Myocardial Elastography for Evaluating the Evolution of Strains and Strain Rates in Canine Myocardium After Myocardial Infarction

Abstract

Myocardial infarction (MI) is caused by occlusion of the coronary artery and can rapidly lead to death, 36% of patients die within 1 month of their first MI. Traditional ECG diagnosis has shown a poor correlation to the degree of MI. Understanding the dysfunction and recovery in myocardial motion following MI using myocardial elastography (ME) may inform future diagnosis and treatment for MI. Ten mongrel canines underwent a ligation procedure at the proximal LAD site for inducing infarction in the papillary and apical levels of the hearts. Transthoracic ultrasound images were taken before and up to 31 days after the ligation procedure. Strain and structural parameters including maximum principal strain (Emax) and maximum shear strain (Gmax), radial strain (Err), circumferential strain (Eθθ), and their strain rates were measured. Territorial differences in strains were also compared. Strain and strain rates in LAD of the apical level were most affected after MI (Fig 3). All strains decreased at the acute MI stage but recovered to the baseline level at the remodeling stage. Eθθ rate also recovered at the remodeling stage after decreasing in magnitude at the acute stage. However, Gmax, Emax and Err rates decreased after MI and remained low throughout the stages of recovery. Territorial strain and strain rates were able to inform the recovery stages as well as the location of dysfunction following MI. This study showed that ME could inform the diagnosis and treatment progression of acute MI.