Faculty Bibliography

A 64-year-old man with complete heart block, status post-Medtronic dual chamber pacemaker insertion, failed ablation for atrial tachycardia at an outside institution. Despite persistent palpitations and known unsuccessful ablation, pacemaker interrogation revealed no evidence of atrial arrhythmias. At electrophysiology study, burst pacing from the high right atrium and distal coronary sinus at 370 ms revealed bidirectional 2:1 interatrial conduction block. Left atrial burst pacing at 260 ms induced an atrial tachycardia (cycle length 340 ms) with 2:1 left to right atrial block and right atrial activation at 680 ms. The tachycardia was localized to the lateral left atrial roof. A series of ablation lesions from left to right superior pulmonary vein terminated the tachycardia. Left to right interatrial conduction block is a mechanism for underdetection of atrial arrhythmias with implantable devices not previously described. As the extent of atrial ablation increases, the incidence of this mechanism of underdetection may increase. Though devices are often considered ideal for atrial arrhythmia detection and are used in multiple trials, detection failures can occur despite appropriate device function. This case underscores the need for electrocardiographic monitoring in addition to device-based electrogram monitoring

Introduction: The Medtronic Fidelis lead family is associated with an unacceptable incidence of premature lead failure. Multiple studies have attempted to identify risk factors for lead failure and include younger age, better ejection fraction, and non-cephalic access. We hypothesized that other factors leading to potential increased forces on the lead including right-sided implantation or subpectoral positioning may be associated with premature lead failure. Methods: We reviewed the implant data from our group and identified 220 patients who received a Medtronic 6949 (dual coil) or 6931 (single coil) Fidelis lead. Implant data including age, sex, venous access site, implant side, implant location, lead length, and number of venous leads was reviewed. Hospital, Pacemaker Clinic, and Medtronic registration database were reviewed for evidence of lead failure, replacement, or abandonment. Data was evaluated in a univariate and multivariate analysis. Results: Of the 220 Fidelis leads implanted, 9 (4%) were noted to develop malfunction. This presented as inappropriate shocks from sensed noise, or elevated impedance measurements. Of the above noted implant features, only right-sided (vs. left-sided) implant, and subpectoral implant (vs. prepectoral) were found in uni- and multivariate analysis to be predictive of lead failure. Of 13 right-sided lead implants, 4 (30.7%) fractured (p<0.001). Of 14 subpectoral implants, 3 (21%) had lead failure (p<0.001). Conclusions: We have identified both right sided implantation and subpectoral generator positioning as factors associated with premature lead malfunction in the Fidelis lead family. Clinical decisions regarding patient management should incorporate these findings in regard to lead replacement in high risk patients

Introduction: Although the majority of rapid monomorphic VTs (faster than 320ms) can be ATP terminated, only Medtronic (MDT) has validated the clinical safety of its detection algorithm to distinguish rapid VT from VF. We set out to determine the performance characteristics of the Boston Scientific (BSC), MDT, and St. Jude Medical (SJM) ICD detection algorithms for VF at the time of ICD implantation and testing. Methods: Data on the detection of induced-VF at device implantation was collected on 62 consecutive patients in a non-randomized prospective cohort. Multi-zone programming for the BSC, MDT and SJM devices was based on data from the PAINFREE-II Trial. R-wave sensing at all implantations was performed with a Medtronic analyzer. Results: 62 patients were included and 124 tests for VFdetection were performed (Table). There were no differences in R-wave sensing or programmed sensitivity among groups. Compared to MDT and SJM, the BSC group had a significantly greater percentage of tests where charging occurred >5s from VF-induction. Mean time to charge initiation was 8s in 19.4% of tests in the BSC group. Marker channel/EGM analysis revealed that prolonged charge times resulted from inappropriate ATP and/or delayed VT/VF discrimination. Conclusions: The BSC VT/VF discrimination algorithm commonly results in delayed VF-detection when programmed with a VT zone from 240 to 320ms. This frequently translates into a prolonged time to device charge initiation. Further studies are needed to determine whether this prolonged detection time leads to clinically significant events. (Table presented)

