Segmental Pulmonary Vein Isolation Research Articles

Is Circumferential Pulmonary Vein Isolation Preferable to Stepwise Segmental Pulmonary Vein Isolation for Patients With Paroxysmal Atrial Fibrillation? A Randomized Study

Stepwise segmental pulmonary vein isolation (SPVI) and circumferential pulmonary vein isolation (CPVI) have been developed to treat patients with atrial fibrillation (AF), but the preferable approach for paroxysmal AF (PAF) has not been established. One hundred and ten patients with symptomatic PAF were randomized into a stepwise SPVI group (n=55) or CPVI group (n=55). Systemic SPVI combined with left atrial linear ablation tailored by inducibility of AF was performed in the stepwise SPVI group. Circumferential linear ablation around the left and right-sided pulmonary veins (PVs) guided by 3-dimensional electroanatomic mapping was performed in the CPVI group. The endpoints of ablation are non-induciblity of AF in the stepwise SPVI group and continuity of circular lesions combined with PV isolation in the CPVI group. After the initial procedures, atrial tachyarrhythmis (ATa) recurred within the first 3 months in 23 of the 55 patients (41.8%) who underwent stepwise SPVI and in 20 of the 55 patients (36.4%) who had CPVI (p=0.69). Repeat procedures were performed in 7 patients from the stepwise SPVI group and 5 from the CPVI group (p=0.76). During the 3-9 months after the last procedure, 46 patients (83.6%) from the CPVI group and 43 (78.2%) from the stepwise SPVI group did not have symptomatic ATa while not taking anti-arrhythmic drugs (p=0.63). Severe subcutaneous hematoma or PV stenosis occurred in 3 patients. The efficacy of stepwise SPVI is comparable to that of CPVI for patients with PAF.

Remote controlled magnetically guided pulmonary vein isolation in canines

Ablation of atrial fibrillation (AF) remains a challenging procedure fraught with significant risks and technical difficulties. A magnetically guided catheter system has been developed that potentially addresses many of these challenges. Fully remote controlled electrical isolation of pulmonary veins was performed in canines, facilitated by a three-dimensional computed tomogram (CT) that depicted the anatomic relationships of the pulmonary veins and the left atrium. The purpose of this study was to evaluate the feasibility of pulmonary vein isolation with a novel remote controlled magnetically guided catheter. CT scans were obtained in seven healthy male canines. A 7-Fr irrigated magnetic catheter was advanced transseptally to the left atrium. A magnetic guidance system was used to control the orientation of the catheter tip. A mechanical device advanced or retracted the catheter as needed. Pulmonary venography was performed and compared with the CT scan. The CT scan was used as a visual reference to set the magnetic field vectors. Radiofrequency energy was delivered through the irrigated magnetic catheter to isolate the superior pulmonary veins, as judged by elimination of pulmonary vein potentials. The isolation procedure was successful in all 14 pulmonary veins, and there was no evidence of stenosis at 80-100 days postprocedure. These results demonstrate that remote controlled catheter ablation is safe and effective for segmental pulmonary vein isolation. This technology could facilitate curative ablation of AF in humans and reduce the occupational hazards to the operator of prolonged procedures and radiation exposure.

New Approach to Pulmonary Vein Isolation for Atrial Fibrillation Using a Multielectrode Basket Catheter

Pulmonary vein (PV) isolation using a circular catheter creates an entrance block from the left atrium (LA) to the PV, which eliminates paroxysmal atrial fibrillation (PAF). A new approach to PV isolation during distal PV pacing is to use a basket catheter. Fifty consecutive patients with PAF underwent basket-catheter-guided PV isolation. PV pacing was performed from the distal electrode pair of the basket catheter. The exit breakthrough point was targeted for segmental PV isolation. The endpoint was the elimination of bidirectional PV - LA conduction. A repeat ablation procedure was performed in 12 of 14 patients who had recurrence of AF. The recovery of PV -LA conduction was noted in 24 of the 48 PVs, and 5 PVs (21%) had unidirectional block. At 12 months, 80% of patients were free of AF without antiarrhythmic drugs. No PV stenosis >50% was detected at 12 months after the procedure. This new approach for PV isolation during distal PV pacing using a basket catheter is useful for confirming bidirectional PV - LA conduction block. PV isolation that creates not only an entrance block but also an exit block at the PV - LA junction may be required to cure paroxysmal AF.

