Head-to-head comparison of arrhythmia discrimination performance of subcutaneous and transvenous ICD arrhythmia detection algorithms: the START study.

BACKGROUND: The development of a totally subcutaneous implantable defibrillator (S-ICD) system requires a new approach for arrhythmia detection. To evaluate arrhythmia discrimination of one such system, the Subcutaneous versus Transvenous Arrhythmia Recognition Testing (START) study was designed as a prospective, multicenter trial comparing simulated sensing performances of the S-ICD system with single- (SC-TV) and dual-chamber transvenous (DC-TV) implantable cardioverter-defibrillator (ICD) systems. METHODS: At ICD implantation, induced ventricular and atrial arrhythmias were recorded simultaneously in transvenous (right ventricular [RV] → superior vena cava [SVC]+ Coil) and cutaneous electrode configurations. Recorded signals of ventricular (n = 46) and atrial arrhythmias (n = 50) with ventricular rates >170 bpm from 64 patients were used to compare detection performance of the S-ICD system with TV-ICD systems from 3 manufacturers. Appropriate detection of ventricular tachyarrhythmias was assessed with devices programmed in single-zone (rate ≥ 170 bpm) and dual-zone configurations (ventricular fibrillation ≥ 240 bpm; ventricular tachycardia ≥ 170 bpm). S-ICD specificity performance for supraventricular arrhythmias was compared to single- and dual-chamber devices in a dual-zone configuration. RESULTS: Appropriate detection of ventricular tachyarrhythmias for subcutaneous and TV devices in single- and dual-zone configurations was 100% and >99%, respectively. Specificity for supraventricular arrhythmias was significantly better for the S-ICD system compared to 2 of 3 TV systems, as well as the composite of TV devices (98.0%[S-ICD] vs 76.7%[SC-TV range: 64.0-92.0%] vs 68.0%[DC-TV range: 32.7-89.8%; P < 0.001]). CONCLUSION: Appropriate ventricular arrhythmia detection is excellent for all ICD systems evaluated; however, specificity of supraventricular arrhythmia discrimination by the S-ICD system is better than discrimination by 2 of 3 TV systems.

Detection of a Riata™ insulation failure by the Medtronic Lead Integrity Alert™.

We describe a case of insulation failure in a Riata implantable cardioverter defibrillator lead [St Jude Medical (SJM), St Paul, MN, USA] detected by the Lead Integrity Alert (LIA)™, without impedance changes. The Medtronic LIA may permit early detection of Riata lead failure.

Primary Crime Prevention Apps: A Typology and Scoping Review.

In the last decade, an array of smartphone apps have been designed to prevent crime, violence, and abuse. The evidence base of these apps has, however, yet to analyzed systematically. To rectify this, the aims of this review were (1) to establish the extent, range, and nature of research into smartphone apps with a primary crime prevention function; (2) to locate gaps in the primary crime prevention app literature; and (3) to develop a typology of primary crime prevention apps. Employing a scoping review methodology and following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, studies were identified via Web of Science, EBSCOhost, and Google Scholar. We included English-language research published between 2008 and 2020 that examined smartphone applications designed explicitly for primary crime prevention. Sixty-one publications met our criteria for review, out of an initial sample of 151 identified. Our review identified six types of crime prevention app examined in these publications: self-surveillance apps, decision aid apps, child-tracking apps, educational apps, crime-mapping/alert apps, and crime reporting apps. The findings of our review indicate that most of these forms of primary crime prevention apps have yet to be rigorously evaluated and many are not evidence-based in their design. Consequently, our review indicates that recent enthusiasm over primary crime prevention apps is not supported by an adequate evidence base.

Understanding Engagement With Forensic Smartphone Apps: The Service Design Engagement Model.

Justice services have begun to integrate the use of mobile applications into treatment, support, and rehabilitative programs for forensic clients. One such application that been adopted to support forensic clients is "eRecovery": a smartphone application that provides clients recovering from a substance addiction with support for managing relapse. In this article, we report on evaluation findings from a trial of eRecovery in an Australian Community Justice Centre, and reflect on several issues relating to fostering and sustaining client engagement with similar applications within forensic and justice settings. We propose the Service Design Engagement Model to organize, visualize, and describe the stages and factors important to adoption, appropriation, and on-going routine use of the software by forensic clients. The model recognizes the role of contextual and environmental factors in supporting users through the early stages of engagement, and the importance of user agency in longer-term engagement with therapeutic apps.

