Multislice computed tomography versus intracardiac echocardiography to evaluate the pulmonary veins before radiofrequency catheter ablation of atrial fibrillation: a head-to-head comparison

OBJECTIVES: The purpose of this study was to perform a head-to-head comparison between multislice computed tomography (MSCT) and intracardiac echocardiography (ICE). BACKGROUND: Different imaging techniques have been used to visualize the pulmonary veins (PV) before radiofrequency ablation of atrial fibrillation. METHODS: The PV and their atrial insertion were evaluated in 42 patients (35 men, 49 +/- 9 years) admitted for ablation of PV ostia. Ostia were measured in two directions (anterior-posterior and superior-inferior) with MSCT. Two-dimensional (2-D) measurements of PV ostia were performed with ICE. Results were compared, considering MSCT as the gold standard. Venous ostium indexes were calculated by dividing MSCT measurements in the anterior-posterior direction and the superior-inferior direction. RESULTS: Common ostia of left PV were observed in 33 (79%) patients with MSCT and 31 (74%) patients with ICE. Common ostia of right PV were observed in 13 (31%) and 16 (38%) patients, respectively. Additional PV were observed in 13 (31%) patients with MSCT and in 7 (17%) patients with ICE. Ostial diameters by MSCT in the anterior-posterior direction were similar to 2-D measurements by ICE. By contrast, diameters by MSCT in the superior-inferior direction were significantly larger than 2-D diameters measured with ICE. Venous ostium indexes were 0.77 +/- 0.18 and 0.90 +/- 0.15 (p < 0.01) for left and right PV respectively, indicating an oval shape of particularly left PV ostia. CONCLUSIONS: Variation in PV anatomy is frequently observed with both techniques. The sensitivity for detection of additional branches is higher for MSCT. Results of measurements of PV ostia suggest an underestimation of ostial size by ICE. Three-dimensional imaging techniques, such as MSCT, are required to demonstrate an oval shape of PV ostia.     

Transesophageal echocardiographic follow-up of pulmonary veins in patients undergoing ostial radiofrequency catheter ablation for atrial fibrillation.

BACKGROUND: Ostial radiofrequency catheter ablation (RFCA) of pulmonary veins (PVs) is a promising invasive approach for the non-pharmacologic treatment of atrial fibrillation, but PV stenosis has been reported as a possible complication of this intervention. The aim of this study was to assess PV anatomy and stenosis (i.e. number and progression) by means of transesophageal echocardiography (TEE) during the follow-up of patients undergoing RFCA. METHODS: Twenty-three consecutive patients with refractory and highly symptomatic atrial fibrillation underwent ostial radiofrequency isolation of arrhythmogenic triggers/foci, localized into the PVs, by an electroanatomic approach (CARTO system) or circular mapping with a multipolar catheter (LASSO) placed under radioscopic guidance. All patients were investigated using TEE and magnetic resonance angiography before radiofrequency application to evaluate PV anatomy. TEE examination was repeated after 2 months of follow-up and, in the presence of a stenosis, 1 year later. RESULTS: TEE allowed to identify 100% of the left and right superior PVs, 96% of right inferior PVs, and 74% of the left inferior PVs. Anatomic variants were detected at TEE in 33% of patients against 37% at magnetic resonance angiography (95% of concordance). After ostial RFCA, TEE disclosed a significant reduction in the mean diameters of the left superior PV (14.1 +/- 3.2 vs 12.0 +/- 2.7 mm, p < 0.01), left inferior PV (11.2 +/- 2.3 vs 9.8 +/- 2.2 mm, p = 0.05) and right superior PV (14.2 +/- 2.6 vs 12.9 +/- 2.7 mm, p < 0.05), and an increase in the mean peak velocities of the left superior PV (69.8 +/- 14.8 vs 91 +/- 42.4 cm/s, p < 0.05) and left inferior PV (59.2 +/- 18.1 vs 79.3 +/- 40.5 cm/s, p < 0.05). From a total of 88 PVs treated, 7 (7.9%) showed a higher significant stenosis in patients treated using the LASSO than the CARTO system (31.3 vs 2.8% respectively, p < 0.01). After 1-year follow-up there was no progression of PV stenosis. CONCLUSIONS: TEE was successful to evaluate PV anatomy and stenosis of patients undergoing ostial RFCA for atrial fibrillation. This complication is not rare and seems to be strictly related to the method of ablation, in particular when circular mapping and disconnection of triggers/foci was carried out by only a circular multipolar catheter without an electroanatomic approach.     

