Background
Endocardial ablation of atrial ganglionated plexi (GP) has been described for treatment of atrial fibrillation (AF). Our objective in this study was to develop percutaneous epicardial GP ablation in a canine model using novel energy sources and catheters.
Methods
Phase 1: The efficacy of several modalities to ablate the GP was tested in an open chest canine model (n=10). Phase 2: Percutaneous epicardial ablation of GP was done in 6 dogs using the most efficacious modality identified in phase 1 using 2 novel catheters.
Results
Phase 1: DC in varying doses [blocking (7 -12μA), electroporation (300-500μA), ablation (3000- 7500μA)], radiofrequency ablation (25–50 W), ultrasound (1.5MHz), and alcohol (2-5ml) injection were successful at 0/8, 4/12, 5/7, 3/8, 1/5 and 5/7 GP sites. DC (500–5000μA) along with alcohol irrigation was tested in phase 2. Phase 2: Percutaneous epicardial ablation of the right atrium, oblique sinus, vein of Marshall, and transverse sinus GP was successful in 5/6 dogs. One dog died of ventricular fibrillation (VF) during DC ablation at 5000 μA. Programmed stimulation induced AF in 6 dogs pre-ablation and no atrial arrhythmia in 3, flutter in 1 and AF in 1 post-ablation. Heart rate, blood pressure, effective atrial refractory period and local atrial electrogram amplitude did not change significantly post-ablation. Microscopic examination showed elimination of GP, and minimal injury to atrial myocardium.
Conclusion
Percutaneous epicardial ablation of GP using direct current and novel catheters is safe and feasible and may be used as an adjunct to pulmonary vein isolation in the treatment of atrial fibrillation in order to minimize additional atrial myocardial ablation.
With the increasing utilization of cardiac implantable electronic devices, the ability to extract leads using the transvenous approach has become important. Devices that are infected and leads that pose a risk to the patient by causing damage to cardiovascular structures, interference with device function or life-threatening arrhythmias should be removed. While the majority of extractions are performed through the vein of implantation, other approaches, such as the femoral approach, are required in some circumstances. Simple traction may be successful in removing the lead in relatively new (<1 year) implants. Older devices invariably require devices such as locking stylets and simple or powered sheaths. With current techniques, complete lead extraction can be achieved in >90% of cases with a major complication rate of <2% and mortality rate of <1%. Transvenous lead extraction should be performed only by experienced operators with the resources to address life-threatening complications.
CRT undertaken with a unit focus on optimal LV lead positioning and device optimisation, along with a multidisciplinary follow-up model, results in an excellent response rate to CRT.
Cardiac electrophysiology has rapidly grown as an interventional therapeutic modality for an increasing number of patients and arrhythmia disorders. A major reason for these advances has been the availability and use of cardiac mapping systems. The practicing electrophysiologist, however, necessarily needs a thorough understanding of appropriate collection of data points to have a result that is anatomically and physiologically meaningful.To properly utilize available mapping systems, not only does the interventional electrophysiologist need to be cognizant of the inherent limitations of these symptoms but must be certain that the raw material being fed into the system (electrograms, annotation, anatomic points, registration, etc.) are meticulously obtained and accurate. In this chapter, we review the techniques for collecting these data points and present an algorithm to troubleshoot common errors resulting from inappropriate data collection.
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