An unusual source of electromagnetic interference: a device-device interaction.

INTRODUCTION: Implantable cardioverter-defibrillators (ICDs) are susceptible to oversensing of extracardiac signals, also known as electromagnetic interference (EMI). We report a case of an unusual source of electrical interference of only the high voltage (HV) impedance measurement in the Teligen ICD (Boston Scientific, St. Paul, MN, USA) caused by electrical interference from an electrosurgical generator with an electrocautery patch located in close proximity to the ICD pulse generator. METHOD AND RESULTS: A patient underwent an uneventful implant of a Boston Scientific Teligen 100 ICD. Once the device was inserted in a pocket, interrogation of the device repeatedly demonstrated HV electrode impedance measurements between <20 and 40 Omega and noise only on the HV electrode. A new lead and generator were implanted without a change in the interrogation results. The erroneous measurements of HV impedance were caused by a combination of the close proximity of the electrocautery patch to the ICD generator. The continuous low-amplitude current emitted by the contact quality monitoring system of the electrosurgical cautery generator interfered with an equally weak current delivered through the lead by the device to measurement HV impedance. The Medtronic Virtuoso (Medtronic Inc., Minneapolis, MN, USA) ICD and the St. Jude Medical Current DR (St. Jude Medical, St. Paul, MN, USA) ICD were not affected by the patch due to greater magnitude of current delivered by the device to measure HV electrode impedance. CONCLUSION: It is important that the operator must be aware of any potential source of EMI, as it may affect the device and require immediate troubleshooting. Failure to recognize this interaction may result in inappropriate and unnecessary pulse generator replacement.

Effect of electrode orientation on lesion sizes produced by irrigated radiofrequency ablation catheters.

BACKGROUND: Irrigated radiofrequency (RF) ablation catheters may produce different lesion sizes dependent upon the electrode orientation to the tissue. This study examined the effect of irrigated electrode orientation on the lesion size and explores a potential mechanism for this effect. METHODS AND RESULTS: Lesions were created in isolated porcine myocardium using an open irrigation, closed irrigation, and nonirrigated RF catheter (all 3.5-4 mm tips). Lesions were created with the electrodes with all permutations of electrode orientation (vertical or horizontal), contact pressure (6 or 20 g), and saline superfusate flow (0.2 or 0.4 m/sec) over tissue interface. The effect of electrode irrigation without RF delivery on tissue temperature was assessed with intramyocardial temperature probes and infrared thermal imaging. For both irrigated catheters, the horizontal orientation produced 25-30% smaller lesion volumes than the vertical orientation despite equal or greater power deliveries. The horizontal orientation produced larger lesion volumes for the nonirrigated catheter. Higher superfusate flow rates were associated with decreased lesion volumes for the irrigated catheters but greater lesion volumes for the nonirrigated catheter. Catheter irrigation alone without RF delivery reduced intramyocardial temperatures up to 4.9 degrees C and the horizontal orientation produced a 2-fold greater area of tissue cooling than the vertical orientation. CONCLUSION: Horizontal electrode orientations reduce lesion volumes for irrigated RF catheters. This effect may be in part due to greater areas of active tissue cooling in the horizontal orientation.

Periprocedural management of anticoagulation and antiplatelet therapies in patients undergoing electrophysiologic procedures.

Electrophysiologic studies, radiofrequency ablation, and device implantations including pacemakers and defibrillators have become essential tools in the armamentarium of electrophysiologists. These procedures are being performed in patients with complex comorbidities, many of whom chronically take anticoagulation or antiplatelet agents. Careful management of anticoagulation before, during, and after electrophysiologic procedures including device implantations is critical to minimize bleeding and thrombotic complications and to optimize patient outcomes.

Benefit of primary prevention implantable cardioverter-defibrillators in the setting of chronic kidney disease: a decision model analysis.

