Evaluation Of Viable Myocardium By Low Dose Dobutamine Echocardiography(LDDE) Combined With Doppler Tissue Imaging(DTI) Test

Objective: To evaluate the myocardial viability by low dose dobutamine echocardiography (LDDSE) combined with Doppler tissue imaging (DTI) test, and the consistence between combined LDDSE with DTI test and 2,3,5-Triphenyltetrazolium-chloride (TTC) staining in evaluation of viable myocardium.Methods: A total of 12 health domestic pigs were studied. Before the operation, all pigs were examined by echocardiography. After anesthesia, angioplasty balloon was positioned in the branch of the left circumflex artery (LCX). The balloon was inflated and occluded the LCX for 90 minutes. Electrocardiography, echocardiography and other parameters were monitored. Every pig underwent LDDSE after acute myocardial infarction. 16-segment model and semiquantitative analysis method were taken. Pulsed-wave Doppler tissue imaging (PW-DTI) was recorded at mid-point of endocardium of every selected segment. In the end, animals were killed, the heart was stained with TTC and the histomography changes of myocardial cells were assessed by microscope. And the two kinds of assessments were compared.Results: 1) 26 out of 192 segments showed hypokinetic or akinetic of wall motion with DTI at rest, and 16 out of 26 segments showed improvement of wall motion during LDDSE combining with DTI, which was documented as viable myocardium (group A), another10 segments showed no improvement of wall motion were documented as non-viable myocardium (group B). 2) During LDDSE, group A and group B showed the tendency of increased peak velocity of ejection phrase (Vs). However, the Vs of group A was larger than that of group B at 10μg/(kg?min) dosage. The other parameters did not show obviously regular change during LDDSE. 3) Regard the results of TTC staining as the standard, the sensitivity and specificity of diagnosis of viable myocardium by combined LDDSE with DTI test were 92.9% and 75% respectively.Conclusions: PW-DTI combined with LDDSE in identification of viable myocardium is feasible, Vs may be the main parameter. Compared with TTC staining, It is a relatively reliable and ideal method.