Does the Age Affect the Fluoroscopy‐Guided Transseptal Puncture in Catheter Ablation of Atrial Fibrillation?

BACKGROUND: The anatomical differences with age may raise difficulty in determining the proper positioning of the transseptal puncture site in the therapeutic left heart catheterization. This study investigated whether age affects the fluoroscopy-guided transseptal puncture in the catheter ablation of atrial fibrillation. METHODS AND RESULTS: Fifty patients (52 +/- 12 years, 35 men) who underwent ablation for paroxysmal/persistent atrial fibrillation were included. The patients were divided into two groups according to their age (cut-point 50 y/o): young group (n = 20) and old group (n = 30). In the 30 degrees right anterior oblique view (RAO), the width between the transseptal puncture site and coronary sinus ostium (H (N-CSO)) was longer in old-age group (14.4 +/- 9.4 vs 10.9 +/- 10.4 mm, P = 0.034). In the 60 degrees left anterior oblique view (LAO) view, the angle of the direction of the transseptal needle (N-angle) was less in the old-age group (56.0 +/- 10.0 degrees vs 58.4 +/- 9.8 degrees , P = 0.041). The ratio of the transseptal puncture site-coronary sinus ostium (CSO) distance over the distance between the superior vena cava-right atrial junction and CSO (V(N-CSO)/V(J-CSO)) was significantly higher in the old-age group (0.73 +/- 0.12 vs 0.63 +/- 0.2, P = 0.009). CONCLUSION: The transseptal puncture site in the RAO view moved higher and more posterior and the transseptal puncture angle in the LAO view decreased with age. These findings highlight the influence of age on the atrial anatomy and transseptal puncture site.     

Progressive remodeling of the atrial substrate--a novel finding from consecutive voltage mapping in patients with recurrence of atrial fibrillation after catheter ablation

Background: Atrial substrate properties have been demonstrated to be related to atrial arrhythmias. This study investigated whether the atrial substrate exhibits progressive remodeling in patients with recurrence of atrial fibrillation (AF) after catheter ablation.
Methods and Results: Fifteen consecutive AF patients (52 ± 12 years old, 12 males) underwent the same mapping technique (NavX, St. Jude Medical, Minnetonka, MN, USA) and same ablation technique for primary AF and recurrence of AF (170 ± 66 days after the first procedure). The bipolar mean peak-to-peak voltage (PPV) of the global left atrium during sinus rhythm significantly decreased in the second procedure (2.25 ± 0.62 vs. 1.79 ± 0.60 mV, P = 0.008). Also, the percentage of the surface area of the low voltage zone (LVZ; less than 0.5 mV) in the left atrium increased from 6 ± 4% to 13 ± 6% (P = 0.001) in the second procedure. There was no significant change in the right atrial bipolar mean PPV or surface area of the LVZ in the second procedure.
Conclusion: Atrial substrate remodeling with a progressive decrease in the left atrial voltage was demonstrated in patients with recurrent AF.     

The electroanatomic characteristics of the cavotricuspid isthmus: implications for the catheter ablation of atrial flutter

Introduction: Radiofrequency ablation (RFA) of typical AFL is sometimes difficult because of the poor electroanatomic approach to the cavotricuspid isthmus (CTI). The aim of this study was to correlate the anatomy of the CTI between contact mapping (NavX) and right atrial angiography (RAG), and to investigate the impact of the electroanatomic characteristics of the CTI on the RFA of typical atrial flutter (AFL).
Methods: One hundred patients with typical AFL undergoing RFA were studied. The image-guided group consisted of 50 consecutive patients with the guidance of NavX. NavX geometry and RAG were performed to investigate the morphology of the CTI. The bipolar voltages of the CTI were collected during sinus rhythm by a NavX. The control group consisted of 50 consecutive patients with the guidance of conventional fluoroscopy.
Results: There was a good correlation between the angiography and NavX for the anatomy of the CTI. The pouch type had a longer length of CTI than the flat type (33.4 ± 5.0 vs 22.6 ± 8.4 mm, P < 0.0001) and deeper depth than the concave type (6.5 ± 2.2 vs 3.7 ± 0.8 mm, P < 0.0001) on the angiography. The pouch-type CTI had a longer ablation time and larger pulses of RFA than the other two types. The control group had a longer ablation time, fluoroscopy time, and larger pulses of RFA than image-guided group.
Conclusions: The 3-D mapping system provided a good reconstruction of CTI, which may help in the RFA in patients with a complex anatomy of the CTI.     

