Changes in left atrial anatomy due to respiration: impact on three-dimensional image integration during atrial fibrillation ablation

Introduction: Patient respiration influences the accuracy of image integration approaches used during atrial fibrillation (AF) ablation procedures. We assessed both absolute and relative changes in left atrial (LA) and pulmonary venous (PV) anatomy due to respiration and their implications for 3D image integration.
Methods and Results: Intensity-based segmentation of the LA and PVs was performed on cardiac computed tomography (CT) images obtained during both inspiration and expiration in 16 patients referred for AF ablation. A 3D LA-PV surface model was reconstructed for each respiratory phase. Absolute and relative respiratory motion components were evaluated from corresponding landmarks in both models. The mean 3D respiratory motion distance for all four PVs was 19 ± 9 mm. The most important motion component was in the inferior direction, with a mean inferior motion distance of 15 ± 8 mm. The mean 3D respiratory motion of the PV centers due to relative geometrical changes was small at the ostial level (2.6 ± 1.4 mm, 95% CI 2.3-3.0 mm) but significantly larger at the level of the first PV bifurcation (4.0 ± 2.3 mm, 95% CI 3.4-4.6 mm, P < 0.001). Relative geometrical changes of the LA body were most pronounced in regions near the mitral valve, resulting in a changed configuration of the mitral annulus during inspiration.
Conclusions: Respiration causes important movements of the PVs and LA. Relative changes in LA–PV geometry are most pronounced in the distal PVs and in the LA body near the mitral valve. Therefore, these regions should be avoided during registration of pre- and per-procedural images unless they are acquired in the same phase of respiration.     

Three-dimensional analysis of pulmonary venous ostial and antral anatomy: implications for balloon catheter-based pulmonary vein isolation

BACKGROUND: Balloon ablation catheters using various energy sources are being developed to perform pulmonary vein (PV) isolation to treat atrial fibrillation. Prior evaluations of 2D CT/MR images are limited by the frequent elliptical shape of the PV ostia, the nonorthogonal orientation of the PVs to the left atrial (LA) chamber, and difficulty in appreciating through-slice curvature. To provide anatomical data relevant to balloon catheter ablation, 3D surface reconstructions of LA-PVs were generated and analyzed to define ostial architecture and size. METHODS AND RESULTS: Using MRI datasets obtained from 101 paroxysmal AF patients, the LA-PVs were segmented to generate 3D LA-PV surface reconstructions. Using both external and endoluminal projections, the PV ostial and antral regions were identified and evaluated. In the left PVs, a common left-sided ostium was identified in 94 patients, with an ostial circumference of 95 +/- 15 mm. Branching of the left PVs occurred 0-5 mm away from the common left ostium in 43 patients (43%), 5-15 mm away from the common os in 37 patients (37%), and >15 mm away from the common os in 14 patients (14%). In patients with either distinct left PV ostia, or common os <15 mm (87 patients), the individual LSPV/LIPV ostial circumferences were 67 +/- 12 mm and 58 +/- 9 mm, respectively. Mean left antral circumference was 114 +/- 17 mm. In the right PVs, the ostial circumferences of the RSPV/RIPV were 68 +/- 11 mm and 66 +/- 11 mm, respectively. Mean right antral circumference was 107 +/- 19 mm. Assuming ideal deformation of the LA chamber anatomy, the minimal diameters of a balloon ablation catheter required to isolate 95% of the RSPV, RIPV, LSPV, LIPV, LCPV, left antrum, and right antrum are 29 mm, 28 mm, 29 mm, 24 mm, 40 mm, 46 mm, and 47 mm, respectively. CONCLUSION: Analysis of 3D surface reconstructions of LA-PV anatomy reveals that balloon catheter-based ablation of the PVs is likely feasible in most patients, but balloon ablation of the common PV antra would be problematic.     

