Right Superior Research Articles

Incidence of pulmonary vein stenosis in two types of cryoballoon systems.

Currently, two types of cryoballoon (CB) systems are available for catheter ablation of atrial fibrillation (AF). Since the POLARx (Boston Scientific) is softer during freezing than the Arctic Front Advance Pro (AFA-Pro; Medtronic), it tends to go more deeply into the pulmonary vein (PV), risking PV stenosis. Ninety-one patients underwent initial CB ablation for paroxysmal AF (AFA-Pro 56; POLARx 35). Twenty-six from each group were extracted using propensity score matching. The PV cross-sectional area (PVA) was measured by tracing the area within the PV plane at 5-mm intervals from the PV ostium in a distal direction for 20 mm or to the bifurcation in each PV. The PVA was compared before and 3 months after ablation. Time to balloon temperatures of -30 and - 40°C was significantly shorter and the nadir temperature was significantly lower with POLARx than with AFA-Pro. In the left inferior (LI) PV and right superior (RS) PV, the freezing balloon position was significantly deeper in POLARx than in AFA-pro. The freezing position in RSPV with mild to moderate narrowing was deeper than those without (10.2 ± 3.3 mm vs. 8.2 ± 1.8 mm, p = .01). In RSPV, the reduction of PVA tended to be greater with the POLARx than with the AFA-Pro (26.1% ± 14.1% vs. 19.9% ± 10.3%, p = .07). There was no significant difference in the incidence of PV stenosis between POLARx and AFA-Pro. However, if POLARx goes deep into the PVs, we will still have to be careful.

Efficacy of nonocclusive separate freezing technique of cryoballoon pulmonary vein isolation: comparison of novel and conventional cryoballoon system

Abstract Background/Introduction Complete occlusion of pulmonary vein (PV) with cryoballoon is an important factor to achieve enough temperature drop and successful pulmonary vein isolation (PVI). However, it is sometimes difficult to occlude PV completely because of large diameter or anatomical difference. Distal cryoblloon positioning in the PV can achieve complete occlusion but it may increase risk of phrenic nerve injury or PV stenosis. Nonocclusive separate freezing technique, freezing superior and inferior portion of the PV at proximal side with no complete occlusion, may be useful for that situation but efficacy of the technique is not well elucidated. Purpose The purpose of this study is to investigate efficacy of nonocclusive separate freezing technique and compare procedure details of the POLARx and the Arctic Front Advance Pro (AFA-Pro). Methods We retrospectively analyzed consecutive patients who underwent cryoballoon ablation with nonocclusive separate freezing technique from September 2019 to February 2023. We defined failure of the nonocclusive separate freezing as the case which needed distal complete occlusion with cryoballoon or touch up radiofrequency ablation to achieve PVI. We analyzed success rate of nonocclusive separate freezing and evaluated nadir temperature, freezing time and number of application times. We also explored incidence of stop of freezing due to phrenic nerve injury (PNI) or esophageal temperature drop during the procedure and permanent PNI and gastroesophageal complications after the procedure between the POLARx and the AFA-Pro. Results One-hundred and one patients, 73 were male (72.3%) and mean age was 66.8 ± 10.5 years, were analyzed. Total PVs were 121 (left superior (LS) PV 31, right superior (RS) PV 53, left common (LC) PV 37) and the POLARx was 45 (LSPV 18, RSPV 24, LCPV 3) and the AFA-Pro was 76 (LSPV 13, RSPV 29, LCPV 34). Success rates of the separate freezing of the POLARx was 84.4% and the AFA-Pro was 77.6% (p=0.48). There were no significant differences in freezing time and number of application times but nadir temperature was significantly lower in the POLARx (-52.1 ± 4.7 °C vs -42.9 ± 7.2 °C, p<0.001). The incidence of stop of freezing had no significant difference between the POLARx and the AFA-Pro but nadir temperature of stop of freezing due to esophageal temperature drop was significantly lower in the POLARx (-53.8 ± 4.3 °C vs -44.7 ± 7.7 °C, p=0.039). Permanent PNI was not seen but two gastric hypomotility events occurred in the POLARx. Conclusions There was no significant difference of success rate of the nonocclusive separate freezing technique but it tended to be higher and nadir temperature was significantly lower in the POLARx. There was no obvious complication in the AFA-Pro but two gastric hypomotility events were seen in the POLARx.