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.     

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.     

Phased-array intracardiac echocardiography during pulmonary vein isolation and linear ablation for atrial fibrillation

INTRODUCTION: Fluoroscopic imaging provides limited anatomic guidance for left atrial structures. The aim of this study was to determine the utility of real-time, phased-array intracardiac echocardiography during radiofrequency ablation for atrial fibrillation. METHODS AND RESULTS: In 29 patients undergoing pulmonary vein isolation (n = 16) or linear (n = 13) left atrial radiofrequency ablation for atrial fibrillation, intracardiac phased-array echocardiography was used to visualize left atrial anatomy and the pulmonary veins, as well as ablation and mapping catheters during ablation procedures. In the 16 pulmonary vein isolation patients, the mean pulmonary vein ostial diameters measured by venography and intracardiac echocardiography were similar for all veins positions, except that left common pulmonary vein diameters were larger as measured by echocardiography (2.50 +/- 0.29 cm) than by venography (1.79 +/- 0.50 cm, P = 0.001). The ostial diameters measured by echocardiography and venography were not correlated, however (r = 0.23, P = 0.19). As directed by echocardiography, only 1 of 25 circular mapping catheters (4%) used in 16 patients was replaced due to inappropriate sizing of the pulmonary veins. Mean pulmonary vein Doppler flow velocities increased after ablation for left-sided veins but ostial diameters were unchanged. In the linear ablation patients, the entire extent of the linear electrode array could be visualized in only 3 of 52 of catheter positions (6%) in the 13 patients. A portion of the catheter could be seen in only 50% of all target catheter positions. CONCLUSION: Phased-array intracardiac echocardiography (1) allows sizing and positioning of pulmonary vein mapping catheters, (2) provides measures of pulmonary vein ostial diameters, (3) continuously monitors pulmonary vein Doppler flow velocities, and (4) has limited use in positioning linear ablation catheters in the left atrium.     

Hypertension and hypertensive heart disease are associated with increased ostial pulmonary vein diameter

INTRODUCTION: Atrial fibrillation (AF) is associated with increased ostial pulmonary vein (PV) diameter and commonly with hypertension. We sought to investigate ostial PV anatomy in patients with and without AF with the goal of characterizing the relationship to hypertension and cardiovascular disease. METHODS AND RESULTS: Ostial PV diameter was assessed by preprocedural spiral computed tomography in 100 AF patients undergoing a PV isolation procedure and in 24 age- and sex-matched non-AF control patients. Ostial diameter of 392 PVs in 100 AF patients was increased compared to 106 PVs in 24 non-AF controls (1.50 +/- 0.31 vs 1.20 +/- 0.31 cm, P <0.001) and diameters of individual PVs were uniformly affected (r=0.45-0.62, P <0.001). Left atrial dilation was associated with a larger PV diameter (1.56 +/- 0.32 vs 1.44 +/- 0.29 cm, P <0.01). PV diameter in AF patients with hypertension (1.55 +/- 0.32 cm), particularly if associated with left ventricular hypertrophy (1.66 +/- 0.37 cm), was larger compared to AF patients without hypertension (1.43 +/- 0.26 cm, P <0.01). PV diameter in control patients with hypertension (n=14) was larger than in those without hypertension (n=10, P <0.01). Patients with persistent AF had larger PV diameters (1.61 +/- 0.34 cm) than patients with paroxysmal AF (1.47 +/- 0.30 cm, P <0.01). Male gender (P <0.01), history of hypertension (P <0.01), and persistent AF (P <0.05) were identified as independent cofactors of increased ostial PV diameter. Conclusion: PV dilation affects all PVs uniformly in AF patients. Hypertension and hypertensive heart disease in patients with and without AF are associated with PV dilation, supporting theories that impaired left ventricular diastolic function is associated with a stretch-induced PV arrhythmia mechanism.     