Reentrant and nonreentrant focal left atrial tachycardias occur after pulmonary vein isolation

Both focal and macroreentrant atrial tachycardia (ATs) can occur after pulmonary vein (PV) isolation for treatment of atrial fibrillation (AF). We report the response to pacing and pharmacologic maneuvers performed in patients with stable focal ATs after segmental PV isolation. The purpose of this study was to determine the mechanism of focal ATs occurring after PV isolation. Patients with persistent left AT after cessation of antiarrhythmic drug therapy presented for mapping and ablation. Electroanatomic mapping during AT was performed. Entrainment was performed from multiple right and left atrial sites. Single-beat resetting was performed. Adenosine was infused intravenously to determine the effect on the tachycardia. Five patients (3 men and 2 women; age 65 +/- 10 years) had focal left AT that persisted in response to pacing maneuvers. Four patients had ATs (cycle length 265 +/- 18 ms) that demonstrated focal areas of early activation at the septal aspect of the right lower (3 patients) or right upper (1 patient) PV ostium. Resetting demonstrated a flat-plus increasing curve in two patients. Adenosine was infused with transient AV block and no change to the tachycardia cycle length in three patients. Tachycardias were entrained from multiple left atrial sites. Recordings from the ablation catheter at the critical isthmus typically demonstrated mid-diastolic or long fractionated potentials. One tachycardia with a longer and more variable cycle length (480-598 ms) did not demonstrate fusion during pacing from distant sites. Persistent focal left ATs may occur after segmental PV isolation. Many of these tachycardias are caused by a focal reentrant circuit located at the PV ostium; however, focal nonreentrant rhythms also may occur.

Disseminated Intravascular Coagulation as a Complication of Radiofrequency Catheter Ablation of Atrial Fibrillation

Since Haissaguerre and his colleagues demonstrated the importance of the pulmonary veins in the generation of atrial fibrillation (AF) in 1998, a variety of different ablative interventions have been performed to eliminate AF. Various complications related to catheterization, ablation itself including pulmonary vein stenosis, pericardial effusion, stroke, and atrioesophageal fistula have been reported. Disseminated intravascular coagulation (DIC) is a systemic syndrome characterized by enhanced activation of coagulation with some intravascular fibrin formation and deposition. This is the first report, to our knowledge, of a patient whose condition was complicated by DIC after segmental ostial isolation of pulmonary veins for persistent AF. The patient has completely recovered from the DIC by hemodialysis, administration of blood constituents for 15 days.

Impact of Duration of Cryothermal Application on Clinical Efficacy of Pulmonary Vein Isolation Using Transvenous Cryoablation

Recent studies have demonstrated that transvenous cryoablation is a safe and feasible method for pulmonary vein (PV) isolation for treatment of atrial fibrillation (AF). However, this technique is limited by a much longer ablation time than conventional radiofrequency ablation. The aim of this study was to determine the effect of duration of cryoablation application with double freeze-thaw cycles on clinical efficacy for PV isolation for treatment of AF. We compared the clinical efficacy and procedural time of cryoablation (CryoCorTM, San Diego, CA, USA) for segmental PV isolation in 30 patients (mean age 51 +/- 13, 20 men) with paroxysmal AF using either double 5-minute (n = 15) or double 2.5-minute (n = 15) freeze-thaw cycle delivered with a 10 F deflectable transvenous catheter. Clinical recurrence of AF and the occurrence of PV stenosis as determined by computer tomography of the thorax were performed at 3- and 12-month follow-up. Acute successful electrical isolation of PV was achieved with cryoablation in 96 of 98 (98%) targeted PVs in 30 patients (mean: 3.2 +/- 0.8 PVs per patient). There were no significant differences between the baseline characteristics, the number of PV isolated per patient, the total number and percentage of effective cryoablation and the acute clinical efficacy between using double 5-minute and double 2.5-minute freezes (P > 0.05). However, the fluoroscopy time (107 +/- 43 vs 138 +/- 113 minutes, P = 0.06) and the procedural time (360 +/- 113 vs 510 +/- 115 minutes, P = 0.01) of using double 2.5-minute freezes was reduced by approximately 30% compared with double 5-minute freezes. At a mean of 20 +/- 8 month follow-up, there was no significant difference in the chronic clinical efficacy of cryoablation in terms of freedom from AF in the absence of antiarrhythmic drug therapy between using double 5-minute (6/15, 40%) and double 2.5-minute freezes (7/15, 46%, P = 0.98). As compared with double 5-minute freeze, the use of a shorter double 2.5-minute freeze protocol significantly reduces the procedural time without affecting the acute and long-term clinical efficacy of cryoablation to isolate PV for treatment of AF.