Predictors of late pulmonary vein reconnection in patients with arrhythmia recurrence after cryoballoon ablation-per vein analysis including cardiac computed tomography-based anatomic factors.

To identify predictors of individual late pulmonary vein (PV) reconnection after second-generation cryoballoon (CB2) ablation. Anatomic indicators of late pulmonary vein reconnection (LPVR) post-CB2 ablation have not yet been studied on an individual PV level, nor weighed against clinical and procedural factors. Clinical, procedural, and PV anatomic data from 125 patients with a repeat procedure for arrhythmia recurrence after index CB2 ablation were analyzed. Preprocedural computed tomography (CT) evaluated 486 PVs for measurement of size; shape (ovality index); carina width; and orientation angle in frontal (superior/inferior) and transversal (anterior/posterior) plane (with horizontal line 0° as reference and upper/lower half circle as positive/negative value, respectively). Durable isolation in all PVs was demonstrated in 50/125 (40%) patients. Late reconnection rates at the different PVs were as follows: 16% left superior (LS), 12% left inferior (LI), 17% right superior (RS), and 31% right inferior (RI) PV. Multivariable analysis performed per vein showed following independent determinants predicting LPVR: ovality index [odds ratio (OR) 1.61, 95% confidence interval (CI) 1.07-2.41, P = 0.022] and carina width (OR 0.75, CI 0.59-0.96, P = 0.024) for LSPV; carina width (OR 0.71, CI 0.53-0.95, P = 0.020) for LIPV; frontal angle (OR 0.91, CI 0.87-0.95, P < 0.001) for RIPV; and transversal angle (OR 1.15, CI 1.03-1.31, P = 0.032) for RSPV. Cardiac CT-based evaluation of anatomic PV characteristics presented higher predictive value compared to clinical and procedural variables for individual LPVR after CB2 ablation. Pre-procedural identification of unfavourable PV anatomy might be important to tailor the ablation approach.

Predictors of durable pulmonary vein isolation after second-generation cryoballoon ablation with a single short freeze strategy — Different criteria for the best freeze of the 4 individual PVs

BackgroundParameters predicting the second-generation cryoballoon pulmonary vein isolation (CB-PVI) durability of each individual PV have not been investigated. ObjectiveWe explored the PVI durability predictors after left superior (LS), left inferior (LI), right superior (RS), and right inferior (RI) PV CB-PVI. MethodsData from 101 consecutive patients who underwent repeat procedures 7.0 [4.5–10.0] months after index cryoballoon procedures with single short freeze strategies were analyzed. ResultsAmong 369 PVs successfully isolated by cryoballoons with mean freezing times of 207 s, 82/94 (87.2%) LSPVs, 78/93 (83.9%) LIPVs, 80/98 (81.6%) RSPVs, and 63/84 (75.0%) RIPVs were durable. In the remaining 25 PVs requiring touch-up ablation, 20 (83.3%) PVs had reconnections. In analyzing all PVs together, lower nadir balloon temperature, faster freezing speed (FS), slower thawing speed (TS), and shorter time-to-isolation were significantly associated with higher PVI durability, however, all parameters significantly differed among the 4 individual PVs (p < 0.0001). In individual analyses, for the LSPV, faster FS to −40 °C predicted higher PVI durability, but younger patients more likely had reconnections. For the LIPV, faster FS to −30 °C predicted higher PVI durability. For the RSPV, a lower nadir temperature, faster FS (to −30 and −40 °C), slower TS (to 0 and 15 °C), shorter time-to-isolation, and smaller PV diameter predicted higher PVI durability. For the RIPV, a slower TS (to 0 and 15 °C) predicted higher PVI durability. ConclusionsThe durability of the CB-PVI was high even with a single short freeze strategy. The parameters predicting the PVI durability differed among the 4 PVs, suggesting that best freeze criterion should be considered separately for each of the 4 PVs.

