Detection of viable myocardium by transvenous myocardial contrast echocardiography using harmonic power Doppler: canine model of acute coronary occlusion and reperfusion

STUDY OBJECTIVE: To assess whether myocardial contrast echocardiography (MCE) using harmonic power Doppler (HPD) in conjunction with the transvenous contrast agent SHU 563A would be useful in detecting stunned but viable myocardium. DESIGN: Acute coronary occlusion (2 to 3 h) followed by 1 h of reperfusion was created in 10 dogs in an open-chest model. Measurements and results: Continuous harmonic B-mode for wall motion analysis and ECG triggered HPD for assessment of myocardial perfusion was employed during coronary occlusion and after reperfusion. Postmortem 2,3,5-triphenyltetrazolium chloride (TTC) staining was performed to verify infarction. Extent of wall motion abnormality (WMA), perfusion defect size, and anatomic infarct size (myocardial infarction [MI]) were analyzed in a 5-segment model. All 10 dogs showed WMA in 23 of 50 segments during coronary occlusion. In eight dogs, HPD detected perfusion defects in 18 of 50 segments. The concordance rate between WMA and perfusion defect was 86%. Mean linearized power (MLP) in segments with WMA was significantly lower compared to normal segments (60.7 +/- 38.9 vs 110.5 +/- 108.8, p < 0.05). After reperfusion, the extent of WMA was larger than the area of perfusion defect (percentage of left ventricular slice area): 30 +/- 13% vs 9 +/- 8%, p < 0.01. Eventual infarct size was 6 +/- 7%. WMAs were seen in 18 of 50 segments. TTC confirmed MI in 7 of 18 segments. MLP in segments with WMA but no MI was significantly higher compared to segments with WMA and MI (84.5 +/- 67.3 vs 13.2 +/- 9.6, p < 0.01). Thus, the extent of WMA after reperfusion was greater than the size of perfusion defect and eventual MI, indicating the presence of stunned but viable myocardium. CONCLUSION: MCE using HPD and the contrast agent SHU 563A can demonstrate the efficacy of reperfusion, identify necrotic regions, and aid in the recognition of stunned but viable myocardium. This approach could be useful clinically in patients with acute MI undergoing reperfusion therapy.     

药物负荷三维超声心动图检测存活心肌的价值

目的：利用药物负荷三维超声心动图试验,检测心肌梗死患者的存活心肌。方法：50例心肌梗死患者行冠脉血液灌注重建术（PCI,CABG）,在术前行三维超声心动图检查和多巴酚丁胺负荷超声试验,根据术后一个月复查心脏超声结果左室整体EF较术前改善〉5％与否分为存活心肌组（41例）和无存活心肌组（9例）,三维超声检查时进行左室三维重建,将左心室分为17个节段,比较负荷试验前后左室整体射血分数（EF）及左室壁各节段的射血分数EF值。结果：术后1月多巴酚丁胺负荷三维超声试验：与负荷试验前比较,存活心肌组于负荷试验时左室整体EF值[（40±13）％比（53±15）％,P〈0．05],梗死区相关节段EF值[（33±12）％比（50±18）％,P〈0．01]均明显改善;无存活心肌组负荷试验前后左室整体EF值,梗死区相关节段EF值无明显改善（P均〉0．05）。心梗患者于冠脉术后1月复查三维超声心动图,存活心肌组左室整体EF值术前、术后为（40±13）％,（49±15）％,改善20％,无存活心肌组EF值术前、术后为（36±8）％,（38±10）％,改善≤5％。结论：多巴酚丁胺负荷三维超声心动图检查对心肌梗死患者存活心肌的检测客观、可定量,有一定的临床应用价值。     

Evaluation of systolic and systo-diastolic function: the Tei index in acute myocardial infarction treated with acute reperfusion therapy--early and late evaluation.