Effect of Heart Rate and Isoproterenol on Pulmonary Vein Flow Velocity Following Radiofrequency Ablation: A Doppler Color Flow Imaging Study

INTRODUCTION: Application of radiofrequency energy at pulmonary vein (PV) ostium during focal atrial fibrillation (AF) ablation procedures increases flow velocity due to PV narrowing. Factors unrelated to ablation that effect PV flow velocity have not been described. AIMS OF THE STUDY: The purpose of this study was to evaluate, using intracardiac echocardiography (ICE) imaging, the effect of isoproterenol (ISO) and heart rate (HR) on PV flow velocity Pre- and Post-ablation. METHODS AND RESULTS: In 31 patients with AF undergoing LA-PV ostial ablation involving at least one PV ostium, an ICE catheter was placed in the RA to image and detect PV flow. PV ostial peak velocity was assessed in sinus rhythm Pre-, Post-ablation, during and after ISO (up to 20 microg/min). To separate HR versus ISO effect, PV velocity was measured during atrial pacing (after HR returned to baseline) at pacing rate matching HR with ISO. PV ostial velocity was assessed with ISO and pacing in 30 non-ablated and 33 ablated PVs. Ostial velocities of non-ablated PVs during ISO infusion (117 +/- 42 cm/s) were greater ( p < 0.03) than those during atrial pacing (78 +/- 26 cm/s) at matched HR (116 +/- 20, range 92-150 bpm). Ostial PV flow velocities of ablated PVs increased from 59 +/- 17 (30-95) cm/s Pre- to 95 +/- 25 (58-136) cm/s Post-ablation. During ISO infusion PV flow velocities in ablated PVs (118 +/- 34 cm/s) were also greater ( p < 0.03) than those during atrial pacing (96 +/- 37 cm/s) at matched HR (116 +/- 14, range 92-130 bpm). Atrial pacing alone produced no significant difference in PV flow velocities measured Pre- or Postablation. CONCLUSION: ISO appears to increase ostial flow velocity of ablated and non-ablated PVs independent of HR effect. These effects are important to recognize when PV velocity is used as an index for interpreting the impact of PV ostial lesions on functionally significant PV narrowing.     

Determination of the spatial orientation and shape of pulmonary vein ostia by contrast-enhanced magnetic resonance angiography.

AIMS: For catheter ablation of atrial fibrillation (AF), proper catheter positioning is crucial and depends on knowledge of pulmonary vein (PV) anatomy. The aim of this study was to assess PV spatial orientation and ostial shape by contrast-enhanced magnetic resonance angiography (CE-MRA). METHODS AND RESULTS: In 30 consecutive AF patients, CE-MRA was performed prior to ostial ablation. Using a centre-line technique, the PV ostium was defined perpendicular to this centre-line. Minimal and maximal ostial diameters, ostial perimeter, and angles in the anatomical frontal and transverse planes were measured. Twenty-one patients had four separate PVs. In four patients, there was a distinct right-middle PV and in five a common left common PV was found. Left-sided PV ostia were smaller and more elliptical than right-sided PVs. In the transverse plane, the ostia of both superior PVs were directed anteriorly (LS -15 +/- 13 degrees , RS -13 +/- 11 degrees ) and both inferior PV ostia were directed posteriorly (LI 23 +/- 15 degrees , RI 39 +/- 15 degrees ). In the frontal plane, both superior PV ostia pointed upwards (LS -27 +/- 14 degrees , RS -33 +/- 12 degrees ) while the inferior ostia were directed horizontally (LI 2 +/- 11 degrees , RI 3 +/- 13 degrees ). CONCLUSION: PV ostial shape and spatial orientation are variable and can be visualized adequately by CE-MRA.     

