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Introduction: During radiofrequency catheter ablation of a common atrial flutter between the tricuspid annulus and the Eustachian valve “septal isthmus”, double potentials were recorded along the Eustachian valve, previously described as an anatomical line of conduction block between the coronary sinus ostium and the inferior vena cava. Results: Just before flutter termination, lengthening and beat to beat delay variations between the 2 components of the double potentials were correlated with simultaneous modifications of the flutter cycle length. Conclusion: The “septal isthmus” is a common pathway for the flutter wavefront and the impulse generating the second component of the double potential. It is also a good target for flutter ablation.

We report 4 cases of congenital and acquired coronary sinus ostial atresia incidentally found during electrophysiologic assessment for supraventricular arrhythmias. Congenital variants consisted of coronary sinus drainage predominantly via persistent left superior vena cavae and partial coronary sinus unroofing into the left atrium. The acquired variant was inadvertently produced during surgery for cor triatriatum. A variety of electrophysiologic substrates including right and left-sided accessory pathways and both typical and atypical AV nodal reciprocating tachycardia were identified. Approaches to imaging and accessing the coronary sinus when the os cannot be cannulated are discussed, including a search for right atrial accessory venous collaterals, venography to rule-out a persistent left superior vena cava, and coronary angiography.

To describe electrocardiographic vector patterns during early VF transition (Wiggers stage 1). In 100 electrophysiology studies with VF induction, the first 3 beats of VF were analyzed in lead I for left/right axis (LA/RA), V1 for left/right bundle (LB/RB), and aVF for superior/inferior axis (SA/IA). Correlation with demographic/clinical factors was performed using regression analyses and mixed effect modeling. VF initiated more likely with LA than RA (P < 0.001) and LB than RB (P = 0.04) suggesting original wavebreak in the right ventricle. The 3-dimensional morphology changed in 69% of VF during the first 3 beats, with predominant increase in RB, suggesting a transition of QRS-originating vector to septum/left ventricle. Conservation of morphology (31%) was favored by initial RB (P = 0.002) and LA morphology (P = 0.01). Initiation of VF with LA vs RA was more likely in African-Americans (P = 0.016) and increasing age (P = 0.032). Ischemic cardiomyopathy favored VF initiation with RB 6.7-fold (P = 0.025), possibly linking LV myocardial scar to initial VF wavebreak location. Male gender and ischemic cardiomyopathy prolonged time-to-loss of predominant vector by 119% (P = 0.002) and 71% (P = 0.017), respectively, suggesting more preserved anatomic/functional reentry. The predominant QRS vectors during early Wiggers stage 1 VF are not random and suggest an initial wavebreak more commonly in the right ventricle, followed by a transitional shift to the septum/left ventricle. Ethnicity, male gender, age, and co-morbidities result in directional preservation of initiating VF vectors possibly due to myocardial mass/fibrosis. Findings may allow new treatment/ablation approaches.

Reversible cryothermal mapping of cardiac arrhythmias has beenperformed intraoperatively. However, a steerable cooling catheter forreversible mapping has not yet been developed. We therefore developed andtested a cooling system consisting of a +15°C hypertonic salinereservoir and a 7F steerable catheter also capable of radiofrequency (RF)ablation. Using excised ovine hearts placed in a 37°C circulating salinebath, we measured the temperatures at depths of 0 mm, 1 mm, and 2 mm. Thetemperature after 90 seconds of cooling was 16.5 ± 2.1°C at 0 mmcompared to 23.9 ± 4.1°C at 1 mm and 31.1 ± 3.9°C at 2mm depth (p < 0.01). These data suggest that a 7F steerable combined RFablation–cooling catheter may achieve temperatures suitable formapping arrhythmias such as atrial tachycardias and right ventricularoutflow tract tachycardias. Further enhancements to achieve lowertemperatures at depth may be needed to reversibly map other arrhythmiassuch as left ventricular tachycardias.

Our goal was to evaluate acute effects of left atrial lesion formation and volume overload on hemodynamics during pulmonary vein antrum isolation (PVAI) as it might be a potential cause of acute pulmonary edema. In consecutive patients presenting for PVAI, open irrigation ablation was performed (50 W, 48°C, 15 s lesion duration, saline flow rate 30 mL/min). Blood samples were drawn from the left atrium and the pulmonary artery immediately before and 30 min after PVAI. The cardiac output (CO) and stroke volume (SV) were calculated by the method of Fick. We included 61 (27 female, 61 ± 11 years) patients suffering from paroxysmal (px; 33) or persistent (per; 28) atrial fibrillation (AF) in this study. A total of 2,917 ± 242 mL of volume was infused (2,651 ± 223 mL pxAF vs. 3,184 ± 255 mL perAF, (p < 0.01)). Total ablation time was 60 ± 7 min (52 ± 7 min in pxAF vs. 69 ± 8 min in perAF; (p < 0.001)). CO increased from 5.2 ± 1.3 to 6.2 ± 1.5 L/min (p < 0.001) during PVAI (5.7 ± 1.3 to 6.5 ± 1.7 L/min in pxAF; (p < 0.002) and 4.8 ± 1.1 to 5.9 ± 1.2 L/min in perAF; (p < 0.001)). SV increased from 74 ± 24 to 83 ± 21 mL (p < 0.005) during PVAI, and subgroups showed an increase of 82 ± 23 to 88 ± 22 mL in pxAF (p < 0.009) and 62 ± 21 to 76 ± 16 mL in perAF (p < 0.009). From our preliminary experience, left atrial scarring and volume overload during PVAI do not seem to impact negatively hemodynamics. On the contrary, an improvement in cardiac output was documented acutely independent of type of AF.