INTRODUCTION: Evaluation of systolic and diastolic function by non-invasive methods in the acute phase of myocardial infarction (MI) is of great importance for risk stratification and prognosis. Ejection fraction (EF), as determined by echocardiography using the Simpson method, is the main parameter for assessing left ventricular (LV) function. The Tei index (TI), a Doppler-derived index that reflects systolic and diastolic function in MI, has an excellent correlation with prognosis. OBJECTIVE: The purpose of this study was to evaluate systolic and systo-diastolic function in the acute and late phase of ST-elevation MI treated with acute reperfusion therapy. METHODS: Patients with ST-elevation MI who underwent acute reperfusion therapy were evaluated by echocardiography in the first 48 hours and after one week. The parameters studied were: EF, wall motion score index (WMSI), and TI. The values obtained at the first and second evaluation were compared and correlated with pain to reperfusion time (PRT) (<3 vs. > or =3 hours), presence of single or multivessel disease, ejection fraction, total CK (<1500 or > or =1500 UI/l), and MI location (anterior vs. other). RESULTS: 40 patients were studied and 19 were included, of whom 15 (80%) were male, mean age 57 +/- 14 years. Risk factors included hypertension (11 patients, 58%), smoking (14, 74%), diabetes (6, 30%), and dyslipidemia (12, 63%). MI location was anterior in 6 patients (32%) and inferior in 13 (68%). Five patients (26%) underwent fibrinolysis and 14 (74%) direct percutaneous coronary intervention. Mean pain to reperfusion time was 3.7 +/- 2.8 hours. Four patients (21%) had single vessel disease and 14 (74%) multivessel disease. Significant differences were found: (a) in mean EF and WMSI between the two evaluations (p < 0.0001 and p = 0.002 respectively); (b) between PRT and EF (p = 0.001) and WMSI (p = 0.020) at 48 hours; (c) between PRT and EF (p = 0.01) and TI (p = 0.033), and MI location and EF (p = 0.005) after one week. DISCUSSION AND CONCLUSIONS: Early systolic function and LV remodeling one week after MI were accurately evaluated by EF and WMSI. Early reperfusion therapy positively influences early and late systolic and systo-diastolic function.     

急性心肌梗死患者心肌灌注状况对经皮冠状动脉介入术后心功能的影响

目的采用经冠状动脉超声心肌声学造影(MCE)评价急性心肌梗死(AMI)患者心肌灌注状况对经皮冠状动脉介入术(PCI)后心功能改善的影响,并探讨其相关临床意义。方法 18例AMI患者于PCI前及术后15 min分别经左主干或右冠状动脉注射超声声学造影剂,进行MCE实时显影,以视觉评分方式定性分析PCI前后相应心肌节段灌注状况;术后1个月经二维超声评价左心室室壁运动;利用灌注评分指数(PSI)及室壁运动评分指数(WMSI)分析PCI前后心肌灌注水平对心功能改善的影响。结果术前心肌灌注评分为0分的30个心肌节段中,20个(66.7%)术后1个月室壁运动评分为3~5分;而术前心肌灌注评分为2分的11个心肌节段中,有8个(72.7%)1个月时室壁运动评分为1~2分;统计学分析显示,PCI前心肌灌注与1个月室壁运动状况有关(P0.05)。术后心肌灌注评分为0分的12个心肌节段中,11个(91.7%)术后1个月室壁运动评分为3~5分;而术后心肌灌注评分为2分的22个心肌节段中,有17个(77.2%)1个月时室壁运动评分为1~2分;统计学分析显示,PCI后心肌灌注与1个月室壁运动状况有关(P0.01)。结合WMSI及PSI综合评价术后心肌灌注水平与左心室收缩功能的关系,发现二者存在明显相关性(P0.01)。结论 AMI患者心肌灌注状况对PCI后心功能改善有明显影响;经冠状动脉MCE可较准确的判断AMI患者微循环灌注范围,评估术后心功能,故可能对患者的临床预后判断有一定预测价值。     

Doppler index of myocardial performance and its relationship with mitral E wave deceleration time in acute Q-wave myocardial infarction]

OBJECTIVE: The objectives of the study were to assess myocardial systolic and diastolic functions by myocardial performance index (MPI) and its relationship with E - wave deceleration time (DT) in early phase of acute Q-wave myocardial infarction (MI). METHODS: We performed nongeometric Doppler-derived echocardiography to assess combined systolic and diastolic functions using myocardial performance index in 50 patients with acute Q-wave MI at early phase of events, (25 pts with anterior MI and 25 pts with inferior MI). The index is defined as the sum of the isovolumic contraction and isovolumic relaxation times divided by ventricular ejection time and was obtained by Doppler measurement from the diastolic mitral inflow and left ventricular outflow velocity-time intervals. RESULTS: As a result, the index was 0.54+/-0.1 in all patients with MI. We also estimated the higher MPI and DT values in anterior than in inferior MI (MPI: 0.61+/-0.07 vs. 0.46+/-0.06, p<0.001; DT: 244+/-64 msec vs. 204+/-31.2 msec, p=0.005, respectively). Myocardial performance index was positively correlated with DT in inferior MI (r=0.42, p<0.035) and negatively correlated with anterior MI; (r=- 0.72, p=0.0001). CONCLUSION: These data suggest that Doppler-derived MPI reflects severity of global left ventricular dysfunction in early phase of acute MI and may be a useful parameter in these patients.     