Pulmonary Vein Isolation Supported by MRI‐Derived 3D‐Augmented Biplane Fluoroscopy: A Feasibility Study and a Quantitative Analysis of the Accuracy of the Technique

MRI‐Derived 3D‐Augmented Biplane Fluoroscopy . Background: Despite the advancement of technology in electroanatomic mapping systems (EAMS), fluoroscopy remains a necessary, basic imaging modality for electrophysiology procedures. We present a feasibility study of new software that enables 3D‐augmented fluoroscopy in biplane catheterization laboratories for planning and guidance of pulmonary vein isolation (PVI). The computer‐assisted overlay registration accuracy was assessed in a clinical setting using an automatic calculation of overlay projection geometry that was derived from hardware sensors in C‐arms, detectors, and patient table. Methods: Consecutive patients (n = 89) underwent left atrium (LA) magnetic resonance imaging MRI scan prior to PVI. Ideal ablation lines encircling the ipsilateral pulmonary veins (PVs) at antral level were drawn onto the segmented LA surface. The 3D‐model was superimposed onto biplane fluoroscopy and matched with angiographies of LA and PVs. Three‐dimensional‐overlay projection geometry was automatically calculated from C‐arm, detectors, and table sensors. Accuracy of technique was assessed as alignment of MRI‐derived 3D overlay and angiographic LA/PV anatomy. Integrity of registered overlay was quantified using landmark measurements. Results: Alignment offsets were 1.3 ± 1.5 mm in left PV, 1.2 ± 1.5 mm in right PV, and 1.1 ± 1.4 mm in LA roof region. Bravais–Pearson correlation of the landmark measurements was r = 0.978 (s  < 0.01), mean offset between landmark distance measurements was 1.4 ± 0.78 mm. Average time needed for overlay registration was 9.5 ± 3.5 seconds. Conclusions: MRI‐derived 3D‐augmented fluoroscopy demonstrated a high level of accuracy when compared with LA/PV angiography. The new system could be especially useful to guide procedures not supported by EAMS, such as cryotechnique PVI. (J Cardiovasc Electrophysiol, Vol. 24, pp. 113‐120, February 2013)     

Cryoballoon Pulmonary Vein Isolation with Real-Time Recordings from the Pulmonary Veins

Introduction: Cryoballoon (CB) ablation represents a novel technology for pulmonary vein isolation (PVI). We investigated feasibility and safety of CB-PVI, utilizing a novel spiral catheter (SC), thereby obtaining real-time PV potential registration.
Methods: Following double transseptal puncture, a Lasso catheter (Biosense Webster, Diamond Bar, CA, USA) and the 28 mm CB were positioned within the left atrium. A novel SC (Promap, ProRhythm Inc., Ronkonkoma, NY, USA) was inserted through the lumen of the CB allowing PV signal registration during treatment. Time to PV conduction block was analyzed. If no stable balloon position was obtained, the SC was exchanged for a regular guide wire and PV conduction was assessed after treatment by Lasso catheter.
Results: In 18 patients, 39 of 72 PVs (54%) were successfully isolated using the SC. The remaining 33 PVs were isolated switching to the regular guide wire. Time to PV conduction block was significantly shorter in PVs in which sustained PVI was achieved as compared to PVs in which PV conduction recovered within 30 minutes (33 ± 21 seconds vs 99 ± 65 seconds). In 40 PVs, time to PV conduction block was not obtained because of: (1) PVI not being achieved during initial treatment; (2) a distal position of the SC; or (3) isolation with regular guide wire. No procedural complications occurred.
Conclusion: Visualization of real-time PV conduction during CB PVI is safe, feasible, and allows accurate timing of PVI onset in a subset of PVs. Time to PV conduction block predicts sustained PVI. However, mechanical properties of the SC need to be improved to further simplify CB PVI.     

Clinical implications of reconnection between the left atrium and isolated pulmonary veins provoked by adenosine triphosphate after extensive encircling pulmonary vein isolation

Introduction: Dormant pulmonary vein (PV) conduction can be provoked by adenosine triphosphate (ATP) after extensive encircling pulmonary vein isolation (EEPVI). However, the clinical implication of reconnection between the left atrium (LA) and isolated PVs provoked by ATP (ATP-reconnection) remains unknown.
Methods and Results: We studied the clinical consequences of ATP-reconnection during intravenous isoproterenol infusion (ISP-infusion). EEPVI severs conduction between the LA and ipsilateral PVs at their junction. Radiofrequency energy is applied at a distance from the PV ostia guided by double Lasso catheters placed within the ipsilateral superior and inferior PVs. This study comprised 82 patients (67 men, 56 ± 9 years old) with atrial fibrillation (AF) who underwent injection of ATP during ISP infusion after successful EEPVI (ATP(+) group). We compared clinical characteristics of 170 patients who underwent earlier EEPVI prior to our use of ATP injection after successful EEPVI (ATP(N/D) group) with those of ATP(+) group patients who underwent one session of EEPVI. ATP-reconnection occurred in 34 (41%) of 82 ATP(+) group patients. Additional radiofrequency applications were performed to eliminate ATP-reconnection in all ipsilateral PVs. Continuous ATP-reconnection of more than 20 seconds duration occurred in six (7.3%) of 82 patients. A total of 102 (60%) of 170 patients in the ATP(N/D) group had no recurrence of AF, whereas 60 (73%) of 82 ATP(+) group patients who underwent only one EEPVI session have had no recurrence of AF in a 6.1 ± 3.3-month follow-up period (P = 0.04).
Conclusion: Radiofrequency application for provoked ATP-reconnection may reduce clinical AF recurrence.     

