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Background— The vein of Marshall (VOM) is an attractive target during ablation of atrial fibrillation because of its autonomic innervation, its location anterior to the left pulmonary veins, and its drainage in the coronary sinus. Methods and Results— We studied 17 dogs. A coronary sinus venogram showed a VOM in 13, which was successfully cannulated with an angioplasty wire and balloon. In 5 dogs, electroanatomical maps of the left atrium were performed at baseline and after ethanol infusion in the VOM, which demonstrated a new crescent-shaped scar, extending from the annular left atrium toward the posterior wall and left pulmonary veins. In 4 other dogs, effective refractory periods (ERP) were measured at 3 sites in the left atrium, before and after high-frequency bilateral vagal stimulation. The ERP decreased from 113.6�35.0 to 82.2�25.4 ms ( P P =NS). The abolition of vagal effects was limited to sites near the VOM (ERP, 104�14 versus 98.6�12.2 ms postvagal stimulation; P =NS), as opposed to sites remote to VOM (ERP, 107.2�14.9 versus 78.6�14.7 ms postvagal stimulation; P Conclusions— Ethanol infusion in the VOM achieves significant left atrial tissue ablation, abolishes local vagal responses, and is feasible in humans.

Multiple imaging modalities are employed independent of one another while managing complex cardiac arrhythmias. To combine electrical, anatomical, and functional imaging in a single catheter system, we developed a balloon catheter that carried 64 electrodes on its surface and an intracardiac echocardiography (ICE) catheter through a central lumen. The catheter system was inserted, and the balloon was inflated inside the left ventricle (LV) of eight dogs with 6-wk-old infarction, created by occlusion in the left anterior descending coronary artery. Anatomy was constructed by ICE imaging (9 MHz) through the balloon. Single-beat noncontact mapping (NCM) was performed via the multielectrode array to reconstruct unipolar endocardial electrograms during sinus rhythm. Standard contact mapping (CM) of the endocardium was also carried out for reference. Myocardial infarction in anterior LV extending from the middle to apical regions was localized both by ICE and NCM and validated by CM and pathology. The overall difference in the activation times between NCM and CM was 3 ± 1 ms. Unipolar voltage in infarcted middle anterior LV was smaller than the voltage in normal middle inferior LV both by NCM (11 ± 4 vs. 16 ± 3 mV; P = 0.002) and CM (11 ± 3 vs. 20 ± 4 mV; P < 0.001). Unipolar voltage was also inversely related to infarct transmurality, both by NCM ( r = −0.87; P = 0.005) and CM ( r = −0.94; P < 0.001). The infarct area by ICE (7.7 ± 2.9 cm2) was in agreement with CM (bipolar voltage, 2; r = 0.80; P = 0.016). Meanwhile, the voltage threshold that depicted the infarct area by NCM was directly related to the smallest unipolar voltage reconstructed within the infarct ( r = 0.96; P < 0.001). In conclusion, combining NCM and ICE imaging in a single catheter system is feasible. The preclinical development of such an integrated system and its evaluation in experimental myocardial infarction demonstrate capabilities for single-beat mapping at multiple sites as well as the online assessment of anatomy and myocardial function.

Objectives The aim of this study was to validate a novel, angle-independent, feature-tracking method for the echocardiographic quantitation of regional function. Background A new echocardiographic method, Velocity Vector Imaging (VVI) (syngo Velocity Vector Imaging technology, Siemens Medical Solutions, Ultrasound Division, Mountain View, California), has been introduced, based on feature tracking—incorporating speckle and endocardial border tracking, that allows the quantitation of endocardial strain, strain rate (SR), and velocity. Methods Seven dogs were studied during baseline, and various interventions causing alterations in regional function: dobutamine, 5-min coronary occlusion with reperfusion up to 1 h, followed by dobutamine and esmolol infusions. Echocardiographic images were acquired from short- and long-axis views of the left ventricle. Segment-length sonomicrometry crystals were used as the reference method. Results Changes in systolic strain in ischemic segments were tracked well with VVI during the different states of regional function. There was a good correlation between circumferential and longitudinal systolic strain by VVI and sonomicrometry (r = 0.88 and r = 0.83, respectively, p Conclusions Velocity Vector Imaging, a new feature-tracking method, can accurately assess regional myocardial function at the endocardial level and is a promising clinical tool for the simultaneous quantification of regional and global myocardial function.

