A 26-Year-Old Man with Palpitations

The Resolution

Differential Diagnosis

• Sinus tachycardia
• Supraventricular tachycardia
• Atrial fibrillation
• Multifocal atrial tachycardia
• Sinus arrhythmia

Diagnosis
The ECG revels sinus arrhythmia, with “p” waves preceding each QRS, excluding atrial fibrillation. The rate is between 60-100, so this is not a tachycardic ECG (excluding MAT, SVT or sinus tachycardia). The PR and QRS intervals are normal, arguing against a bundle branch block or a ventricular rhythm. There are no ischemic changes suggestion of acute coronary syndrome (no ischemic ST changes or abnormal T wave inversions).

Learnings

• Sinus arrhythmia is common in young patients and is a normal physiologic response, typically due to increased or decreased vagal tone during breathing (inspiration decreases the vagal tone, causing an increase in the heart rate)
• This is a benign rhythm that sometimes will be appreciated by the patient and other times may be asymptomatic
• The complaint of palpitations is common, and a history should be taken looking for electrolyte abnormalities, ischemia, SVT, drug use, and medication interactions/effects.
• If the history is not suggestive or concerning for a serious underlying problem, lab testing is not required

Pearls for Initial Management and Considerations for Transfer

• Although a sinus arrhythmia is a benign rhythm, the patient should be questioned for a serious underlying cause
• If the rhythm is found incidentally and the patient is asymptomatic/without new symptoms, no further testing is necessary
• Compare the ECG to previous ECGs if available
• Indications for transfer include suspicion of ischemia, cerebral hypoperfusion (dizziness, altered consciousness, hypotension), sepsis, respiratory distress, pulmonary embolism, drug toxicity, or consideration of other life-threatening etiology