Multipoint Pacing Research Articles

A Novel Technique of Multi-point Pacing in Substrate Evaluation Using Conduction Velocity with Non-contact Mapping

Introduction: Complex electrophysiological mapping is based on the principles of activation, voltage-substrate, pace, and entrainment mapping. The pathology underlying many arrhythmias is related to functional conduction changes, which is not seen directly with any of the current techniques. Non-contact mapping, and the dynamic substrate mapping system, could be extended to examine for changes in conduction velocity. Method: Under general anaesthetic, a geometric construct was acquired with a roving mapping catheter in the right atrium of eight cross-bred sheep. Non-contact virtual electrograms were collected prior to, and post creation of a cavo-tricuspid line of ablation, during pacing from multiple sites within the right atrium. Post-processing included: (1) Reference beat selection by user. (2) Automated detection of location activation by maximum negative dv/dt. (3) Calculation of local speed by comparing the distance and activation timing of surrounding points. (4) Consolidation of multiple local speeds for a single point from various pacing sequences. Results: Bidirectional block was successful in all eight animals. There were no significant changes in global measures pre and post ablation, such as global velocity (11.7 ± 1.1 mm/s vs 10.7 ± 1.3 mm/s, p = NS). Locally, the area underlying the ablations changed velocity significantly (10.8 ± 2.4 mm/s, pre-ablation vs 0.75 ± 1.25 mm/s post-ablation, p < 0.001). Conclusion: Multi-point pacing with this semi-automated conduction velocity substrate mapping technique can identify areas of slowed or blocked conduction. This can lead to further comprehensive evaluation of substrate in complex electrophysiological mapping which is of particular significance in macro-reentry circuits such as ischaemic ventricular tachycardia.

847 Effect of Multi-Point Gastric Electrical Pacing (MGP) On Symptoms, Gastric Emptying and Electrical Activity in Diabetic Gastroparesis

other sites (incidental TICs) were excluded from this analysis. Daily fiber & abstinence from ASA & NSAIDs were recommended. Outcomes were analyzed for PRES vs. DEF subgroups & by baseline treatment groups (MED, ENDO, SURG) post-60 days after initial diagnosis & treatment. Data were recorded on standard forms by research coordinators & SAS was used for data management & analysis. RESULTS: Patients were similar in all demographics, except for more RBC's & ENDO treatments in the DEF group. The mean age was 72 yrs, 29% were female, 16% took anticoagulants & all had co-morbidities. 43 pts (37.7%) had definitive & 71 pts (62.3 %) presumptive TIC Bleeds. Mean F/U was 1195±77 days. Compliance with fiber & ASA/NSAIDs was low. The rates of rebleeds & other TIC COMPL for DEF (N=43) vs. PRES (N=71); & MED (N=74), ENDO (N=32) & SURG (N=8) are shown in the Table. No differences were significant (p> 0.05). The cumulative death rate was 16.7% & no one died of TIC bleed or TIC-COMPL. CONCLUSIONS: For patients with documented diverticular hemorrhage followed long-term: 1. Rebleeding rates were low, but as likely to be from TICs as other GI sites. 2. No one died of TIC bleeds or TIC complications, which were also very rare. 3. There were no significant outcome differences after medical, endoscopic, or surgical therapies. Based upon these data, the recommendation of surgery for an index diverticular bleed should be revised. Partially supported by NIH grants (K24DK002650) & CURE (P30-DK040301) Human Studies Core.