There has been a significant increase in cancer patients with implanted electronic devices which have been exposed to the risk of malfunction when undergoing radiotherapy in the last few years. In this review, we provide a short summary of radiotherapy principles, later analyzing in vitro and in vivo data and recent recommendations, in order to present the current evidence on predictive factors, risk stratification, and management of patients with implanted electronic devices requiring radiotherapy. The risk of device failure is usually transient, seldom permanent and mainly related to patients' characteristics and cumulative doses administrated during radiotherapy. The strongest predictive factors of implanted electronic device malfunction are higher radiation doses and higher beam energy. Indeed, energy <6 MV and a total dose of 2 Gy are recommended. A close multidisciplinary collaboration involving cardiac electrophysiologists, radiotherapists, and physicists may have important consequences in clinical practice, enabling then to minimize this risk.

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Background: The aim of this study is to investigate the role and method of intracardiac echocardiography (ICE) in left bundle branch pacing. Subjects and Methods: A total of 12 patients who underwent ICE-guided left bundle branch pacing from February 2018 to June 2018 in the Department of Cardiology of the First People's Hospital of Yunnan Province were enrolled in this observational case analysis. The study was approved by the Institutional Ethical Committee of the First People's Hospital of Yunnan Province, China (approval No. KHLL2019-KY018). The patients' sex, age, weight, disease history, and the results of color Doppler echocardiography were recorded before surgery. The duration of surgery, X-ray exposure, pacing parameters (threshold, perception, and impedance), electrocardiogram characteristics, pacing parameters, clinical symptoms, and echocardiographic results were recorded after surgery. Results: The left bundle branch pacing guided by ICE was successfully in all 12 patients. There were four cases of sick sinus syndrome, six cases of atrioventricular block, and two cases of atrial fibrillation with long R-R interval. The mean operation time was 1.75 ± 0.28 hours, and the X-ray exposure was 61.2 ± 13.6 mGy. The implantation time of left bundle branch electrode was 1.23 ± 0.24 hours, and X-ray exposure of left bundle branch electrode implantation was 48.9 ± 12.3 mGy. There was no electrode dislocation, pneumothorax, or infection after operation. Two of them had a small hematoma of the pacemaker pocket, and hematoma disappeared after compression. Conclusion: This study demonstrates the feasibility of ICE guidance for left bundle branch pacing, which may increase the success rate and reduce the risk of surgery.

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Background: Little is known about characteristics of dynamic electrocardiogram (DCG), heart rate (HR) variability (HRV), and invasive electrophysiological study (EPS) in the presence, pattern, and stage of vasovagal syncope (VVS) during head-up tilt test (HUTT). The present study aims to explore predictive value of these tests for HUTT outcomes with underlying mechanisms. Subjects and Methods: This retrospective study consecutively enrolled 519 patients with VVS from January 2007 to December 2017. Parameters of DCG, HRV, and EPS were evaluated according to the presence, pattern, and stage of syncope during HUTT. Results: Mixed pattern was the predominant subtype of VVS, and vasodepressor patients had a positive response earlier than in cardioinhibitory patients. Compared with negative group, positive group with mixed and cardioinhibitory patterns had significantly slower maximal HR and mean HR all day, at daytime, nighttime, and each hour point. No significance was observed in parameters of HRV between negative and positive groups. There was no significant difference in HR, spectral power components, and time-domain variables among syncopal patterns and syncopal stages. Positive group had longer durations of A-H interval, sinus node recovery time, Wenckebach point, and Wenckebach 2:1 point than negative group. There was a significant difference only in sinus node recovery time among syncopal patterns as well as A-H interval among syncopal stages. Conclusion: DCG-derived HR and EPS properties rather than 24-h HRV may be used to predict positive responses, but they could not predict syncopal patterns and syncopal stages.

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Background: The aim is to study the feasibility and efficacy of His-Purkinje conduction system pacing (HPCSP) in cardiac resynchronization therapy (CRT) candidates of chronic heart failure with permanent atrial fibrillation (AF). Subjects and Methods: Patients with chronic heart failure and permanent AF (n = 16) were enrolled from the Department of Cardiology, Zhongshan Hospital of Fudan University, from September 2017 to April 2019 in this observational case study. The patients with chronic heart failure (left ventricular ejection fraction [LVEF] <40%) and permanent AF with low ventricular rate were indicated for CRT implantation. The study was approved by the Institutional Ethical Committee of Zhongshan Hospital of Fudan University, China. At baseline, 13 cases had narrow QRS duration (<120 ms) and 3 cases had left bundle branch block with QRS duration >120 ms. HPCSP lead connected to the RA port of the generator was implanted together with conventional biventricular pacing (BVP) and was programmed as HPCSP postprocedure. QRS durations were measured and compared during intrinsic, BVP, and HPCSP. Pacing parameters were measured and compared during postimplantation immediately and 6 months postimplantation. Echocardiogram parameters, New York Heart Association (NYHA) class, and 6-min walking distance (6MWD) were collected and compared between baseline and 6 months postimplantation. Results: QRS durations were significantly different during HPCSP compared with BVP (P < 0.0001). Pacing parameters including threshold and R wave amplitude were not significantly different during postimplantation immediately and 6 months postimplantation, whereas impedance was significantly different (P = 0.028). LVEF, left atrial diameter, left ventricular end-diastolic diameter, left ventricular end-systolic diameter, mitral regurgitation, tricuspid annular plane systolic excursion, pulmonary artery systolic pressure, and the percentages of moderate-to-severe mitral regurgitation and tricuspid regurgitation were not significantly different between baseline and 6 months postimplantation, whereas NYHA class and 6MWD were significantly different (P < 0.0001). Conclusion: HPCSP was feasible and effective in CRT candidates of chronic heart failure with permanent AF and low ventricular rate. It could significantly reduce QRS duration as compared to BVP. Moreover, although LVEF was not obviously improved, the pacing parameters were stable and NYHA class and 6MWD were improved during HPCSP at 6-month follow-up.

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