Biatrial substrate properties in patients with atrial fibrillation

Introduction: The atrial substrate plays an important role in the maintenance of atrial fibrillation (AF). Further investigation of the biatrial substrate may be helpful for understanding the mechanism of AF. The aim of this study was to investigate the properties of right and left atrial (RA and LA) substrate in AF patients and their impact on the catheter ablation.
Methods: Biatrial electroanatomic mapping using a three-dimensional mapping system (NavX) was performed in 117 consecutive patients with paroxysmal (n = 99) and persistent (n = 18) AF. The biatrial voltage and total activation time (TAT) were obtained during sinus rhythm.
Results: The LA had a lower voltage (1.6 ± 0.5 vs 2.0 ± 0.6 mV, P < 0.001) than the RA. The TAT correlated with the voltage (r =–0.65, P< 0.001). The patients with persistent AF had a lower atrial voltage, higher coefficient of variance for the LA voltage, longer LA TAT, and more extensive scar than those with paroxysmal. The patients with recurrent AF after catheter ablation had a lower LA voltage and higher incidence of LA scarring than those without recurrence. A scar located in the low anteroseptal or low posterior wall of LA was related to recurrence of AF. LA scarring was the independent predictor of AF recurrence after catheter ablation.
Conclusion: The LA voltage was lower than the RA, and the atrial voltage correlated with the TAT. Electroanatomical remodeling of the atria could be crucial to the maintenance of AF. The LA substrate properties may play an important role in the recurrence of AF after catheter ablation of AF.     

Substrate mapping to detect abnormal atrial endocardium with slow conduction in patients with atypical right atrial flutter.

OBJECTIVES: The purpose of this study was to investigate the relationship between the abnormal substrate and peak negative voltage (PNV) in the right atrium (RA) with atypical flutter. BACKGROUND: The impact of a local abnormally low voltage electrogram on the local activation pattern and velocity of atrial flutter (AFL) remains unclear. METHODS: Twelve patients with clinically documented AFL were included to undergo noncontact mapping of the RA. The atrial substrate was characterized by the: 1) activation mapping; 2) high-density voltage mapping; and 3) conduction velocity along the flutter re-entrant circuit. The normalized PNV (i.e., the relative ratio to the maximal PNV) in each virtual electrode recording was used to produce the voltage maps of the entire chamber. The protected isthmus was bordered by low voltage zones. RESULTS: Atypical AFL of the RA was induced by atrial pacing in 12 patients, including 10 upper loop re-entry and 2 RA free wall re-entry flutter. These protected isthmuses were located near the crista terminalis. The mean width of the protected isthmus was 1.7 +/- 0.3 cm and mean voltage at the isthmus was -0.91 +/- 0.39 mV. The conduction velocities within these paths were significantly slower than outside the path (0.30 +/- 0.18 m/s vs. 1.14 +/- 0.41 m/s, respectively; p = 0.004). The ratiometric PNV of 37.6% of the maximal PNV had the best cut-off value to predict slow conduction, with a high sensitivity (92.3%) and specificity (85.7%). CONCLUSIONS: Characterization of the RA substrate in terms of the unipolar PNV is an effective predictor of the slow conduction path within the critical isthmus of the re-entrant circuit.     

Preexisting pulmonary vein stenosis in patients undergoing atrial fibrillation ablation: a report of five cases

INTRODUCTION: Acquired pulmonary vein (PV) stenosis is a well-known complication following catheter ablation of atrial fibrillation (AF). However, the details of congenital PV stenosis have not been reported in patients who underwent catheter ablation of AF. METHODS AND RESULTS: A total of 178 patients (110 men, age: 54 +/- 11 years) with drug-refractory AF received MRA or multidetector CT (MDCT) before ablation for delineation of PV morphologies. Five PVs in 5 patients (2.8%) showed at least 50% stenosis before ablation. We demonstrated two types of preexisting PV stenosis. Type I is the external compression of PV by the descending aorta, observed in LIPV of the three patients. Type II is the focal narrowing of PV, observed in RSPV of the two patients. CONCLUSION: Preexisting stenosis of PV may be a consequence of congenital focal narrowing or external compression by the adjacent structures. Detection of this condition by 3D CT or MRA before catheter ablation can provide information for planning of ablation strategy and prevent misdiagnosis of ablation-related PV stenosis.     