LEFT ATRIAL FLOW IN PATIENTS WITH PAROXYSMAL ATRIAL FIBRILLATION USING 4D PHASE CONTRAST MAGNETIC RESONANCE IMAGING

Atrial fibrillation (AF) is a common arrhythmia associated with elevated morbidity and mortality from systemic thrombo-embolism. Patterns of left atrial (LA) flow may provide valuable insights for thrombogenic risk. However, such fluid dynamics are challenging to explore given 3-dimensional complexity and possible dependence on pulmonary vein inflow symmetry. This study aimed to explore patterns of LA flow in patients with paroxysmal AF and provide preliminary insights surrounding need to consider pulmonary vein inflow symmetry to understand such patterns. 30 subjects (20 with paroxysmal AF, and 10 controls) in sinus rhythm were scanned using a 3T MRI scanner with a standardized protocol inclusive of full heart 4D flow MRI (Fig. 1A-B). Analysis planes were prescribed at the posterior, middle, and distal third (close to mitral valve) of the left atrium (Fig. 1C) as well as in the ostium of each dominant pulmonary vein (Fig. 1D). Blood flow analyses for each plane included: peak velocity (PVel), net flow, forward flow, retrograde flow, and regurgitant fraction (%). Left atrial flow patterns were visually scored for vortex formation, rotation and fractionation in all subjects. Age was 53±17 years in AF subjects and 48±11 years in controls. At the basal, mid and distal planes LA PVel were significantly lower in subjects with AF versus controls (0.38±0.10 m/s vs. 0.57±0.18 m/s, p=0.003; 0.40±0.12 m/s vs. 0.53±0.22 m/s, p=0.043; 0.44±0.15 m/s vs. 0.66±0.32 m/s, p=0.017, respectively). Pulmonary vein PVel were similarly between AF and control subjects, both for individual veins and for mean patient values. Patients with AF showed significant asymmetry in PVel between the left superior (LS) and right superior (RS) pulmonary veins (0.51±0.16 m/s vs. 0.41±0.11 m/s, p=0.003, respectively). Vortical LA flow patterns were observed in all subjects and reliably followed a clockwise rotation pattern. Patients with AF demonstrated broader, more complex, and fractionated vortical flow patterns than control subjects (Fig. 1E). This study demonstrated that 4D flow imaging of LA inflow and vortex formation is clinically feasible and identifies observable differences in LA vortices between patients with paroxysmal AF and healthy controls. Loss of pulmonary vein inflow symmetry was observed in those with AF. Whether this is a cause or a result of altered LA flow vortex characteristics remains unknown. Future work in larger patient cohorts, inclusive of developing standardized measures of vortex behavior, is required to explore the prognostic role of LA vortex analysis in patients with atrial disease.