Atrial Volume Reduction Following Catheter Ablation of Atrial Fibrillation and Relation to Reduction in Pulmonary Vein Size: An Evaluation Using Magnetic Resonance Angiography

Catheter ablation to achieve pulmonary vein (PV) isolation has become an increasingly used treatment strategy for patients with atrial fibrillation (AF). The purpose of this study was to evaluate the impact of segmental isolation of PVs on volume of left atrium and its relation to the decrease in the size of the pulmonary veins. Gadolinium enhanced Magnetic Resonance Angiography (MRA) was performed in 51 AF patients before and 6 approximately 8 weeks post PV isolation, using cooled radio-frequency (RF) energy. Three-dimensional reconstruction with maximum intensity projections and multiplanar reformations was performed. Oblique coronal projections were used to measure the ostial size of PVs. Three orthogonal dimensions of LA chamber were measured and computed to assess the volume of the left atrium. The mean LA volume decreased by 15.7% after ablation (p<0.001). The mean PV ostial diameter decreased by 11%, from 18.3+/-0.8 mm to 16.7+/-1.0 mm (p=0.005). Moderate PV stenosis was noted in two veins out of the 192 veins analyzed. There was a significant correlation between changes in the size of PV ostium to that of the LA. Catheter ablation of AF using a segmental PV isolation approach results in a significant reverse remodeling in the left atrium. Significant stenosis of PVs appears to be rare after the segmental isolation procedure.

Transvenous Cryoablation Reduces Platelet Activation During Pulmonary Vein Ablation Compared with Radiofrequency Energy in Patients with Atrial Fibrillation

Radiofrequency (RF) ablation procedures for atrial fibrillation (AF) are associated with potential risks of thromboembolism, which may be minimized by the use of cryoablation that preserves the integrity of endocardium. The objective of this study was to compare the thrombogenic potential of transvenous cryoablation versus RF ablation during pulmonary vein (PV) isolation. Thirty consecutive patients with paroxysmal AF were randomized to undergo segmental PV isolation procedure using 4-mm tip RF ablation (n = 15) or cryoablation (CryoCor, San Diego, CA, USA) (n = 15). Blood samples were drawn after sheath insertion (baseline), after transseptal puncture, before ablation (after heparin administration), and after isolation of a superior PV. Activation of coagulation was measured with plasma levels of prothrombin fragment 1 + 2 (F1 + 2) and thrombin-antithrombin III complex (TAT), and platelets by plasma level of beta-thromboglobulin (beta-TG) and flow cytometric enumerating of P-selectin (CD62)-positive platelets. In both groups, the plasma level of beta-TG, F1 + 2, and TAT were elevated after sheath insertion. The percentage changes in plasma level of beta-TG, F1 + 2, and TAT and CD41/62-positive platelets from baseline after transseptal puncture and before ablation were similar (P > 0.05). However, the percentage changes in CD62-positive platelets from baseline were significantly higher in patients treated with RF ablation (82 +/- 20%) than with cryoablation (22 +/- 14%, P = 0.02), although their plasma levels of beta-TG, F1 + 2, and TAT were not different (P > 0.05). Significant platelet and coagulation activations were observed during PV ablation procedures, and heparin administration only prevented activation of coagulation but not platelets. Persistent platelets activation was observed during RF energy application, but not during cryoablation.