Dilated left atrium and pulmonary veins in patients with calcified coronary artery: a potential contributor to the genesis of atrial fibrillation

Introduction: Coronary artery disease (CAD) is an important etiology of atrial fibrillation (AF). Coronary artery calcification is a marker of coronary atherosclerosis and coronary events. The purpose of this study was to investigate whether larger left atrium (LA) and pulmonary veins (PVs) were seen by multidetector computed tomography (MDCT) scans in those patients with higher coronary calcium scores.
Methods and Results: A total of 166 patients undergoing MDCT for general check-up (n = 128, 77%) or suspected CAD (n = 38, 23%) were enrolled and divided into a control (calcium score = 0, n = 60), medium calcium score (calcium score = 100∼400, n = 47), and high calcium score (calcium score >400, n = 59) groups. Diameters and areas of the LA, left atrial appendage (LAA), and PVs were measured by MDCT. The high calcium score group had significantly larger PVs diameters, LAA orifice area (1.9 ± 1.4 cm², 0.9 ± 0.5 cm², 0.8 ± 0.4 cm², P < 0.005), LA anterior-posterior distance (32.2 ± 6.8 mm, 30.4 ± 6.5 mm, 27.3 ± 6.0 mm, P < 0.05), and transverse distance (52.6 ± 7.3 mm, 50.2 ± 9 mm, 49.5 ± 4.6 mm, P < 0.05) than the medium calcium score and control groups. Six (3.6%) patients with paroxysmal AF had higher calcium scores and larger diameters of LA, LAA, and PVs than those (96.4%) without paroxysmal AF. Two patients in the high calcium score group had calcified PVs localized to the right upper and left upper PVs. The incidence of calcified PVs was 1.2% for the total patients and 3.3% for the high calcium score patients.
Conclusion: In the presence of high calcium scores in this patient population, the LA, LAA, and PVs were enlarged.     

Image‐Integration of Intraprocedural Rotational Angiography‐Based 3D Reconstructions of Left Atrium and Pulmonary Veins into Electroanatomical Mapping: Accuracy of a Novel Modality in Atrial Fibrillation Ablation

DynaCT Cardiac Integration into Electroanatomical Mapping. Introduction: Exact visualization of complex left atrial (LA) anatomy is crucial for safety and success rates when performing catheter ablation of atrial fibrillation (AF). The aim of our study was to validate the accuracy of integrating rotational angiography‐based 3‐dimensional (3D) reconstructions of LA and pulmonary vein (PV) anatomy into an electroanatomical mapping (EAM) system. Methods and Results: In 38 patients (62 ± 8 years, 25 females) undergoing catheter ablation of paroxysmal (n = 19) or persistent (n = 19) AF, intraprocedural rotational angiography of LA and PVs was performed. The subsequent 3D reconstruction and segmentation of LA and PVs was transferred to the EAM system and registered to the EAM. The distances of all EAM points to corresponding points on the LA syngo® DynaCT Cardiac surface were calculated. Segmentation of LA with clear visualization of adjacent structures was possible in all patients. Also, the integrated segmentation of the LA was used to guide the encirclement of ipsilateral veins, which resulted in PV isolation in all patients. Integration into the 3D mapping system was achieved with a distance error of 2.2 ± 0.4 mm when compared with the EAM surface. Subgroups with paroxysmal and persistent AF showed distance errors of 2.3 ± 0.3 mm and 2.1 ± 0.4 mm, respectively (P = n.s.). Conclusion: Intraprocedural registration of LA and PV anatomy by contrast enhanced rotational angiography was feasible and accurate. There were no differences between patients with paroxysmal or persistent AF. Therefore, integration of rotational angiography‐based reconstructions into 3D EAM systems might be helpful to guide catheter ablation for AF. (J Cardiovasc Electrophysiol, Vol. 21, pp. 278–283, March 2010)     

