Using synthetic M-mode imaging to measure temporal differences in left ventricular contraction patterns during ischemia

Myocardial ischemia is usually identified by echocardiography using qualitative analysis of regional left ventricular (LV) endocardial excursion. This is often hampered by sub-optimal endocardial visualization and lack of quantitative standards and measurement techniques Ischemia changes the temporal pattern of LV contraction, and a method for quantifying changes in this temporal sequence would have clinical applicability. The authors developed and tested a computer-assisted technique using Synthetic M-mode (SMM) to measure the temporal variations in regional LV contraction. Using a LV short axis image, 6 SMM images were created through a user-defined LV center. The time to peak (t) contraction in 6 LV segments was then measured using the R-wave as a timing reference point. In the authors' study of 15 closed chest dogs with induced regional ischemia, t was significantly prolonged only in those LV segments subtended by the occluded artery. Temporal SMM is a promising technique for defining temporal contraction patterns indicative of regional ischemia.