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    • The outcome of sinus node modification with radiofrequency a

    2019-06-05

    The outcome of sinus node modification with radiofrequency ablation has been reported, but it involves a high invasive risk associated with the ablation. Thus, careful confirmation of the earliest activation site and ablation of that site is important [2,3]. The clinical use of the 3D-mapping system for IST ablation has been reported [3], and our case suggested that a temporal modification of the sinus node tachycardia by landiolol administration combined with 3D mapping is useful to avoid complications.
    Financial support
    Conflict of interest
    Introduction
    Case report An 87-year-old woman with chronic heart failure and chronic kidney disease (CKD) was admitted to our hospital due to worsening dyspnea and lower extremity edema. She had undergone permanent pacemaker implantation 6 years before because of 2:1 atrioventricular (AV) block with a narrow QRS complex (Fig. 1A). Her medications included torasemide 4mg, carvedilol 5mg, and valsartan 40mg. A 12-lead electrocardiogram (ECG) showed atrial sensed ventricular pacing with a QRS duration of 140ms (Fig. 1B). Pacemaker interrogation revealed that her native cardiac rhythm remained 2:1 AV block with a narrow QRS, and ventricular pacing was greater than 99%. Echocardiography showed a left ventricular ejection fraction (LVEF) of 33%. Chest X-ray revealed an enlarged cardiothoracic ratio (CTR) of 60% and bilateral pleural effusions (Fig. 2A). Coronary angiography and echocardiography performed before pacemaker implantation had revealed normal coronary ARCA and a LVEF of 65%, respectively. PICM was highly suspected. Further medical treatment with carperitide and intravenous furosemide did not improve the pleural effusions or LVEF. CRT by either HBP or a standard LV lead was considered. Because the patient׳s native cardiac rhythm remained 2:1 AV block with a narrow QRS, we thought HBP would be better than BiVP, and thus we attempted permanent HBP as the first-line treatment. Although the His bundle (HB) electrogram could not be clearly identified, narrow QRS complexes suggesting nonselective HBP (His capture fused with local ventricular septal capture) were easily obtained using a SelectSecure 3830 screw-in lead inserted through a SelectSite C304 deflectable catheter (Medtronic, Minneapolis, MN, USA) by pace-mapping the AV septum. The pacing thresholds of the HB and the adjacent septal myocardium were 1.0V/0.4ms and 0.75V/0.4ms, respectively. The HB pacing lead was connected to the LV port of a biventricular (BiV) pacemaker (Viva CRT-P, Medtronic). We chose this device because it has no sensing ability in the LV lead (in this case, the HB lead) and thus does not cause double counts with a delay in the HV interval and safety pacing in RV pacing. The BiV pacemaker was programmed to DDD mode with a LV–RV delay of 80ms. This delay was set to provide back-up RV pacing in case the HB pacing lead failed to capture the right ventricle. After the 1-week follow-up, the pacing threshold of the HB had improved slightly to 0.75V/0.4ms, while that of the adjacent septal myocardium was 1.0V/0.4ms. Echocardiography at 1 month after the upgrade demonstrated improvement in the patient׳s LVEF from 33% to 45%, and the brain natriuretic peptide level decreased from 1208pg/ml to 97pg/ml. At the 6-month follow-up, she was asymptomatic. Chest X-ray revealed improvement of the CTR to 45% without pleural effusion (Fig. 2B). Echocardiography demonstrated further improvement of her LVEF to 55%. The pacing threshold of the HB remained stable at 0.75V/0.4ms and that of the adjacent septal myocardium was 1.0V/0.4ms. ECGs following HBP are shown in Fig. 1C, D, and E.
    Discussion Upgrading to BiVP has been reported as an effective therapy for PICM; however, about 30–40% of patients do not respond to this treatment [1]. In addition, performing BiVP can be challenging with a long procedural time and might even be impossible due to the coronary sinus anatomy. Rehwinkel et al. demonstrated that upgrading to HBP could be an effective alternative to BiVP for PICM with preserved His-Purkinje conduction [2].