The vein of Marshall (VOM) is an attractive target during ablation of atrial fibrillation due to its autonomic innervation and its location anterior to the left pulmonary veins and drainage in the coronary sinus. We studied 14 dogs. A coronary sinus venogram showed a VOM in 10, which was successfully cannulated with an angioplasty wire and a 2 mm balloon. In 5 dogs, electroanatomical (Carto) maps of the left atrium were performed at baseline and after ethanol (100%, 4 – 8 cc) was infused in the VOM, which demonstrated the creation of a new crescent-shaped scar in the left atrium, extending from the annular left atrium towards the posterior wall and left pulmonary veins. In 4 dogs, both cervical vagal trunks were isolated in the carotid sheath and cuff stimulation electrodes were attached to them. Effective refractory periods (ERP) were measured in 3 sites of the left atrium, before and after high-frequency bilateral vagal stimulation. The baseline ERP was 113.6±35.0 ms, and decreased to 82.2±25.4 ms (p

Imaging RF Ablation Lesions. Introduction: The inability to determine the extent and intramural depth of ablation lesions can hamper the success of catheter ablation. The study tested the feasibility of differentiating radiofrequency ablation lesions from normal myocardium and quantifying their dimensions by myocardial contrast echocardiography (MCE). Methods and Results: In 11 normal dogs, we created 14 focal and 4 linear lesions at different left ventricular sites. MCE was performed both before and after ablation by using an intracardiac echocardiography catheter (9 MHz) and infusing contrast microbubbles through the left coronary artery. We initially used two-dimensional MCE to image focal lesions and subsequently three-dimensional MCE to image linear lesions. An independent observer examined the lesion pathology. We found that intracardiac echocardiography alone could not delineate lesion dimensions. However, after ablation, MCE localized the lesions as well-defined, low-contrast areas within the normally opacified myocardium. Lesion dimensions by MCE immediately after ablation and 30 minutes later were similar. In 12 focal lesions, the average maximum depth (5.55 ′ 1.38 mm) and average maximum diameter (10.38 ′ 2.09 mm) by MCE were in excellent agreement with the pathologic depth (5.20 ′ 1.45 mm) and diameter (10.61 ′ 1.67 mm). Two focal lesions could not be detected by MCE and later were found to be superficial. Three-dimensional MCE correctly reconstructed the extent and shape of linear lesions compared to pathology (length: 18.7 ′ 5.7 vs 18.5 ′ 5.6 mm; maximum longitudinal cross-sectional area: 81.2 ′ 9.6 vs 76.0 ′ 10.3 mm 2 ). Conclusion: MCE accurately localized and quantified radiofrequency ablation lesions in the normal left ventricle. This new application of MCE may advance ablation for managing ventricular arrhythmias that involve intramural or epicardial regions by providing instantaneous anatomic feedback on the effects of ablation during catheterization.

Objectives The goal of this study was to examine the diagnostic utility of the time to onset of early (Ea) diastolic velocity of the mitral annulus by tissue Doppler (TD) in comparison with the time to onset of mitral inflow (TEa-E) for the assessment of left ventricular (LV) relaxation. Background Tissue Doppler imaging of the mitral annulus provides useful information about myocardial function. So far, studies have focused on the measurement of peak Ea, but have not evaluated the diagnostic utility of the time to onset of Ea. Methods Simultaneous left heart catheterization and Doppler echocardiography (DE) were performed in 10 dogs. Left atrial pressures and LV volumes and pressures were measured before and after constriction of the circumflex (cx) coronary artery. The delay in Ea was next examined in 60 consecutive patients, undergoing simultaneous right heart catheterization and DE. Furthermore, (TEa-E) was used to predict filling pressures in a prospective group of 33 patients. Results In canine studies, significant prolongation in the time interval (TEa-E) was noted after cx constriction, which had a significant relation with tau (τ) (r = 0.93, p < 0.01). In human studies, Ea was significantly delayed in patients with impaired relaxation and pseudonormal LV filling in comparison with age-matched controls. In the prospective group, pulmonary capillary wedge pressure (PCWP) derived as: PCWPDoppler= LVend-systolic pressure× e−IVRT/(TEa-E), where IVRT is isovolumetric relaxation time; PCWPDopplerrelated well to PCWPcatheter(r = 0.84, p < 0.001). Conclusions TEa-Eis a useful novel index of LV relaxation. It can be used to identify patients with diastolic dysfunction and predict PCWP.