176-09: Eso-pericardial fistula after pulmonary vein isolation

A 62 yo hypertensive woman (47kg, 150cm) underwent an elective isolation of the pulmonary veins (PVI) because of paroxysmal atrial fibrillation (AF). The procedure was successfully performed in general anesthesia using a cooled-tip (8ml/min) ablation catheter (SmartTouch SF, BW). An accessory PV was found postero-medially to the right superior (RS) PV (arrow, panel A of the figure). Ablation was performed at 20W at the posterior and 25W at the anterior left atrium (LA) for 40sec, with Visitag set at 5mm spatial averaging and FTI targeting ≥400gs. Note that the ablation included the accessory RSPV (panel A, pink-red dots). Ten days after the procedure, the patient complained of AF recurrence, followed by a transfixing chest pain 48h later. A transthoracic echocardiogram showed a minor pericardial effusion. A CAT scan revealed a pneumo-mediastinum and a pneumo-pericardium suggestive of an esophageal perforation (arrows, panel B). Because of the absence of neurological symptoms, she underwent a gastroscopy that showed an esophageal perforation 34cm below the dental arch. A right exploratory thoracotomy revealed an eso-pericardial fistula complicated by a pyopericardium (green arrow, panel C), but no perforation of the posterior LA wall. The esophageal perforation (blue arrow) was sutured and the esophagus (black arrows) wrapped with a diaphragmatic patch. Postoperative evolution was favorable under antibiotics over 4 weeks. Eso-atrial fistula is one of the most lifethreatening complications following PVI. Herein, we report a rather unique case of eso-pericardial fistula without perforation of the posterior LA. As recently shown, the catheter cooling limits local tissue damages but can shift RF energy delivery to adjacent unprotected tissue. Interestingly, an accessory PV forced us to medially extend the ablation, which might have moved the RF energy closer to the esophagus. Open in new tabDownload slide

Clinical recurrence and electrical pulmonary vein reconnections after second-generation cryoballoon ablation

Electrical reconnections after pulmonary vein isolation (PVI) are less common after second-generation cryoballoon than radiofrequency ablation. The purpose of this study was to investigate the incidence and characteristics of pulmonary vein (PV) reconnections after second-generation cryoballoon ablation in patients with and those without clinical recurrences. Forty patients with paroxysmal atrial fibrillation undergoing second procedures after cryoballoon ablation were enrolled. Twenty-five patients experienced clinical recurrences, and the remaining 15 did not. All 158 PVs were reevaluated a median [25th, 75th percentiles] of 6.0 [4.0-9.0] months after the initial procedure. In total, reconnections were detected in 39 PVs (24.7%) among 25 patients (62.5%). Reconnected PVs included 6 left superior (LS) (15.8%), 7 left inferior (LI) (18.4%), 5 right superior (RS) (12.5%), 20 right inferior (RI) (50.0%), and 1 left common (LC) (50.0%) PV. Reconnected PV potential conduction delays were a median of 112 [76-130], 103 [82-133], 84 [66-96], 68 [49-73], and 204 ms in the LS, LI, RS, RI, and LC PV, respectively. There was no significant difference between those with and those without clinical recurrences with regard to clinical characteristics, procedural results, incidence of reconnections (25/98 vs 14/60, P = .758), and PV conduction delays in each PV. The most common gap location was the RI PV bottom in both groups. Among 5 patients with reconnections of arrhythmogenic PVs (with atrial fibrillation initiation), 2 experienced clinical recurrences, whereas 3 did not. Non-PV foci (with atrial fibrillation initiation) were identified in a second procedures in 10 of 25 patients with clinical recurrences. The incidence and characteristics of PV reconnections after second-generation cryoballoon ablation were similar between patients with and those without clinical recurrences. The results should be considered when discussing the optimal dose of cryoballoon applications.

Atrial Fibrillation in Patients with Wolff–Parkinson–White Syndrome:

We aimed to characterize electrophysiological properties of pulmonary veins (PVs) in patients with Wolff-Parkinson-White (WPW) syndrome and atrial fibrillation (AF), and to compare them to those in patients with WPW without AF. A total of 31 patients (mean age 40 ± 15 years, 23 males) with WPW were recruited: 16 patients with (AF group) and 15 without (controls) a history of AF. The basic electrophysiological (EPS) and echocardiographic data were not different between the 2 groups. Effective refractory periods (ERPs) of PVs were significantly shorter in the AF group compared to controls: left superior (LS) PV ERP 185±29 versus 230 ± 24 ms, P = 0.001; left inferior PV ERP 198 ± 25 versus 219 ± 26 ms, P = 0.04; right superior (RS) PV ERP 207 ± 25 versus 236 ± 19 ms, P = 0.001; right inferior PV ERP 208 ± 30 versus 240 ± 19 ms, P = 0.003. Maximal veno-atrial conduction delay (i.e., the maximal prolongation of interval from stimulus delivered at PV ostia to proximal coronary sinus after extrastimulus compared to the basic drive cycle) was longer in the AF group when pacing from LSPV (69.3 ± 37.9 vs 32.6 ± 16.1 ms, P = 0.01) and RSPV (74.1 ± 25.9 vs 50.2 ± 26.5 ms, P = 0.04). During EPS, AF was induced more often in the AF group (n = 7) compared to controls (n = 1; P = 0.04). Follow-up revealed that AF recurred in 3 patients in the AF group and none of the controls. Patients with WPW syndrome and AF have shorter ERPs of PVs and greater maximal veno-atrial conduction delay compared to patients with WPW without AF. These findings suggest a potential role of PVs in the development of AF in patients with WPW.