Ischemic and viable myocardium in patients with non-Q-wave or Q-wave myocardial infarction and left ventricular dysfunction: a clinical study using positron emission tomography, echocardiography, and electrocardiography

OBJECTIVES: We investigated whether patients with non-Q-wave myocardial infarction (NQMI) have more ischemic viable myocardium (IVM) than patients with Q-wave myocardial infarction (QMI). BACKGROUND: Non-Q-wave myocardial infarction is associated with higher incidences of cardiac events than QMI, suggesting more myocardium at risk in NQMI. METHODS: To identify myocardial ischemia, hibernation, and scar, the resting and stress (82)rubidium perfusion and F-18 fluorodeoxyglucose metabolic positron emission tomographic imaging (PET) was performed in 64 consecutive patients with NQMI (n = 21) or QMI (n = 43). Echocardiography was performed for assessment of left ventricular function and wall motion index (WMI). The relationships between PET, echocardiographic, and electrocardiographic findings were analyzed. RESULTS: There were no significant differences in left ventricular ejection fraction (LVEF) between NQMI and QMI groups (28 +/- 10% vs. 25 +/- 11%, p > 0.05). Ischemic and viable myocardium was more common in NQMI than in QMI (91% vs. 61%, p < 0.05). The total amount of IVM was significantly higher in NQMI than in QMI (6.5 +/- 5.2 vs. 2.9 +/- 2.8 segments, p < 0.001). Neither the number of Q waves, residual ST-segment depression of >or=0.5 mm or elevation of >or=1 mm, nor LVEF and WMI were significant predictors for IVM. Wall motion index correlated with scar segments (r = 0.54, p < 0.001) and LVEF (r = -0.67, p < 0.001). CONCLUSIONS: Ischemic and viable myocardium is common in patients with NQMI and left ventricular dysfunction, suggesting that aggressive approaches should be taken to salvage the myocardium at risk in such patients.     

Coronary recanalization in anterior myocardial infarction: the open perforator hypothesis

OBJECTIVE: Patent perforators, noninvasively imaged by transthoracic color-Doppler echocardiography, may reflect adequate reperfusion in anterior myocardial infarction (MI). BACKGROUND: The Thrombolysis In Myocardial Infarction (TIMI) classification may not fully reflect adequate myocardial reperfusion in MI. METHODS: We studied 61 patients with anterior MI undergoing thrombolysis (n = 28), primary stenting (n = 20), or neither one (n = 13). High-resolution color-Doppler ultrasound was used to image the left anterior descending coronary artery (LAD) and perforators in four segments of the anterior-apical wall and to build a new recanalization score (RS). The TIMI flow was assessed by angiography. Wall motion score index (WMSI), ejection fraction (EF), end-diastolic volume index, and end-systolic volume index (ESVI) were measured by echocardiography at baseline and at three-month follow-up. Linear regression equations, considering RS or TIMI flow as independent variables, were compared among these functional recovery parameters. A multivariate linear model, predicting percent changes of WMSI, EF, or ESVI, was used to investigate the contribution of several clinical covariates along with RS and TIMI flow. RESULTS: Sensitivity, specificity, and diagnostic accuracy of color-Doppler ultrasound in detecting LAD patency were 86%, 98%, and 97%, respectively. Mean and peak flow velocities discriminated (0.004 < p < 0.008) TIMI flow but not RS. Regression equations showed that RS discriminated better than TIMI flow recovery of ventricular function (p < 0.012). The RS was the best single multivariate predictor (p < 0.0001) of percent changes in WMSI, EF, and ESVI. CONCLUSIONS: Transthoracic color-Doppler ultrasound detects an open LAD after MI. Perforators reflect adequate myocardial reperfusion and are early noninvasive markers of myocardial viability.     

Early prediction of 30-day mortality after Q-wave myocardial infarction by echocardiographic assessment of left ventricular function--a pilot investigation