INTRODUCTION: Primary prevention ICD trials have excluded patients with CKD. Comorbidities and lower life expectancy in patients with CKD make the benefit of primary prevention ICD implantation uncertain. METHODS: A decision analysis model was devised to evaluate the risks and benefits of implantable cardioverter-defibrillators (ICD) implantation in patients with chronic kidney disease (CKD) who meet current criteria for a primary prevention ICD. Published data capturing event rates, infection risks, and overall survival in CKD patients with and without ICDs were utilized. Variables included patient's age, GFR and stage of CKD, probability of sudden cardiac death (SCD), and device implantation mortality. RESULTS: The benefit of an ICD for primary prevention of SCD in patients with CKD depends primarily on the patient's age and stage of kidney disease. With stages 1 and 2 CKD, ICD implantation reduces mortality. However, in patients with more advanced stages of CKD, the benefit is less significant and age-dependent. This is attributed to patients with advanced CKD having a higher procedural risk and decreased life expectancy. With average procedural mortality, ICD implantation is favored at ages <80 for stage 3, ages <75 for stage 4, and ages <65 for stage 5. As procedural mortality rates increase, age thresholds for ICD implantation decrease. CONCLUSIONS: Our model shows that benefit from primary prevention ICD implantation is determined by the patient's age and stage of kidney disease. While there is limited impact with lower stages of CKD, careful consideration of ICD implantation is suggested for older patients with more advanced stages of kidney disease.

Sensing failure associated with the Medtronic Sprint Fidelis defibrillator lead.

INTRODUCTION: The diameter of implantable cardioverter-defibrillator (ICD) leads has become progressively smaller over time. However, the long-term performance characteristics of these smaller ICD leads are unknown. METHODS: We retrospectively evaluated 357 patients who underwent implantation of a Medtronic Sprint Fidelis defibrillating lead at two separate centers between September 2004 and October 2006. Lead characteristics were measured at implant, at early follow-up (1-4 days post implant), and every 3-6 months thereafter. RESULTS: During the study period, 357 patients underwent implantation of the Medtronic Sprint Fidelis lead. The mean R-wave measured at implant through the device was not different (P = NS) when compared with that measured at first follow-up (10.5 +/- 5.0 mV vs 10.7 +/- 5.1 mV). Forty-one patients (13%) had an R-wave amplitude

Implantable cardiac defibrillator lead failure or myopotential oversensing? An approach to the diagnosis of noise on lead electrograms.

The appearance of noise on electrograms (EGMs) recorded from the lead of an implantable cardioverter-defibrillator (ICD) may be owing to oversensing of myopotentials, insulation breach, conductor coil fracture, loose set screw, or electromagnetic interference from an external source. The extraneous noise may lead to inappropriate shocks or inhibition of pacing. We describe two cases of pectoral myopotentials oversensing in patients with ICD and an approach to distinguish among the various extraneous noises recorded on EGMs. A systematic approach to identify the cause of the noise is important to render an appropriate treatment, which might include simple device re-programming or require re-operation and lead revision or replacement.

Long-term follow-up after radiofrequency catheter ablation for atrial fibrillation.

AIMS: Data on long-term follow-up of patients who have undergone catheter ablation for atrial fibrillation (AF) are very limited. This report aimed at presenting clinical outcome and AF-free survival after pulmonary vein (PV) isolation over an extended (>3 years) follow-up period. METHODS AND RESULTS: Thirty-nine patients subjected to PV isolation for paroxysmal AF were followed-up for at least 3 years according to a strict protocol. Fourteen patients (35.8%) had one, 19 patients (50%) had two, and 6 patients (15.4%) had three ablation procedures. At end of follow-up (42.2 +/- 6.0 months), 17 patients (43.5%) were completely free of AF or other atrial arrhythmia, and 26 patients (66.6%) had symptomatic improvement. The long-term success rate was 21.4% for patients subjected to a single ablation procedure, 52.6% for patients subjected to two catheter ablation procedures, and 66.7% for patients who underwent three ablation procedures (P = 0.094). There was also a trend for patients who underwent a combination of different ablation procedures (ostial, antral, and/or circumferential) to have a higher AF-free survival when compared with patients subjected to the same procedure (P-value for log-rank test = 0.036). CONCLUSION: Catheter ablation does not eliminate paroxysmal AF in up to 56% of patients in the long term, despite the use of two or three ablation procedures in two-thirds of them. However, it confers symptomatic improvement in 67% of treated patients.