Distortion of Right Superior Pulmonary Vein Anatomy by Balloon Catheters as a Contributor to Phrenic Nerve Injury

Cryothermal, HIFU, and laser catheter-based balloon technologies have been developed to simplify ablation for AF. Initial enthusiasm for their widespread use has been dampened by phrenic nerve (PN) injury. The interaction between PN and pulmonary vein (PV) geometry contributing to PN injury is unclear. After right thoracotomy, the PN course along the epicardial right atrial surface was mapped directly in 10 dogs. The location of the PN and its relationship with the right superior (RS) PV, and potential RSPV surface distortions after balloon inflation were established by electroanatomic mapping. In 5 dogs, the PN was captured within the RSPV, but could not be stimulated in the remaining 5 dogs. The distance between the RSPV and the PN was significantly shorter in the captured group than in the noncaptured group (6.3 +/- 3.1 mm vs 10.2 +/- 3.2 mm, P < 0.001). Importantly, 96% of the captured sites within the RSPV were observed at a distance >5 mm into the PV. The inflated balloon surface anteriorly extended 5.6 +/- 3.7 mm outside the PV diameter, with distortion of anatomy narrowing the distance from the balloon surface to the PN to 4.8 +/- 2.3 mm. (Distance of the original RSPV-to-PN: 9.4 +/- 2.7 mm, P < 0.001.) PN injury with balloon technologies may stem from anatomic distortion of the PV orifice/PN relationship, through increasing contact or shortening the relative distance between the ablation site and the PN, even without displacement of the balloon into the PV. These data are important in the refinement of these technologies to improve procedural safety.

Arrhythmogenic Potential of Pulmonary Venous Tissue: Triggers for Atrial Fibrillation Identified within the Remnant of a Vein

Pulmonary veins (PVs) have frequently been identified as triggers for atrial fibrillation (AF), and higher arrhythmogenic potential of superior PVs has been attributed to their larger size, which can more rigorously support abnormalities of impulse formation and/or conduction. Contrary to this belief, we report our observations in a 63-year-old patient with history of lung cancer, S/P left upper lobectomy, undergoing ablation for paroxysmal AF. Circular mapping (Lasso) and ablation (ABL; 8-mm) catheters were deployed in left atrium (LA). Intracardiac ultrasound revealed separate right superior (RS) and inferior (RI) PVs and a single left PV. Segmented LA anatomy from the CT angiogram images corroborated this, although on the latter there appeared to be a "stump" at superior aspect of the left PV. This stump likely was the remnant of the left superior (LS) PV. Thus, the patent left vein was likely the dilated left inferior (LI) PV. With the Lasso and ABL deployed at the LIPV ostium and LSPV remnant, respectively, AF was reproducibly seen to initiate with earliest activity in the latter. Single radio-frequency ablation (RFA) lesion within the LSPV remnant abolished AF triggers. Additional RFA was done to isolate LI, RS, and RI PVs. Over a follow-up period of 24 months, this patient has remained free from AF off any drugs. Our observations suggest that even very proximal remnants of PVs can serve as triggers for AF. Recognition of this phenomenon was facilitated by the use of advanced imaging technique and the deployment of multiple catheters.

