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  • Additionally the selection for subcutaneous ICD implant

    2019-04-26

    Additionally, the selection for subcutaneous ICD implant is based on pre-implant electrographic body surface mapping. The sensing algorithm for this system depends on the surface elecrtrocardiogram (ECG) morphology, specifically the R-and T-wave amplitudes, R/T and R/P ratios, QRS duration and QT interval. A pre-implant screening tool developed by the manufacturer (Boston Scientific Corp., Marlborough, MA, USA) is used in all patients under consideration for this device to select individuals with ECG morphology that offers appropriate signal configuration to satisfy the requirements of the subcutaneous ICD sensing algorithm, which are critical for an appropriate and effective delivery of the ICD implantation therapy [7]. In this article, we report the intramuscular implantation of a subcutaneous ICD device using a left dorsal configuration with an 8-cm-single coil electrode in a patient with pectus excavatum. There were no associated complications with the device implantation or lead positioning, and also the defibrillation threshold testing did not indicate any problem resulting from the abnormal anatomy of the study subject. There is a relatively high rate of wound complications in the Asian population [8]. Therefore, the intramuscular approach for the subcutaneous ICD appears feasible and a safe alternative to the standard subcutaneous placements in thin and active patients. Also, the more dorsal placement of the pulse generator may provide an improved vector toward the shocking coil capturing of the large part of the left ventricle in comparison to the conventional subcutaneous approach.
    Conclusions
    Conflict of interest
    Introduction Ventricular tachycardia (VT) secondary to a myocardial infarction can arise from an epicardial substrate and may require treatment with epicardial catheter ablation. However, it has been reported that a percutaneous subxiphoidal pericardial approach is usually challenging in patients with a history of open Cy3 hydrazide surgery due to pericardial adhesions [1–5]. This case report illustrated a successful percutaneous epicardial catheter ablation of a VT arising from the crux of the heart in a patient with prior coronary artery bypass grafting (CABG).
    Case report A clinical VT was induced by extrastimulation from the right ventricle (RV) and exhibited a left bundle branch block and left superior axis QRS morphology with a QS pattern in the inferior leads and a cycle length of 440ms (Fig. 1A). Activation and pace mapping was performed with a 7.5 French, 3.5mm irrigated tip ablation catheter (Navistar ThermoCoolTM, Biosense Webster, Diamond Bar, CA, USA), and no pre-systolic ventricular activation or excellent pace map was observed in the RV, left ventricle (LV), or coronary sinus. A decision was then made to attempt subxiphoidal pericardial access despite a history of CABG. The access was successfully obtained through the inferior approach, but the guidewire could not be advanced beyond the left lateral region (Fig. 1B). Epicardial mapping with the ablation catheter was performed, but it was limited to the LV posterior region presumably due to a pericardial adhesion secondary to the CABG. The epicardial voltage map revealed a large scar in the infero-posterior LV wall (Fig. 2A). During the VT, an early-diastolic potential with an interval to QRS onset of 210ms (48% of the VT cycle length) was recorded within the scar at the crux of the heart (Fig. 2B). Entrainment pacing was performed at this site, resulting in termination of the VT. A distinct and split isolated diastolic potential (IDP) was recorded at this site during a biventricular paced rhythm (Fig. 2C and D). Several irrigated radiofrequency applications targeting the IDPs were delivered, resulting in elimination of those IDPs. A coronary arteriogram was not performed prior to the ablation as both the bypass graft and native coronary artery feeding this area were occluded. Thereafter, the VT became non-inducible. The procedural and fluoroscopic times were 215 and 38min, respectively. No complications occurred. During the one year of follow-up period, the patient has been free of any VT recurrences.