Comparing Different Strategies for Catheter Ablation of Atrial Fibrillation

To doubt everything or to believe everything are two equally convenient options; both dispense with the necessity of reflection . — —Jules Henry Poincare Opportunities for progress in clinical medicine often follow contradiction of previously accepted data. The impact of the first study comparing circumferential pulmonary vein (PV) ablation (left atrial catheter ablation) and segmental PV isolation was sweeping. The finding by Oral and colleagues that left atrial ablation improved outcomes over PV isolation in patients with paroxysmal atrial fibrillation (AF)1 was immediately accepted. This acceptance was based on the respect due these investigators, as well as on the consistency of these results with those reported using the separate techniques via different programs; previous reports of circumferential PV ablation2 and PV isolation3 estimated single-procedure success rates of 85% and 56%, respectively, in patients with mostly paroxysmal AF. Many practitioners “waiting in the wings” were convinced to begin AF ablation programs using the left atrial ablation technique on the basis of this information. This reaction was reinforced because most viewed this technique as easier, requiring a single transseptal puncture and avoiding the complexities of interpreting PV electrogram end points. See p 2875 The study by Karch and coworkers, presented in this issue of Circulation , takes on even greater importance when viewed through this perspective.4 The authors compared circumferential PV ablation and segmental PV vein isolation in 100 patients with frequent, drug-refractory, and mostly (89%) paroxysmal AF. Their hypothesis, in line with conventional wisdom, was that circumferential ablation would reduce the relative risk of recurrent AF by 66% as compared with PV isolation. The authors held to the conceptual standards developed by the respective founders of each technique.2,3 Circumferential ablation was guided by electroanatomic mapping using separate right and left PV circles, 5 mm from the …

Is catheter ablation of atrial fibrillation better than atrioventricular junction ablation plus pacing therapy for elderly patients with paroxysmal atrial fibrillation? Insight from a very long-term (52 months) follow-up

Background: Catheter ablation of atrial fibrillation (AF) (segmental pulmonary vein isolation plus non-pulmonary vein ablation) has become another nonpharmacologic therapeutic option for medically refractory paroxysmal AF. Whether this method is better than atrioventricular (AV) junction ablation plus pacing therapy is unknown. The purpose of this study was to compare the very long-term (longer than 4 years) clinical outcomes of the two methods in elderly patients (¾65 years old) with medically refractory and frequent episodes of paroxysmal AF (≥ 2 antiarrhythmic drugs, ≥ one AF episode/week) .

Recurrence of atrial fibrillation after initially successful pulmonary vein isolation

Background: Radiofrequency catheter ablation (RFCA) by either segmental pulmonary vein isolation (PVI) or left atrial (LA) circumferential ablation (CA) has resulted in cure of atrial fibrillation (AF) in 50% to 80% of patients. However, AF recurrences after initial PVI or LACA are not uncommon, and multiple sessions are required to achieve better clinical outcome. This study evaluated the electrophysiological characteristics of patients with recurrent AF after initially successful ablation and the final outcome after repeat procedure.