Pulmonary vein conduction is the major finding in patients with atrial tachyarrhythmias after intraoperative maze ablation

Introduction: Electrophysiological (EP) data from patients with recurrent atrial tachyarrhythmias (ATa) after intraoperative maze ablation are limited. Furthermore, the clinical course after accomplishing pulmonary vein (PV) isolation using the double lasso technique (DLT) is unknown.
Methods and Results: EP study and catheter ablation (CA) was guided by a three-dimensional electroanatomic mapping system (3-D EA, CARTO, Biosense-Webster) combined with simultaneous ipsilateral PV mapping using the DLT. Defined endpoints were: (1) identification of conduction gaps within the ipsilateral PVs, (2) elimination of all PV spikes, and (3) ablation of clinical ATas.
CA was performed in eight patients (four females, 62 ± 5 years, LA: 50 ± 6 mm) with drug refractory ATa (9.1 ± 6.3 years) despite non-"cut and sew" maze operation. Electrical PV conduction was demonstrated in the majority of patients (7/8). All endpoints were achieved. Repeat ablations were required in three patients. Second ablation was due to typical atrial flutter (n = 1) and atrial fibrillation (n = 2). One patient required three ablations due to a left atrial macroreentrant tachycardia. During a mean follow-up of 15.5 ± 4.8 months, 7/8 patients were free of ATa recurrences.
Conclusion: Incomplete lesions after non-"cut and sew" maze operation are associated with PV conduction and recurrence of ATas. Electrical isolation of ipsilateral PVs and completion of linear lesions guided by 3-D EA mapping is feasible and successful in maintaining sinus rhythm during mid term follow-up. Completeness of linear lesions using EP endpoints should be confirmed during the initial surgical procedure to minimize ATa recurrences.     

Electroanatomic reconstruction of the left atrium, pulmonary veins, and esophagus compared with the "true anatomy" on multislice computed tomography in patients undergoing catheter ablation of atrial fibrillation.

BACKGROUND: Current concepts of catheter ablation for atrial fibrillation (AF) commonly use three-dimensional (3D) reconstructions of the left atrium (LA) for orientation, catheter navigation, and ablation line placement. OBJECTIVES: The purpose of this study was to compare the 3D electroanatomic reconstruction (Carto) of the LA, pulmonary veins (PVs), and esophagus with the true anatomy displayed on multislice computed tomography (CT). METHODS: In this prospective study, 100 patients undergoing AF catheter ablation underwent contrast-enhanced spiral CT scan with barium swallow and subsequent multiplanar and 3D reconstructions. Using Carto, circumferential plus linear LA lesions were placed. The esophagus was tagged and integrated into the Carto map. RESULTS: Compared with the true anatomy on CT, the electroanatomic reconstruction accurately displayed the true distance between the lower PVs; the distances between left upper PV, left lower PV, right lower PV, and center of the esophagus; the longitudinal diameter of the encircling line around the funnel of the left PVs; and the length of the mitral isthmus line. Only the distances between the upper PVs, the distance between the right upper PV and esophagus, and the diameter of the right encircling line were significantly shorter on the electroanatomic reconstructions. Furthermore, electroanatomic tagging of the esophagus reliably visualized the true anatomic relationship to the LA. On multiple tagging and repeated CT scans, the LA and esophagus showed a stable anatomic relationship, without relevant sideward shifting of the esophagus. CONCLUSION: Electroanatomic reconstruction can display with high accuracy the true 3D anatomy of the LA and PVs in most of the regions of interest for AF catheter ablation. In addition, Carto was able to visualize the true anatomic relationship between the esophagus and LA. Both structures showed a stable anatomic relationship on Carto and CT without relevant sideward shifting of the esophagus.     

