Myocardium Extending from the Left Atrium onto the Pulmonary Veins: A Comparison Between Subjects with and Without Atrial Fibrillation

Rapid discharges from the myocardium extendingfrom the left atrium onto the pulmonary vein (PV) have been shown to initiate AF, and AF may be eradicated by the catheter ablation within the PV. However, if there is any difference in the distribution patterns of the myocardial sleeve onto the PV between the subjects with and without AF is to be determined. Twenty-one autopsied hearts were examined. Eleven patients previously had AF before death and another 10 patients had normal sinus rhythm as confirmed from the medical records including ECGs before death. After exposing the heart, the distance to the peripheral end of the myocardium was measured from the PV-atrial junction in each PV. Then, the PVs were sectioned and stained and the distal end of myocardium and the distribution pattern were studied. The anteroposterior diameter of the left atrium was also measured. In 74 of 84 PVs, the myocardium extended beyond the PV-atrial junction. The myocardium was localized surrounding the vascular smooth muscle layerforming a myocardial sleeve. The peripheral end of the myocardial sleeve was irregular and the maximal and minimal distances were measured in each PV. The myocardium extended most distally in the superior PVs compared to the inferior ones and the maximal distance to the peripheral end was similar between the AF and non-AF subjects (8.4 +/- 2.8 vs 8.7 +/- 4.4 mm for the left superior and 6.5 +/- 3.5 vs 5.1 +/- 3.9 mm for the right superior PV, respectively). A significant difference was found in the maximal distance in the inferior PVs: 7.3 +/- 4.6 vs 3.3 +/- 2.8 mm for the left (P < 0.05) and 5.7 +/- 2.4 vs 1.7 +/- 1.9 mm for the right inferior PV (P < 0.001) in the subjects with and without AF, respectively. The diameter of left atrium was slightly dilated in AF patients but insignificantly (4.1 +/- 0.1 vs 3.6 +/- 0.1 cm, P > 0.07). The myocytes on the PV were less uniform and surrounded by more fibrosis in patients with AF compared to those without AF. In conclusion, the myocardium extended beyond the atrium-vein junction onto the PVs. The distribution patterns of the myocardium was almost similar between subjects with and without AF, but the histology suggested variable myocytes in size and fibrosis in patients with AF.     

Three-Dimensional Reconstruction of Pulmonary Veins in Patients with Atrial Fibrillation and Controls:

PEREZ-LUGONES, A., et al.: Three-dimensional Reconstruction of Pulmonary Veins in Patients with Atrial Fibrillation and Controls: Morphological Characteristics of Different Veins. Multidetector computed tomography can be used to evaluate the anatomy of pulmonary veins (PVs) in patients with AF. The study evaluated two groups. Group 1 included 61 patients assessed following PV ablation with ultrasound or RF energy. Group 2 included 15 patients undergoing ablation for AF and 14 control subjects without a history of AF matched for age and sex. The anatomy of the PVs was analyzed in this group prior to the ablation and compared to controls. Computed tomography was used to measure the ostium of the left superior, left inferior, right superior, right inferior PVs, and the left atrial appendage size. In group 1, PV stenosis was seen in 14 (30%) of 46 patients undergoing ablation with RF energy and in none of the 15 patients receiving ablation with ultrasound energy. In group 2, the ostium size was not different between patients with AF and controls. Similarly, the ostium of the PV that appeared to trigger AF was not larger than the ostium of the remaining veins. A "clustering pattern" of PV branches near the right inferior PV ostium was seen in almost every patient, independent of the presence of the arrhythmia. Computed tomography frequently detects PV stenosis following RF ablation. Ultrasound ablation does not appear to result in PV narrowing. Overall, patients with AF do not have larger sizes of PV ostia. Multiple ramifications from the right inferior PV ostium is a common pattern and may represent a protective anatomic variant. (PACE 2003;26[Pt. I]:8–15)     

Incremental value of isolating the right inferior pulmonary vein during pulmonary vein isolation procedures in patients with paroxysmal atrial fibrillation

