Objective     To evaluate the myocardial viability by combined low-dose dobutamine echocardiography (LDDSE) with Doppler tissue imaging (DTI)

and compare the efficacy of combined LDDSE with DTI to that of 2

3

5-triphenyltetrazolium-chloride (TTC) staining in evaluating viable myocardium.      Methods     Twelve healthy pigs were examined by electrocardiography before operation. After anesthesia

balloon angioplasty was performed in the branch of the left circumflex artery (LCX). The balloon was inflated and occluded LCX for 90 min. Electrocardiography

blood pressure and other parameters were monitored. Every pig underwent LDDSE after acute myocardial infarction. 16-segment model and semiquantitative analysis were adopted. Finally all pigs were killed by intravenous injection of 10% KCl

and hearts were stained with TTC and the histochemical changes of myocardial cells were assessed by microscopy. The results by the two methods were compared.      Results     In 26 of 192 segments that were hypokinetic or akinetic of wall motion with DTI at rest

16 segments showed improvement of wall motion during LDDSE combined with DTI

documented as viable myocardium (group A)

and 10 segments showed no improvement of wall motion

documented as non-viable myocardium (group B). Taking TTC staining results as gold standard

the sensitivity and specificity of LDDSE combined with DTI for viable myocardium were 92.9% and 75% respectively.      Conclusion     DTI combined with LDDSE in identifying viable myocardium is a relatively reliable and ideal method.