| ObjectivesCoronary sinus (CS) diverticula have been associated with posteroseptal and left posterior accessory pathways. These diverticula contain myocardial fibers that connect to both the ventricle and the CS myocardial coat. The CS myocardial coat, present in all individuals, is anatomically and electrically connected to both atria. Completing the accessory connection.We hypothesized that a connection between the CS myocardial coat and the ventricle could produce an accessory pathway (CSAP) in the absence of a diverticulum(Figure 1). In an anatomic study of 240 human hearts, von Ludinghausen and coworkers found sleeve -like extensions of the CS myocardial coat covering the terminal portion of the middle cardiac vein and posterior vein in 3% and 2% of hearts, respectively. They also found myocardial cords extending around the atrioventricular groove branch of the distal left circumflex coronary artery in 6% of hearts. These myocardial sleeves or cords could serve as a connection between the ventricle and the CS myocardial coat, forming a CSAP.The purpose of the present study was to use CS and its tributaries to identify electrophysiological criteria for CSAP and to determine the incidence and relationship between CSAPs and anatomy of the CS and its branches, including diverticula and to find the best method of catheter ablation of AP andits safety.MethodsThe study population consisted of 480 consecutive patients referred for catheter ablation of a posteroseptal or left posterior accessory pathway.Retrograde CS angiography was performed in all patients suspected of having a CSAP . An angiographic catheter with a compliant balloon located close to the tip was inserted into the CS and great cardiac vein. The balloon was inflated with 0.5 to 1.5 ml of air to occlude the great cardiac vein. Contrast media (5 to 15 ml) was slowly injected, filling the venous system distal to the balloon.The earliest endocardial ventricular activation (rapid downstroke on the unfiltered unipolar electrogram, local V, was recorded >15 ms after the onset of the far-field ventricular potential at a site located >1 cm apical to the tricuspid and mitral annuli. Ventricular activation recorded from the MCV, PCV, or CS diverticulum preceded endocardial ventricular activation. A high frequency potential similar to an antegrade accessory pathway activation potential, presumably generated by an extension of the CS myocardial coat was recorded from the MCV, PCV, or neck of a CS diverticulum before the earliest far-field ventricular potential, and the antegrade CSE potential was dissociated from local atrial and ventricular activation by the use of ventricular extrastimuli.ResultsCSAP was defined by accessory pathway(AP) potential or earliest activation in the MCV or PCV and late activation at anular endocardial sites. A CSAP was identified in 171 of 480 patients undergoing ablation of a posteroseptal or left posterior AP. CS angiography revealed a CS diverticulumin 36(21%) and fusiform or bulbous enlargement of the small cardiac vein, MCV, or CS in 15(9%) patients. The remaining 120(70%) patients had an angiographically normal CS. A CSMC extention potential(CSE), like an AP potential, was recorded in the MCV in 98(82%), in the PCV in 13(11%), in both the MCV and PCV in 6(5%), and in the CS in 3(2%) of 120 patients. CSMC potentials were recorded between the timing of atrial and CSE potentials. In 98 patients with CS angiography, the successful rate of ablation in the ideal target sites was 100% in patients with the distance more than 2mm between target site and coronary artery and no coronary arterial injury. Although the successful rate was also 100% in patients with the distance equal to or less than 2mm, but 63% patients had coronary arterial injury. The successful rate of intravenous ablation with small distance away from ideal ablation site was 67%, and 74% for extravenous ablation, (including isolation between CS and left atrium by ablation.)Conclusionl.CSAPs are formed by CS and the conne...
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