Cardiology · Arrhythmias
The facts most likely to be tested
Atrial flutter is characterized by a sawtooth pattern of atrial activity on ECG, most prominently seen in inferior leads (II, III, aVF).
The classic atrial rate in typical atrial flutter is approximately 250–350 beats per minute.
The most common ventricular response is a 2:1 AV block, resulting in a regular ventricular rate of approximately 150 beats per minute.
The underlying mechanism of typical atrial flutter is a macro-reentrant circuit involving the cavotricuspid isthmus in the right atrium.
Patients with atrial flutter require anticoagulation based on the same CHA2DS2-VASc score criteria used for atrial fibrillation.
Electrical cardioversion is the treatment of choice for hemodynamically unstable patients presenting with atrial flutter.
Radiofrequency catheter ablation of the cavotricuspid isthmus is the definitive, curative treatment for typical atrial flutter.
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A 68-year-old male presents to the emergency department with palpitations and lightheadedness for the past 24 hours. His medical history is significant for hypertension and heart failure with preserved ejection fraction. On physical examination, his blood pressure is 110/70 mmHg and his heart rate is 150 bpm. An ECG reveals a regular rhythm with a sawtooth pattern in the inferior leads and a ventricular rate of 150 bpm. The patient is currently stable but symptomatic.
What is the most appropriate definitive management for this patient's condition?
Radiofrequency catheter ablation
The ECG findings of a sawtooth pattern and 2:1 AV block are diagnostic of typical atrial flutter, which is definitively treated by ablation of the cavotricuspid isthmus.
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Etiology / Epidemiology
Common in structural heart disease, COPD, and post-CABG patients.
Clinical Manifestations
Palpitations and syncope; sawtooth waves on ECG.
Diagnosis
Diagnosis via 12-lead ECG showing atrial rate of 250-350 bpm.
Treatment
Hemodynamically unstable: synchronized cardioversion; stable: rate control.
Prognosis
High risk of thromboembolism; requires CHA2DS2-VASc risk stratification.
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Epidemiology & Etiology
Frequently associated with atrial septal defects, mitral valve disease, and thyrotoxicosis. It is a common complication following cardiac surgery. Patients often present with underlying hypertension or obesity.
Pertinent Anatomy
The circuit typically involves the cavotricuspid isthmus (CTI) in the right atrium. This anatomical region is the target for radiofrequency ablation.
Pathophysiology
A macro-reentrant circuit rotates around the tricuspid annulus. This creates a rapid, regular atrial rhythm, usually at 300 bpm. The AV node typically conducts in a 2:1 block, resulting in a ventricular rate of 150 bpm.
Clinical Manifestations
Patients present with palpitations, lightheadedness, or syncope. Physical exam may reveal a regular tachycardia. Sawtooth flutter waves are best visualized in leads II, III, and aVF. Hemodynamic instability (hypotension, altered mental status) requires immediate intervention.
Diagnosis
The 12-lead ECG is the diagnostic gold standard. Look for a regular atrial rate of 250-350 bpm with a fixed or variable AV block. If the diagnosis is unclear, vagal maneuvers or adenosine can transiently slow AV conduction to reveal the flutter waves.
Treatment
Unstable patients require synchronized cardioversion (50-100J). Stable patients receive rate control with beta-blockers or non-dihydropyridine CCBs (e.g., diltiazem). Do not use adenosine as a long-term treatment; it only aids in diagnosis. Radiofrequency ablation is the definitive treatment for recurrent cases.
Prognosis
Atrial flutter carries a similar risk of thromboembolism as atrial fibrillation. Long-term management requires anticoagulation based on the CHA2DS2-VASc score. Failure to anticoagulate leads to increased risk of ischemic stroke.
Differential Diagnosis
Atrial Fibrillation: irregularly irregular rhythm without discrete flutter waves
AVNRT: sudden onset/offset tachycardia with narrow QRS
Sinus Tachycardia: P waves present before every QRS
Atrial Tachycardia: P wave morphology differs from sinus P wave
Wolff-Parkinson-White: delta waves present on baseline ECG