Experimental study
Regional asynchrony during acute myocardial ischemia quantified by ultrasound strain rate imaging

https://doi.org/10.1016/S0735-1097(01)01113-5Get rights and content
Under an Elsevier user license
open archive

Abstract

OBJECTIVES

We propose a new method to easily quantify asynchronous wall motion due to postsystolic shortening (PSS). We also studied the relationship of the spatial and temporal extent of PSS to the extent of myocardium at ischemic risk after variable duration of ischemia.

BACKGROUND

Postsystolic shortening is a sensitive marker of asynchrony during ischemia. Current techniques for detection of asynchrony are either subjective, or invasive and time-consuming. Strain rate imaging (SRI) can noninvasively depict PSS as prolonged compression/expansion crossover.

METHODS

Nineteen open-chest pigs were scanned from apical views, before and after left anterior descending coronary artery occlusion. Strain rates were derived offline from tissue Doppler velocity cineloops. The time from electrocardiographic R-wave to the occurrence of compression/expansion crossover (TCEC) was calculated. Prolonged TCECduring ischemia was identified using a standardized analysis and both spatial (% of left ventricle) and temporal extent were quantified. The extent of myocardium at risk was measured in seven animals from dye-stained specimens.

RESULTS

Prolonged TCECwas found in all ischemic segments. There was a good correlation (r = 0.91; p < 0.001) and good agreement between the spatial distributions of prolonged TCECand myocardium at risk. The extent of myocardium at risk was better approximated by TCECmeasurement (36 ± 7% vs. 39 ± 8%, respectively; p = NS) than by wall motion analysis (47 ± 17%, p < 0.05). The duration of occlusion did not prolong TCEC.

CONCLUSIONS

Prolonged TCECconsistently occurs in ischemic myocardium and is apparently not affected by the duration of ischemia. Standardized analysis of TCECin SRI closely quantifies the extent of ischemic myocardium. This new method may be a useful tool in other cardiac conditions associated with regional diastolic asynchrony.

Abbreviations

LAD
left anterior descending coronary artery
LV
left ventricle, left ventricular
PSS
postsystolic shortening
SD
standard deviation
SRI
strain rate imaging
TCEC
time to compression/expansion crossover
WMS
wall motion score

Cited by (0)

This work was supported in part by a grant from the National Heart, Lung and Blood Institute, HL41046.