Sarcomere shortening and mean sarcomere length during left ventricular ejection were similar between the anterior and posterior walls in isolated dog hearts.
Sarcomere shortening during left ventricular ejection is similar in the anterior and posterior walls, indicating that functional measurements of relative myocardial shortening may not reflect regional sarcomere length heterogeneity.
Previous studies of regional differences in myocardial deformation between the anterior and posterior walls of the canine left ventricle were based on strain, which is not an absolute measure of deformation. We thus compared sarcomere lengths at anterior and posterior sites during ejection in isolated dog hearts. Cineradiographic imaging of regional deformation with radiopaque markers implanted near the midwall in five hearts and just below the epicardium in six hearts, combined with postmortem histology, allowed sarcomere length reconstruction throughout the cardiac cycle. The amount of sarcomere shortening accompanying left ventricular ejection was similar in both walls of the left ventricle for sarcomeres located at epicardial and midwall sites. The mean sarcomere length (taken at the middle of the ejecting range) was also similar between the anterior and posterior sites when averaged over all hearts. The similarity of sarcomere function held not only at end systole but throughout ejection and over wide ranges of ventricular pre- and afterloads. Hence functional measurements of relative myocardial shortening may not be indicative of regional sarcomere length heterogeneity.
Guccione et al. (Wed,) conducted a other in Isolated dog hearts (n=11). Anterior vs posterior left ventricular wall sites was evaluated on Sarcomere length and shortening during ejection. Sarcomere shortening and mean sarcomere length during left ventricular ejection were similar between the anterior and posterior walls in isolated dog hearts.