Pulmonary vein isolation under direct visual identification of the left atrium—pulmonary vein junction using intra-cardiac echography

Introduction: Intra-cardiac echocardiography (ICE) which has some benefits, can be used to obtain detailed anatomy of the heart chambers or large vessels, and the catheter positions, and it has been considered useful for improving the outcome of the ablation. In the present study, we performed pulmonary vein isolation (PVI) under real time monitoring of ICE imaging utilizing an ICE catheter placed at the junction of the left atrium (LA) and PVs (LA-PV junction). Methods: PVI for atrial fibrillation (AF) was performed in 30 cases with drug-resistant AF (mean age: 66-years-old; including 22 males). An ICE catheter utilizing a 9 MHz frequency was inserted into the LA via the atrial septum, and placed at the LA-PV junction. Circumferential ablation was performed in the LA outside of the PV ostium, encircling both the superior and inferior ostia together under ICE imaging. Results: The anatomy of the LA to the PVs and catheter sites were clearly identified by the ICE during the procedure, which enabled a precise and safe catheter manipulation with minimal fluoroscopy. Further, the wall thickness of the PV and LA, and position of the esophagus could be obtained by ICE, facilitating care in adjusting the power and/or duration of the current delivery. Conclusion: ICE imaging of the LA-PV junction permitted real time monitoring of the target sites for PVI during the ablation procedure, and was considered a useful technique for performing PVI.     

A transoesophageal echocardiographic image acquisition protocol for wide-view fusion of three-dimensional datasets to support atrial fibrillation catheter ablation

Purpose

The aim of this paper is to propose a transoesophageal echocardiography (TOE) image acquisition protocol which provides a systematic manner of acquiring a minimal number of overlapping 3D TOE datasets allowing the reconstruction of a wide 3D view of the left atrium (LA) with anatomical landmarks that are important for atrial fibrillation catheter ablation.

Methods

In eight cardiac surgical patients, 3D TOE datasets were acquired with a six-step protocol. In the protocol, step 1 aims to acquire the central view of the mitral valve (MV), aortic valve (AV) and left atrial appendage (LAA). Step 2 was developed to acquire the left pulmonary veins (PVs) and step 3 to acquire the right PVs. Steps 4, 5 and 6 were developed to create a sufficient overlap between different datasets. 3D TOE datasets were registered and fused manually in end diastole.

Results

The image acquisition protocol was feasible in all patients. In the fused 3D dataset, a wide 3D view of the LA is shown, and left and right PVs could be seen simultaneously. The LAA, MV, AV and fossa ovalis (FO) were visualised clearly in the 3D TOE datasets. The PV ostia, which are located at the edges of the 3D datasets, suffered more from the artefact of echo loss. The volume overlaps between neighbouring TOE datasets were 50–75 %.

Conclusion

The major part of the LA anatomy incorporating the PVs, LAA, MV, AV and FO as important anatomical landmarks can be reconstructed by registering and fusing 3D datasets acquired with the six-step TOE image acquisition protocol.     

Morphologic characteristics of the left atrial appendage, roof, and septum: implications for the ablation of atrial fibrillation

Introduction: The left atrium (LA) ablation in different regions, including LA appendage (LAA), LA roof, and LA septum, has recently been proposed to improve the success rate of treating patients with atrial fibrillation (AF). The purpose of this study was to investigate the anatomy of LAA, LA roof, and LA septum, using computed tomography (CT).
Methods and Results: Multidetector CT scan was used to depict the LA in 47 patients with drug-refractory paroxysmal AF (39 males, age = 50 ± 12 years) and 49 control subjects (34 males, age = 54 ± 11 years). The area of LAA orifice, neck, and the length of roof line were greater in AF group than in control subjects. Three types of LAA locations and two types of LAA ridges were observed. Higher incidence of inferior LAA was noted in AF patients. The different morphologies of LA roof were described. Roof pouches were revealed in 15% of AF and 14% of controls. Moreover, we found septal ridge in 32% of AF and 23% of controls.
Conclusions: Considerable variations of LAA and LA roof morphologies were demonstrated. Peculiar structures, including roof pouches and septal ridges, were delineated by CT imaging. These findings were important for determining the strategy of AF ablation and avoiding the procedure-related complications.     

