Intra-Atrial Conduction Block Along the Mitral Valve Annulus During Accessory Pathway Ablation: Evidence for a Left Atrial "Isthmus (original) (raw)
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Pacing and Clinical Electrophysiology
Catheter ablation of accessory pathways using radiofrequency current has been shown to be effective in patients with Wolff-Parkinson-White syndrome, by using either the ventricular or atrial approach. However, the unipolar electrogram criteria for identifying a successful ablation at the atrial site are not well established. One hundred patients with Wolff-Parkinson-White were treated by delivering radiofrequency energy at the atrial site. Attempts were considered successful when ablation (disappearance of the delta wave) occurred in < 10 seconds. In eight patients with concealed pathway, the accessory pathway location was obtained by measuring the shortest V-A interval either during ventricular pacing or spontaneous or induced reciprocating tachycardia. In 92 patients both atrioventricular valve annuli were mapped during sinus rhythm, in order to identify the accessory pathway (K) potential before starting the ablation procedure. When a stable filtered (30-250 Hz) "unipolar...
Left Atrial Anatomy Relevant to Catheter Ablation
Cardiology Research and Practice, 2014
The rapid development of interventional procedures for the treatment of arrhythmias in humans, especially the use of catheter ablation techniques, has renewed interest in cardiac anatomy. Although the substrates of atrial fibrillation (AF), its initiation and maintenance, remain to be fully elucidated, catheter ablation in the left atrium (LA) has become a common therapeutic option for patients with this arrhythmia. Using ablation catheters, various isolation lines and focal targets are created, the majority of which are based on gross anatomical, electroanatomical, and myoarchitectual patterns of the left atrial wall. Our aim was therefore to review the gross morphological and architectural features of the LA and their relations to extracardiac structures. The latter have also become relevant because extracardiac complications of AF ablation can occur, due to injuries to the phrenic and vagal plexus nerves, adjacent coronary arteries, or the esophageal wall causing devastating consequences.
Pacing and Clinical Electrophysiology, 1992
SILKA, M.J., ET AL.: Analysis of Local Electrogram Characteristics Correlated with Successful Radiofrequency Catheter Ahlation of Accessory Atrioventricular Pathways. Due to the limited myocardial lesions produced hy radiofrequency current, the ablation of accessory pathways (AP) requires precise localization of such connections. The purpose of this study was to ascertain which characteristicfs) ofthe local bipolar electrogram, recorded from the abiation and adjacent electrode immediately prior to the application of radio/requency current, correlated with precision in localization adequate to permit AP ahlation. Signal analysis was performed/or 326 sets of eiectrograms preceding fhe attempted ablation of 107 APs in 100 consecutive patients. For 80 antegrade APs, the following variables were evaluated; (1) the presence or absence of an AP potential: (2} the local atriai-AP interval; (3) the local afrioventricular (AV] interval; and (4) the relationship between the onset of local ventricular depolarization and onset of delta wave of the surface electrocardiogram. For the 27 concealed APs, the following characteristics were evaluated: (1J the presence or absence of an AP potential: and (2) the local VA interval during reciprocating (achycardia or ventricular pacing. Results: Antegrade APs: By statistical analysis, the best correlate of successful abJation of an antegrade AP was a local AV interval < 40 msec (positive predictive value = 94%: 95% confidence intervals fCIj-81%-100%}. Local AV intervals < 50 msec preceded 88% of successful AP ablations, compared to only 8% of failed radiofrequency current applications. The positive predictive value of the other variables were; presence of an AP potential; 35% (95% Cl = 27%-40%): local atrial-AP intervals ^ 40 msec: 54% (95% Cl-43%-66%}: and local ventricular depolarization preceding onset of the delta wave 43% (95% Cl = 34%-52%}. For concealed APs, the positive predictive value of a VA interval < 60 msec was 71% (95% Cl = 48%-88%); the positive predictive value for the presence of an AP potential was 58% (95% Cl-32%-81%). Conclusions: No single electrogram characteristic had a positive predictive value and a sensitivity > 90% for AP Jocalization adequate for radiofrequency current ablation. For antegrade APs, the best correlate of adequate Jocalization was a local AV interval ^ 40 msec; as a corollary, radiofrequency current applications at sites where the local AV was > 60 msec, were unlikely to be effective. Objective criteria for the localization of concealed APs were less certain. EJectrogram analysis, as a guide to AP localization and ablation, requires careful analysis of multiple variables, with analysis of the local AV interval a salient objective factor.