BACKGROUND: The GUSTO angiographic substudy demonstrated that left ventricular function measured 90 min after thrombolytic therapy was given had important prognostic implications at 30 days in patients with an acute myocardial infarction (MI). HYPOTHESIS: Thirty-day prognosis after Q-wave MI can be determined by early echocardiographic assessment of left ventricular function. METHODS: Using transthoracic echocardiography, semiquantitative ejection fraction and wall motion score index was assessed prospectively in 201 consecutive patients within 24 h following Q-wave MI. Independent experts blinded to the patient's status performed the echocardiographic assessment. All patients received standard medical care as dictated by the attending cardiologist. RESULTS: Of the 201 patients, 24 (11.9%) died within 30 days, with 70% of the deaths occurring within 10 days after the infarction. Three deaths occurred in the 120 patients with an ejection fraction > or = 45% (2.5% mortality rate). In contrast, 21 deaths occurred among the 81 patients with an ejection fraction <45% (25.9% mortality rate) p = 0.0003. Two of the three patients who died in the high ejection fraction group died as a result of intracerebral hemorrhage from thrombolytic therapy. Ejection fraction was lower in nonsurvivors (32.3+/-10.3 vs. 46.3+/-13%) than in survivors, p < 0.0002. Wall motion score index (WMSI) of < 1.4 was associated with a 2.9% 30-day mortality (two deaths in 76 patients); WMSI of > or = 1.4 was associated with a 17.6% 30-day mortality (22 deaths in 125 patients), p = 0.0007. Average WMSI was higher in the nonsurvivors (1.95+/-0.5) than in survivors (1.52+/-0.45), p = 0.00001. CONCLUSIONS: Echocardiographic assessment of left ventricular function during the first 24 h after an acute Q-wave MI can be performed in all patients regardless of stability. High-risk patients are identified early in the hospital course, with relative ease, at no risk and at an acceptable cost. An ejection fraction < 45% or WMSI > or = 1.4 identifies patients who are at a high risk of dying within 30 days. These are the patients who may benefit most from aggressive medical therapy and early angiography to assess coronary pathology.     

小剂量多巴酚丁胺超声心动图试验和双核素心肌显像检测急性心肌梗死后患者存活心肌比较

目的比较小剂量多巴酚丁胺超声心动图试验（LDDE）和^99mTc-甲氧基异丁腈（MIBI）／^18F-脱氧葡萄糖（FDG）双核素同时采集法（DISA）单光子发射型断层显像（SPECT）对急性心肌梗死早期存活心肌检出的准确性。方法对44例急性心肌梗死患者于发病后5～10天内行LDDE和DISA—SPECT,所有患者在LDDE和DISA检查后接受经皮冠状动脉介入术。两种方法均采用16节段半定量法分析图像。心肌梗死后3个月随访二维超声,以局部室壁运动改善作为心肌存活标准,比较两种方法检测存活心肌的敏感性和特异性。结果LDDE检出存活心肌的敏感性、特异性、诊断准确性、阳性预测值和阴性预测值分别为77％、82％、79％、82％和77％。DISA检出存活心肌的敏感性、特异性、诊断准确性、阳性预测值和阴性预测值分别为85％、62％、74％、71％和79％。LDDE和DISA两者对运动异常节段检出存活心肌的一致性为70％。对于运动减低节段,LDDE和DISA对存活心肌检出率差异无统计学意义（74．1％比77．6％,P〉0．05）;对于无运动节段,LDDE对存活心肌检出率低于DISA（29％比53％,P〈0．01）。结论对急性心肌梗死后的患者,DISA检出存活心肌的敏感性高于LDDE,而特异性低于LDDE,联合应用起互补作用,提高检测存活心肌的能力。     

Stress-induced ST-segment elevation following myocardial infarction and its role in wall motion abnormality, myocardial ischemia and viability: comparison of response to exercise, dobutamine and dipyridamole.

Stress-induced ST-segment elevation following myocardial infarction (MI) has been correlated with myocardial ischemia, viability and wall motion abnormality, but its mechanism is still unclear, so the present study compared ST-segment elevation and wall motion response during exercise, dobutamine and dipyridamole stresses. Twenty-five patients with their first anterior MI underwent exercise, dobutamine and dipyridamole echocardiography on different days 4-6 weeks after MI. Left ventricular wall motion was analyzed using 5-grade/16-segment model and myocardial ischemia was considered as a worsening of the wall motion score index (WMSI) during the stress test; myocardial viability was defined as a reduction of WMSI during low dose dobutamine. Dyskinesis formation was defined by visual analysis as akinesis that became dyskinetic or if the dyskinesis worsened. Both exercise and dobutamine induced ST-segment elevation, but dipyridamole did not. There was no significant difference in the degree of ST-segment elevation between the patients with and without myocardial ischemia or dyskinesis formation. Exercise induced a higher ST-segment elevation in patients with myocardial viability than those without (0.17+/-0.09 mV vs 0.09+/-0.07 mV, p<0.05). Exercise-induced ST-segment elevations correlated with dobutamine-induced ST-segment elevations (p<0.01), changes in heart rate (p<0.05) and systolic blood pressure (p<0.05). In conclusions, stress-induced ST-segment elevation does not correlate with either myocardial ischemia or stress-induced dyskinesis, but may be associated with myocardial viability.     

