suppress conduction in patients at risk

4. Avoidance of Triggers:

• Adjustment of medications that may worsen bradycardia (e.g., digoxin, calcium channel blockers)

Prognosis

With timely diagnosis and appropriate treatment, especially pacemaker implantation, the prognosis for Adams–Stokes syndrome is excellent. Most patients experience complete resolution of syncopal episodes and regain normal function. However, if left untreated, the condition carries a risk of sudden cardiac death due to prolonged asystole or ventricular arrhythmias.

Long-term follow-up and device monitoring are important to ensure continued cardiac stability and prevent recurrence.