While atrial fibrillation (AF) begets AF via structural, contractile, and electrical remodeling, it was shown that successful radiofrequency ablation of AF has effectively reversed left atrial (LA) remodeling. However, there was little data regarding the efficacy of cryoablation on LA remodeling. Herein, we aimed to assess the impact of cryoablation on LA structural and potential electrical remodeling in paroxysmal AF patients. A total of 41 symptomatic patients with non-valvular paroxysmal AF underwent their first catheter ablation via cryoballoon technique. All patients had transthoracic echocardiography before, 6 and 12 months after cryoablation. LA volume index (LAVI), left intra-, right intra-, and inter-atrial electromechanical conduction delay (AEMD) were calculated in all patients. Postprocedural first 3 months was accepted as blanking period. All 179 pulmonary veins were isolated successfully in 41 patients with no major complication. During median 18 months (12–20 months) follow-up, recurrent atrial arrhythmia was found in nine patients (21.9 %). In multivariate Cox regression analysis, only early recurrence was found as the independent predictor of late recurrence. At 12th month visit compared to baseline, there was no change in LAVI (p = 0.647) but significant increase in left intra- and inter-AEMD (p < 0.05). However, in non-recurrent group, both LAVI (30.63 ± 3.6 to 28.42 ± 3.63, p < 0.001), left intra-AEMD (18.75 ± 8.77 to 12.5 ± 4.65, p < 0.001), and inter-AEMD (25.2 ± 13.2 to 18.84 ± 8.52, p < 0.001) were significantly decreased. Our study findings revealed that successful cryoballoon-based AF ablation yields LA structural and potential electrical reverse remodeling. However, LA remodeling process cannot be halted by cryoablation in patients with AF recurrence during follow-up.

Cardiac resynchronization therapy (CRT) is an effective treatment for heart failure (HF); however, a third of patients are non-responders. The development of quadripolar left ventricular (LV) lead was shown, mainly in single manufactures’ registry, to improve LV remodeling and overall mortality. However, limited reports exist on the impact of quadripolar LV leads on HF hospitalization rates in real-life cohorts. We evaluated the clinical outcomes associated with quadripolar LV leads in a large nation-wide registry including all patients implanted with a cardiac resynchronization therapy with defibrillator (CRT-D). Between July 2010 and October 2016, 2913 consecutive patients were implanted with a CRT-D and all were prospectively enrolled in the Israeli ICD Registry. Quadripolar LV leads were implanted in 973 (33.4%) patients during this period, and their clinical outcomes were compared to CRT-D recipients implanted with a bipolar LV lead. Primary endpoint was HF hospitalization rate. Quadripolar leads were implanted more in patients with non-ischemic cardiomyopathy and for primary prevention indication and less in post-infarction patients and for secondary prevention of sudden death. Longer QRS duration was observed with quadripolar leads (147 ± 23 vs 143 ± 25; p < 0.001). Outcome event rate for 100 patient years revealed no difference in HF hospitalization rates between bipolar and quadripolar LV leads. Quadripolar lead implant led to lower cardiac mortality, with no influence on overall mortality. Multivariate analysis revealed no significant differences in study endpoints between bipolar and quadripolar LV leads. In a large real-life registry, implantation of quadripolar LV leads in patients with CRT-D did not influence HF hospitalization rates.

An important attenuation of the atrial signal recorded with mini-electrodes (ME) embedded in an 8-mm tip was associated with a transmural radiofrequency lesion. Our aim was to assess if parameters obtained from ME or conventional bipoles before applications predict successful atrial lesions. We prospectively included 33 consecutive patients undergoing cavotricuspid isthmus (CTI) ablation. Electrogram voltages and pacing thresholds were measured with ME and conventional bipoles before and after radiofrequency (RF) applications. The time before the loss of capture during applications was recorded. Lesions were considered successful, in accordance with preclinical data, if ME voltage decreased > 54%. Of 207 applications, 107 could be analyzed. During applications, voltages decreased more in the ME than in the conventional bipoles (66.8 ± 26.1% vs 37.5 ± 42.5%, P = 0.001). Likewise, pacing threshold increased significantly more using the ME (86.3 ± 22.9% ME, 52.6 ± 35.6% conventional, P = 0.001). ME pre-ablation voltages were significantly higher and pacing thresholds significantly lower in successful lesions (voltage 0.88 ± 0.71 vs 0.26 ± 0.18 mV, P = 0.0001; threshold 1.6 ± 1.7 vs 2.8 ± 3.0, P = 0.04). Neither of these parameters with conventional bipoles nor time to loss of capture showed differences. A ME voltage > 0.33 mV and a pacing threshold < 1.5 mA predicted a successful lesion with 0.78 and 0.6 sensitivity and 0.78 and 0.59 specificity. Certain pre-ablation parameters derived from ME such as electrogram voltage and pacing threshold differ from those obtained by a conventional configuration and can predict a successful atrial lesion.