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Radiofrequency ablation of a posteroseptal atrioventricular accessory pathway in a patient with mechanical mitral valve
  1. J Hong,
  2. X Li,
  3. J Guo

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A 32 year old woman presented with nine years of paroxysmal palpitation which became more frequent recently. The baseline 12 lead ECG showed normal sinus rhythm with no pre-excitation. ECG during palpitation documented supraventricular tachycardia. She had a history of mitral valve replacement with a bileaflet prosthetic mechanical valve nine months previously for severe rheumatic mitral stenosis and regurgitation.

Electrophysiologic study suggested a concealed left posteroseptal atrioventricular accessory pathway associated with the tachycardia. As ablation above the mitral annulus by the transseptal approach was unlikely to succeed, and mapping in the coronary sinus demonstrated no ideal target site, we decided to ablate beneath the annulus by the transaortic approach. To avoid damaging the mechanical valve with the ablation catheter during the procedure, the ablation catheter tip was not advanced with a curve when it reached the aortic valve. When the catheter tip entered the left ventricle, it was kept on the side of left ventricle under careful fluoroscopic monitoring. Then the catheter was manipulated to below the mitral annulus. The earliest atrium activation site during ventricular pacing was mapped at the annulus below the posterior cusp of the mitral valve in the posteroseptum region (1.5 cm from the coronary sinus ostium) (panel A). The inscription of the atrial electrogram in the terminal ventricular electrogram was targeted. Atrioventricular morphology was not affected by the rheumatic lesion. Radiofrequency application at 60°C was attempted during ventricular pacing. Retrograde pathway function was lost (panel B). Tachycardia could no longer be induced.

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Right anterior oblique view during ablation. HRA, HIS, CS, RV, and ABL represent catheters for high right atrium, His bundle, coronary sinus, right ventricular electrograms, and ablation, respectively.

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Surface ECG and intracardiac electrograms during radiofrequency energy delivery.