Close relationship between the bronchi and pulmonary veins: implications for the prevention of atriobronchial fistula after atrial fibrillation ablation

Introduction: Atrio-bronchial fistula (ABF) can be a rare but potentially lethal complication following the catheter ablation of atrial fibrillation (AF). Understanding the extent of the contact between the bronchial tree and pulmonary veins (PVs) is critical to avoid this complication. We investigated the anatomic relationship between the four PVs and bronchial tree using multi-detector computed tomography (MDCT) images.
Methods and Results: Seventy patients with drug refractory AF were included. They underwent 16-slice MDCT before the ablation. The spatial relationship between the bronchus and PVs was demonstrated by the multi-planar images. The bronchus was in direct contact with four PVs in the vast majority of patients. The mean distances between the bronchus and the ostia of right superior, left superior, right inferior, and left inferior PV were 7.1 ± 5.5, 3.5 ± 4.8, 12.3 ± 5.6, and 17.9 ± 6.8 mm, respectively. Patients were categorized into two groups: Group I: proximal contact (<5 mm from the PV ostium) and Group II: distal contact (>5 mm from the PV ostium). For the right superior pulmonary vein (RSPV), the Group I patients were associated with thinner connective tissue between them (P = 0.001), a larger RSPV (17.2 ± 2.2 vs 15.5 ± 2.1 mm, P < 0.001), and right inferior pulmonary vein (RIPV) diameter (15.9 ± 1.9 vs 14.6 ± 1.6 mm, P < 0.01). For the left superior pulmonary vein (LSPV), the Group I patients were associated with an older age (P = 0.02).
Conclusion: Isolation of the superior PVs may carry the potential risk of bronchial damage. The clinical or anatomic characteristics associated with the proximal contact between the bronchi and superior PVs can provide useful information to prevent this complication.     

Anatomy of the pulmonary veins in patients with atrial fibrillation and effects of segmental ostial ablation analyzed by computed tomography

INTRODUCTION: The anatomic arrangement of pulmonary veins (PVs) is variable. No prior studies have quantitatively analyzed the effects of segmental ostial ablation on the PVs. The aim of this study was to determine the effect of segmental ostial radiofrequency ablation on PV anatomy in patients with atrial fibrillation (AF). METHODS AND RESULTS: Three-dimensional models of the PVs were constructed from computed tomographic (CT) scans in 58 patients with AF undergoing segmental ostial ablation to isolate the PVs and in 10 control subjects without a history of AF. CT scans were repeated approximately 4 months later. PV and left atrial dimensions were measured with digital calipers. Four separate PV ostia were present in 47 subjects; 3 ostia were present in 2 subjects; and 5 ostia were present in 9 subjects. The superior PVs had a larger ostium than the inferior PVs. Patients with AF had a larger left atrial area between the PV ostia and larger ostial diameters than the controls. Segmental ostial ablation resulted in a 1.5 +/- 3.2 mm narrowing of the ostial diameter. A 28% to 61% focal stenosis was present 7.6 +/- 2.2 mm from the ostium in 3% of 128 isolated PVs. There were no instances of symptomatic PV stenosis during a mean follow-up of 245 +/- 105 days. CONCLUSION: CT of the PVs allows identification of anatomic variants prior to catheter ablation procedures. Segmental ostial ablation results in a significant but small reduction in ostial diameter. Focal stenosis occurs infrequently and is attributable to delivery of radiofrequency energy within the PV.     

Paroxysmal Atrial Fibrillation Maintained by Nonpulmonary Vein Sources Can Be Predicted by Dominant Frequency Analysis of Atriopulmonary Electrograms

Introduction: Increasing evidence suggests that high-frequency excitation in the pulmonary vein (PV) plays a dominant role in the maintenance of paroxysmal atrial fibrillation (AF). However, in a certain population of patients, AF remains inducible after PV isolation (PVI). We sought to clarify whether dominant frequency (DF) analysis of atriopulmonary electrograms can predict paroxysmal AF maintained by non-PV sources.
Methods and Results: Sixty-one patients with paroxysmal AF (aged 59 ± 12 years) were studied. Before PVI, bipolar electrograms during AF were recorded simultaneously from three PV ostia, the coronary sinus (CS), and the septum and free wall of the right atrium (RA). DF was obtained by fast Fourier transform (FFT) analysis. AF was rendered noninducible after PVI in 39 of the 61 patients (noninducible group), but was still inducible in the remaining 22 (inducible group). Among the six recording sites, the highest DF was documented in the PV in all of the patients in the noninducible group; the maximum DF among the three PVs (PV-DF_max) was higher than that among the CS and two RA sites (atrial DF_max; 7.2 ± 1.0 Hz vs 5.8 ± 0.7 Hz, P < 0.0001). In contrast, the highest DF was documented in the CS or RA in 45.5% of the patients in the inducible group; PV-DF_max was comparable with atrial DF_max (6.6 ± 0.8 Hz vs 6.6 ± 0.6 Hz). AF inducibility after PVI was predicted by a PV-to-atrial DF_max gradient of <0.5 Hz, with a sensitivity of 90.9% and a specificity of 89.7%.
Conclusion: Paroxysmal AF maintained by non-PV sources can be predicted by the PV-to-atrial DF gradient.     

