Notes: Conduction Properties of the Crista Terminalis. Introduction: Previous mapping studies in patients with typical atrial flutter have demonstrated the crista terminalis to he a posterior harrier of the reentrant circuit forming a line of block. However, the functional role of the crista terminalis in patients with or without a history of atrial flutter is not well known. The aim of this study was to determine whether the conduction properties of the crista terminalis are different between patients with and those without a history of atrial flutter. Methods and Results: The study population consisted of 12 patients with clinically documented atrial flutter (group 1) and 12 patients with paroxysmal supraventricular tachycardia as well as induced atrial flutter (group 2). A 7-French, 20-pole, deflectable Halo catheter was positioned around the tricuspid annulus. A 7-French, 20-pole Crista catheter was placed along the crista terminalis identified by the recording of double potentials with opposite activation sequences during typical atrial flutter. After sinus rhythm was restored, pacing from the low posterior right atrium near the crista terminalis was performed at multiple cycle length to 2:1 atrial capture. No double potentials were recorded along the crista terminalis during sinus rhythm in both groups. In group 1, the longest pacing cycle length that resulted in a line of block with double potentials along the crista terminalis was 638 ± 119 msec. After infusion of propranolol, it was prolonged to 832 ± 93 msec without change of the interdeflection intervals of double potentials. In group 2, the longest pacing cycle length that resulted in a line of block with double potentials along the crista terminalis was 214 ± 23 msec. After infusion of procainamide, it was prolonged to 306 ± 36 msec with increase of interdeflection interval of double potentials. Conclusion: The crista terminalis forms a line of transverse conduction block during typical atrial flutter. Poor transverse conduction property in the crista terminalis may be the requisite substrate for clinical occurrence of typical atrial flutter.

Notes: AV Junction Ablation and Pacing. Introduction: The precise role of irregular ventricular response in atrial fibrillation (AF) has not been fully elucidated. This study examined the independent effects of rhythm regularity in patients with chronic AF. Methods and Results: This study included 50 patients who had chronic lone AF and a normal ventricular rate. Among these patients, 21 who underwent AV junction ablation and implantation of a VVIR pacemaker constituted the ablation group; the other 29 patients were the medical group. Acute hemodynamic findings were measured in 21 ablation patients before ablation (during AF, baseline) and 15 minutes after ablation (during right ventricular pacing). Compared with baseline data, ablation and pacing therapy increased cardiac output (4.7 ± 0.8 vs 5.2 ± 0.9 L/min; P = 0.05), decreased pulmonary capillary wedge pressure (16 ± 5 vs 13 ± 4 mmHg; P = 0.001), and decreased left ventricular end-diastolic pressure (14 ± 4 vs 11 ± 3 mmHg; P 〈 0.05). After 12 months, the ablation group patients showed lower scores in general quality of life (−20%; P 〈 0.001), overall symptoms (−24%; P 〈 0.001), overall activity scale (−23%; P = 0.004), and significant increase of left ventricular ejection fraction (44% ± 6% vs 49% ± 5%; P = 0.02) by echocardiographic examination. Conclusion: AV junction ablation and pacing in patients with chronic AF and normal ventricular response may confer acute and long-term benefits beyond rate control by eliminating rhythm irregularity.

Notes: Right Posteroseptal Atrium and Atrium-PV Junction. introduction: The fractionated atrial electrogram. a signal helpful in identifying the target site for radiofrequency catheter ablation of the slow AV nodal pathway, is considered to arise from nonuniform anisotropic electrical activity. However, the effects of pacing sites and radiofrequency ablation on these electrograms are not clear. Similarly, the nature of the fractionated atrial electrogram in the atrium-pumonary vein junction has yet to be determined. Methods and Results: Two experiments were performed in this study. Experiment 1 evaluated the fractionated atrial electrogram at target sites before and after slow AV nodal pathway ablation during sinus rhythm or during pacing from different sites, Group 1A consisted of 16 patients with dual AV nodal pathway physiology and AV nodal reentrant tachycardia who underwent successful ablation without residual slow AV nodal pathway. Group IB consisted of 7 patients who underwent successful elimination of AV nodal reentry but with residual dual AV nodal pathway physiology. Group IC consisted of 6 patients who still had AV nodal reentrant tachycardia after two applications of radiofrequency energy. In Group 1D, there were 16 patients with dual AV nodal pathway physiology, but without inducible AV nodal reentrant tachycardia. In group 1E, there were 15 patients without dual AV nodal pathway physiology. Experiment 2 investigated the fractionated atrial electrogram in the ostium of the left and right superior pulmonary veins I 18 patients with paroxysmal strial fibrillation (2A) and in 8 patients without paroxysmal atrial fibrillation (2B). Before radiofrequency ablation, eletrogram duration in the right posteroseptal atrium during pacing from the middle coronary sinus or the right posterolateral atrium was shorter than that during pacing from the high right atrium (HRA) in all group 1 patients. After the successful elimination of the slow AV nodal pathway conduction in group 1A, atrial electrogram duration during HRA pacing was shorter than that before ablation. In experiment 2 patients, electrogram duration during pacing from the proximal or distal coronary sinus was shorter than that during pacing from HRA or sinus rhythm. Conclusion: These findings suggest that the fractionated atrial electrogrms in the right posteroseptal atrium and ostium of left or right superior pulmonary veins are potentially consistent with nonuniform anisotropic propagation. Alternations of electrogram characteristics after successful radiofrequency ablation of the slow AV nodal pathway may arise from the changes of nonuniform anisotropic activity in the right posteroseptal atrium.