Electrical isolation of the left superior, left inferior, and right superior pulmonary veins (PVs) is often, but not always, effective in eliminating paroxysmal atrial fibrillation (PAF). The incremental clinical value of also isolating the right inferior PV has not been well defined. PV isolation by ostial applications of radiofrequency energy guided by PV potentials was performed in 176 consecutive patients (mean age 52 +/- 11 years) with PAF. The left superior, left inferior, and right superior PVs were targeted in 106 patients, and all four PVs were targeted 70 patients. Successful isolation was achieved in 96% of targeted PVs. The mean duration of follow-up was 15 +/- 7 months. At 1-year follow-up, 58% of patients in whom three PVs were isolated were free of recurrent PAF in the absence of antiarrhythmic drug therapy, compared to 73% of patients in whom all four PVs were isolated (P = 0.07). There is a trend towards a better outcome when all four PVs are isolated than when only the three major PVs are isolated. Whenever feasible, the right inferior PV should be isolated along with the other three PVs during the first ablation procedure in patients with PAF.     

Fiberoptic balloon catheter ablation of pulmonary vein ostia in pigs using photonic energy delivery with Diode laser

Circumferential lesions to the pulmonary vein (PV) ostia to cause conduction block at the junction of the PV and left atrium could offer a new approach during catheter ablation of patients with paroxysmal (focal) atrial fibrillation. Diode laser can deliver energy through diffusing or ring fiber tips. In three pigs weighing between 60 and 65 kg, transseptal puncture was performed and a fiberoptic balloon catheter with a collapsed profile of 10 Fr was advanced through a sheath under fluoroscopic guidance to the ostium of the right and left PVs. The balloon was inflated with a 3-cc mixture of D2O (deuterium oxide) and contrast to deliver circumferential lesions with a 15-mm diameter x 3-mm ring width of light. Applications consisted of 3.2 to 3.8 W/cm for 120 seconds; the animals were sacrificed 3 hours after ablation for pathological examination. Photonic energy was delivered successfully to the ostium of five of the five targeted PVs, and was well tolerated hemodynamically in each animal without ectopy. Gross inspection revealed endocardial lesions at the ostium of four of five PVs, confined to the atrium in each and circumferential in three of five PVs. Microscopically, transmural coagulation necrosis of the atrium was present at the ostium of three of five PVs, and extended into the myocardial sleeves of two PVs. Photonic energy delivery using a fiberoptic balloon catheter can create circumferential lesions to the PV ostia, suggesting that this new form of energy delivery may be therapeutically advantageous for pulmonary vein ablation with need to pursue chronic studies.     

Full-motion two- and three-dimensional pulmonary vein imaging by intracardiac echocardiography after pulmonary vein isolation

Background: The pulmonary veins (PVs) are topographically complex and motile, so angiographic visualization of the PVs anatomy is limited. An imaging technique that accurately portrays the pulmonary vein ( PV) anatomy would be valuable during and after catheter ablation procedures.
Purpose: We investigated whether three-dimensional (3D) intracardiac echocardiography (ICE) can visualize radiofrequency (RF)-induced tissue changes after PV isolation.
Methods: We performed 3D ICE studies with a 9F, 9-MHz ICE catheter after segmental or extended PV isolation. The ICE catheter was placed 3–4 cm inside the PV ostium and mounted onto a pullback device. Sequential two-dimensional (2D) images of the full length of the vein were obtained in 0.3 mm steps with cardiac and respiratory cycle gating. Each image was fed into a computer, and the aggregate data set was reconstructed into a 3D, full-motion image. RF lesion location and lesion size were studied on 67 pullback images from 29 patients.
Results: The 2D and 3D reconstruction was possible for 27 left superior PVs, 13 left inferior PVs, 26 right superior PVs, and one right inferior PV. The ablation site was identified 3–7 mm inside the PV ostium, and a 1/2 – 4/5 circumferential area was ablated with no clinically relevant stenosis. No significant differences were found on the ablated area or ablation site between segmental and extensive PV isolation.
Conclusion: The 2D and 3D ICE of the PVs provides detailed anatomical information of the proximal PVs, and RF-induced tissue changes in the PV wall can be visualized by ICE.     