Comparison of eprosartan and captopril in left ventricular systolic dysfunction: relation of efficacy to myocardial viability

Patients with left ventricular ejection fraction below 45% (mean 39+/-3.7%) were randomized either to captopril (n=33) or eprosartan after miocardial infarction (n=33) on days 3-7 of myocardial infarction. All patients were subjected to echocardiography and 40 to perfusion myocardial scintigraphy with (99m)TC-Technetril. Myocardial viability was defined as presence of perfusion reserve in dysfunctional segments during test with nitroglycerin. Dysfunctional myocardium was found to be viable in 62.5% of patients. Fifty six patients completed 3 months follow up and were restudied. By the time of the second study 28 patients continued captopril (37.5-150 mg, average dose 72+/-34.2 mg/day) and 28 - eprosartan (300-600 mg, average dose 471+/-151 mg/day). Captopril was stopped or its dose corrected in 28% of patients. In eprosartan group there were no side effects which required withdrawal of the drug. Similar increases of ejection fraction occurred on both groups (from 38+/-2.1 to 49+/-6.7%, p<0.001 and from 39+/-4 to 51+/-6.5%, p<0.001, in eprosartan and captopril groups, respectively). Magnitude of left ventricular ejection fraction change did not depend on the presence of viable myocardium. However in both treatment groups improvement of myocardial perfusion and decrease of left atrial dimensions were found only in patients with viable myocardium at initial study.     

Viability of Q-wave infarcted myocardium with restored positive and persistent negative T waves after optimal revascularization compared with dobutamine stress echocardiography

To clarify the clinical difference in viability of myocardium with negative and positive T waves in Q-wave anterior or anteroseptal myocardial infarction, we performed low-dose dobutamine stress echocardiography in 17 patients with negative T waves and in 13 patients with positive T waves with optimal revascularization of infarct-related arteries in the chronic phase of infarction. At baseline the wall motion score (WMS) of the negative and positive T groups was 25.8 +/- 3.0 and 22.3 +/- 2.2 points (p <0.05), respectively. At peak stress WMS in each group was 27.2 +/- 4.2 and 19.8 +/- 2.4 points (p <0.0001), respectively. With dobutamine stress WMS in the positive T group was more decreased than that of the negative T group (p <0.0001). We conclude that the restored positive T waves in Q-wave myocardial infarction indicate a significantly greater amount of viable myocardium than the negative T waves, showing better regional wall motion improvement with low-dose dobutamine stress.     

Early evaluation of coronary microcirculation by echocardiography with contrast medium in patients with acute myocardial infarction treated with primary percutaneous transluminal coronary angioplasty

AIM: In about 30% of patients with ST elevated myocardial infarction (STEMI), in which a TIMI 3 flow is obtained in the infarct related artery (IRA) after primary percutaneous transluminal coronary angioplasty (PTCA), it's not possible to obtain a good perfusion of coronary microcirculation (no reflow). Aim of the study is to estimate the prognostic value of microcirculation study by echocardiography with contrast medium (MCE) within 48 h from procedure and to point out if there're clinical or procedural factors correlated with no reflow. METHODS: From February 2002 to June 2003 we have analyzed the integrity of microcirculation by MCE in patients with STEMI treated with PTCA. We have included in this study 62 patients with anterior myocardial infarction (MI) (first event), within 12 h from symptoms onset, with great echocardiographic window and TIMI 3 flow in the IRA after PTCA, excluding shock. We have obtained the evaluation of myocardial perfusion by MCE within 48 h from the treatment. We have used Sonovue as contrast medium, infused through peripheral vein. In each patient we have measured: perfusion index (PI) (sum of single segments scores divided by total number of myocardial segments) and regional perfusion index (RPI) (number of normal perfused segments between the diskinetic ones divided by diskinetic segments). RPI varies from 0 to 1: when >0.5 it has been considered index of good perfusion. Ejection fraction (EF) and wall motion score index (WMSI) have been calculated within 48 h and at 6 weeks follow up. ST resolution (STR) has been evaluated at 90 min from procedure and it was considered significant when >70%. RESULTS: Patients have been divided into 2 groups by myocardial perfusion: group R (33 patients with RPI>0.5) and group NR (29 patients with RPI =/<0.5). The 2 groups were similar for age (group R: mean age 61 years old; group NR: mean age 64 years old, P=n.s.), glycoprotein inhibitors use (group R 90%, group NR 97%, P=n.s.), diabetes (group R 12%, group NR 17%, P=n.s.), hypertension (group R 22%, group NR 23%, P=n.s.), incomplete revascularization (group R 12%, group NR 10%, P=n.s.). Group NR has shown a major women percentage (33%) than group R (9%) P=0.026. In group R we have appreciated a trend to a major percentage of TIMI 2-3 flow preprocedure (66% vs 36%, P=n.s.), a shorter ischemic time (209 min vs 258 min, P=n.s.) and a major STR at 90 min (72% vs 53%, P=n.s.), not statistically significant. Echocardiographic analysis and MCE show a better myocardial perfusion in group R (RPI 0.7 vs 0.14 and PI 0.96 vs 0.86, P<0.0001); better left ventricular kinetics at 6 weeks follow up (EF 54.2% vs 50.8%, P=n.s. and WMSI 1.07 vs 1.2, P=0.014) but not in the acute phase (EF 46.8 vs 42.9 and WMSI 1.3 vs 1.34, P=n.s.) 30 days mortality is similar in the 2 groups (both 3%). CONCLUSIONS: Myocardial perfusion evaluation correlates with left ventricular contractility measured at 6 weeks from acute MI, but doesn't correlate with contractility in the acute phase or 30 days mortality.     

