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Myocardial Wall (myocardial + wall)
Selected AbstractsFree Right Internal Thoracic Artery in a "Horseshoe" Configuration: A New Technical Approach for "In Situ" Conduit LengtheningJOURNAL OF CARDIAC SURGERY, Issue 6 2005Jacob Zeitani M.D. We present a method to revascularize the left antero-lateral myocardial wall using the right internal thoracic artery as a "free graft" anastomosed side to end to the "in situ" left internal thoracic artery, in a "horseshoe" fashion. The two ends of the "free graft" were anastomosed to the left anterior descending coronary artery and the second obtuse marginal branch, respectively. This method was successfully used in a 74-year-old patient with severe chronic obstructive pulmonary disease. [source] Optical Mapping of Transmural Activation Induced by Electrical Shocks in Isolated Left Ventricular Wall Wedge PreparationsJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 11 2003OLEG F. SHARIFOV Ph.D. Introduction: It is believed that electrical shocks interrupt fibrillation by directly stimulating the bulk of ventricular myocardium in excitable states, but how shocks activate intramural tissue layers is not known. In this study, Vm responses and transmural activation patterns induced by shocks during diastole were measured in isolated coronary perfused preparations of porcine left ventricle. Methods and Results: Rectangular shocks (duration = 10 ms; field strength, E = 1,44 V/cm) were applied across preparations (thickness = 14.9 ± 2.5 mm, n = 9) via large mesh electrodes during diastole or action potential (AP) plateau. Vm responses at the transmural surface were measured using optical mapping technique (resolution = 1.2 mm). Depending on shock strength, three types of Vm responses were observed. (1) Weak shocks (E , 1,4 V/cm) applied in diastole induced APs with simple monophasic upstrokes. The latency and time of transmural activation (TTA) rapidly decreased with increasing shock strength. Earliest activation occurred predominantly at the cathodal side of preparations in the areas that exhibited maximal ,Vm during AP plateau. (2) Intermediate shocks (E , 4,23 V/cm) induced monophasic and biphasic upstrokes that were paralleled with predominantly negative plateau ,Vm. Activation was initiated at multiple transmural sites and rapidly spread across the myocardial wall (TTA = 0.6 ± 0.2 ms). (3) Very strong shocks (E , 23,44 V/cm) could cause triphasic upstrokes, likely reflecting occurrence of membrane electroporation, and delayed activation (TTA = 6.7 ± 3.8 ms) at sites of largest negative plateau ,Vm. Conclusion: Shocks applied during diastole cause direct and rapid (within 1 ms) activation of ventricular bulk over a wide range of shock strengths, supporting the excitatory hypothesis of defibrillation. Very strong shocks can cause multiphasic Vm responses and delayed activation. (J Cardiovasc Electrophysiol, Vol. 14, pp. 1215-1222, November 2003) [source] Nondestructive optical determination of fiber organization in intact myocardial wallMICROSCOPY RESEARCH AND TECHNIQUE, Issue 7 2008Rebecca M. Smith Abstract Mapping the myocardial fiber organization is important for assessing the electrical and mechanical properties of normal and diseased hearts. Current methods to determine the fiber organization have several limitations: histological sectioning mechanically distorts the tissue and is labor-intensive, while diffusion tensor imaging has low spatial resolution and requires expensive MRI scanners. Here, we utilized optical clearing, a fluorescent dye, and confocal microscopy to create three-dimensional reconstructions of the myocardial fiber organization of guinea pig and mouse hearts. We have optimized the staining and clearing procedure to allow for the nondestructive imaging of whole hearts with a thickness up to 3.5 mm. Myocardial fibers could clearly be identified at all depths in all preparations. We determined the change of fiber orientation across strips of guinea pig left ventricular wall. Our study confirms the qualitative result that there is a steady counterclockwise fiber rotation across the ventricular wall. Quantitatively, we found a total fiber rotation of 105.7 ± 14.9° (mean ± standard error of the mean); this value lies within the range reported by previous studies. These