The differences between posteroseptal and the other atrioventricular accessory pathways: the coronary sinus morphology and the conduction over accessory pathways

Abstract

62.2±4.5 mV, p<0.0t), maximal diastolic potential (80.4±2.2 vs. 58.7±5.4 mV, p<0.05), dV/dt (156.6±12.7 vs. 26.4±6.5 V/sec, p<0.05), and ADPg0 (208.3±7.2 vs. 145.2±7.4 ms, p<0.01), consistent with slow conduction and unidirectional block occurred in the BZ. In conclusion, sustained monomorphic VTs developed after MI were due to functional spiral wave reentry or anatomic macroreentry around the infarction area. Both types of reentries involved in the BZ with delayed conduction and unidirectional block. Background: Increased left atdal volume (LAV) is associated with a higher risk of recurrent atdal fibdllation (AF) and atdal arrhythmias. Two-dimensional (2-D) transthorecic echocardio- graphy is validated as a reliable method by which to assess LAV compared to cine-computed tomography (cine-CT). Using the biplane method of disks, LAV measured by transthoracic echocardiography is well correlated with that obtained by cine-CT, but under estimates the LAV by 20-32%. Magnetic electroanatomic mapping (MEAM) is valuable for defining the ana- tomic location of catheter-based electrophysiologic recordings by creating a detailed shell of the endocardial anatomy in three-dimensional that can help guide focal AF ablation. We sought to validate the accuracy of volume measurements by MEAM by compadng MEAM LAV measurements against those measured by two-dimensionaJ transthoracic echocardiogrephy. Methods: Forty-seven patients underwent 2-D echocardiography and detailed MEAM of the left atdum (LA). The entire LA was mapped with 78-224 distinct points (mean 126 ± 37) acquired dudng atdal end-diastole, MEAM measurement of LAV was computed by using the built-in volume function of the Biosense TM system. The LAV was assessed using 2-D tran- sthoraclc echocardiography by the biplane methods of disks. The endocardial outlined was digitally traced in the apical 4-chamber and 2-chamber views at end-atrial diastole with exclu- sion of the pulmonic veins and appendage. Results: The LAV by 2-D echocardiography was 92.7 + 25.9 cc versus the LAV by MEAM which was 125.4 + 28,4 cc. There is good correlation between the results of echocardio- graphy and MEAM (r=0.90, p<0.001) for LAV, although the average value obtained by echocardiography is about 26% lower than that obtained by MEAM. Conclusions: Magnetic electroanatomic catheter mapping appears to be a retiable method by which to assess LAV. The results of MEAM correlate well with the echocardiographic assessments of LAV. Echocardiography underestimates LAV by a similar percentage when compared to MEAM as it does when compared to cine-CT. MEAM may prove useful in track- ing LAV with repeat mapping procedures and helping to plan post.ablative management. Bmckorounds: There were few reports about the differences between posteroseptal and the other atdoventdcular accessory pathways lAPs) in anatomy and electrophysiology. Methods: The size and shape of coronary sinus (CS) were measured in 21 patients with posteroseptal APs (11 right and 10 Jeff posteroseptal wall), 83 with the other APs (63 left lateral, 13 right lateral, 7 right anteroseptal wall) and 25 control subjects after CS angiogra- phy. CS diameter and morphoiogic features were measured. In 38 patients with APs, we investigated the electrophysiological charactedstics about anterograde and retrograde con- duction over APs, Rssults: The proximal CS in patients with posteroseptal APs was larger than in those with the other APs and the control (13.8 +/- 1.3 mm vs. 10.9 +/- 2.1 mm (p < 0.001) and 9.7 +/- 1.5 mm (p < 0.001), respectively). At a distance of 5 mm from the CS ostium, the CS mea- sured 10.8 +/- 0.8 mm, compared with 8.9 +/- 1.9 mm (p < 0.05) and 8.2 +/- 1.8 mm (p < 0.01). The dilatation persisted 10 mm into the CS, with the measurement of 8.6 +/- 1.2 mm, compared with 7.5 +/- 1.8 mm (p<0.05) and 7.2 +/- 1.7 mm (p<0.05). There were no differ- ences in these distal diameter, tn 67% of patients with posteroseptal APs, the proximal CS had the wind-cone appearance. This morphology was found in 16% of patients with the other APs. In all of control subjects and 84% of patients with the other APs, the CS was the tubular. Only 1 patient with a posteresaptal AP had retrograde and anterograde decremen- tal conduction over the AP. Three patients with postereseptal APs, 2 with left lateral, 2 with dght rataral and 1 with anteroseptal had only retmgrada conduction. Posteroseptal APs with dacramental conduction were located only in the right side. C.onclusions: The larger size of proximal CS was a structural characteristics in patients with posterosaptal APs. The appearance of proximal CS was like a wind-cone in these patients. Right posteroseptal APs were prone to have the high incidences of decremental conduction. These findings may have a clue to trace arrthythmia pathogenesis to its origin.