Assessment of residual myocardial viability in regions with chronic electrocardiographic Q-wave infarction

Background Q waves on the electrocardiogram are often considered to be reflective of irreversibly scarred myocardium due to antecedent transmural myocardial infarction. However, there are some indications that residual viable tissue may be present in Q-wave-infarcted regions. It is clinically relevant to know how many Q-wave regions contain viable tissue because these patients may benefit from revascularization in terms of improvement of function and long-term survival.Methods Patients (n = 150) with chronic electrocardiographic Q-wave infarction, heart failure symptoms, and chronic coronary artery disease underwent dobutamine-atropine stress echocardiography to assess myocardial viability. Residual viability in regions with Q-wave infarction was considered present when the end-diastolic wall thickness (EDWT) was >6 mm and the response during dobutamine infusion indicated viable tissue.Results Baseline echocardiography revealed 517 dysfunctional myocardial regions; 202 of the dysfunctional regions were related to Q waves on the electrocardiogram and the other 315 dysfunctional regions were not. EDWT was ≤6 mm in 13 regions with a Q wave on the electrocardiogram, with only 1 region exhibiting viable tissue during dobutamine stress echocardiography. EDWT was >6 mm in 189 regions with a Q wave, with 118 (62%) having viable tissue on do- butamine stress echocardiography. In 6 dysfunctional regions without a Q wave, EDWT was ≤6 mm, with all being non-viable on dobutamine stress echocardiography; of the 309 regions without a Q wave and EDWT >6 mm, 204 (66%) exhibited viability on dobutamine stress echocardiography.Conclusions Fifty-eight percent of dysfunctional regions related to chronic Q waves were viable according to the combined information of EDWT and dobutamine stress echocardiography. EDWT ≤6 mm virtually excludes viability; regions with EDWT >6 mm need additional testing to detect or exclude viability.     

Tissue velocity imaging during dobutamine stimulation for assessment of myocardial viability: segmental analysis in patients after myocardial infarction

BACKGROUND: Dobutamine stress echocardiography (DSE) is an established method for the detection of viable myocardium, but evaluation of this method is subjective. Tissue velocity Imaging (TVI) allows quantitative analysis of regional myocardial wall motion by assessment of systolic myocardial velocities. The aim of this study was to evaluate the diagnostic value of DSE and TVI for detection of viable myocardium. METHODS: In 56 patients (58+/-12 years) with previous myocardial infarction (130+/-42 days, mean ejection fraction 42+/-15%) low-dose DSE was combined with analysis of peak systolic myocardial velocities (Vpeak) by TVI for assessment of myocardial viability. As reference served a follow-up echocardiography after successful revascularization (mean 91+/-3 days). RESULTS: Of a total of 896 segments 200 showed abnormal wall motion (31 mildly hypokinetic, 50 severely hypokinetic, 115 akinetic, 4 dyskinetic). In 125 of these 200 segments regional improvement of regional wall motion was observed (62.5% viable). An increase of Vpeak>1 cm/s during dobutamine stimulation allowed the identification of viable myocardium with a sensitivity of 82% and a specificity 82% (DSE: 77% and 80%). By receiver operating characteristic (ROC) curve analysis, a cut-off value of 1.0 cm/s was the best parameter to differ viable from nonviable myocardium (area under the curve 0.85; p<0.01; 95% CI 0.79 to 0.90). Improvement of global ejection fraction after revascularization (47+/-13%, p=0.11) corresponded with three TVI viable segments with a sensitivity of 92% and a specificity of 89% (p=0.012). CONCLUSIONS: TVI allows the identification of viable myocardium during dobutamine stimulation and enables a quantitative interpretation of DSE.     

