His bundle tachycardia

His bundle tachycardia, also known as junctional ectopic tachycardia (JET), is a rare cardiac arrhythmia originating from the His bundle or the atrioventricular (AV) junction. The His bundle is a critical part of the heart's electrical conduction system, located between the atria and ventricles. In this condition, abnormal automaticity within the His bundle generates rapid heart rates that can compromise cardiac output. The arrhythmia is characterized by a narrow QRS complex tachycardia with AV dissociation, where the ventricles beat faster than the atria. This condition primarily affects the cardiovascular system and can present in two distinct forms: a congenital form that typically manifests in infancy and an acquired (postoperative) form that occurs after cardiac surgery, particularly in children undergoing repair of congenital heart defects. The congenital form tends to be more refractory to treatment and carries a higher mortality risk. Key symptoms include rapid heart rate (tachycardia), poor feeding in infants, irritability, signs of heart failure such as shortness of breath and edema, low blood pressure, and in severe cases, cardiogenic shock. Treatment of His bundle tachycardia can be challenging. Initial management often includes cooling (mild hypothermia), correction of electrolyte imbalances, and reduction of catecholamine stimulation. Antiarrhythmic medications such as amiodarone and procainamide are commonly used. In the postoperative form, the arrhythmia is often self-limiting. For refractory congenital cases, catheter ablation of the ectopic focus may be considered, though this carries a risk of complete heart block requiring permanent pacemaker implantation. Ivabradine has also been explored as a therapeutic option in some cases.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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