Mechanism of focal atrial tachycardias occurring after pulmonary veins isolation

Introduction: A proarrhythmic consequence of pulmonary vein isolation (PVI) to treat atrial fibrillation can be a persistent left atrial tachycardia (LAT). We previously described that focal LATs can occur; however it is unclear whether the mechanism of these focal arrhythmias is reentry, triggered activity, or abnormal automaticity. We performed detailed pacing and pharmacologic maneuvers to determine the mechanism of focal LATs occurring after PVI. Methods: PVI was performed by segmental ostial ablation guided by a circular mapping catheter (Lasso). Patients whose recurrent arrhythmia was a LAT that persisted for more then 8 weeks returned for mapping and ablation. Results: Of 15 pts with persistent LAT, three (age 66 14, all male) had focal LAT (cycle length 268 21 ms) that remained stable in response to pacing. Electroanatomic maps demonstrated focal areas of early activation at the septal aspect of the right lower (2 pts) or right upper (1 pt) PV. Adenosine caused transient AV block but no change in tachycardia cycle length (TCL). Entrainment from multiple LA sites (N 23) outside the PVs demonstrated long post-pacing-intervals (PPI) (mean PPI-TCL 73 27 ms, range 46-127 ms). Entrainment from multiple poles around the Lasso catheter had a wide range of PPIs (PPI-TCL 22 18 ms, range -3 to 50 ms), suggesting both isthmus sites and sites outside the circuit. Septal Lasso sites and not lateral sites had PPI TCL. A single beat resetting curve in 2 pts demonstrated a mixed flat-increasing curve, consistent with reentry. In one pt, burst atrial pacing terminated and reinitiated the same tachycardia. Recordings at the critical isthmus demonstrated mid diastolic potentials or a long fractionated signal suggesting slow conduction. Ablation at the site of mid diastolic electrograms or best PPI (PPI-TCL 2 6 ms) resulted in LAT termination. Conclusions: Focal left atrial tachycardias may occur after segmental PVI, particularly at the septal aspect of the right pulmonary veins. Detailed entrainment mapping and resetting confirm that the mechanism of the stable tachycardias we studied is reentry. RF application at the critical isthmus results in tachycardia termination.

Disseminated intravascular coagulation as a complication of radiofrequency catheter ablation of atrial fibrillation

Since Haissaguerre and his colleagues demonstrated the importance of the pulmonary veins in the generation of atrial fibrillation (AF) in 1998, a variety of different ablative interventions have been performed to eliminate AF. Various complications related to catheterization, ablation itself including pulmonary vein stenosis, pericardial effusion, stroke, and atrioesophageal fistula have been reported. Disseminated intravascular coagulation (DIC) is a systemic syndrome characterized by enhanced activation of coagulation with some intravascular fibrin formation and deposition. This is the first report, to our knowledge, of a patient whose condition was complicated by DIC after segmental ostial isolation of pulmonary veins for persistent AF. The patient has completely recovered from the DIC by hemodialysis, administration of blood constituents for 15 days.

Comparison of efficacy of three different atrial fibrillation ablation methods

Background: A comprehensive strategy for percutaneous atrial fibrillation (AF) ablation should probably involve pulmonary vein (PV) isolation, ablation of non pulmonary initiators (NPIs), and left atrial (LA) linear ablation. To assess the relative contribution of linear ablation within the left atrium, we used three different approaches with increasing area of ablation within the LA. Method 1: segmental ostial PV isolation; Method 2: circumferential periostial PV isolation; and Method 3: wide area circumferential ablation (WACA) including a roof and LA isthmus line guided by electroanatomical mapping.

Recurrence of PV conduction and atrial fibrillation after pulmonary vein isolation: Segmental versus circumferential strategy

Background: Both segmental and circumferential pulmonary vein (PV) isolation have been proven effective in the treatment of atrial fibrillation (AF). Recurrence of AF and PV conduction after the two different strategies, however, remains controversial.

Technology Insight: catheter ablation of the pulmonary veins in the treatment of atrial fibrillation

Over the past 5 years, catheter ablation of atrial fibrillation (AF) has evolved from being an experimental procedure to one that is performed in most large medical centers throughout the world. The rapid and widespread acceptance of this procedure reflects encouraging reports of the safety and efficacy of a pulmonary vein (PV) approach, which has 70-80% efficacy and around a 5% risk of major complications. Currently three PV-based ablation strategies are employed for catheter ablation of AF, termed segmental PV isolation, circumferential PV ablation and circumferential PV isolation. Three main research activities are ongoing in the field of catheter ablation of AF. One aim is to better define the safety and efficacy of AF ablation using the three approaches listed. The second research focus is to improve safety and efficacy by the development of new mapping and ablation tools. And the third major area of research is the development of new strategies for AF ablation. It is highly likely during the next 5 years that catheter ablation of AF will become a routine and well-accepted treatment strategy for this common arrhythmia condition.

