From the Guidelines
Sinus rhythm with marked sinus arrhythmia is a normal heart rhythm variant that doesn't typically require treatment, as it is considered a physiologic finding rather than a pathological condition. This condition describes a normal sinus rhythm (where electrical impulses start appropriately in the sinoatrial node) with exaggerated variations in heart rate, usually corresponding with the breathing cycle. The heart rate increases during inhalation and decreases during exhalation. According to the guidelines from the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society 1, sinus node dysfunction (SND) is a broad array of abnormalities in sinus node and atrial impulse formation and propagation, but marked sinus arrhythmia is not typically considered a form of SND.
Key points to consider:
- Marked sinus arrhythmia is particularly common in children, young adults, and athletes with high vagal tone.
- No medications or interventions are needed as this is considered a physiologic finding rather than a pathological condition.
- The mechanism involves respiratory-mediated changes in vagal tone affecting the sinoatrial node, as described in the guidelines 1.
- During inspiration, vagal tone decreases, allowing the heart rate to increase; during expiration, vagal tone increases, causing the heart rate to decrease.
- If symptoms like dizziness or palpitations are experienced, consultation with a healthcare provider is recommended, but in most cases, marked sinus arrhythmia requires only reassurance that this is a normal variant and not a sign of heart disease.