Usefulness of phased-array intracardiac echocardiography for the assessment of left atrial mechanical "stunning" in atrial flutter and comparison with multiplane transesophageal echocardiography(*)

We compared transesophageal and phased-array intracardiac echocardiography (TEE/ICE) for the 2-dimensional and spectral Doppler assessment of left atrial (LA) mechanical function. TEE is commonly used to assess LA body and LA appendage mechanical function in patients who are undergoing radiofrequency ablation of typical atrial flutter. Fifteen patients underwent TEE and ICE imaging before and after ablation of typical atrial flutter. The following parameters were measured: (1) LA appendage emptying velocity and fractional area change, (2) severity of LA spontaneous echo contrast (graded 0 to 4), (3) maximal inflow velocity of the left and right upper pulmonary veins, and (5) maximal mitral valve E- and A-wave inflow velocities in sinus rhythm. Diagnostic quality imaging was achieved in all patients with TEE and ICE. Comparing TEE and ICE, the following absolute values and linear correlation coefficient (R) were obtained: preablation LA appendage emptying velocity: 0.45 +/- 0.21 versus 0.44 +/- 0.21 m/s (r = 0.95, p = <0.001); postablation LA appendage velocity: 0.33 +/- 0.24 versus 0.34 +/- 0.24 m/s (r = 0.97, p <0.001); LA appendage fractional area change: 35.3 +/- 13.7 versus 35.9 +/- 17.1% (r = 0.81, p <0.001); left upper/right upper pulmonary vein inflow velocity: 0.50 +/- 0.17/0.49 +/- 0.18 versus 0.51 +/- 0.17/0.47 +/- 0.20 m/s (r = 0.93/0.90, p <0.001); mitral valve E/A wave: 0.66 +/- 0.14/0.31 +/- 0.14 versus 0.69 +/- 0.17/0.35 +/- 0.23 (r = 0.84/0.97, p <0.002); LA spontaneous echo contrast (pre- and postablation): 1.1 +/- 1.2/1.3 +/- 1.2 versus 1.2 +/- 1.3/1.4 +/- 1.3 (r = 0.92/0.90, p <0.001). No patients were identified with LA appendage thrombus. Thus, TEE and phased-array ICE provided equivalent imaging data with high statistical correlation. ICE may be an imaging alternative to TEE in the evaluation of a "stunned" left atrium.     

Intracardiac Doppler echocardiographic quantification of pulmonary vein flow velocity: an effective technique for monitoring pulmonary vein ostia narrowing during focal atrial fibrillation ablation