Left Atrial and Pulmonary Vein Ostial Ablation as a New Treatment for Curing Persistent Atrial Fibrillation Initial Experience and Results

Segmental pulmonary vein (PV) isolation has been performed to eliminate paroxysmal atrial fibrillation (AF). However, this technique is not effective in most patients with persistent AF. Left atrial catheter ablation (LACA) was performed by encircling the left- and right-sided PV 1-2 cm from the ostia, guided by an electroanatomical mapping system in 16 patients with persistent AF (>1 month). Twelve patients (75%) had a history of unsuccessful transthoracic cardioversion and prophylactic antiarrhythmic drugs. Ablation lines were also created in the mitral isthmus and posterior LA. PV isolation was also performed for each PV if there were residual PV potentials after the LACA. After LACA, 38 PV (59%) were completely isolated, and complete PV isolation was achieved with only a few radiofrequency energy applications (2.7+/-2.0 min) on a narrow area of the PV ostium (24+/-15%) in the remaining PV. The mean procedure time was 200+/-38 min. During the follow-up period (17+/-3 months), 12 patients (75%) had normal sinus rhythm and were free of symptomatic AF with (n = 10) or without antiarrhythmic drugs (n = 2). One patient had a stroke just after the procedure. No other complications including PV narrowing (>50%) occurred. This approach was effective in persistent AF, however, concomitant use of antiarrhythmic drugs was often required.

Successful release of entrapped circumferential mapping catheters in patients undergoing pulmonary vein isolation for atrial fibrillation

The purpose of this study was to demonstrate a method for successful and safe release of an entrapped circular catheter. Segmental pulmonary vein (PV) isolation is widely practiced for patients with symptomatic drug-refractory atrial fibrillation. A circular mapping catheter is sometimes used with this technique to map the electrical connection between the left atrium (LA) and the PVs. This catheter reportedly can become entrapped in the mitral valve apparatus. Attempts to free the entrapped catheter can result in serious complications, including damage to the mitral valve chordae tendineae or fracture of the catheter itself. Three patients were referred for PV isolation for atrial fibrillation. A circular mapping catheter was used to map the sites of LA-PV electrical connections. During the procedure, the circular mapping catheter became entrapped in the mitral valve apparatus in two patients and in the PV in one patient. A series of maneuvers, which included use of another catheter and guiding sheaths as well as pushing forward rather than pulling back on the entrapped catheter, allowed safe and successful release of the entrapped catheter in all patients. Entrapment of the circular mapping in the mitral valve apparatus or the PVs during PV isolation is a rare complication associated with use this catheter. We describe a series of maneuvers that may allow safe and successful release of the entrapped catheter.

Response of pulmonary vein potentials to burst pacing.

Pulmonary vein potentials recorded at the ostia of pulmonary veins (PV) are a useful guide for segmental isolation of the PV in patients with atrial fibrillation (AF). Even during coronary sinus pacing at 600 ms, atrial (A) and PV potentials can overlap in 50-60% of patients making the accurate identification of PV potentials very difficult. Nineteen patients (M:F 15:4) with paroxysmal AF underwent segmental isolation of one or more PV. Coronary sinus (CS) pacing was performed at cycle lengths of 600/550/500/450/400/350/300 ms and bipolar electrograms were recorded from the 10 or 20 pole Lasso catheter placed at the atrial-PV junction in 27 pulmonary veins. Stimulus (S) to A, S-PVP and A-PVP intervals were measured during CS pacing at the different cycle lengths at sweep speed of 200 mm/sec. During CS pacing at 600 ms the A and PV potentials were significantly overlapped (A-PVP < or = 25 ms) in 15 of 27 (55%) veins. During pacing at 300 ms, the A and PV potentials were significantly separated (A-PVP > or = 25 ms) in 9 of the 15 veins where A and PV potentials overlapped and 21 of all 27 (78%) veins. In two patients pacing at 300 ms was associated with 2:1 conduction block from atrial to PV fascicle. Coronary sinus pacing at cycle length of 300 ms demonstrated better separation of A and PV potentials compared to pacing at 600 ms. This strategy is easier and less time consuming compared to extrastimuli testing. It also confirms that the electrophysiological properties of PV fascicles are different from that of the adjacent atrial musculature.

828-2 Factors predictive of a late recurrence of atrial fibrillation after segmental pulmonary vein isolation

828-2 Factors predictive of a late recurrence of atrial fibrillation after segmental pulmonary vein isolation