Notes: Pulmonary Vein Ablation-Induced Bradycardia. Introduction: Information is lacking about the occurrence of radiation-related proarrhythmic events during application of radiofrequency (RF) energy at (he pulmonary veins in patients with paroxysmal focal atrial fibrillation. The purpose of this study was to assess the theoretical risk of reflex bradycardia and hypotension response during RF ablation of these regions rich in endocardial nerve terminals. Methods and Results: Among the 40 consecutive patients (29 men, 11 women; mean age 65 ± 12 years) with clinically documented frequent attacks of paroxysmal atrial fibrillation who underwent superior pulmonary vein ablation for left local atrial fibrillation, 6 patients (15%) developed bradycardia-hypotension syndrome during energy delivery. A single atrial fibrillation trigger focus in the left or right superior pulmonary vein was found in 3 and 1 patients, respectively. Two patients had two trigger foci originating from the orifice or proximal part of both superior pulmonary veins. After RF current was applied for a period of 14 ± 10 seconds, 2 patients developed functional rhythm and sinus bradycardia, another 2 patients had profound sinus bradycardia, I patient had two episodes of sudden onset of complete AV block with resultant 9.5-second a systole, and I patient showed profound sinus bradycardia, transient AV block, and an K-second asystole due to sinus arrest. Blood pressure fell when any substantial bradyarrhythmias occurred. All 6 patients were free of rhythm disturbances during The postablation follow-up period (mean 8 ± 2 months). Conclusion: RF catheter ablation of the pulmonary vein tissues could evoke a variety of profound bradycardia-hypotension responses. The Bezold-Jarisch-like reflex might be the underlying mechanism.

Notes: Arrhythmosenic Foci of Atrial Fibrillation. Introduction: Use of endocardial atrial activation sequences from recording catheters in the right atrium. His bundle, and coronary sinus to predict the location of initiating foci of atrial fibrillation (AF) before an atrial transseptal procedure has not been reported. The purpose of the present study was to develop an algorithm using endocardial atrial activation sequences to predict the location of initiating foci of AF before transseptal procedure. Methods and Results: Seventy-five patients (60 men and 15 women, age 68 ± 12 years) with frequent episodes of paroxysmal AF were referred for radiofrequency ablation. By retrospective analysis, characteristics of the endocardial atrial activation sequences of right atrial, His-bundle, and coronary sinus catheters from the initial 37 patients were correlated with the location of initiating foci of AF, which were confirmed by successful ablation. The endocardial atrial activation sequences of the other 38 patients were evaluated prospectively to predict the location of initiating foci of AF before transseptal procedure using the algorithm derived from the retrospective analysis. Accuracy of the value 〈0 msee (obtained by subtracting the time interval between high right atrium and His-bundle atrial activation during atrial premature beats from that obtained during sinus rhythm) for discriminating the superior vena cava or upper portion of the crista terminalis from the pulmonary vein (PV) foci was 100%. When the interval between atrial activation ostial and distal pairs of the coronary sinus catheter of the atrial premature beats was 〈0 msec, the accuracy for discriminating left PV foci from right PV foci was 92% in the 24 foci from the left PVs and 100% in the 19 foci from the right PVs. Conclusion: Endocardial atrial activation sequences from right atrial, His-bundle, and coronary sinus catheters can accurately predict the location of initiating foci of AF before transseptal procedure. This may facilitate mapping and radiofrequency ablation of paroxysmal AF.

