A 17-year-old woman was resuscitated from cardiac arrest due to ventricular fibrillation and was diagnosed with concealed long QT syndrome. She underwent subcutaneous implantable cardiac defibrillator (S-ICD) implantation at our hospital. The device electrogram immediately after implantation was normal. Four days after implantation, she received an inappropriate shock. The device interrogation revealed a continuous baseline shift and frequent oversensing for low amplitude signals, followed by a shock. A chest radiograph in the orthogonal view showed entrapped subcutaneous air surrounding the distal electrode. Entrapped subcutaneous air can cause inappropriate shocks in the early period after S-ICD implantation.
A 70-year-old woman who presented with intermittent palpitation symptoms for the past few years. There was no pre-excitation during sinus rhythm on 12-lead surface ECG and a Holter ECG showed supraventricular tachycardia (SVT) (Figure 1A). After informed consent was obtained, catheter ablation was performed. Early atrial excitation during right ventricular (RV) apex pacing was recorded in the left posterolateral wall (Figure 1B), showing an intermittent block and no decremental property. SVT was induced by an atrial double-coupled extra stimulus with a cycle length of 270 ms, and early atrial excitation was identical to that during RV pacing (Figure 1B,C). Because of non-sustained status, electrophysiologic studies during tachycardia were not available, but based on other findings, SVT was diagnosed as orthodromic reciprocating tachycardia (ORT) via a concealed left posterolateral AP. To identify the location of the intermittent retrograde AP conduction, the open window mapping (OWM) during RV apex pacing was performed via a trans-septal approach by using a multipolar catheter and three-dimensional mapping system (Pentaray, CARTO3; Biosense Webster, Inc, Irvine, CA). The reference was set to the pacing spike, and the window of interest was set from +20 ms to +200 ms to include ventricular to atrial potentials. Local ventricular and atrial potentials around the posterolateral wall of the mitral annulus (MA) were acquired using Pentaray. These potentials are annotated on the wavefront where the distal electrode's steepest unipolar negative dV/dt coincides with the bipolar downslope. Early Meets Late (EML) displays a white line when there is a time-phase difference between any two adjacent points showing the activation delay between the ventricle and the atrium, which could be regarded as an atrioventricular annulus. The lower threshold was adjusted to 30% to match the propagation map. A typical AP location is shown as a white line gap where the ventricular and atrial potentials are continuous. However, there was no white line defect, and the earliest atrial activation site (EAAS) was located 2 cm above the MA (Figure 2A). The propagation map showed that after the ventricular excitation by RV pacing conducted to the MA, the excitation temporarily disappeared, and propagated as if it was springing from the left atrial posterolateral wall (Figure 3, Supplemental Movie S1). Atrial excitation on the MA was apparently delayed and no AP potential was observed. Radiofrequency applications to the EAAS area were performed. The power output was 30 W and the average contact force was 11–15 g. The effective sites where intermittent AP conduction blockade was achieved, and the successful site required over 5–10 s of radiofrequency application. Each application continued for 30–50 s. The EAAS subtly sifted to the adjacent region after effective applications and then multiple times ablation to the wider area was required to eliminate the AP on the epicardial side (Figure 2B). SVT has not recurred for more than 1 year. OWM is a useful mapping technique that reduces annotation errors and facilitates AP location because the near-field potentials are obtained regardless of their origin.1 Visualization of APs using OWM with EML has been reported.2 However, it is equally useful for the diagnosis of accessory pathways that are located away from the AV annulus as in this case. Anatomically, APs exist within the AV groove subepicardial fat and they may course at a variable depth from subepicardial to subendocardial.3 In cases with atrial insertion remote from the annulus, the AP body itself crossing the annulus would also be expected to be at a distance from the annulus. It would have been difficult to eliminate AP according to the MA with conventional EPS-based mapping. Since multiple ablations to a wide area were required, a slightly wider connection was assumed between the AP and the left atrium on the epicardial side. There have been a few reports of left-sided APs located away from the MA. Long DY et al. reported 5 patients who had atrial insertion of AP at the base of the left atrial appendage and 2 patients at the anterior roof of the left atrium.4 In all these patients, ablation to the atrial insertion site successfully abolished AP conduction. Hwang C et al. reported 4 case series of left-free wall APs that were connected to the Marshall bundle.5 These were successfully eliminated by endocardial radiofrequency application toward the vein of Marshall (VOM) marked by insertion of a microcatheter or CS angiography. The success sites were reported to be the left atrial free wall 1 cm above the MA. In the present case, AP atrial attachment was located at the left free wall 2 cm above the MA, and atrial excitation on the coronary sinus (CS) catheter was delayed, which means AP was not attached to the MA or CS musculature. Although intra-cardiac echocardiography was not performed, it may give us more detailed information on the MA and the EAAS. In view of the successful site, the possibility of a connection between the AP and the Marshall bundle cannot be ruled out. EML correctly drew the continuity of the white line. The advantage of using the OWM method is that the AP location can be easily visualized even in challenging cases with conventional methods, not only multiple APs, and wide AP, but also the AP located away from the AV annulus. This report was not supported by any grant or company. The authors have no conflict of interest to declare. The patient has provided consent for publication. Not applicable. None. 