Abstract 15078: Non-selective but Not Selective His Bundle Pacing Uniquely Resolves Acute and Chronic Right Bundle Branch Block

Introduction: While acute (Ac) right bundle branch block (RBBB) may be in proximal HB (lead fixation injury) and chronic (Ch) RBBB in distal HB, they both cause terminal QRS delay. Both types of RBBB may be corrected with non-selective (NS) His bundle pacing (HBP), however the mechanism is unknown. Hypothesis: To study the role of high (5V) and low (1V) pacing voltage as well as presence of pre-excitation (in NS-HBP) in resolving Ac and chronic Ch-RBBB. Methods: Of the thirty-nine patients (27 ChRBBB and 12 AcRBBB), 25 ChRBBB and 10 AcRBBB patients showed NS-HBP at 5V and 11/25 ChRBBB and 6/12 AcRBBB patients transitioned to selective (S)-HBP at 1V. Four patients showed S-HBP at 5V and 1V. Results: 1)During NS-HBP at 5V: (In 25 ChRBBB and 10 Ac-RBBB) Complete resolution occurred 12/25ChRBBB and in all 10 AcRBBB. A partial resolution of ChRBBB occurred 13/25 ChRBBB.2. During NS-HBP at 1V: (6/14 ChRBBB and 2/4 AcRBBB showed complete resolution at 1V, remainder showed incomplete RBBB3. During S-HBP at 5V : (2 ChRBBB 2 AcRBBB) only 1 AcRBBB showed resolution of RBBB. 4. During S-HBP at 1V : All 13 ChRBBB and 8 AcRBBB did not show resolution os RBBB including 11 Ch-RBBB and 6 Ac-RBBB RBBB which resolved during 5V NS-HBP, abruptly recurred on transition to S-HBP at a mean of 2.4±0.8V. Conclusions: 1)The lack of RBBB resolution with S-HBP suggests that pacing site was proximal to site of block, however, from the same site NS-HBP either completely or incompletely resolved both Ac- and Ch-RBBB. 2) Partial resolution of RBBB in NS-HBP may be explained by right ventricular free wall pre-excitation when site of Ch-RBBB is distal.3) Complete resolution of both acute and Ch-RBBB in NS-HBP, more so at high pacing voltage, suggest that peri-Hisian tissues may behave more like a specialized conduction tract which uniquely resolves conduction block.

The back-up lead in his bundle pacing: evolution over the years

Background His bundle pacing (HBP) can be affected by high thresholds and low sensing. Thus, in selected patients including a back-up lead is advisable. Objective Single-centre retrospective analysis of a large HBP experience, focusing on the back-up lead utilization over the years. Methods 677 pts (76±8 years; 433 males) were implanted with HBP from 2004 to 2019 July. The pts received S-HBP (67%) or NS-HBP by the 3830 lead. The pacing indications were AV block 54%, sinus node disease 17%, slow atrial fibrillation 23%, heart failure 6%. Ischemic cardiopathy was found in 26%; hypertension in 83%, diabetes in28% pts. Baseline QRS duration was 123±32 ms and EF 56±12%. Results 266 (39%) pts received the back-up lead. In sinus rhythm we implanted 3-chamber PM (His lead:LV port; VV delay 80 ms: His pulses and apical pacing during the refractory period). 30 pts (11%) received a particular type of 3-chamber PM which provides back-up pacing only if His capture fails, thus saving energy. In atrial fibrillation 2-chamber PM was implanted (His lead: atrial port, DVI). We recorded a significant decrease of back-up lead use over the years, strictly related to operators/centre experience (>70% during the first years, nearly 10% during the last year). The C315 fixed curve sheath, strongly contributed to the rapid reduction of back-up lead use thanks to better lead fixation and stability. Conclusion The back-up lead utilization is progressively decreasing. It is strictly related to the operator/centre experience. The presence of the back-up lead could strengthen the Hisian pacing reliability, potentially impacting pacing indication even in advanced conduction disturbances and saving device longevity. Funding Acknowledgement Type of funding source: None

