His-Purkinje Conduction System Pacing in Atrioventricular Block: New Insights Into Site of Conduction Block.

OBJECTIVES: This study aims to assess the safety and feasibility of achieving His-Purkinje conduction system pacing (HPCSP) in consecutive patients with atrioventricular block (AVB) and to describe the site of conduction block in patients with infranodal AVB. BACKGROUND: HPCSP has evolved as the preferred form of physiologic pacing. Left bundle branch area pacing (LBBAP) has emerged as an effective alternative to His bundle pacing (HBP). METHODS: Consecutive patients with AVB referred for pacemaker implantation were included in the study. HBP or LBBAP was attempted in all patients. Site of conduction block was identified as nodal or infranodal (intra-Hisian or infra-Hisian) AVB. RESULTS: HPCSP was attempted in 333 consecutive patients with AVB and was successful in 322 (97%) patients. HBP was achieved in 140 patients, LBBAP in 179 patients, and both in 3 patients. Site of conduction block was nodal in 55% and infranodal in 45% (intra-Hisian 89%; infra-Hisian 4%; indeterminate 7%). QRS duration at baseline was 111 ± 27 versus 129 ± 31 (P < 0.001) compared to 126 ± 24 vs 125 ± 21 milliseconds (P = 0.75) during HBP and LBBAP, respectively. HBP thresholds at implant were higher compared to LBBAP (1.2 ± 0.7 V at 0.9 milliseconds vs 0.6 ± 0.3 V at 0.5 milliseconds; P < 0.001) but remained stable during follow-up. Lead revision was required in 3% and 2% of patients with HBP and LBBAP, respectively. CONCLUSIONS: HPCSP pacing was successfully performed in 97% of unselected patients with AVB irrespective of the site of conduction block. True infra-Hisian block (distal His-Purkinje conduction disease) is rare. HBP and LBBAP were complementary in achieving stable and low capture thresholds.

His bundle pacing capture threshold stability during long-term follow-up and correlation with lead slack.

AIMS: His bundle pacing (HBP) is the most physiologic form of pacing. Long-term HBP capture threshold stability and its relation to lead characteristics at the time of implantation have not been adequately described. The aim of this study was to characterize HB capture threshold in follow-up and to identify potential lead characteristics predictive of lead capture instability. METHODS AND RESULTS: Consecutive patients with successful HBP for bradycardia indications were identified from the Geisinger HBP registry. His bundle capture thresholds, baseline comorbidities, and radiographic lead slack characteristics were analysed. An increase in HB capture threshold ≥1 V above implant values at any time during follow-up was tracked. Forty-four of the 294 studied (15%) experienced HB capture threshold increase by ≥ 1 V. Threshold increase was seen early (41% by 8 weeks, 66% by 1 year). Eighteen (6%) patients required lead revision in follow-up. Abnormal slack shape was associated with a trend toward capture threshold increase [hazard ratio (HR) 2.07; 95% confidence interval (CI) 0.9-4.6; P = 0.08]. Non-perpendicular angle of lead insertion on radiography was associated with the capture threshold increase (HR 2.81, 95% CI 1.4-5.8; P < 0.01). CONCLUSION: His bundle capture threshold remains stable in the majority (85%) of patients. Implant characteristics may predict the threshold rise. Further evaluation of the aetiology of threshold increase and design changes in lead and delivery systems may lead to chronically stable capture thresholds.

The cost of seeking an edge: Recurrent renal infarction in setting of recreational use of anabolic steroids.

INTRODUCTION: Anabolic-androgenic steroid (AAS) use and testosterone therapy have been well established risk factors for the creation of a pro-thrombotic state, and to precipitate formation of thromboemboli in individuals already predisposed to thrombosis. CASE REPORT: Here, we present the case of an amateur bodybuilder, with a negative thrombophilia workup, who experienced primary renal infarction while using the AAS trenbolone acetate and testosterone, as well as a subsequent renal infarction while anticoagulated with apixaban. DISCUSSION: The development of subsequent infarctions in an anticoagulated patient with discontinued recreational steroid use poses a unique situation and challenges the current understanding of a thrombophilic state associated with steroids. The lifetime prevalence of anabolic steroid use is estimated to be 1% in the male population in the United States which is significant. CONCLUSION: Further understanding and recommendations of appropriate anticoagulant should be further elucidated to appropriately medically manage patients from this confounding social and medical history.