Jason S. Chinitz

Needle-in-needle epicardial access: Preliminary observations with a modified technique for facilitating epicardial interventional procedures.

to flex over the course of insertion, and tactile assessment of force and perception of cardiac motion was limited. In this report, we describe our initial experience with the “needle-inneedle” (NIN) technique of epicardial access in which a short 18G needle is inserted under the sternum and the long 21G needle is inserted through the 18G needle. It is hoped that this technique improves the stability of the small needle and potential tactile feedback, thus reducing the risk of significant pericardial bleeding. We report preliminary results of its procedural success and acute complications compared with the standard Sosa technique, 1 which uses a 17G or 18G Touhy needle.

Correlates and Prognosis of Early Recurrence After Catheter Ablation for Ventricular Tachycardia due to Structural Heart Disease

Background—Catheter ablation for ventricular tachycardia (VT) from structural heart disease has a significant risk of recurrence, but the optimal duration for in-hospital monitoring is not defined. This study assesses the timing, correlates, and prognostic significance of early VT recurrence after ablation. Methods and Results—Of 370 patients (313 men; aged 63.0±13.2 years) who underwent a first radiofrequency ablation for sustained monomorphic VT associated with structural heart disease from 2008 to 2012, sustained VT recurred in 81 patients (22%) within 7 days. In multivariable analysis, early recurrence was associated with New York Heart Association classification ≥III (odds ratio [OR] 1.90, 95% confidence interval [CI] 1.03–3.48; P=0.04), dilated cardiomyopathy (OR 1.93, 95% CI 1.03–3.57; P=0.04), prevalence of VT storm before the procedure (OR 2.62, 95% CI 1.48–4.65; P=0.001), a greater number of induced VTs (OR 1.24, 95% CI 1.07–1.45; P=0.006), and acute failure or no final induction test (OR 1.88, 95% CI 1.03–3.40; P=0.04). During a median of 2.5 (1.2, 4.0) years of follow-up, early VT recurrence was an independent correlates of mortality (hazard ratio 2.59, 95% CI 1.52–4.34; P=0.0005). Conclusions—Patients who have early recurrences of VT after ablation are a high risk group who may be identifiable from their clinical profile. Further study is warranted to define the optimal treatment strategies for this patient group.

Avoiding tachycardia alteration or termination during attempted entrainment mapping of atrial tachycardia related to atrial fibrillation ablation

BACKGROUND Entrainment can be useful for mapping atrial tachycardias (ATs) after atrial fibrillation (AF) ablation but may result in AT alteration or termination. OBJECTIVE We aimed to determine the incidence and risk factors for AT alteration or termination. METHODS In 30 consecutive patients, 62 ATs (mean cycle length [CL] 268 ± 53 ms) in which overdrive pacing for entrainment mapping was performed were retrospectively analyzed. AT was classified as altered if the CL or activation pattern remained altered 10 seconds after pacing. The variability in the PP intervals was determined over 10 beats from 2 measures: (1) the difference between the shortest and the longest CL expressed as a percentage of the CL and (2) the mean difference between sequential PP intervals expressed as a percentage of the AT CL (CLDmean). RESULTS Of 386 total pacing attempts (tachycardia CL [TCL] - pacing CL [PCL] difference 15 ± 6 ms), 5 (1.3%) altered or terminated AT and 381 did not change AT (98.7%). When the TCL - PCL difference was ≤20 ms, only 2 of 353 (0.5%) attempts altered or terminated AT. When the TCL - PCL difference was >20 ms, 3 of 33 (9%) attempts altered or terminated AT. The difference between the shortest and the longest CL expressed as a percentage of the CL was significantly greater in ATs that were altered or terminated by pacing than in those unchanged (11.0% ± 9.6% vs 4.5% ± 4.5%; P = .007), but the mean difference between sequential PP intervals expressed as a percentage of the AT CL was not significantly different (3.8% ± 2.6% vs 1.9% ± 2.1%; P = .06). CONCLUSION Overdrive pacing for entrainment mapping rarely alters or terminates after atrial fibrillation AT, provided that AT is stable before pacing and that the PCL is ≤20 ms shorter than the AT CL.

Better outcome of ablation for sustained outflow-tract ventricular tachycardia when tachycardia is inducible.