Problems with implantable cardiac device therapy.

Implantable cardioverter-defibrillators (ICDs) improve survival in patients who have left ventricular dysfunction; however, they are associated with numerous problems at implant and during follow-up. The diagnosis and management of these problems is usually straightforward, but more difficult problems may include the management of patients who have elevated energy requirements to terminate ventricular fibrillation or of those who have postoperative device infections. Long-term issues in ICD patients include the occurrence of inappropriate or frequent appropriate shocks. ICD generators and leads are more prone to failures than are pacing systems alone; management of patients potentially dependent on "recalled" devices to deliver life-saving therapy is a particularly complex issue. The purpose of this article is to review the diagnosis and management of these more troublesome ICD problems.

Gender disparity in the use of cardiac resynchronization therapy in the United States.

BACKGROUND: Although several studies have shown the effectiveness of cardiac resynchronization therapy (CRT) for advanced congestive heart failure (CHF), gender differences in utilization of CRT are not known. METHODS: We used the Healthcare Cost and Utilization Project (HCUP) to study national rates for admissions due to CHF along with procedures for initial CRT implantation, including both CRT-defibrillator (CRT-D) and CRT-pacemakers (CRT-P) during the years of 2002-2004. Chi-square tests were used for comparison between number of women and men. A P < 0.05 was considered significant. RESULT: Women had consistently higher rates of admission for CHF during each year (574,037 (54%) vs 482,005 (46%), 2002; 601,181 (54%) vs 517,202 (46%), 2003; and 580,913 (53%) vs 521,280 (47%), 2004). The number of initial CRT device implantations (both CRT-D and CRT-P) was significantly lower during each year for women compared to men (659 (25%) vs 1,931 (75%), 2002; 6,928 (26%) vs 19,646 (74%), 2003; and 11,286 (27%) vs 42,196 (73%), 2004; P < 0.01 for all). Both CRT-P and CRT-D were used less frequently in women compared to men; however, this difference was consistently less prominent during each year with CRT-P compared to CRT-D (301 (41%) CRT-P vs 358 (19%) CRT-D, 2002; 659 (39%) CRT-P vs 2,530 (28%) CRT-D, 2003; and 2,891 (39%) CRT-P vs 8,395 (24%) CRT-D, 2004; P < 0.05). CONCLUSION: Our data clearly demonstrate a significant gender disparity in utilization of CRT devices. Further studies are needed to find possible reasons behind this disparity.

Remote magnetic versus manual catheter navigation for ablation of supraventricular tachycardias: a randomized, multicenter trial.

INTRODUCTION: The potential benefits of remote robotic navigation for catheter ablation procedures have not been demonstrated in controlled clinical trials. The purpose of this study was to compare remote magnetic catheter navigation to manual navigation for the ablation of common supraventricular arrhythmias. METHODS AND RESULTS: Patients with supraventricular arrhythmias due to atrioventricular (AV) nodal reentry, accessory pathways, or undergoing AV junctional ablation for complete heart block were randomized in a 3:1 ratio between magnetic (Niobe system and Helios II catheter, Stereotaxis, Inc., St. Louis, MO) and manual navigation for radiofrequency ablation at 13 centers. The primary endpoint of the study was total fluoroscopic time. Fifty-six patients were randomized to magnetic navigation and 15 to manual navigation. AV nodal reentry was the most common arrhythmia in both groups. Total fluoroscopy time was reduced in the magnetic navigation group (median 17.8 minutes, interquartile (IQ) range 9.9,27.8 minutes) compared to manual navigation (27.1, IQ 19.0,48.0, P < 0.05). The acute success rates (91% for magnetic and 87% for manual navigation, P > 0.05) did not differ between groups. The number of lesions delivered was less for magnetic navigation (6, IQ 4,9 vs 10, IQ 7, 26, P < 0.05). Total procedure time (median 151, IQ 111, 221 minutes magnetic and 151, IQ 110, 221 minutes manual) and complication rates (5.4% patients magnetic and 6.7% patients manual) were similar between the groups (both P > 0.05). CONCLUSIONS: Remote magnetic catheter navigation reduces fluoroscopic time and radiofrequency lesion deliveries for the ablation of common supraventricular arrhythmias compared to manual catheter navigation.