INTRODUCTION: Ablation at the pulmonary vein (PV) ostium to isolate triggers for atrial fibrillation (AF) may induce PV narrowing. The AcuNav ultrasound catheter can image PV flow and quantify peak velocity and may be useful in assessing the degree of narrowing of PV ostia. METHODS AND RESULTS: In 93 patients with AF undergoing PV ostial ablation (up to 40 W, 52 degrees C, 90 sec), the ultrasound catheter was placed in the right atrium and PV peak flow velocities were measured during systole and diastole before and after ablation. Ostial PV electrical isolation was achieved in 216 of the 219 targeted PVs. The ultrasound catheter provided flow imaging of all PVs. The ostial peak flow velocities measured 56 +/- 12 cm/sec before ablation and increased to 101 +/- 22 cm/sec after ablation (P < 0.001). Peak velocity >100 cm/sec was detected in 103 (47%) of 219 and > or = 158 cm/sec (estimated pressure gradient 10 mmHg) with turbulent flow features, in 7 (3.2%) of 219 PVs. The highest velocity detected in one PV was 211 cm/sec (17.7 mmHg). Follow-up ultrasound catheter measurements were obtained in 13 patients (30 previously ablated PVs) during repeat ablations. The ostial peak velocity had decreased by 22 +/- 14 cm/sec and in 25 (83%) of 30 PVs was within the baseline range (<100 cm/sec) at a mean follow-up of 4.9 +/- 2.2 months. Follow-up magnetic resonance imaging (MRI) or contrast-enhanced CT was obtained at 7.0 +/- 3.8 months in seven patients with PV velocity > 158 cm/sec after initial ablation. No significant stenosis (<30%) was identified, and no patient suffered clinical symptoms (follow-up 6-18 months) related to the described acute changes in PV flow after an initial ablation procedure. Of 13 patients with repeat ablation, two had PV velocities >100 cm/sec before repeat ablation, and three PVs in two patients had flow velocity >158 cm/sec after repeat ablation. One of these patients developed symptoms of exertional dyspnea; MRI at 4 months showed 50% to 60% ostial narrowing. CONCLUSION: Ostial ablation for PV isolation may induce a mild-to-moderate increase in PV flow velocity, which can be identified using an ultrasound catheter with Doppler color flow imaging. Increases in PV flow velocity (<158 cm/sec) after a primary ablation procedure appear to be well tolerated, and a return toward baseline flow characteristics should be anticipated by 3 months. A more cautious approach may be required for patients undergoing repeat PV isolation.     

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.     

Effects of left atrial ablation of atrial fibrillation on size of the left atrium and pulmonary veins

OBJECTIVES: The purpose of this study was to determine the effect of left atrial circumferential ablation on the size of the left atrium and pulmonary veins (PVs). BACKGROUND: The long-term effects of left atrial circumferential ablation on left atrial and PV size and anatomy have not been analyzed in quantitative fashion. METHODS: PV and left atrial sizes were analyzed in 41 consecutive patients (mean age 54 +/- 12 years) with paroxysmal (n = 25) or chronic (n = 16) atrial fibrillation. Computed tomography of the chest with three-dimensional reconstruction was performed before and 4 +/- 2 months after left atrial circumferential ablation. Left atrial circumferential ablation was performed to encircle the PVs 1 to 2 cm from the ostia, using a power output of 70 W. Additional ablation lines were created in the posterior left atrium and mitral isthmus. Radiofrequency energy also was delivered within the circles and at the PV ostia in 51% of patients at a reduced power output of 35 W. RESULTS: At 6 months, 36 patients (88%) were in sinus rhythm without antiarrhythmic drug therapy, including 3 patients (7%) who developed persistent left atrial flutter and underwent subsequent successful ablation of atrial flutter. There was a 15 +/- 16% decrease in left atrial volume (P < .01) and 10 +/- 35% decrease in PV ostial area (P < .01), without focal narrowing, in patients with a successful outcome. Focal PV stenosis did not occur in any of the 41 patients. CONCLUSIONS: Maintenance of sinus rhythm after left atrial circumferential ablation is associated with reduced left atrial and PV ostial size. Left atrial circumferential ablation for atrial fibrillation does not cause PV stenosis.     

Technique and results of pulmonary vein angiography in patients undergoing catheter ablation of atrial fibrillation

INTRODUCTION: Delineation of pulmonary vein (PV) anatomy is an integral part of the PV isolation procedure. The aims of the present study were to (1) describe the technique of selective PV angiography, (2) show the typical fluoroscopic locations and appearance of the PVs, and (3) compare the ostial diameters of PVs measured by angiography and magnetic resonance imaging (MRI). METHODS AND RESULTS: Twenty consecutive patients undergoing a PV isolation procedure underwent selective PV angiography using a deflectable 8-French lumened catheter (Naviport, Cardima). The left superior PV (LSPV) runs upward and away from the spine in the right anterior oblique (RAO) projection and upward and toward the spine in the left anterior oblique (LAO) projection. The opposite is true for the right superior PV (RSPV). The left inferior PV (LIPV) has a bull's-eye appearance in the RAO projection, and the right inferior PV (RIPV) has a bull's-eye appearance in the LAO projection due to their end-on trajectories. The LIPV in the LAO projection and the RIPV in the RAO projection run horizontally toward the spine. An excellent correlation was noted in PV ostial size as assessed by angiography and MRI (r(2) < 0.90, P < 0.0001). CONCLUSION: This study describes the technique and results of PV angiography and fluoroscopy. The study also demonstrates good correlation of PV ostial diameters by contrast venography and MRI. PV angiography can be used as an alternate to MRI or computed tomographic imaging, particularly when these tests are unavailable or are contraindicated in the patient.     