经静脉心肌声学造影评价心肌梗死后存活心肌的价值

目的　探讨经静脉心肌声学造影 (MCE)对心肌梗死后存活心肌的诊断价值。方法　 2 4例心肌梗死患者用二维超声评价室壁运动情况 ,同时经静脉进行MCE ,以 3个月后静态超声心动图左室心肌节段性运动改善为依据评价MCE对心肌梗死后存活心肌的诊断价值。结果　在 2 4例病人的 384个心肌节段中 ,运动异常节段 184个。在运动异常的 184个节段中 ,MCE1分 39段 ,0 5分 5 0段 ,0分 95段。 3个月复查 79个节段有运动改善 ,其中 39段来自MCE1分的心肌 ,4 0段来自MCE0 5分的心肌。MCE对预测心肌梗死后室壁运动改善的敏感性、特异性、阳性预测值、阴性预测值及准确率分别为 :10 0 %、89 7%、84 8%、10 0 %和 94 6 %。结论　MCE能比较准确地预测心肌梗死后心肌的存活性     

Deferoxamine infusion during coronary artery bypass grafting ameliorates lipid peroxidation and protects the myocardium against reperfusion injury: immediate and long-term significance.

AIMS: Previous reports have demonstrated enhanced myocardial protection and better post-ischaemic recovery using the oxygen free radical scavenger deferoxamine (DEF) during cardioplegia. The aim of this study was to test whether, in patients undergoing coronary artery bypass grafting (CABG), DEF i.v. infusion can reduce reperfusion injury on a short- and long-term basis. METHODS AND RESULTS: Forty-five consecutive male patients were randomly allocated to two groups: in group D (n=25, age 60.8+/-8.6 years), 4 g of DEF were infused for 8 h starting immediately after the induction of anaesthesia; in group C (n=20, age 62.2+/-6.4 years) dextrose solution was given for the same time as placebo. Haemodynamic monitoring and measurement of oxygen free radical production [by measuring thiobarbituric acid reactive substances (TBARS)] were carried out before and after CABG. Left ventricular ejection fraction (EF) and wall motion score index (WMSI) were measured before and after CABG and 12 months later. Haemodynamic measurements were similar in both groups before and after CABG. TBARS peaked at 4.8+/-1.1 nmol/mL in group C, but remained unchanged (2.4+/-0.9 nmol/mL) in group D (P=0.01). At baseline, both the EF and WMSI were similar between the groups. Following CABG, EF increased more in group D (8.8+/-8.4%) than in group C (1.3+/-6.7%), P=0.008, while WMSI decreased more in group D (-0.7+/-0.3) than in group C (-0.2+/-0.2), P=0.0001. Dividing group D according to the pre-operative median EF value (38%), we observed that after 1 year follow-up, DEF infusion conferred more protection in patients with a lower EF (EF increased by 19.3+/-6.2%, WMSI decreased by -1.1+/-0.2) than in those with a higher EF (EF increased by 7.7+/-4.5%, WMSI decreased by -0.8+/-0.2), P=0.001, respectively. CONCLUSION: In patients undergoing CABG, DEF i.v. infusion ameliorates oxygen free radical production and protects the myocardium against reperfusion injury. Patients with a lower EF seem to benefit more by DEF i.v. infusion.     

Identification of viable myocardium by echocardiography during dobutamine infusion in patients with myocardial infarction after thrombolytic therapy: comparison with positron emission tomography

To assess the presence of viable myocardium salvaged by coronary artery reperfusion, 17 patients with acute anterior myocardial infarction were studied. Each received intravenous thrombolysis within the first 3 h of symptoms and underwent two-dimensional echocardiography before and during dobutamine infusion (10 micrograms/kg per min) 7 +/- 4 days after admission and positron emission tomography 9 +/- 5 days after admission. Echocardiography and positron emission tomography were again performed 9 +/- 7 months later. Six comparable segments specific for the territory of the left anterior descending artery were selected for comparison of the two techniques. Wall thickening was evaluated by using an echocardiographic score index. Segmental perfusion and glucose uptake were measured and normalized to the peak activity. A ratio of glucose uptake to perfusion was calculated for each segment. Concordant interpretation of the two techniques was found in 79% of affected segments for both acute and follow-up studies. Positron emission tomography revealed the presence of viable myocardium in 11 patients (group 1); perfusion was within normal limits in 5 of these (group 1A). Myocardial thickening improved with dobutamine infusion in these five patients, the echocardiographic score index decreasing from 12 +/- 2 at rest to 7.8 +/- 1.3 during dobutamine infusion (p = 0.003). Functional recovery was demonstrated in all five patients (follow-up score index 7.4 +/- 1.7). Six patients exhibited decreased perfusion but an abnormally high glucose to perfusion ratio (group 1B); their score index improved with dobutamine from 14.8 +/- 2.2 to 12 +/- 2.1 (p = 0.05), but late functional recovery was found in only one of the six patients (mean follow-up score index in group 1B 16 +/- 1.7). In the six remaining patients in whom no viable myocardium was detected with positron emission tomography (group 2), the echocardiographic score index did not change with dobutamine (15 +/- 0.9 to 14.7 +/- 0.8, p = NS) and there was no functional recovery (follow-up score index 15.5 +/- 1.0). Echocardiography during dobutamine infusion is a promising method to unmask viable myocardium in acute myocardial infarction. Early recovery of perfusion in the area at risk is associated with a good functional outcome, whereas a high glucose to perfusion ratio indicates jeopardized myocardium that frequently loses viability.     