results show that optical clearing, in combination with a fluorescent dye and confocal microscopy, is a practical and accurate method for determining myocardial fiber organization. Microsc. Res. Tech., 2008. © 2008 Wiley-Liss, Inc. [source] The effects of droperidol and ondansetron on dispersion of myocardial repolarization in childrenPEDIATRIC ANESTHESIA, Issue 10 2010DISHA MEHTA BSc Summary Objectives:, To compare the effects of droperidol and ondansetron on electrocardiographic indices of myocardial repolarization in children. Aim:, To refine understanding of the torsadogenic risk to children exposed to anti-emetic prophylaxis in the perioperative period. Background:, QT interval prolongation is associated with torsades des pointes (TdP), but is a poor predictor of drug torsadogenicity. Susceptibility to TdP arises from increased transmural dispersion of repolarization (TDR) across the myocardial wall, rather than QT interval prolongation per se. TDR can be measured on the electrocardiogram as the time interval between the peak and end of the T wave (Tp-e). Tp-e may therefore provide a readily available, noninvasive assay of drug torsadogenicity. The perioperative period is one of high risk for TdP in children with or at risk of long QT syndromes. Droperidol and ondansetron are two drugs commonly administered perioperatively, for prophylaxis of nausea and vomiting, which can prolong the QT interval. This study investigated their effects on myocardial repolarization. Methods:, One hundred and eight ASA1-2 children undergoing elective day-case surgery were randomized to receive droperidol, ondansetron, both or neither. Pre- and post-administration 12-lead electrocardiogram (ECGs) were recorded. QT and Tp-e intervals were measured and compared within and between groups, for the primary endpoint of a 25 ms change in Tp-e. Results:, Eighty children completed the study. There were no demographic or baseline ECG differences between groups. QT intervals lengthened by 10,17 ms after allocated treatments, with no between-group differences. Values remained within normal limits for all groups. Tp-e intervals increased by 0,7 ms, with no between-group differences. There were no instances of dysrhythmia. Conclusions:, Droperidol and ondansetron, in therapeutic anti-emetic doses, produce equivalent, clinically insignificant QT prolongation and negligible Tp-e prolongation, suggesting that neither is torsadogenic in healthy children at these doses. [source] Quantitative Assessment of Regional Right Ventricular Myocardial Velocities in Awake Dogs by Doppler Tissue Imaging: Repeatability, Reproducibility, Effect of Body Weight and Breed, and Comparison with Left Ventricular Myocardial VelocitiesJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 6 2005Valérie Chetboul Right ventricular myocardial (RVM) motion is poorly documented. The objective of this study was to determine the variability of RVM velocities by tissue Doppler imaging (TDI) in healthy dogs (study 1), to analyze RVM motion in a large healthy canine population (study 2), and to compare the results with those obtained for the left ventricular free wall. Six healthy Beagle Dogs were monitored in study 1, and 64 healthy dogs of 14 different breeds were monitored in study 2. Velocities were recorded in 2 segments (basal and apical) of the right and left myocardial walls. In study 1, 36 TDI examinations were performed for 4 days, whereas a single TDI examination was performed on each dog in study 2. All velocity profiles included 1 positive systolic wave and 2 negative diastolic waves. The lowest intraday and interday coefficient of variation values of the right TDI variables were observed at the base (3.5,16.1%). The variability of the right apical velocities was much higher, with most coefficient of variation values >15%. RVM velocities were higher in the basal than in the apical segments (P < .001) and were higher than the left velocities of the corresponding segment (P < .01). Body weight and breed had an effect on only a few right and left TDI variables. TDI provides a repeatable and reproducible method for evaluating basal RV function in the dog. These data also demonstrate the heterogeneity of the myocardial velocities between the left and the right ventricles and between the base and the apex. [source] | ||||||||||