Phased-Array intracardiac echocardiography to guide radiofrequency ablation in the left atrium and at the pulmonary vein ostium

INTRODUCTION: We sought to evaluate the utility of a phased-array intracardiac echocardiography (ICE) device to identify left atrial (LA) and pulmonary vein (PV) anatomy; accurately guide radiofrequency ablation (RFA) to the right or left PV ostium and LA appendage (LAA); and evaluate PV blood flow before and after RFA using Doppler parameters. METHODS AND RESULTS: Twelve adult sheep were anesthetized and an Acuson 10-French, 7-MHz ICE transducer introduced via the internal jugular vein into the right atrium. The LA was imaged and PV anatomy and blood flow documented using two-dimensional and pulsed-wave Doppler. Mean LA dimensions were 4.6 +/- 0.4 x 3.5 +/- 0.5 cm; mean single right and left main PV ostium diameters were 1.5 +/- 0.2 and 1.3 +/- 0.3 cm; and mean right and left PV first-order branch diameters were 0.8 +/-0.2 and 0.6 +/- 0.1 cm. Mean PV maximum inflow velocity for the right PV were 0.30 +/- 0.05 m/sec and for the left PV were 0.35 +/- 0.04 m/sec. The PV ostia and LAA could be targeted accurately for RFA using ICE guidance. At pathologic evaluation, the mean distance of the lesion center to the right or left PV-LA junction was 3.0 +/- 2.0 mm. The mean distance of the lesion center to the posterior margin of the LAA was <4 mm in all cases. There was no significant increase in PV maximum inflow velocity or decrease in PV diameter following RFA at the PV ostium. Absence of PV obstruction was confirmed at pathology. CONCLUSION: Phased-array ICE allows detailed assessment of LA and PV anatomy when imaged from the right atrium; accurate guidance of RFA to the PV ostium and LAA; and immediate evaluation of PV patency after RFA.     

Anatomical Predictors for Acute and Mid‐Term Success of Cryoballoon Ablation of Atrial Fibrillation Using the 28 mm Balloon

Anatomical Predictors for Acute and Mid‐Term Success of Cryoballoon Ablation. Introduction: Cryoballoon (CB) pulmonary vein isolation (CB‐PVI) for the treatment of paroxysmal atrial fibrillation (AF) has been demonstrated to be safe and reliable. Preprocedural patient selection to address the high variability in pulmonary vein (PV) anatomy may improve the acute and chronic success of CB‐PVI. The purpose of this study was to identify anatomical predictors for CB‐PVI failure using the 28 mm balloon. Methods and Results : We included 47 patients with paroxysmal AF undergoing CB‐PVI with the 28 mm CB. Anatomical global left atrial and PV selective parameters were quantified from 3‐dimensional reconstructed preprocedural computed tomography or magnetic resonance imaging data. The mean follow‐up was 26 ± 9 months (range: 12–32 months). Multivariate logistic regression analysis revealed that a continuous sharp left lateral ridge between the left PVs and the left lateral appendage (OR, 7.09; 95% CI, 1.17–43.47) and a sharp carina between the left superior and left inferior PV (OR, 5.99; 95% CI, 1.33–27.03) predict acute and mid‐term failure. For the right inferior PVs, a non‐perpendicular angle between the axis of the PV and the ostial plane (OR, 6.33; 95% CI, 1.20–33.33) and an early branching PV with change in the axis angle (OR, 7.41; 95% CI, 1.44–38.46) were predictors of acute and mid‐term failure. Conclusion: Anatomical variables preventing maximal heat transfer from the tissue to the CB could be identified as predictors for CB‐PVI failure with the 28 mm balloon. These findings may be a step toward a more tailored ablation strategy based on individual anatomical variations. (J Cardiovasc Electrophysiol, Vol. 24, pp. 132‐138, February 2013)     