Assessment of pulmonary vein anatomic variability by magnetic resonance imaging: implications for catheter ablation techniques for atrial fibrillation

INTRODUCTION: Pulmonary vein (PV) isolation for atrial fibrillation (AF) currently is performed using either an ostial or an extra-ostial approach. The objective of this study was to analyze by three-dimensional (3D) magnetic resonance angiography (MRA) the anatomy of the PVs in order to detect structural variability that would impact the choice of ablation approach. METHODS AND RESULTS: Three-dimensional MRA was performed in 105 patients undergoing PV isolation. The ostial diameter, branching pattern, and PV angulation were analyzed. Fifty-nine (56%) patients had the typical pattern of 4 PVs with 4 separate ostia, 30 (29%) patients had an additional PV, and 18 (17%) patients had a left common PV trunk. In two patients, there were three right-sided veins and a common left-sided trunk, giving rise to four ostia: three on the right and one on the left. Two different populations of right middle PVs were noted: one where the additional vein projected anteriorly to drain the right middle lobe and one posterior to drain the superior portion of the right lower lobe. The average intrapatient variability in PV diameter was 7.9 +/- 4.2 mm. The PV ostium was <10 mm in 26 (25%) patients and >25 mm in 15 (14%) patients. The first branch originated 6.7 +/- 2.3 mm from the ostium. The left superior, right superior, right inferior, and left inferior PVs were found to enter the left atrium at the following angles: 32 +/- 13 degrees, 131 +/- 11 degrees, 206 +/- 16 degrees, and 329 +/- 14 degrees, respectively. Forty-nine patients (47%) had at least one funnel shaped PV. CONCLUSION: This largest PV imaging study to date demonstrates that MRA is a valuable tool that allows detection of marked intrapatient and interpatient anatomic variability of the PVs. These findings suggest that, at least in some patients, circumferential extra-ostial left atrial encirclement of the PVs may be preferable to ostial PV isolation. These findings also may have significant implications on the future development of coil- and balloon-based catheter ablation designs for AF ablation.     

Use of intracardiac echocardiography for prediction of chronic pulmonary vein stenosis after ablation of atrial fibrillation

INTRODUCTION: Measurements of pulmonary vein (PV) flow with intracardiac echocardiography (ICE) immediately before and after PV isolation may be a useful method for predicting which patients will develop chronic PV stenosis. METHODS AND RESULTS: We assessed preablation and postablation flows in each of the four PVs using a phase-array ICE catheter in 95 patients (mean age 52 +/- 13) undergoing atrial fibrillation ablation. The ostium of each of the PVs was defined using angiography, electrical mapping, and ICE imaging. Ostial electrical isolation of all PVs was achieved using a 4-mm cooled-tip radiofrequency ablation catheter. Change in PV flow, when present, was examined as both an absolute value and as a percentage of the baseline flow. All patients underwent spiral computed tomography (CT) scans of the PVs 3 months after the procedure for detection of stenosis. The average preablation diastolic flows for the left superior, left inferior, right superior, and right inferior veins were 0.56, 0.54, 0.47, and 0.45 m/sec, respectively. These values increased to 0.74, 0.67, 0.58, and 0.59 m/sec postablation (P < 0.001). Of 380 PVs ablated, the CT scans revealed 2 (1%) with severe (>70%) stenosis, 13 (3%) with moderate (51%-70%) stenosis, and 62 (16%) with mild (< or = 50%) stenosis. The r value between flow and stenosis was only 0.09 (P = NS). CONCLUSION: Acute changes in PV flow immediately after ostial PV isolation do not appear to be a strong predictor of chronic PV stenosis.     

