Assessment Of Myocardial Perfusion And Prediction Of Regional Myocardial Function Recovery After Coronary Artery Bypass Graft Surgery By Realtime Myocardial Contrast Echocardiography

PART 1. Assessment of myocardial perfusion by intravenous real-time myocardial contrast echocardiography before and after coronary artery bypass graft surgery (CABG) in patients with coronary artery diseaseObjectives This study was undertaken to assess resting myocardial perfusion by real-time myocardial contrast echocardiography (MCE) in patients with coronary artery disease (CHD) before and after CABG .Methods Fifteen patients underwent intravenous real-time myocardial contrast echocardiography by slow and homogeneous venous injections of SonoVue before and after CABG. MCE Images were obtained from the apical 4-chamber, 2-chamber, and long-axis views. Time intensity curves were constructed and fit to an exponential function, y(t)=A[1-e -kt] +B. B represents tissue signal intensity. A, k and the product A×k reflect myocardial blood volume, blood velocity and myocardial blood flow respectively.Results Before CABG, A, k and the product A×k were significantly lower in the myocardial segments supplied by severely stenosed coronary artery than those with normal coronary artery (4.50±2.61dB vs 7.83±2.35dB,P=0.001, 0.32±0.15 vs 0.45±0.15,P=0.02, 1.28±0.75 vs (3.52±1.50,P<0.001,respectively), A and the product A×k were both higher after CABG than those before operation (4.50±2.61dB vs 6.06±2.52dB,P=0.02, 1.28±0.75 vs 1.99±0.92,P<0.001, respectively ). Accordingly, the normalized value of A and the product A×k were both higher after CABG than those before operation (0.52±0.22 vs 0.78±0.32,P=0.018, 0.37±0.18 vs 0.58±0.20,P<0.001, respectively).Conclusion Perfusion abnormalities are present in patients with severe coronary artery stenoses and can be detected by real-time MCE. Further more, real-time MCE can provide valuable information on the outcome of CABG in these patients. PART 2. Prediction of regional myocardial function recovery after coronary artery bypass graft surgery(CABG)with the replenishment parameters of real-time myocardial contrast echocardiography.Objectives The purpose of this study was to assess resting myocardial perfusion by real-time myocardial contrast echocardiography (MCE) and regional myocardial function recovery in patients with coronary artery disease (CHD) after CABG and to determine if the replenishment parameters could predict regional myocardial function recovery after surgery.Methods Fifteen patients underwent intravenous real-time myocardial contrast echocardiography by slow and homogeneous venous injections of SonoVue before and 15d after CABG. Besides, tissue Doppler strain and strain rate imaging were acquired before and 15d,30d after surgery. MCE Images were obtained from the apical 4-chamber, 2-chamber, and long-axis views. The replenishment parameters of time intensity curves were obtained to analyze myocardial perfusion quantitatively.Results The replenishment parameters k value,A×k value and regional myocardial peak systolic strain,peak systolic strain rate improved 15 days after surgery. The greater the replenishment parameters k value and A×k value at baseline, the greater the improvement of regional myocardial function assessed at 30d after surgery(r=0.65,p<0.01, r=0.68,p<0.01, respectively ). A cutoff value of k>0.26 at baseline predicted regional myocardial peak systolic strain recovery 30d after surgery with a sensitivity of 83.33%, specificity of 88.90%. Furthermore, a cutoff value of (A×k)>1.12 at baseline predicted that with a sensitivity of 76.67%, specificity of 88.88%.Conclusion After surgery myocardial perfusion and regional myocardial function recovered to a certain extent. After surgery regional myocardial function recovery had a significant correlation with regional myocardial perfusion. And the replenishment parameters could predict regional myocardial function recovery after surgery.