Mechanism of Tissue Heating During High Intensity Focused Ultrasound Pulmonary Vein Isolation: Implications for Atrial Fibrillation Ablation Efficacy and Phrenic Nerve Protection

The purpose of this study was to examine tissue temperatures around pulmonary veins (PVs) during high intensity focused ultrasound (HIFU) balloon ablation for atrial fibrillation. The thermodynamics and extent of PV and phrenic nerve (PN) heating during HIFU ablation have not been established. Tissue temperatures were recorded from epicardial thermocouples at right superior (RS) PV orifice and PN in eight dogs undergoing 51 RSPV HIFU ablations (40 seconds, 40 W). Maximum tissue temperatures, reflected by 288 recording profiles, were negatively correlated with distance from balloon surface (r =-0.79, P < 0.001). Average maximum RSPV temperature was 56.8 +/- 16.8 degrees C (distance: 6.6 +/- 4.1 mm), resulting in full-thickness, circumferential PV isolation in 7 of 8 animals. Direct local mechanical heating restricted to the focused ultrasound zone showed temperature rise to > or =50 degrees C within 10 seconds to a maximum temperature of 82.6 +/- 8.9 degrees C (n = 31). Apparent conductive heating showed gradual heating patterns (<50 degrees C within 10 seconds) at greater distance. PN temperature at all recording sites was 45.0 +/- 11.3 degrees C (distance: 9.2 +/- 5.0 mm). Intentional PN injury (10 of 51 [19.6%] ablations), occurred at 63.7 +/- 16.0 degrees C with closest distance of 4.4 +/- 2.5 mm, which was closer than in PNs without injury (7.3 +/- 4.3 mm, P = 0.005). HIFU ablation is highly effective in generating temperatures needed for full-thickness, circumferential ablation through rapid direct mechanical heating. Gradual heating of surrounding tissue supports the presence of conductive heating. This study also discloses direct HIFU effects as the mechanism of PN injury occurring within 4-7 mm from balloon surface.

P Wave Morphology of an Arrhythmogenic Focus in Patients With Atrial Fibrillation Originating From a Pulmonary Vein or the Superior Vena Cava

It was hypothesized that atrial premature contractions (APCs) originating in the pulmonary veins (PVs) or superior vena cava (SVC) can be localized by evaluating characteristics of the P wave. Thirty-eight patients with paroxysmal atrial fibrillation were studied. P wave polarity and morphology of the ECGs during pacing from PVs were analyzed and compared to those of APCs originating from PVs. The P wave angle and notch in lead II during pacing from the right superior (RS) PV and SVC was compared to those of spontaneous APCs originating from those veins. A positive P wave in lead I was helpful in predicting right PV origin. A positive P wave in lead II distinguished superior PV origin. A notched P wave was helpful in predicting left PV origin. P wave polarity in lead II was positive during RSPV and SVC pacing. P waves in lead II during RSPV pacing had notching in 80%, but all P waves were smooth during SVC pacing. A P wave angle of > 40 degrees and notching in lead II showed RSPV origin. These criteria are helpful in selecting which of the 4 PVs should be isolated when APCs cannot be recorded after transseptal puncture.

Combined Effect of Pulmonary Vein Isolation and Ablation of Cardiac Autonomic Nerves for Atrial Fibrillation