Favorable effect of pulmonic vein isolation by partial circumferential ablation on ostial flow velocity

OBJECTIVES: The aim of this study was to determine the effect of electrical isolation of pulmonic vein (PV) on flow velocity. BACKGROUND: We report our experience with electrical isolation of PV by partial circumferential ablation and its effect on ostial peak flow velocity as assessed by phased-array ultrasound catheter imaging. METHODS: Sixty-two patients participated in the study. Magnetic electroanatomic mapping, ultrasound catheter imaging, and Lasso mapping catheter were used. Electrical isolation was achieved by delivering radiofrequency ablation (RFA) lesions proximal to Lasso mapping catheter bipoles showing PV entry. Following this, the number of RFA lesions/PV and their segment-wise distribution (maximum 4/PV) were assessed. RESULTS: Fifty right superior, 51 left superior, 32 left inferior, and 17 right inferior PVs were isolated. RFA involved 4 segments in 42 PVs, 3 segments in 61 PVs, and 90% reduction in AF burden, either with or without previously ineffective antiarrhythmic agents, was achieved in 54 patients (87%). CONCLUSIONS: In the majority of PVs (72%), electrical isolation can be achieved by partial circumferential ablation (targeting 相似文献   

Interatrial defect sizing by intracardiac and transesophageal echocardiography compared with fluoroscopic measurements in patients undergoing percutaneous transcatheter closure.

The purpose of this study was to evaluate prospectively the feasibility and accuracy of using echocardiographic measurements by transesophageal and intracardiac echocardiography (TEE and ICE, respectively) for interatrial septal defect sizing during percutaneous transcatheter closure. Forty-two patients underwent balloon sizing of interatrial septal defects using TEE in 21 of them and ICE in the other half. These measurements were correlated with quantitative fluoroscopic analysis and evaluated for bias and agreement between methods using a Bland-Altman analysis. Echocardiographic measurements were obtained by ICE and TEE in all patients. An excellent correlation was found between TEE and quantitative fluoroscopy (r = 0.898; P < 0.001) and between ICE and quantitative fluoroscopy (r = 0.876; P < 0.001), with a significant agreement (P < 0.001) and minimal positive bias toward the echocardiographic measurements. Both TEE and ICE are excellent methods of interatrial defect sizing when compared with quantitative fluoroscopic measurements.     

Pulmonary vein stenosis by ostial irrigated-tip ablation: incidence,time course,and prediction

INTRODUCTION: The incidence of pulmonary vein (PV) stenosis and its time course for ostial trigger elimination in paroxysmal atrial fibrillation (PAF) is uncertain. In addition, the clinical value of serial computed tomographic (CT) scanning of the PV ostia and the predictive value of energy requirements for radiofrequency ablation have yet to be established. METHODS AND RESULTS: We performed irrigated-tip ablation in 37 patients with drug-resistant PAF. Serial spiral CT scans were taken prospectively in 34 patients the day before the procedure, at prehospital discharge, and at 3- and 6-month follow-up. Using a clock model, energy requirements were analyzed for every segment of the PV circumference. One hundred fifteen PVs were targeted in 57 procedures. Compared to baseline, 7 (6.08 %) of 115 PV showed minor (<50%) PV stenosis. Two severe (>90%) PV stenoses (1.73%) were detected with a mean follow-up of 275 +/- 100 days. Luminal narrowing occurred most frequently in the left inferior PV (6/9 stenosed PV). Minor stenosed PVs showed their maximal luminal regression within the 3-month follow-up. Two of two PVs with narrowing >50% at 3 months progressed to high-grade stenosis. Analysis of delivered energy showed no significant correlation with the degree of stenosis. However, for the left inferior PV, more energy was applied in the superior segment of a stenotic PV (6697 +/- 930 J vs 3555 +/- 380 J, P = 0.005). CONCLUSION: Assessment of PV diameter by serial spiral CT scanning shows a low incidence of severe stenosis. The left inferior PV is at higher risk. Minor stenosed PV showed no progression after 3 months. Occurrence of stenosis tended to be related to the amount of energy delivered.     