Atrio-Pulmonary Vein Conduction Delay during Pulmonary Vein Isolation for Atrial Fibrillation Is Related to Vein Anatomy, Age, and Focal Activity

Background: During pulmonary vein isolation for treatment of atrial fibrillation (AF), a significant delay in atrio-pulmonary vein (PV) conduction is often observed. We sought to investigate this conduction delay in various PV in individual patients.
Methods: We studied 385 AF patients (mean age: 54 ± 11 years, 74 women) who underwent segmental PV isolation (PVI). A circular decapolar catheter was used to record electrograms at the PV ostia. The time delay from local atrial potential to PV potential was measured in each vein. Conduction delay (CD) was defined as the longest time interval >20 ms observed during PVI.
Results: For patients treated for the first time, CD was more frequently observed in the left common and the right and left superior PVs (84.2%, 67.9%, and 66.2%, respectively) and less frequently in the left and right inferior and right middle PVs (54.3%, 40.0%, and 30.8%, respectively). Veins with CD required more ablation applications (12.4 vs 9.9) and a higher ablated segmental fraction (72.3% vs 63.7%). CD was observed in 75.2% (109/145) of the PVs in which focal activity was detected. Older patients had a higher incidence of PVs with CD than younger patients. There were no gender differences.
Conclusions: The incidence of CD was highest in the left common and superior PVs, in older patients and in PVs with focal activity. PVs with CD required more ablation applications and a larger area of ablation around the ostia. These observations were not found during repeat procedures.     

Pulmonary vein internal electrical activity does not contribute to the maintenance of atrial fibrillation

Whether the electrical activity generated in the pulmonary veins (PVs) during atrial fibrillation (AF) contributes to the maintenance of arrhythmia is not known. The study population consisted of 22 patients (mean age 58 +/- 9.5 years, 16 men) with persistent (12 patients) or intermittent (10 patients) AF. Mapping of the left atrium (LA) was performed with a 64-electrode basket catheter. PVs were mapped simultaneously with the LA with a quadripolar catheter. PV were defined as arrhythmogenic (if frequent ectopic activity induced AF) or nonarrhythmogenic (if no ectopic activity was observed during the procedure). AF cycle lengths in arrhythmogenic and nonarrhythmogenic PV were 130 +/- 50 ms and 152 +/- 42 ms, respectively (P < 0.001). Both were significantly longer than simultaneous AF activity recorded from the posterior wall of the LA (116 +/- 49 ms, P < 0.001). AF cycle lengths in arrhythmogenic PVs as compared to nonarrhythmogenic PVs were: right superior PV 125 +/- 49 ms versus 148 +/- 51 ms; left superior PV 140 +/- 52 ms versus 161 +/- 30 ms; left inferior PV 127 +/- 48 ms versus 147 +/- 45 ms; and right inferior PV 129 +/- 38 versus 152 +/- 44 ms (P < 0.001 for all four comparisons). AF activity in the PV was more organized than in the posterior wall of the LA and the veins were activated in a proximal-to-distal direction during sustained AF episodes. In patients with AF not related to rheumatic heart disease, the posterior wall of the LA has faster activity than the PVs. The AF activity generated inside the PV during sustained AF episodes originates from the posterior wall of the LA rather than from focal firing.     

Characteristics in image integration system guiding catheter ablation of atrial fibrillation with a common ostium of inferior pulmonary veins

BACKGROUND: Common ostium of the inferior pulmonary veins (PVs) is a kind of unusual variation in pulmonary venous drainage to the left atrium (LA), whose feature of anatomy, electrophysiology, and catheter ablation is rarely demonstrated, and the consecutive series of research for catheter ablation of atrial fibrillation (AF) in patients with that anomaly have not been reported. METHODS: A total of 1,226 patients with drug-refractory AF received magnetic resonance angiography (MRA) or multidetector computed tomography (MDCT) scan before ablation. Electrophysiological mapping was used to detect the focal triggers in paroxysmal AF. Basic catheter ablation strategy was circumferential PV isolation with "tricircle" under the guidance of image integration system: two circles surround two superior PVs, and the other surround the common trunk. RESULTS: LA and PVs reconstruction by image integration system showed a common pulmonary venous ostium of the right and left inferior PVs before ablation in 11 patients (0.9%). This anomaly could be classified into two types: type A without a short common trunk of inferior PVs and type B with a short common trunk. Fifty-seven percent paroxysmal AF was revealed focal triggers in the common ostium. The success rate of that strategy was 90%. CONCLUSION: Common ostium of inferior PVs could be classified into two types according to the presence of a short common trunk or not. The common ostium was usually an important triggering focus in paroxysmal AF. Catheter ablation strategy of circumferential PV isolation with "tricircle" under the guidance of image integration system would be a good choice.     

