| Objective This study was undertaken for the determination of the correlation between myocardial viability and regional mitral annular motion indices response to dobutamine stress in patients with old myocardium infarction(OMI) with pulsed Doppler tissue imaging.Methods The study included 40 patients(mean age, 58.34±9.16 years) with OMI and 20 age-matched normal subjects ( mean age 57.12±7.54 yeas ). 99m Tc-methoxyisobutylisonitrile scintigraphy was performed to divide the patients'left ventricular walls into 2 groups: the viable myocardium group(n=40) and the non-viable myocardium group(n=33).Dobutamine was infused (at 2.5,5,10ug/kg/min), and the peak systolic velocity(Vs) , peak early diastolic velocity(Ve) , pre-ejection period (PEP) and ejection time (ET) were measured at the level of the mitral annular corresponding to the infarct regions in the OMI group and to the 6 mitral annular sites in the control group at baseline and every step of dobtamine infusion. In addition, the maximal left atrial dimention, left ventricular end-systolic and end-diastolic dimention, left ventricular ejection fraction(length-area rule) were determined with 2-dimentional echocardiography in three groups and the left ventricular wall motion score index(WMSI) corresponding to the infarct regions was measured in the OMI group.Results⑴There were significant difference among Vs in control group at baseline, the Vs of lateral wall was the greatest, the second was posterior wall, the last one was anteroseptal wall (12.51±1.85cm/s, 11.13±1.57cm/s , 8.77±1.02cm/s, respectively). So is the Ve.⑵At baseline, the Vs was significantly lower in both the viable myocardium group and non-viable myocardium group than that in control group, but there was no significant difference between the former. After dobutamine infusion, the mean increase of Vs was significantly greater in viable myocardium group than that in non-viable myocardium group. With an increase of Vs≥2.0cm/s with 5ug/kg/min of dobutamine, viable myocardium was detected, with a sensitivity of 75% and a specificity of 76%. With an increase of Vs≥3.0cm/s with 10ug/kg/min of dobutamine, the sensitivity and specificity were increased to 83% and 79% respectively.⑶At baseline, the Ve was significantly lower in both the viable myocardium group and non-viable myocardium group than that in control group(8.64±2.13cm/s ,7.41±1.60cm/s, 10.50±2.46cm/s,respectively, P<0.001). But the Ve in viable myocardium group was significantly greater than that in non-viable myocardium group ( (P<0.05) when compare the former.⑷The ratio of pre-ejection period to ejection time (PEP/ET) was significantly longer in both viable myocardium group and non-viable myocardium group than that in control group at baseline(0.44±0.11,0.48±0.14,0.33±0.06,P<0.001). There was no significance between viable myocardium group and non-viable myocardium group. When the cutoff value of PEP/ET≥100% with Dobutamine 5ug/kg/min was used, the sensitivity and specificity for diagnosing non-viable myocardium were 73% and 85%. When the cutoff value of PEP/ET≥100% with Dobutamine 10ug/kg/min was used, the sensitivity and specificity for diagnosing non-viable myocardium were 82% and 85%.⑸The PEP, ET,PEP/ET were not significant in the control group at baseline.⑹The sensitivity and specificity were not significant between PW-DTI and 2DE in detection myocardial viability (83%vs75%,79%vs79%) when Dob was infused at 10ug/kg/min, But the sensitivity would increased to 92% when combination this two methods. The combination sensitivity was significantly higher than 2DE (P<0.05).Conclusions⑴This study shows that there are physiological heterogeneity in systolic velocities and early diastolic velocity and synchrony in systolic velocities at the 6 sides of mitral annular⑵The diastolic function is impaired heavier in non-viable myocardium group than that in viable myocardium group.⑶Viable myocardium is identified with peak systolic mitral annular velocity and PEP/ET during Dob infusion.⑷The sensitivity will be improved when combination 2DE and PW-DTI in detecting viable myocardium.
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