Journal of …, 2005
Morphology and Structure of the Inferior Right Atrial Isthmus. Background: Although linear ablation of the right atrial isthmus in patients with isthmus-dependent atrial flutter can be highly successful, recurrences and complications occur in some patients. Our study provides further morphological details for a better understanding of the structure of the isthmus. Methods and Results: We examined the isthmic area in 30 heart specimens by dissection, histology, and scanning electron microscopy. This area was bordered anteriorly by the hinge of the tricuspid valve and posteriorly by the orifice of the inferior caval vein. With the heart in attitudinal orientation, we identified and measured the lengths of three levels of isthmus: paraseptal (24 ± 4 mm), central (19 ± 4 mm), and inferolateral (30 ± 3 mm). Comparing the three levels, the central isthmus had the thinnest muscular wall and the paraseptal isthmus the thickest wall. At all three levels, the anterior part was consistently muscular whereas the posterior part was composed of mainly fibro-fatty tissue in 63% of hearts. The right coronary artery was less than 4 mm from the endocardial surface of the inferolateral isthmus in 47% of hearts. Inferior extensions of the atrioventricular node were present in the paraseptal isthmus in 10% of hearts, at 1-3 mm from the endocardial surface. Conclusions: The thinner wall and shorter length of the central isthmus together with its distance from the right coronary artery, and nonassociation with the atrioventricular node or its arterial supply, should make it the preferred site for linear radiofrequency ablation.
Complete left atrial ablation with bipolar radiofrequency☆☆☆
European Journal of Cardio-Thoracic Surgery, 2008
Objective: Despite its efficacy and swiftness, bipolar radiofrequency is generally not used on the left isthmus for concern of injuring a coronary branch. Incomplete lesion sets or use of an additional unipolar device are often considered. We report a technique to perform a full left lesion set involving the mitral line using a standard bipolar radiofrequency device. Methods: An innovative complete left atrial lesion set was performed using only bipolar radiofrequency in 70 consecutive patients (study group). In 67/70 patients (96%) mitral valve disease was the main indication to surgery. Atrial fibrillation was permanent in 42 patients (60%), persistent in 25 (36%) and paroxysmal in three patients (4%). After beating-heart pulmonary vein isolation on-pump, the coronary-free area of the AV groove was marked epicardially by sticking a needle into the left atrial wall, behind the coronary sinus. The projection of the needle marker on the mitral annulus was then identified through the atriotomy and an endo-epicardial ablation was performed with the bipolar device involving the atrial wall, the coronary sinus, up to the annulus. The lesion set was then completed by connecting the encirclings and the left appendage, which was then sutured. Followup was 100% complete. Results were compared with those of a control group of 33 patients receiving bipolar radiofrequency left atrial ablations and a mitral connecting line with a second unipolar device. Results: All patients survived. No major complication occurred. Haematoma of the AV groove was observed during retrograde cardioplegia in one case. No myocardial ischaemia or re-exploration for bleeding (median 325 cc, interquartile range 250-442) occurred. Two out of 70 patients required a permanent pacemaker for AV block. Freedom from atrial fibrillation was 84% (95% CI: 75%, 93%) at 6 months and 81% (95% CI: 70%, 93%) at 1 year. One patient had left flutter. Comparison with the control group did not show any difference in clinical outcomes, but revealed bipolar ablation to the mitral annulus to abate the per patient cost of the ablation devices (1245 AE 50 s vs 2403 AE 17 s; p < 0.0001). Conclusions: Performing the mitral line with bipolar radiofrequency is safe and cost-effective. A complete left atrial ablation with a single bipolar radiofrequency device yields excellent clinical mid-term results. #
Early and Delayed Alteration of Atrial Electrograms Around Single Radiofrequency Ablation Lesion
Frontiers in Cardiovascular Medicine, 2019
Purpose: The acute effect of radiofrequency (RF) ablation includes local necrosis and oedema. We investigated the spatiotemporal change of atrial electrograms in the area surrounding the site of single standardized pulse of RF energy. Methods: The study enrolled 12 patients (45-67 years, 10 males) with paroxysmal atrial fibrillation (AF) undergoing ablation procedure with irrigated-tip ablation catheter and 3D navigation. The high-density mapping/remapping (129 ± 63 points) within the circular area with radius of ∼10 mm, centered at the pre-specified posterior left pulmonary vein antrum ablation site was performed at baseline, immediately after single RF energy delivery (25 W, 30 s, 20 ml/min) and after 30 min waiting period. Bipolar voltages of atrial electrograms (A-EGM-biV) were averaged within the central and 12 adjacent left atrium segments and their relative change was studied. Results: After the ablation, overall A-EGM-biV within the mapping zone (3.51 ± 1.89 mV at baseline) reduced to 2.83 ± 1.77 mV (immediately) and to 2.68 ± 1.58 mV (after 30 min waiting period). In per-segment pair-wise comparison, we observed highly significant change in A-EGM-biV that extended up to the distance of 8.8 mm from the lesion core. The maximum early A-EGM-biV attenuation by 39-49% (P < 0.001) was registered in segments adjacent to pulmonary vein ostia. The subsequent (delayed) A-EGM-biV reduction by 17-24% (P < 0.05) was observed in opposite direction from the lesion center. Conclusions: Significant alteration of atrial electrograms was detectable rather distant from the central lesion. Spatiotemporal development of ablation lesion was eccentric/asymmetric. While acute A-EGM-biV reduction can be attributed predominantly to direct thermal injury, delayed effects are probably due to oedema progression.