Mechanisms of preejection and postejection velocity spikes in left ventricular myocardium: interaction between wall deformation and valve events.

Background— Normal left ventricular myocardium demonstrates distinct spikes in the velocity trace before and after left ventricular ejection. We tested the hypothesis that the preejection and postejection velocity spikes reflect early systolic shortening and late systolic lengthening that are interrupted by mitral and aortic valve closure, respectively. Methods and Results— In 11 anesthetized dogs, timing of valve closure was determined by pressure variables; left ventricular dimensions were determined by sonomicrometry. Myocardial shortening started 20±10 ms (mean±SD; P<0.001) before mitral valve closure and was interrupted at the time of mitral valve closure (time difference, 4±7 ms). Similarly, myocardial lengthening started 31±15 ms (P<0.001) before aortic valve closure and was interrupted at the time of aortic valve closure (time difference, 0±3 ms). Prevention of mitral (n=4) and aortic (n=4) valve closure by stenting the valves abolished the preejection and postejection velocity spikes, respectivel...