Permanent junctional reciprocating tachycardia in a dog

Area of Science:

• Cardiology
• Veterinary Medicine
• Electrophysiology

Background:

• Paroxysmal supraventricular tachycardia (SVT) can significantly impact canine health.
• A 5-year-old English Bulldog presented with a year-long history of SVT, showing partial response to amiodarone.
• Surface ECG revealed sustained narrow QRS tachycardia with alternating sinus rhythm.

Observation:

• A 5-year-old English Bulldog presented with a year-long history of narrow QRS complex tachycardia (ventricular cycle length 260 ms) alternating with sinus rhythm.
• Surface ECG confirmed sustained runs of tachycardia, indicating an underlying arrhythmia.
• Endocardial mapping was essential to pinpoint the tachycardia's origin and mechanism.

Findings:

• The SVT mechanism was identified as a circus movement tachycardia involving a concealed postero-septal atrioventricular pathway (AP) with retrograde decremental conduction.
• Anterograde conduction occurred via the atrioventricular node, consistent with permanent junctional reciprocating tachycardia (PJRT).
• Radiofrequency catheter ablation targeting the accessory pathway (AP) resulted in immediate and complete termination of the PJRT.

Implications:

• Radiofrequency catheter ablation is a highly effective treatment for canine PJRT.
• Successful ablation provides a long-term, curative solution for SVT in dogs, improving prognosis.
• This case highlights the importance of advanced electrophysiological mapping in diagnosing and treating complex cardiac arrhythmias in veterinary patients.