Notes: Introduction: High recurrence rate is still a major problem associated with ablation of paroxysmal atrial fibrillation (AF). Most of the recurrences occur within 6 months after ablation. The characteristics of very late recurrent AF (〉12 months after ablation) have not been reported. Methods and Results: Two hundred seven patients with drug-refractory AF underwent successful focal ablation or isolation of AF foci. After the first ablation procedure, Holter monitoring and event recorders were used to evaluate symptomatic recurrent AF. A second ablation procedure was recommended if the antiarrhythmic drugs could not control recurrent AF. During long-term follow-up (mean 30 ± 11 months, up to 51 months), 70 patients had recurrent AF, including 13 patients (6%) with very late (〉12 months) recurrent AF (group 1) and 57 patients (28%) with late (within 12 months after ablation) recurrent AF(group 2). Group 1 patients had a significantly lower incidence of multiple (≥2) AF foci (23% vs 63%, P = 0.02) than group 2 patients. In addition, the incidence of antiarrhythmic drugs use (38% vs 84%, P = 0.001) to maintain sinus rhythm after the first episode of recurrent AF was significantly lower in group 1 than group 2 patients, and the incidence of a second intervention procedure (8% vs 35%, P = 0.051) tended to be lower in group 1 than group 2 patients. Conclusion: The incidence of very late recurrent AF after ablation of paroxysmal AF is very low, and the clinical outcome of patients with very late recurrent AF is benign. (J Cardiovasc Electrophysiol, Vol. 14, pp. 598-601, June 2003)

Notes: Introduction: The superior vena cava (SVC) and right superior pulmonary vein (RSPV) are anatomically close structures. Using 12-lead ECG may facilitate identification of ectopic foci from SVC or RSPV. The aim of this study was to assess whether P wave polarity on surface ECG is helpful in distinguishing an arrhythmogenic focus of paroxysmal atrial fibrillation (AF) from SVC or RSPV. Methods and Results: Thirty-four patients with paroxysmal AF from the SVC (group I: 17 patients, 10 men and 7 women; mean age 57 ± 12 years ) or RSPV (group II: 17 patients, 15 men and 2 women, mean age 62 ± 14 years ) underwent electrophysiologic study and radiofrequency (RF) catheter ablation. All of the AF foci were confirmed by successful ablation. P wave polarities on surface ECG inferior leads were positive during sinus rhythm and ectopic beats in both groups. Leads I, aVR, aVL, and V1 were further analyzed. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) in predicting an arrhythmogenic focus of AF from SVC or RSPV were provided. P wave polarity in lead aVR was negative in all 34 patients. P wave polarity in lead V1 was positive in 47.1% of SVC ectopy but positive in all RSPV ectopy. The combination of a biphasic or isoelectric P wave polarity in lead V1 or a biphasic P wave polarity in lead aVL had a sensitivity of 71%, specificity of 82%, PPV of 80%, and NPV of 74% in predicting an arrhythmogenic focus of AF from SVC. Conclusion: P wave polarity in leads V1 and aVL may predict an arrhythmogenic focus of AF from SVC or RSPV. (J Cardiovasc Electrophysiol, Vol. 14, pp. 350-357, April 2003)

Notes: Pulmonary Vein Electrogram in Paroxysmal AF. Introduction: The major source of ectopic beats initiating paroxysmal atrial fibrillation (AF) is from pulmonary veins (PVs). However, the electrogram characteristics of PVs are not well defined. Methods and Results: Group I consisted of 129 patients with paroxysmal AF. (Group II consisted of 10 patients with a concealed left-sided free-wall accessory pathway. All group I patients bad spontaneous AF initiated by ectopic beats, including 169 ectopic foci originating from the PVs. We analyzed PV electrograms from the 169 ectopic foci during sinus beats and ectopic beats. During AF initiation, most (70%) ectopic beats showed PV spike potential followed by atrial potential; 16% of ectopic beats showed PV fragmented potential followed by atrial potential; and 14% showed fusion potentials. The coupling interval between the sinus beat and the ectopic beat was significantly shorter in the inferior PVs than in the superior PVs (171 ± 48 msec vs 222 ± 63 msec. P = 0.0((l) and was significantly shorter in the distal foci than in the ostial foci of PVs (206 ± 52 msec vs 230 ± 56 msec, P = 0.01). The incidence of conduction block in the PVs during AF initiation was significantly higher in the inferior PVs than in the superior PVs (12/24 vs 37/145, P = 0.03) and was significantly higher in the distal foci than in the ostial foci of PVs (43/121 vs 6/48, P = 0.04). The maximal amplitude of PV potential was significantly larger in the left PVs than in the right PVs, and the maximal duration of PV potential was significantly longer in the superior PVs than in the inferior PVs during sinus beats in both group I and II patients. Conclusion: PV electrogram characteristics were different among the four PVs. Detailed mapping and careful interpretation are the most important steps in ablation of paroxysmal AF originating from PVs.

Notes: Ablation of AF Initiated by PV Ectopic Beats. Ectopic beats from the pulmonary veins (PVs) have been demonstrated to initiate atrial fibrillation (AF). This article describes the conceptual approach to mapping, interpretation of different electrograms, and ablation of AF initiated by PV ectopic beats.