Abstract
Catheter ablation of inappropriate sinus tachycardia (IST) is limited by lack of reliable efficacy coupled with possible complications: need for pacing or phrenic palsy. We review short term results and safety for a novel mapping and ablation strategy for IST. Patients were referred after exhausting conventional therapies, e.g. betablockers and ivabradine. Under general anesthesia, anterior pericardial access was obtained, a Tyshak II 22mm balloon was directed to the anterolateral pericardial space, adjacent to the right atrial-superior vena cava junction and inflated to 0.75 ATM. High density mapping was used to localize endocardial sinus node (SN) activation at resting heart rate and during isoproterenol drug infusion. Ablation targeted SN breakout associated with faster heart rates, while avoiding baseline breakout. Phrenic nerve could not be pace captured with balloon in place. Abrupt heart rate drop was ablation endpoint. Six consecutive patients (all female, mean age 38 years) are reported. Median follow up was 95 days (IQR 67-97). Mapping showed a mean distance of 17mm between baseline SN and maximal isoproterenol SN break out. Ablation (mean total 15, IQR 10-17) was done with a mean heart rate of 138BPM and acutely decreased to an average of 78BPM. No phrenic palsy or bradycardia occurred. All patients have had marked or complete resolution of symptoms without ongoing IST medications; three had pericarditis. We show feasibility, safety and short term efficacy. Ablation targeting only faster SN activation can avoid bradycardia while pericardial balloon prevents phrenic palsy. Long term follow up will assess durability.
Published Version
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