CD151对大鼠心肌梗死后血管新生及心功能的影响

目的观察CD151基因对心肌梗死后大鼠梗死心肌微血管密度和心功能的影响,以明确CD151体内促血管新生作用。方法结扎大鼠冠状动脉左前降支建立心肌梗死模型。构建PAAVCD151重组质粒,分点注射至梗死心肌及周围进行基因转染。另外设置心肌内不转染及转染PAAVGFP心肌梗死对照组。4周后测定心肌微血管密度及心功能。结果心肌注射PAAVCD151转染后心肌中CD151蛋白表达明显高于对照组(P<0.01)。转染CD151组心肌微血管密度[(385.4±79.9)N/MM2]明显高于对照组[(240.8±40.3)N/MM2](P<0.01)。心脏收缩功能指标射血分数、短轴缩短率、左室内压最大上升和下降速率等参数亦明显高于对照组(P<0.01)。结论CD151在体内具有明确的促血管生成作用,通过促进缺血心肌的血运重建起到保护心脏功能的作用。     

Time course of left ventricular remodeling after myocardial infarction: a two-dimensional echocardiographic study

In order to forecast the clinical course of acute myocardial infarction (MI), the time course of the functional changes of the left ventricular myocardium that result in remodeling was evaluated with two-dimensional echocardiography (2DE). The study group comprised 45 patients with anterior MI treated with successful percutaneous transluminal coronary angioplasty. 2DE studies were performed on days 1, 3, 7 and 14; months 1 and 3 and 1 year after MI, and the following parameters were recorded: (1) infarcted wall thickness, (2) traced length of the endocardium and of the epicardium on end-diastolic apical long axis images, and (3) wall motion score (total of asynergy scores of 16 segments of left ventricle (LV); normal: 0, hypokinesis: 1, akinesis: 2, dyskinesis: 3). According to the peak creatine kinase (CK) level, patients were classified into L group (CK > or =8000 U/L, n=16), M group (8000> CK > or =4000, n=13) and S group (CK <4000, n=16). The following results were obtained. (1) There was progressive thinning of the infarcted myocardium up to 1 month after (1 day: 9.3+/-1.7, 14 days: 6.3+/-1.7 vs 1 month: 5.9+/-1.8 mm, p<0.05; vs 1 year: 5.9+/-1.9 mm, NS). (2) Dilatation of the LV cavity occurred shortly after MI and continued up to 14 days (endocardium at 14 days: 176.8+/-13.6 vs 1 day: 164.1+/-11.4 mm, p<0.01; vs 1 year: 176.3+/-12.7 mm, NS). (3) The wall motion score improved rapidly by 14 days, and continued to improve gradually to 1 year (1 day: 12.2+/-3.4, 14 days: 6.8+/-4.0, 1 year: 4.6+/-3.1). (4) The expansion ratio (endocardial length at 14 days/1 day) was significantly greater in the L group than in the S group (p<0.05). Comparing the groups, the LV cavity of the L group remained dilated up to 14 days, whereas that of the S and M groups was dilated up to 7 days (L group 14 days: 179.3+/-11.9 vs 1 day: 156.9+/-9.2mm, p<0.01; vs 1 year: 180.0+/-14.1 mm, NS) (S group 7 days: 171.7+/-13.6 vs 1 day: 161.5+/-7.2 mm, p<0.01; vs 1 year: 172.7+/-14.4 mm, NS) (M group 7 days: 170.5+/-10.5 vs 1 day: 157.7+/-14.5 mm, p<0.05; vs 1 year: 177.08+/-9.6 mm, NS). Serial 2DE on days 1 and 14 after MI were useful for evaluating the course of LV remodeling and to forecast cardiac function in the chronic phase of MI. Determining the length of hospital stay on the basis of infarction size is justified.