Clinical judgment versus decision analysis for managing device advisories.

INTRODUCTION: Implantable cardioverter-defibrillator (ICD) and pacemaker (PM) advisories may have a significant impact on patient management. Surveys of clinical practice have shown a great deal of variability in patient management after a device advisory. We compared our management of consecutive patients in a single large university practice with device advisories to the "best" patient management strategy predicted by a decision analysis model. METHODS: We performed a retrospective review of all patients who had implanted devices affected by an advisory at our medical center between March 2005 and May 2006 and compared our actual patient management strategy with that subsequently predicted by a decision analysis model. RESULTS: Over 14 months, 11 advisories from three different manufacturers affected 436 patients. Twelve patients (2.8%) were deceased and 39 patients (8.9%) were followed at outside facilities. Management of the 385 remaining patients varied based on type of malfunction or potential malfunction, manufacturer recommendations, device dependency, and patient or physician preferences. Management consisted of the following: 57 device replacements (15.2%), 44 devices reprogrammed or magnets issued (11.7%), and 268 patients underwent more frequent follow-up (71.3%). No major complications, related to device malfunction or device replacement, occurred among any patient affected with a device advisory. Concordance between the decision analysis model and our management strategy occurred in 57.1% of cases and 25 devices were replaced when it was not the preferred treatment strategy predicted by the decision model (43.9%, 37.3% when excluding devices replaced based on patient preference). The decision analysis favored replacement for all patients with PM dependency, but only for four patients with ICDs for secondary prevention. No devices were left implanted that the decision analysis model predicted should have been replaced. CONCLUSIONS: We found that despite a fairly conservative device replacement strategy for advisories, we still replaced more devices when it was not the preferred device management strategy predicted by a decision analysis model. This study demonstrates that even when risks and benefits are being considered by experienced clinicians, a formal decision analysis can help to develop a systematic evidence based approach and potentially avoid unnecessary procedures.

Effects of gap geometry on conduction through discontinuous radiofrequency lesions.

BACKGROUND: Gaps of sufficient cross-sectional dimensions within linear radiofrequency (RF) lesions may allow conduction through the lesion. The purpose of this study was to examine the effects of different gap geometries on conduction through discontinuous RF lesions. METHODS AND RESULTS: Radiofrequency lesions were created in isolated, perfused rabbit right ventricular (RV) free wall preparations to produce gaps with 3 different lesion geometries: straight, bifurcated, and angled (n=10 each group). Angled preparations contained 2 right angles within the conduction path. Optical mapping was used to assess bidirectional conduction through the myocardium before and after gap formation during pacing at 1000-, 400-, and 200-ms cycle lengths. Histological analysis was performed on each preparation after optical mapping. After lesion formation, 9 of 10 straight gap preparations and 1 of 10 angled gap preparations demonstrated bidirectional conduction (P<0.001) at all cycle lengths. Nine of 10 bifurcated gap preparations demonstrated bidirectional conduction and 1 demonstrated unidirectional conduction at all cycle lengths. Two bifurcated gap preparations showed rate-dependent unidirectional 2:1 conduction. All unidirectional and rate-dependent block occurred during impulse propagation in the direction of diverging arms of the bifurcation. The occurrence of bidirectional conduction in the gaps was associated with the gap geometry (P<0.0001). Histological analysis confirmed the continuity of viable myocardium transmurally throughout the length of the gap in each preparation. The sites of conduction block were demonstrated to be just after the first angle in the conduction path for angled gaps and at the branch point of a bifurcated gap. The predominant myofiber orientation was changed relative to the conduction path at angulations of the gaps. Flecainide (0.1 micromol/L) produced bidirectional conduction block in straight and bifurcated gap preparations with bidirectional conduction at baseline. CONCLUSIONS: Conduction through discontinuities in RF lesions is associated with gap geometry. Complex gap geometry may allow for unidirectional and/or rate-dependent block. Gaps within RF lesions are susceptible to pharmacological blockade.