Fixation beats – a novel marker for reaching the left bundle branch area during deep septal lead implantation

IntroductionOne of the challenges of left bundle branch (LBB) pacing is to place the pacing lead deep enough in the septum to obtain capture of the LBB, yet not too deep to avoid perforation. We hypothesized that the occurrence of the ectopic beats of qR/rsR’ morphology in V1 lead (fixation beats) during the lead fixation would predict that the final desired intraseptal lead depth was just reached, while the lack of fixation beats would indicate too shallow position, and need for more lead rotations.MethodsConsecutive patients during LBB pacing device implantation were analyzed retrospectively and then prospectively with respect to the occurrence of the fixation beats during each episode of lead rotation. We compared the presence of fixation beats during the lead rotation event directly before the LBB capture area depth was reached versus during the events before intermediate/unsuccessful positions.ResultsA total of 339 patients and 1278 lead rotation events were analyzed. In the retrospective phase, the fixation beats were observed in 327/339 of final lead positions and in 9/939 of intermediate lead positions (p<0.001). The sensitivity, specificity, positive and negative predictive value of the LBB area fixation beats as a marker for reaching the LBB capture area was 96.4%, 99.0%, 97.3% and 99.0%, respectively. In the prospective, fixation-beats-guided, implantation phase the fixation beats were observed in all patients and only at the LBB capture depth.ConclusionsMonitoring fixation beats during deep septal lead deployment can facilitate the procedure and possibly increase the safety of lead implantation.

FM2-7 Paediatric robot-assisted DBS surgery: electrode problems and revision techniques

ObjectivesWe review our cases of hardware problems requiring revision surgery and consider the technical aspects of revising the electrodes, including a frameless technique using the Renishaw Guide tubes.DesignRetrospective Review.SubjectsChildren (≤18 years old) who presented with hardware problems following implantation of a DBS for dystonia at King’s College Hospital between May 2005 and April 2018.MethodsInformation was obtained from a prospectively kept database.ResultsOf 166 paediatric patients with DBS, 25 patients had hardware problems, and of these 21 (13%) patients had specifically electrode problems requiring replacement/revision of one or more electrodes. 7 patients had high impedances requiring revision, without obvious lead migration of fracture. 7 patients had lead migration and a further 7 patients had a lead fracture with or without lead migration. 15 patients had original DBS insertion with the Leksell Stereotactic System utilising the Medtronic Stimlock for lead fixation. 6 patients had DBS inserted with the Renishaw Sterotactic Robot and utilised the Renishaw Guide Tubes, in these patients who required lead replacement it was possible to revise the electrode without using stereotactic apparatus. As the guide tubes are implanted in the correct trajectory it is possible to measure the distance required to advance/implant the lead within this to target without the need for full stereotactic reimplantation.ConclusionsElectrode dysfunction is relatively common in children with DBS and a systematic approach is required to identify the cause. When an electrode requires repositioning or replacement, the procedure can be performed in the conventional manner with a stereotactic frame, or freehand without a frame if a Renishaw Guide tube is used at time of first insertion.

Electrode movement prevention – an animal model

Electrode migration is the most common complication of spinal cord stimulation (SCS). The problem of longitudinal migration has already been solved, but lateral migration remains the most common current complication. The present article describes new electrodes fixation opportunities for the reduction of lateral migration in SCS. The pig was chosen as an animal model to illustrate a new protocol of electrode fixation for the control of lateral and longitudinal migration. The displacement of the electrode was measured using two different optical methods: the digital image stereo-correlation and the digital image processing methods. Fixation with two anchors has always considerably reduced electrode displacement and when fixation is done with two anchors and a loop then lateral migration is reduced by 62.5 % and longitudinal migration is reduced by 94.1 %. It was shown that the results are significantly different at the α=0.001 significance level. Based on a statistical evaluation it is possible to state that the differences between experimental results obtained for three different protocols of lead fixation are statistically significant and we can recommend the new fixation method for common practice.