Migration of the breakthrough: the advantage of noncontact mapping in targeting inappropriate sinus tachycardia.

ABSTRACT

We report on a 42-year-old female patient with inappropriate sinus tachycardia (IST), in whom an effective sinus node modification was made by using the noncontact mapping system. The patient was admitted with palpitations and a heart rate between 90-110 beats per minute (bpm). Her heart rate increased to 150 bpm during minimal exercise. After confirming the diagnosis of IST by an electrophysiological study, radiofrequency catheter ablation was performed. A color-coded isopotential map was created when the heart rate was 95 bpm and the initial breakthrough of the sinus node (SNB) was labeled. After administration of isoproterenol, a new color-coded map recording was created when the heart rate reached 160 bpm, showing a new breakthrough 24 mm away from the SNB. Radiofrequency was delivered to this region and the heart rate decreased to 120 bpm. After another infusion of isoproterenol, the maximum heart rate reached 140 bpm and another isopotential map recording was created, which demonstrated migration of the breakthrough 16 mm away from the SNB. Radiofrequency was delivered to the second site and the heart rate decreased to 90 bpm and increased to a maximum of 120 bpm after a new isoproterenol infusion. A subsequent infusion caused no increase in the heart rate, and the ablation procedure was terminated. During a follow-up of one year, the patient was in sinus rhythm with a mean heart rate of 80 bpm.