This study was designed to determine whether endocardial high-frequency stimulation at the pulmonary vein (PV) antrums can localize cardiac autonomic ganglionated plexi (GP) and whether ablation at these sites can evoke a vagal response and provide a long-term benefit after PV isolation (PVI) for atrial fibrillation (AF). Radiofrequency ablation of each PV antrum was performed in 21 patients with paroxysmal AF (n = 17) or persistent (n = 4) AF. In 8 patients with paroxysmal AF, a ring electrode catheter was placed at each PV antrum. High-frequency stimulation prolonged the R-R interval in 6 of 8 patients at the left superior (LS) PV, in 3 of 8 patients at the left inferior (LI) PV, in 3 of 8 patients at the right superior (RS) PV, and in 3 of 8 patients at the right inferior (RI) PV. A decrease in sinus rate > 20% was observed in 4 of 21 patients during LS PVI, in 2 of 21 patients during RS PVI, and in 1 of 2 patients during RI PVI. Atrioventricular block or a > 5 second pause was observed in 5 of 21 patients during LS PVI. AF recurred during the follow-up period in 5 of the 16 patients (31%) who had no atrioventricular block or > 5 second pause during PVI but did not recur in 5 patients in whom atrioventricular block or a > 5 second pause developed during PVI. GP can be identified by endocardial stimulation. The AF recurrence rate is decreased when a vagal response is achieved by radiofrequency ablation.

Electrical Stimulation to Identify Neural Elements on the Heart: Their Role in Atrial Fibrillation

Anesthetized dogs were subjected to a right then left thoracotomy. Two modes of electrical stimulation were used to activate ganglionated plexi (GP) on the epicardium of the atria: (1) Near the base of each pulmonary vein (PV), trains of high frequency stimuli (HFS) were coupled to each atrial paced beat so as to fall within the refractory period to achieve nerve stimulation without atrial excitation; and (2) Continuous HFS was applied via plaque electrodes sutured to epicardial fat pads (containing a GP) near the right superior (RS) and left superior (LS) PVs. The chest was then closed. An ablation catheter, inserted percutaneously, was positioned fluoroscopically in the right atrium across from the epicardial plaque electrode near the RSPV. Transeptal puncture was used to place an ablation catheter at the LSPV-left atrial junction. HFS applied to each of the epicardial fat pads induced atrial fibrillation (AF) and also caused high grade AV block due to a strong parasympathetic effect on the AV node. Radiofrequency ablation from the right and left atrial endocardium abolished the vagal response to HFS delivered to the plaque electrodes on the fat pads close to the RSPV and LSPV, respectively. Sixty (60) patients with paroxysmal or persistent AF underwent PV antrum isolation (27 patients) or PV antrum isolation plus left atrial GP ablation (33 patients). Endocardial HFS at the border of the PV antra near the 4 GPs produced AF and high grade AV block (vagal response) during AF. RFA at these sites abolished the vagal response. Testing in a small number of patients with very short follow-up suggests that adding GP ablation to PV antrum isolation may increase ablation success (absence of AF recurrence) from 70% to 91%. These basic and clinical studies suggest that localized cardiac autonomic ganglia (GPs) may play a critical role in the initiation and maintenance of AF.

Circumferential reentrant pulmonary vein tachycardia - an unusual cause of left atrial “flutter”

A 46 year old man presented with recurrent symptomatic persistent atrial tachycardia (AT) four months after circumferential periostial pulmonary vein (PV) isolation for atrial fibrillation (AF). An out-patient ECG during tachycardiaand and on the day of ablation showed atrial tachycardia with cycle length of 273 ms and 2:1 AV conduction block. At electrophysiology study no diastolic or pre-systolic activation could be found in the RA, so a 15mm circumferential decapolar catheter was placed in the right superior (RS) PV via a transseptally placed sheath. This showed macroreentry in the RSPV with a cycle length of 144 ms that was completely mapped as a circumferential reentrant circuit with 2:1 conduction to the LA (Figure). The exit point to the LA demonstrated fusion of PV potentials to LA potentials (small arrows on figure) at PV 3–4. A single application of RF energy at PV 3–4 ablated the RSPV to LA connection with restoration of sinus rhythm in the LA and RA, without disrupting RSPV tachycardia. A single further application of RF energy at PV DS/PX then terminated the RSPV tachycardia. This is the first report of a persistent circumferential reentrant PV tachycardia with a 2:1 exit block simulating left atrial tachycardia (LAT). That the entire circuit was mapped by the circumferential catheter, with termination of tachycardia by a single application of RF energy at an area of fractionation within the circuit, provides good evidence that this was a reentrant tachycardia. PV reentry should be considered as one of the causes of AF or AT after a PV isolation procedure.