Dilatation of the pulmonary veins in atrial fibrillation: a transesophageal echocardiographic evaluation

Ectopic beats originating from sleeves of atrial tissue within the pulmonary veins (PVs) can induce and sustain paroxysmal atrial fibrillation (AF). Left atrial stretch and dilatation favors the development of atrial ectopy and AF. Similarly, PV dilatation, if present, might trigger PV ectopy in patients with AF. This study was designed to evaluate whether PV dilatation is present in patients with nonfocal AF and whether the PV diameter correlates to the left atrial diameter (LAD). The diameters of the right superior (RSPV) and left superior PV (LSPV) were measured at the ostium and at a depth of 1 cm in 170 patients (AF, n = 75; sinus rhythm [SR], n = 95) using transesophageal echocardiography. The LAD was determined by transthoracic echocardiography. The diameters of the PVs were significantly larger in patients with AF than in patients with SR (LSPV(ostium): AF 13.6 +/- 3.5 mm vs SR 10.6 +/- 2.7 mm, P < 0.001; LSVP(1cm): AF 12.5 +/- 2.9 mm vs SR 10.2 +/- 2.5 mm, P < 0.001; RSPV(ostium): AF 13.9 +/- 3.5 mm vs SR 11.7 +/- 2.9 mm, P < 0.001; RSVP(1cm): AF 12.8 +/- 2.8 mm vs SR 10.6 +/- 2.6 mm, P < 0.05). Similarly, LAD was larger in patients with AF (44.7 +/- 7.7 mm) as compared to patients with SR (38.8 +/- 6.8 mm, P < 0.001). Neither for the SR nor the AF group did the PV size correlate to the LAD. AF is associated with a significant enlargement of the RSPV, LSPV, and LAD. There is no correlation between LAD and PV diameters. This raises the question whether PV dilatation in patients with AF is a cause or a consequence of AF and whether it may contribute to the development and perpetuation of AF.     

Characterization of the dynamic function of the pulmonary veins before and after atrial fibrillation ablation using multi-detector computed tomographic images

Understanding pulmonary vein (PV) function before and after catheter ablation can validate the benefit of the treatment and provide mechanistic insight into atrial fibrillation (AF). This study was aimed to investigate the functional remodeling process of PVs by multi-detector computed tomography (MDCT). We assessed the dynamic function of four PVs by MDCT at systolic and diastolic phases. Twelve points around each PV ostium were used to assess the magnitude and abnormalities of the regional wall motion. The axis of PV shifting during cardiac cycle was also determined. Seventy-four paroxysmal AF patients and 29 controls were enrolled. In those of AF, the superior PVs had poorer contractile function (ejection fraction: P?=?0.01 for left; P?=?0.009 for right; magnitude of the motion: P?=?0.01 for left; P?=?0.02 for right) which mainly resulted from the decreased movement of the posterior wall. In contrast, the function of inferior PVs was similar between two groups. After a mean follow-up of 158?±?95?days, the PV motion improved in the patients without any AF recurrence. In addition, analysis of the pre-ablation PV function showed that the angles, which shifted during cardiac cycle of left (P?=?0.035) and right (P?=?0.014) inferior PV, were significantly decreased in recurrent patients. The contractile function of the superior PVs was impaired in paroxysmal AF patients. This was attributed to the hypokinesia of the posterior wall of PVs and improved after circumferential ablation in the patients without recurrence. MDCT images can effectively delineate the functional characteristics of PVs.