Detection of inadvertent catheter movement into a pulmonary vein during radiofrequency catheter ablation by real-time impedance monitoring

Introduction: During radiofrequency ablation to encircle or isolate the pulmonary veins (PVs), applications of radiofrequency energy within a PV may result in stenosis. The aim of this study was to determine whether monitoring of real-time impedance facilitates detection of inadvertent catheter movement into a PV.
Methods and Results: In 30 consecutive patients (mean age 53 ± 11 years) who underwent a left atrial ablation procedure, the three-dimensional geometry of the left atrium, the PVs, and their ostia were reconstructed using an electroanatomic mapping system. The PV ostia were identified based on venography, changes in electrogram morphology, and manual and fluoroscopic feedback as the catheter was withdrawn from the PV into the left atrium. Real-time impedance was measured at the ostium, inside the PV at approximately 1 and 3 cm from the ostium, in the left atrial appendage, and at the posterior left atrial wall. There was an impedance gradient from the distal PV (127 ± 30 Ω) to the proximal PV (108 ± 15 Ω) to the ostium (98 ± 11 Ω) in each PV (P < 0.01). There was no significant impedance difference between the ostial and left atrial sites. During applications of radiofrequency energy, movement of the ablation catheter into a PV was accurately detected in 80% of the cases (20) when there was an abrupt increase of ≥4 Ω in real-time impedance.
Conclusion: There is a significant impedance gradient from the distal PV to the left atrium. Continuous monitoring of the real-time impedance facilitates detection of inadvertent catheter movement into a PV during applications of radiofrequency energy. (J Cardiovasc Electrophysiol, Vol. 15, pp. 1-5, June 2004)     

Pulmonary vein stenosis: still the Achilles heel of ablation for atrial fibrillation?

Atrial fibrillation (AF) can be eliminated by (i) targeted deliveryto focal ‘sites’ within the pulmonary vein (PV),by (ii) PV isolation through circumferential or segmental ablationat the venoatrial junction, or by (iii) electrical isolationfrom the left atrium (LA) outside the PV ostia. PV stenosisdevelops in 1–10% of patients undergoing ablation. Sofar, the clinical presentation, investigation, management, andoutcome of this disease have been incompletely reported. Understanding PV anatomy is crucial both for PV ablation andfor prevention of PV stenosis. Using magnetic resonance (MR)scanning, Cato et al.¹ have reported that 38% of patientsexhibit a variant anatomy (short or long common left trunk,right middle or right upper PV). In addition, very close proximitybetween the ostia of the right and the left PVs was observed.The diameters of the four regular PVs did not differ significantly,but PV and LA seemed larger     

Long-term outcome following successful pulmonary vein isolation: pattern and prediction of very late recurrence

Background:  Despite encouraging results of pulmonary vein isolation (PVI) ablation for atrial fibrillation (AF), it is unclear whether there is genuine cure or there is an important attrition rate. We sought to determine the long-term outcome of the initial responders who experienced a prolonged AF-free complete response.
Methods:  From a series of 350 consecutive patients who underwent PVI for AF, 264 patients (75%) (males 71%, age 57 ± 12 years, paroxysmal AF 87%) who demonstrated ≥1 year AF-free follow-up on no antiarrhythmic drugs were followed for 1–5 years.
Results:  During 28 ± 12 months follow-up, 23 of 264 (8.7%) patients had recurrence of AF. The actuarial recurrence at 2 years postablation was 5.8% and increased to 25.5% at 5 years. Compared with long-term responders, more patients with late recurrence had hypertension (HR = 2.18, P = 0.009) and hyperlipidemia (HR = 4.01, P = 0.0005). Among 18 patients with recurrent AF necessitating repeat PVI, 15 (83%) required re-isolation of > 1 PV and 28 of 45 (58%) PVs showed reconnection. All PVs were re-isolated and five (28%) patients had additional linear ablation. All 15 patients became AF-free again.
Conclusions:  Although most patients following PVI remain AF-free, some patients develop "late" recurrence of AF. The "late" recurrence patients are more likely to have hypertension and hyperlipidemia. Most late recurrences are associated with PV reconnections. Our observations emphasize the importance of continued long-term vigilance for AF recurrence, and also raise concerns regarding the need for long-term anticoagulation therapy.