Time to electrode rewarming after cryoablation predicts lesion size.

INTRODUCTION: There are no methods in clinical use to assess tissue cooling during catheter cryoablation. Cryoablation electrode temperature may be a poor predictor of lesion size. The purpose of this study was to determine whether the time necessary for the cryoablation electrode to cool to target temperature or to rewarm after cryoablation can predict lesion size. METHODS AND RESULTS: Cryoablation was performed on live porcine left ventricle in a saline bath (37 degrees C) using 8-mm-tip catheter. Cryoablation was given for 300 seconds under all permutations of the following conditions: electrode orientation vertical or horizontal, contact pressure 6 or 20 g, superfusate flow over electrode-tissue interface at 0.2 or 0.4 m/s (N = 10 each condition set, total 80 experiments). The time intervals necessary to cool the electrode to the target temperature of -75 degrees C and to rewarm to + 30 degrees C after termination of cryoablation were recorded. Lesion volume was predicted best by the time necessary to rewarm the electrode to +30 degrees C (r2 = 0.65, P < 0.0001), followed by electrode temperature (r2 = 0.28, P < 0.0001) and time to cool the electrode to -75 degrees C (r2 = 0.24, P < 0.0001). Time to +30 degrees C and time to -75 degrees C were associated with superfusate flow rate, contact pressure, and electrode orientation (r2 = 0.80 and 0.61, respectively, both P < 0.0001). Superfusate flow rate, contact pressure, and orientation were also highly predictive of lesion volume (r2 = 0.93, P < 0.0001). CONCLUSIONS: Time to cryoablation electrode rewarming is a better predictor of cryoablation lesion size than is electrode temperature. Time to cryoablation electrode rewarming reflects important determinants of cryoablation lesion formation--convective warming, contact pressure, and electrode orientation--that are not ascertainable during clinical ablation procedures.

Slow atrioventricular nodal reentrant arrhythmias: clinical recognition, electrophysiological characteristics, and response to radiofrequency ablation.

BACKGROUND: Atrioventricular nodal reentrant tachycardia (AVNRT) is a common form of supraventricular tachycardia (SVT). Rarely, patients may present with an unusual form of atrioventricular nodal reentrant arrhythmia (AVNRA) with a cycle length greater than 600 ms. We describe the clinical presentation, electrophysiology characteristics, and response to radiofrequency ablation in a group of patients with AVNRA. METHODS AND RESULTS: Six patients with slow documented sustained supraventricular arrhythmias at rates <100 bpm underwent electrophysiology study. Baseline clinical and electrophysiologic characteristics were: mean age 77 +/- 5 years; left ventricular ejection fraction 51 +/- 10%; hypertension 66%; diabetes mellitus 33%; coronary artery disease 33%; sinus cycle length 874 +/- 110 ms; PR 261 +/- 54 ms; atrial to His (AH) 181 +/- 49 ms. AVNRA was diagnosed based on previously described criteria for AVNRT. Mean tachycardia cycle length (TCL) during AVNRA was 668 +/- 74 ms. The AH and His to atrial (HA) intervals during the AVNRA was 434 +/- 50 and 234 +/- 81 ms, respectively. Two patients had slow-fast AVNRA while the others had slow-slow AVNRA. Most common symptoms reported during AVNRA were shortness of breath, fullness in the throat, chest tightness, dizziness, near-syncope, and syncope. Radiofrequency catheter ablation (RFCA) of the slow pathway was performed successfully in five of six patients. Post-ablation AV nodal Wenckebach occurred at 666 +/- 49 ms compared with 521 +/- 91 ms at baseline. CONCLUSION: AVNRA may occur at rates less than 100 bpm in the elderly and may be misdiagnosed as junctional rhythm. Slow AVNRA can cause significant symptoms. Slow pathway ablation can be successfully performed in AVNRA.