AIMS In patients presenting with spontaneous sustained ventricular tachycardia (VT) from the outflow-tract region without overt structural heart disease ablation may target premature ventricular contractions (PVCs) when VT is not inducible. We aimed to determine whether inducibility of VT affects ablation outcome. METHODS AND RESULTS Data from 54 patients (31 men; age, 52 ± 13 years) without overt structural heart disease who underwent catheter ablation for symptomatic sustained VT originating from the right- or left-ventricular outflow region, including the great vessels. A single morphology of sustained VT was inducible in 18 (33%, SM group) patients, and 11 (20%) had multiple VT morphologies (MM group). VT was not inducible in 25 (46%) patients (VTni group). After ablation, VT was inducible in none of the SM group and in two (17%) patients in the MM group. In the VTni group, ablation targeted PVCs and 12 (48%) patients had some remaining PVCs after ablation. During follow-up (21 ± 19 months), VT recurred in 46% of VTni group, 40% of MM inducible group, and 6% of the SM inducible group (P = 0.004). Analysis of PVC morphology in the VTi group further supported the limitations of targeting PVCs in this population. CONCLUSION Absence of inducible VT and multiple VT morphologies are not uncommon in patients with documented sustained outflow-tract VT without overt structural heart disease. Inducible VT is associated with better outcomes, suggesting that attempts to induce VT to guide ablation are important in this population.

Determinants of Heparin Dosing and Complications in Patients Undergoing Left Atrial Ablation on Uninterrupted Rivaroxaban

Patients on rivaroxaban have variable international normalized ratios (INRs) but it is uncertain if INR impacts procedural heparin requirement during left atrial ablation. We sought to examine the determinants of heparin dosing in this patient population.

Downstream overdrive pacing and intracardiac concealed fusion to guide rapid identification of atrial tachycardia after atrial fibrillation ablation

Aims Atrial tachycardia (AT) related to atrial fibrillation (AF) ablation frequently poses a diagnostic challenge. Downstream overdrive pacing (DOP) can be used to rapidly detect reentry and assess proximity of a pacing site to an AT circuit or focus. We hypothesized that systematic DOP using multielectrode catheters would facilitate AT mapping. Methods and results DOP identified constant fusion when the post-pacing interval (PPI)-tachycardia cycle length (TCL) <40 ms and stimulus to adjacent upstream atrial electrogram interval >75% of TCL. Mapping was performed as follows: (i) CS DOP, (ii) DOP at left atrial (LA) roof, (iii) DOP at selected LA sites based on prior DOP attempts, and (iv) mapping and ablation at regions of fractionated electrograms in region of AT. Activation mapping was performed at operator discretion. AT diagnosis was confirmed by successful ablation or additional mapping when ablation was unsuccessful. Fifty consecutive patients with sustained AT underwent mapping of 68 ATs, of whom 42 (62%) were macroreentrant, 19 were locally reentrant (28%), and 7 (10%) were focal. AT was correctly identified with a median of three DOP attempts. All macroreentrant ATs were identified with ≤6 DOP attempts. One AT (1.6%) was terminated by DOP, and three ATs (4.8%) required activation mapping. Intracardiac concealed fusion was seen in 26 ATs (38%), each of which was successfully ablated. Conclusion Reentry could be demonstrated in a substantial majority of AF ablation-related AT. A stepwise diagnostic approach using DOP and recognition of intracardiac concealed fusion can be used to rapidly identify and ablate reentrant AT.

Impedance-guided Radiofrequency Ablation: Using Impedance to Improve Ablation Outcomes

Despite the achievement of acute conduction block during catheter ablation, the recovery of conduction at previously ablated sites remains a primary factor implicated in arrhythmia recurrence after initial ablation. Real-time markers of adequate ablation lesion creation are needed to ensure durable ablation success. However, the assessment of acute lesion formation is challenging, and requires interpretation of surrogate markers of lesion creation that are frequently unreliable. Careful monitoring of impedance changes during radiofrequency catheter ablation has emerged as a highly specific marker of local tissue destruction. Ablation strategies guided by close impedance monitoring during ablation applications have been demonstrated to achieve high levels of success for ablation of atrial fibrillation. Impedance decrease during ablation may therefore be used as an additional endpoint beyond acute conduction block, in order to improve the durability of ablation lesions. In this manuscript, available methods of real-time lesion assessment are reviewed, and the rationale and technique for impedance-guided ablation are described.

Selective His-Bundle Pacing May Preserve Intrinsic Repolarization as Well as Depolarization

A 79-year-old man with chronic atrial fibrillation underwent single-chamber His-bundle pacemaker implantation. The post-implant electrocardiogram (ECG) demonstrated selective His-bundle capture, with a narrow paced QRS and repolarization pattern similar to that of the baseline ECG. Furthermore, repolarization changes prototypic of ventricular pacing did not occur with selective His-bundle capture. While His-bundle pacing, with or without selective His-bundle capture, can preserve physiologic patterns of depolarization, only His-bundle selective pacing can preserve intrinsic ST- and T-wave patterns. Thus, the maintenance of physiologic repolarization may have various advantages, including accurate interpretation of ECG changes that are not generally interpretable in the setting of ventricular pacing.