Anatomic characteristics of the left atrial isthmus in patients with atrial fibrillation: lessons from computed tomographic images

Introduction: Left atrial (LA) isthmus ablation was reported to improve the success rate of catheter ablation of paroxysmal atrial fibrillation (AF). LA isthmus ablation could also cure a subset of LA flutter. Therefore, understanding the anatomy of the LA isthmus is important for performing the ablation effectively.
Methods and Results: Group I included 45 patients (40 male, mean age = 50 ± 13 years) with paroxysmal AF who underwent catheter ablation. Group II included 45 patients (37 male, mean age = 54 ± 10 years) without a history of AF. They underwent a 16-slice multidetector computed tomography (MDCT) scan to delineate the LA structures before the ablation procedure. The average length of the LA isthmus was longer in group I than in group II (lateral isthmus: 3.30 ± 0.68 vs 2.71 ± 0.60 cm, P < 0.001; medial isthmus: 5.12 ± 0.94 vs 4.45 ± 0.63 cm, P < 0.001), and morphological patterns of lateral and medial isthmus were similar between groups. In addition, the average depth of lateral isthmus was similar between groups (0.62 ± 0.32 vs 0.55 ± 0.33 cm, P = 0.41), but the average depth of medial isthmus was larger in group I than in group II (0.60 ± 0.32 vs 0.44 ± 0.25 cm, P = 0.01). The medial isthmus had more ridges, as compared to the lateral isthmus (13% vs 0%, P = 0.026). Furthermore, the distances between esophagus and lateral isthmus were longer in group I than in group II (at the middle of isthmus and mitral annulus level: 21.0 ± 4.8 vs 18.4 ± 6.0 mm, P < 0.001; and 37.1 ± 5.7 vs 29.6 ± 8.1 mm, P < 0.001, respectively).
Conclusion: The LA isthmus was longer in the AF patients. The morphology of the isthmus was variable. Compared with the lateral isthmus, the medial isthmus was longer and had more ridges. A peculiar configuration of the isthmus provided by CT images could influence the ablation strategy.     

Effects of a Na+/Ca2+ exchanger inhibitor on pulmonary vein electrical activity and ouabain-induced arrhythmogenicity

OBJECTIVE: Pulmonary veins (PVs) are the most important focus for generation of atrial fibrillation. The Na(+)/Ca(2+) exchange (NCX) current is important in PV electrical activity and cardiac glycosides-induced arrhythmias. The purpose of this study was to investigate whether KB-R7943, a NCX current blocker with preferential inhibition of the Ca(2+) influx, may alter PV electrophysiological characteristics and reduce glycoside-induced arrhythmogenicity. METHODS: Conventional microelectrodes were used to record the effects of KB-R7943 on action potentials and contractility in isolated rabbit PV tissue specimens with and without administration of ouabain. The ionic currents and intracellular calcium were studied in isolated single cardiomyocytes before and after KB-R7943 by the whole-cell patch clamp and indo-1 fluorimetric ratio techniques. RESULTS: KB-R7943 (0, 3, 10, 30 microM) concentration-dependently prolonged APD(50) and APD(90) and decreased the PV firing rates (2.3 +/- 1.2 Hz, 2.1 +/- 1.2 Hz, 1.9 +/- 0.9 Hz, 1.7 +/- 1.1 Hz, n = 7, p < 0.05) and incidences of delayed afterdepolarizations (DADs). KB-R7943 (3, 30 microM) decreased transient inward currents, Ca(2+) transient and sarcoplasmic reticulum Ca(2+) content. Ouabain (0, 0.1, 1 microM) concentration-dependently increased the PV firing rates and DADs in PVs with spontaneous activity (n = 7) and induced nonsustained spontaneous activity (1 microM) in the PVs without spontaneous activity (n = 14). However, in the presence of KB-R7943 (30 microM), ouabain (1 microM) did not increase the PV firing rates or induce spontaneous activity in the PVs without spontaneous activity (n = 7). CONCLUSIONS: KB-R7943 reduces the PV arrhythmogenic activity and prevents the ouabain-induced arrhythmogenicity. Our findings support the role of the NCX current in the PV electrical activity.