An acute model for spontaneous, sustained atrial fibrillation arising from the pulmonary vein-atrial junction

High frequency stimulation of autonomic ganglia (AG) on the atrium near the pulmonary veins (PV) can convert delivered atrial extrastimuli into paroxysmal atrial fibrillation (AF). In order to induce spontaneous sustained AF we injected parasympathomimetics (PSPMs) into the AG located at the PVs. Methods: In 12 Na-pentobarbital anesthetized dogs, a right thoracotomy was performed and an electrode catheter was apposed to the right superior (RS) PV. After a pericardiotomy, a 26-gauge needle with a polyethylene tube attached was inserted into the fat pad (FP) containing AG on the atrium adjacent to the RSPV. The cannula was held in place by tissue glue. ECG leads, right atrial and His bundle electrograms (EGs) and blood pressure were continuously monitored. The 12 dogs were divided into 2 groups. In each group we measured average cycle lengths (CL) and durations of induced AF in the baseline state due to rapid atrial pacing. Acetylcholine (Ach, 1-100mM, Group I) or carbachol (CARB, 1-10mM, Group II) was injected (0.5cc) into the FP at the base of the RSPV. The former is hydrolyzed cholinesterases, whereas the latter is not. Results: Table 1 details the significant increase in the duration of the spontaneous (4) and induced (8) AF after the PSPM were injected into the FP. Furthermore, CARB injection significantly increased both the shortest EG CL at the PV-A junctions and duration of AF compared to control, p 0.05. In 3 cases of CARB injection, AF was sustained for more that 1 hour. CONCLUSIONS: Injection of Ach and CARB into the FP/AG at the base of the RSPV results in a spontaneous or induced sustained AF showing marked shortening of the refractory period of the PV or atrial electrograms adjacent to the injected FP. EGs with the shortest CL were found at the PV-atrial junctions suggesting that local AG hyperactivity can incite focal “drivers” for the induction of AF.

Change in distant atrial activation patterns during circumferential pacemapping of pulmonic vein ostium: implications for localizing triggers for atrial fibrillation.

Unique intracardiac activation patterns recorded from multipolar catheters in the coronary sinus (CS) and posteromedial right atrium (RA) when pacing from ostium (os) of each pulmonic vein (PV) can serve as template for determining PV of origin of atrial premature complexes. Development of an accurate template requires knowledge of variations in activation pattern during pacing from different aspects of same PV. In 25 patients undergoing catheter ablation for AF, a decapolar Lasso mapping catheter was placed at PV os of interest and multipolar catheters were placed in CS and RA-medial to crista terminalis (CT). For each PV, pacing was performed from Lasso catheter poles 1 through 10. For each bipole paced, activation sequence in CS (proximal to distal & vice-versa) was assessed, activation time (pacing stimulus to earliest electrogram recorded in catheters in CS/along CT) was measured and difference (CS - CT time) was determined. Significant interpolar variation was defined as the difference between the shortest and longest CS - CT activation time of >/=25 msec when pacing from different bipoles of same PV. In 59 PVs [19 right superior (RS), 20 left superior (LS), 8 right inferior (RI) and 12 left inferior (LI)], 259 bipoles were paced (median of 4 bipoles/PV). During circumferential PV pacing activation sequence in CS catheter was distal to proximal in 84.4% left-sided PVs (LSPV and LIPV) and proximal to distal in 92.6% right-sided PVs (RSPV and RIPV) with no change in activation sequence observed during pacing from different bipoles in same PV. Significant interpolar variation was observed with circumferential pacing in 1 of 19 RSPV (5.3%), 2 of 20 LSPV (10%), 1 of 12 LIPV (8.3%) and none of RIPV. Unique intracardiac activation patterns during ostial pacing from individual PV are not influenced by circumferential location of pacing site.