Introduction: Left ventricular diverticulum is a rare abnormality for which the etiology, management, and natural history are poorly understood. LV diverticuli are reported to be associated with ventricular tachycardia and sudden cardiac death, though the mechanisms of these ventricular arrhythmias have not been well characterized. Conversely, focal PVC triggers of idiopathic VF emanating from the distal Purkinje system have been well described. Here we report the first case of Purkinje fiber-mediated VF mapping to a LV diverticulum that was successfully treated with catheter ablation. Methods: N/A Results: An otherwise healthy 38 year old woman presented with sudden cardiac arrest. Electrocardiography demonstrated repeated episodes of polymorphic VT/VF. The initiating beats of VF were of a left-bundle branch pattern and were identical in ECG morphology to isolated PVCs that were observed in the aftermath of resuscitation. Cardiac MRI demonstrated a normal LVEF and, notably, a focal diverticulum at the inferoseptal wall. At electrophysiology study, a mapping/ablation catheter was positioned in the LV diverticulum via retrograde approach, where distinct purkinje potentials were noted to precede the onset of QRS complexes during sinus rhythm. Pace mapping from within the diverticulum demonstrated a 11/12 lead match for the index PVCs. Delivery of RF energy to this region terminated both the PVCs and future VF events. Conclusions: This is the first description of purkinje-fiber mediated VF mapping to a LV diverticulum and successfully treated with RF ablation. (Figure presented)

BACKGROUND: Atrial fibrillation catheter ablation is frequently guided by identification of fractionated electrograms, which are thought to be critical for maintenance of the arrhythmia. Objective automated means for identifying fractionation independent of physician interpretation have not been standardized or validated. OBJECTIVE: The purpose of this study was to standardize and validate an automated algorithm to rapidly identify fractionated electrograms for high-density atrial fibrillation fractionation mapping. METHODS: Left and right atrial fractionation maps were generated by EnSite NavX 6.0 software, using standardized ablation catheters in eight patients with atrial fibrillation. Two blinded electrophysiologists interpreted all electrograms as either fractionated or not fractionated. A stepwise approach was used to optimize automated settings to accurately identify fractionation. High-density fractionation maps were generated with a 20-pole mapping catheter in eight other patients. Two blinded electrophysiologists interpreted all electrograms as near field or far field. The algorithm was refined to optimize settings to exclude far-field signals and retain near-field signals. The sampling segment length was adjusted to optimize recording time to ensure reproducibility. RESULTS: Using 1,514 points, the automated software achieved sensitivity of 0.75 and specificity of 0.80 for identification of fractionated electrograms. Using 725 points collected via multipole catheters with optimal automated settings, 94% of near-field fractionated electrograms were accurately identified. A 6-second sampling length was needed for reproducible fractionation measurements. CONCLUSION: Standardized settings of EnSite NavX 6.0 software with 6-second data collection per point can rapidly and accurately generate high-density fractionation maps independent of physician electrogram interpretation. This may allow for an automated, standardized approach to atrial fibrillation fractionated ablation

A 21-year-old woman presented with a pacemaker-associated superior vena cava (SVC) syndrome refractory to medical therapy. In the past, treatment of this condition has involved surgical exploration which is invasive. With the evolution of percutaneous techniques, treatment has included venoplasty and stenting over the pacemaker lead. There is limited experience with a more advanced percutaneous technique in which the lead is extracted by an excimer laser sheath. The extraction is immediately followed by venoplasty and stenting at the site of stenosis with subsequent implantation of a new permanent pacemaker at the previously occluded access site. The patient underwent this procedure which proved to be safe, minimally invasive, and an efficient method of treating SVC syndrome secondary to a single chamber atrial pacemaker

OBJECTIVE: This article describes the development, administration, and reliability of the Cornell Services Index (CSI), a new instrument that measures health service use. The CSI was developed to create a standardized measure of the quantity and characteristics (for example, site and provider) of services used by adults. Descriptive data are provided to illustrate the application of the CSI in a community sample of adults who were newly admitted to outpatient mental health clinics. These data provide information about the pathways to care. METHODS: The interrater and test-retest reliability of the CSI were evaluated by using a sample of 40 adults who were seeking mental health treatment. Descriptive data on service use in a sample of 1,279 adults seeking care in outpatient mental health clinics was provided to demonstrate the application of the CSI. RESULTS: The CSI is a portable, easy to use, and brief assessment of service use. It has good interrater and test-retest reliability among adults without cognitive impairment. In the three months before seeking care, 31 percent of the adults interviewed had made a mental health visit, 36 percent had been hospitalized, and more than half (59 percent) had made a medical visit. Twenty-three percent of adults had sought care from a hospital's emergency department. CONCLUSIONS: The CSI is a reliable method to assess health service use for adults. The measure can extend assessment of use beyond the traditional mental health service use questions and provide a snapshot of service use patterns across types, providers, and sites of service among adults who seek mental health care