Mechanisms of recurrent atrial fibrillation after pulmonary vein isolation by segmental ostial ablation

OBJECTIVES: The aim of this study was to determine the mechanisms responsible for recurrent atrial fibrillation (AF) after pulmonary vein isolation (PV) by segmental ostial ablation. BACKGROUND: Recovery of conduction into a previously isolated PV is a common observation when there is recurrent AF soon after segmental ostial ablation. However, the mechanisms of recurrent AF have been unclear. METHODS: A repeat ablation procedure was performed in 50 patients who had recurrent paroxysmal AF at a mean of 7 +/- 6 months after segmental ostial ablation to isolate the PVs. During the repeat procedure, a ring catheter was inserted into each PV during sinus rhythm and AF to determine whether the veins were still isolated and, if not, whether there were PV tachycardias with a cycle length shorter than in the adjacent left atrium during AF. RESULTS: There was recovery of conduction over a previously ablated muscle fascicle in >/=1 PV in 49 patients (98%). There were 10 +/- 2 episodes of PV tachycardia per minute in 36 (72%) of the 50 patients during AF. Repeat ablation was performed by segmental ostial ablation (23 patients) or by left atrial catheter ablation to encircle the left- and right-sided PVs 1 to 2 cm from the ostia, with additional ablation lines in the posterior left atrium and mitral isthmus (27 patients). At 6-month follow-up, among 23 patients who underwent repeat ablation by segmental ostial ablation, AF recurred in 4 (21%) of the 19 patients who had PV tachycardias and in 3 (75%) of the 4 patients who did not (P = .03). Among the 27 patients who underwent left atrial ablation, AF recurred in 2 (12%) of the 17 patients who had PV tachycardias and in 1 (10%) of the 10 patients who did not (P = 0.7). CONCLUSIONS: Recovery of conduction in previously ablated muscle fascicles is a common finding in patients with recurrent AF after segmental ostial ablation. The efficacy of repeat segmental ostial ablation depends on the presence of PV tachycardias, whereas left atrial ablation is effective regardless of whether PV tachycardias are present or not during AF.     

Blinded correlation study of three-dimensional electro-anatomical image integration and phased array intra-cardiac echocardiography for left atrial mapping.

AIMS: The purpose of this study was to compare, in a prospective and operator-blinded fashion, the mapping accuracy of the three-dimensional (3D) electro-anatomical image integration and phased array intracardiac echocardiography (ICE) as a real-time imaging modality. METHODS AND RESULTS: Prospectively, 18 patients undergoing pulmonary vein antrum isolation (PVAI) were included. Patients underwent a cardiac computerized tomography scan to define PV and left atrial (LA) anatomy. Image segmentation and integration was performed by CARTOMERGE, followed by 3D volume rendering and image integration. Error profiles between ICE-guided to CARTO and CARTO-guided to ICE were performed in an operator-blinded fashion over PV predetermined points. All patients underwent successful PVAI. The mean age was 55 +/- 10 years, with a mean LA size of 4.5 +/- 0.3 cm. CARTOMERGE-guided catheter positioning was subject to spatial errors on the order of 0.5-1.0 cm relative to ICE imaging, with greatest magnitude near the LA appendage (LAA) and least near the RIPV. The magnitude of spatial error between these two methods is demonstrable regardless of the choice of reference. CONCLUSION: During electro-anatomical mapping of the LA, CARTO-guided navigation is associated with considerable spatial error relative to anatomic features as identified by ICE. Adjunctive real-time imaging is needed to ensure accurate delivery of radiofrequency lesions.