Comparison of adenosine stress and dobutamine stress by real-time myocardial contrast echocardiography in detecting myocardium ischemia in dogs

Background Real-time perfusion imaging （RTPI） using ultrasound contrast agents has shown good ＂accuracy＂ in detecting myocardial infarction, however its accuracy in the assessment of peri-infarct ischemia and stress echocardiography are not known. The aim of this study was to determine the accuracy of RTPI in assessment of peri-infarct ischemia during dobutamine and adenosine stress. Methods We employed the RTPI modality （Agilent and ATL Philips） in a canine model （18 dogs） of distal coronary occlusion and proximal coronary stenosis. Using coronary flow probe recordings, the physiologic significance of proximal coronary stenosis was established by confirming abolition of the coronary reserve. The contrast agent Optison was given as a slow bolus injection at baseline, during prolonged distal coronary occlusion, during adenosine bolus stress and during dobutamine stress. Triphenyltetrazolium chloride （TTC） staining was used to verity a distal infarction. RTPI recordings at baseline, the distal coronary occlusion and stress protocols were randomly mixed and reviewed blindly. Results In all but one dog, RTPI detected a distal infarct as small as 9% of the left ventricle. The sensitivity, specificity and overall diagnostic accuracy of RTPI in the detection of distal infarcts were： 94%, 89% and 92%, respectively. The sensitivity, specificity, and overall diagnostic accuracy of RTPI in the assessment of peri-infarction ischemia were 83%, 92% and 88% for adenosine stress and 95%, 86% and 91% for dobutamine stress, respectively. Conclusions Even small distal infarcts can be detected by RTPI; peri-infarct ischemia can be accurately recognized by RTPt during stress; adenosine and dobutamine stress appear equally reliable in the RTPI evaluation of peri-infarct ischemia.

Cirrhotic cardiomyopathy:Isn't stress evaluation alwaysrequired for the diagnosis?

AIM:To describe the proportion of patients with cirrhotic cardiomyopathy(CCM) evaluated by stress echocardiography and investigating its association with the severity of liver disease.METHODS:A cross-sectional study was conducted.Cirrhotic patients without risk factors for cardiovascular disease were included.Data regarding etiology and severity of liver disease(Child-Pugh score and model for end-stage liver disease),presence of ascites and gastroesophageal varices,pro-brain natriuretic peptide(proBNP) and corrected QT(QTc) interval were collected.Dobutamine stress echocardiography(conventional and tissue Doppler imaging) was performed.CCM was considered present when diastolic and/or systolic dysfunction was diagnosed at rest or after pharmacological stress.Therapy interfering with cardiovascular system was suspended 24 h before the examination.RESULTS:Twenty-six patients were analyzed,17(65.4%) Child-Pugh A,mean model for end-stage liver disease(MELD) score of 8.7.The global proportion of patients with CCM was 61.5%.At rest,only 2(7.7%)patients had diastolic dysfunction and none of the patients had systolic dysfunction.Dobutamine stress echocardiography revealed the presence of diastolic dysfunction in more 6(23.1%) patients and of systolic dysfunction in 10(38.5%) patients.QTc interval prolongation was observed in 68.8%of the patients and increased pro-BNP levels in 31.2%of them.There was no association between the presence of CCM and liver impairment assessed by Child-Pugh score or MELD(P= 0.775,P= 0.532,respectively).Patients with QTc interval prolongation had a significant higher rate of gastroesophageal varices comparing with those without QTc interval prolongation(95.0%vs 50.0%,P= 0.028).CONCLUSION:CCM is a frequent complication of cirrhosis that is independent of liver impairment.Stress evaluation should always be performed,otherwise it will remain an underdiagnosed condition.

Value of Low Dose Dobutamine Doppler Tissue Imaging for Detecting Hibernating Myocardium

Summary: In order to assess the value of Doppler tissue imaging (DTI) in detecting viable hibernating myocardium, 20 patients with coronary artery disease and chronic left ventricular dysfunction underwent low dose dobutamine stress echocardiography and low dose dobutamine stress DTI. The results showed that among the 100 asynergic segments, 35 segments showed improvement after dobutamine infusion (group H) and no changes were observed in the remaining 65 segments (group N). The left ventricular echocardiographic score index decreased from 1.60±0. 35 to 1.44±0.36 ( n =20, P <0.01). During low dose dobutamine stress DTI, there was no difference in the values of velosity of S wave (V s) before dobutamine infusion between two groups. However, after dobutamine infusion, the values of V s and VR in group H were significantly higher than those in group N (V s:10.1±3.0 cm/s vs 7.3±2.2 cm/s, P <0.01; VR: 60 %±41 % vs 25 %±32 %, P <0.001). 95.7 % asynergic myocardial segments with VR≤0 had no viability while 86 % asynergic segments with VR>80 % were viable myocardium. It is concluded that the different reactions to dobutamine stress between hibernating and necrosis myocardium could be showed by DTI and it is more clinically significant when VR≤0 and VR>80 %.

Viable Myocardium Impact on Left Ventricular Function after Late Revascularization of Infarct-related Artery in Acute Myocardial Infarction

Objectives The long-term benefit of late reperfusion of infarct-related artery （IRA） after acute myocardial infarction （AMI） is controversial, and the benefit mechanisms remain uncertain. Low dose dobutamine stress echocardiography （LDSE） can identify viable myocardium and predict improvement of wall motion after revascularization. Methods Sixtynine patients with first AMI who did not received early reperfusion therapy were studied by LDSE at 5 to 10 days after AMI. Wall motion abnormality and left ventricular size were measured at the same time. Successful PCI were done in all patients at 10 to 21 days after AMI onset. Patients were divided in two groups based on the presence or absence of viable myocardium. Echocardiography was repeated six months later. Results There were 157 motion abnormality segments. 89 segments （57%） were viable during LDSE. 26 patients （38%） with viability and 43 （62%） without. In viable group, left ventricular ejection fraction （LVEF） was increased （P 〈 0.05）, and left ventricular end systolic volume index （LVESVI） and wall motion score （WMS） were decreased （P 〈 0.05 and P 〈 0.01） significantly at 6 months compared with baseline. But in patients without viability, LVEF was decreased （P 〈 0.01）, and LVESVI and left ventricular end diastolic volume index （LVEDVI） were increased （P 〈 0.05） significantly after 6 months, and the WMS did not changed （P 〉 0.05 ）. LVEF increased （P 〈 0.05 ） and WMS decreased （P 〈 0.05） on LDSE during acute phase in patients with viability, but they were not changed in the nonviable group. Conclusions Late revascularization of IRA in patients with presence of viable myocardium after AMI is associated with long-term preservation left ventricular function and less ventricular remodeling. Improvement of left ventricular systolic function on LDSE indicates late phase recovery of left ventricular function after late revascularization.