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Abstract Introduction Radiofrequency (RF) ablation for ventricular arrhythmia in patients with reduced left ventricular ejection fraction (LVEF) is recognized to be one of the important strategies for suppressing the fatal arrhythmia events. Although, RF ablation for those patients has been performed for decades, the optimal endpoint remains unclear. Hypothesis We assessed the hypothesis that non-inducibility of any ventricular tachycardia (VT) or ventricular fibrillation (VF) immediately after VT ablation predicts long-term recurrence free rate of ventricular arrhythmia in patients who were diagnosed sustained VT with reduced LVEF. Methods From January 2014 to August 2019, we conducted a single center retrospective analysis for 127 consecutive patients with right or left ventricular arrhythmia who performed the first time RF ablation. Exclusion criteria were LVEF >50% and RF ablations for premature ventricular contraction or for non-sustained VT. Then 26 patients (age 69 ± 7, male 92%) were enrolled. All of the ablation procedures were performed using irrigated RF catheters and 3D mapping systems. We defined non-inducible group as the patients without monomorphic VT (clinical monomorphic VT or non-clinical monomorphic VT with any cycle length), polymorphic VT and VF by electrophysiological study (EPS) immediately after the ablation. The primary endpoint of this study was a recurrence of any sustained VT and VF during the follow up period. Results All of 26 patients were followed for a mean of 30.9 ± 22.3months.Of those patients, 7 patients were non-inducible group and 19 patients were inducible group. Age, sex, body mass index, coronary risk factors, LVEF (non-inducible:42 ± 5% vs inducible:35 ± 10%, p = 0.12), renal function and the etiology of LV dysfunction did not differ between patients with non-inducible group and inducible group (all non-significant). Catheter ablation procedural characteristics including activation mapping (non-inducible:29% vs inducible:36%, p = 1.00), entrainment mapping (14% vs 42%, p = 0.19), substrate mapping (86% vs 95%, p = 0.47), pace-mapping (86% vs 68%, p = 0.63), RF time (21 ± 13vs 18 ± 21min, p = 0.70), number of RF applications (27 ± 13vs 27 ± 32, p = 0.89), fluoroscopy time (77 ± 50vs 87 ± 42min, p = 0.59) and procedure time (309 ± 87vs 282 ± 61min, p = 0.37) did not differ between two groups. Medications before and after the VT ablation did not differ between two groups. The recurrence of any sustained VT and VF significantly lower in patients with non-inducible group than those with inducible group (Figure). Conclusion This study demonstrated that, in patients with reduced LVEF presenting sustained VT who performed RF ablation, non-inducibility of any VT and VF immediately after RF ablation predicts long-term decreased risk of recurrence of any sustained VT and VF. Not only clinical but also non-clinical VT and VF may be targeted as well at the first time VT ablation for those patients. Abstract Figure
Abstract Background Inappropriate shock (IAS) caused by subcutaneous air entrapment (AE) in an early period after subcutaneous implantable cardioverter defibrillator (S‐ICD) implantation has been reported, however, no detailed data on air volume are available. We evaluated the subcutaneous air volume after implantation and its absorption rate one week after implantation. Methods Patients who underwent S‐ICD implantation in our hospital received chest CT scans immediately after implantation and followed up 1 week later. The total subcutaneous air volume, air around the generator, the distal electrode, and the proximal electrode within 3 cm were calculated using a three‐dimensional workstation. Fat areas at the level of the lower edge of the generator were also analyzed. Result Fifteen patients received CT immediately after implantation. The mean age was 45.6 ± 17.9 (66.7% of men), and the mean body mass index was 24.3 ± 3.3. The three‐incision technique was applied in seven patients and two‐incision technique was in the latter eight patients. The mean total subcutaneous air volume was 18.54 ± 7.50 mL. Air volume around the generator, the distal electrode, and the proximal electrode were 11.05 ± 5.12, 0.72 ± 0.72, and 0.88 ± 0.87 mL, respectively. Twelve patients received a follow‐up CT 1 week later. The mean total subcutaneous air was 0.25 ± 0.45 mL, showing a 98.7% absorption rate. Conclusion Although subcutaneous air was observed in all patients after S‐ICD implantation, most of the air was absorbed within 1 week, suggesting a low occurrence of AE‐related IAS after a week postoperation.
Coronary sinus (CS) lead placement in persistent left superior vena cava (PLSVC) cases is challenging because of the poor backup force of the guiding catheter within the enlarged CS. Active fixation Quadripolar leads (Attain Stability™ Quad 4798, Medtronic) can expand choice to CS branches with limited access; however, no cases of anchoring to the main body of the CS have been published to date. We describe a case of cardiac resynchronization therapy pacemaker upgrade in a 79-year-old female who developed pacing-induced cardiomyopathy after pacemaker implantation via the right superior vena cava (SVC) for atrioventricular block eight years ago wherein PLSVC was revealed during the procedure. Retrograde giant CS angiography via SVC confirmed the lateral vein ostium. Attain Stability Quadripolar lead was selected; however, due to the tortuousness and stenosis of the target vein, the proximal electrodes could not advance into the target vein. Therefore, the side helix between the third and fourth electrodes was crimped to the anterior wall of the giant CS using the distal end curve of the subselection catheter and successfully screwed into the main body of the CS. At more than 6 months, left ventricular ejection fraction improved without lead dislodgement. Fixation of CS lead to the main body of the dilated CS was feasible by devising a guiding catheter and a subselection catheter. Nevertheless, the safety of active fixation lead retraction after long-term indwelling in CS is unknown and it should be carefully considered.
