November 16, 2018Open Access
Programmed His bundle pacing - a novel maneuver for the diagnosis of His bundle capture
Key Result
Programmed His bundle pacing correctly diagnosed all non-selective His bundle cases by demonstrating a shorter RV-myocardial ERP compared to His bundle ERP (271.8 vs 353.0 ms, p<0.0001).
Study Design
Type
Observational (n=32)
Structured PICO
Does programmed His bundle pacing differentiate non-selective His bundle capture from RV-myocardial capture in patients undergoing His bundle pacemaker implantation?
P
Population
32 consecutive patients undergoing His bundle pacemaker implantation
I
Intervention
Programmed His bundle pacing (premature beats introduced at 10 ms steps during intrinsic rhythm and after a drive train of 600 ms)
O
Outcome
Differentiation of non-selective His bundle capture from RV-myocardial capture based on effective refractory period (ERP) differencessurrogate
Programmed His bundle pacing is a novel and effective method to differentiate non-selective His bundle capture from RV-myocardial capture by exploiting differences in effective refractory periods.
Main Result
Absolute Event Rate: 271.8% vs 353%
p-value: p=<0.0001
Abstract
Abstract Background During permanent non-selective (ns) His bundle (HB) pacing, it is crucial to confirm HB capture / exclude that only right ventricle (RV)-myocardial septal pacing is present. Because the effective refractory period (ERP) of the working myocardium is different than the ERP of the HB, we hypothesized that it should be possible to differentiate ns-HB capture from RV-myocardial capture using programmed extra-stimulus technique. Methods In consecutive patients during HB pacemaker implantation, programmed HB pacing was delivered from the screwed-in HB pacing lead. Premature beats were introduced at 10 ms steps during intrinsic rhythm and also after a drive train of 600 ms. The longest coupling interval that resulted in an abrupt change of QRS morphology was considered equal to ERP of HB or RV-myocardium. Results Programmed HB pacing was performed from 50 different sites in 32 patients. In 34/36 cases of ns-HB pacing, the RV-myocardial ERP was shorter than HB ERP (271.8±38 ms vs 353.0±30 ms, p < 0.0001). Programmed HB pacing using a drive train resulted in a typical abrupt change of paced QRS morphology: from ns-HB to RV-myocardial QRS (34/36 cases) or to selective HB QRS (2/36 cases). Programmed HB pacing delivered during supraventricular rhythm resulted in obtaining selective HB QRS in 20/34 and RV-myocardial QRS in 14/34 of the ns-HB cases. In RV-myocardial only pacing cases (“false ns-HB pacing”, n=14), such responses were not observed – the QRS morphology remained stable. Therefore, the PHB pacing correctly diagnosed all ns-HB cases and all RV-myocardial pacing cases. Conclusions A novel maneuver for the diagnosis of HB capture, based on the differences in ERP between HB and myocardium was formulated, assessed and found as diagnostically valuable. This method is unique in enabling to visualize selective HB QRS in patients with otherwise obligatory ns-HB pacing (RV-myocardial capture threshold < HB capture threshold). What this study adds Programmed His bundle pacing – a novel and straightforward method for unquestionable diagnosis of His bundle capture during non-selective pacing was developed and assessed. A method for visualization of selective HB capture QRS in patients with obligatory non-selective pacing (myocardial capture threshold < His bundle capture threshold) was discovered and physiology behind it explained.