Accuracy of intracardiac echocardiography for assessing the esophageal course along the posterior left atrium: a comparison to magnetic resonance imaging.

BACKGROUND: Atrioesophageal fistula is a potentially fatal complication of ablation in the left atrium (LA) to treat atrial fibrillation. OBJECTIVE: The objective of our study was to systematically evaluate the diagnostic potential of intracardiac echocardiography (ICE) for accurately assessing the esophageal course along the posterior LA. METHODS: Thirty-five patients underwent magnetic resonance imaging (MRI) before and ICE during pulmonary vein (PV) isolation to visualize the esophagus. The location of the esophagus was determined in relation to the PVs and anatomic regions of the LA by both ICE and MRI. Using the MRI images as a reference, the accuracy of ICE localization was assessed. RESULTS: The most common location for the esophagus to appear was the mid-posterior wall (80% of patients by ICE, 71% of patients by MRI), followed by the left posterior wall (71% of patients by ICE, 63% of patients by MRI) and the right posterior wall (60% of patients by ICE, 51% of patients by MRI). The esophagus was seen to course near the left PV antrums (left superior PV antrum 34% of patients by ICE and MRI; left inferior PV antrum 34% of patients by ICE, 37% of patients by MRI), left superior PV (17% of patients by ICE, 20% of patients by MRI), left inferior PV (17% of patients by ICE and MRI), right inferior PV antrum (29% of patients by ICE, 37% of patients by MRI) and the right inferior PV (3% of patients by ICE, 17% of patients by MRI). The sensitivity for esophageal location by ICE compared to that by MRI ranged between 33% (right inferior PV) and 92% (left superior PV antrum, left inferior PV antrum, and mid-posterior wall). The specificity for esophageal location by ICE compared to that by MRI ranged between 60% (mid-posterior wall) and 100% (right inferior PV). The positive predictive value ranged between 80% (left inferior PV) and 100% (right inferior PV). The negative predictive value ranged between 84% (right inferior PV antrum) and 96% (left superior PV antrum). CONCLUSION: Phased array ICE provides rapid, real-time localization of the esophagus during LA ablation that is comparable to MRI.

Cryoablation inside the pulmonary vein after failure of radiofrequency antral isolation.

BACKGROUND: Antral pulmonary vein (PV) ablation with radiofrequency (RF) energy has become widely used as a curative approach for the treatment of atrial fibrillation. In some patients, despite antral ablation, PV entry and exit conduction block (BDB) cannot be achieved with RF energy. Cryoablation inside the PV may be an effective method to achieve BDB. OBJECTIVE: This study sought to describe a strategy of cryoablation within the PV to produce BDB in patients in whom antral RF ablation has failed. METHODS: In 15 of 148 consecutive patients (57 +/- 8.9 years old, 80% male) with atrial fibrillation (14 paroxysmal, 1 chronic) undergoing PV isolation cryoablation (CryoCath Technologies, Inc., Montreal, Canada) was performed 12 +/- 2 mm inside the PV after RF antral isolation failed. Nine patients were undergoing a repeat PV isolation procedure. Procedural and follow-up data were recorded and collected. RESULTS: In these 15 patients, BDB could not be achieved in 23 veins (12 left superior PV) with antral or ostial ablation alone. After cryoablation inside the vein, all patients had documented PV BDB and were in normal sinus rhythm at the end of the procedure. The average PV diameter before and after the procedure was unchanged (1.77 +/- 0.18 vs 1.74 +/- 0.19, P = .641). The average fluoroscopic and procedure times were 57 +/- 16 min and 5.3 + 1.2 hours, respectively. At 1-year follow-up, 75% of patients remained in sinus rhythm off antiarrhythmic medication; 7 of 9 patients undergoing a repeat procedure were in sinus rhythm at 1 year off antiarrhythmics. None of the patients had clinical evidence of PV stenosis after cryoablation. CONCLUSION: Cryoablation inside the PV after failed antral isolation with RF is a safe and effective method to achieve acute BDB.