Changes in Regional Myocardial Function after Coronary Artery Bypass Graft Surgery Are Predicted by Intraoperative Low-dose Dobutamine Echocardiography

Background: Left ventricular dysfunction is often reversed after coronary artery bypass graft (CABG) surgery; however, this change is not easily predicted. The authors hypothesized that functional changes after a low dose of dobutamine (5 [mu]g [middle dot] kg-1 [middle dot] min-1) intraoperatively would predict functional changes when complete revascularization was achieved.

Methods: The authors analyzed 560 segments in 40 patients scheduled for elective CABG surgery for regional wall motion (1-5 scoring system) at four stages: baseline (after induction and intubation), with administration of low-dose dobutamine before cardiopulmonary bypass, after separation from cardiopulmonary bypass (early), and after administration of protamine (late). Two independent observers scored the myocardial regions according to a 16-segment model in multiple imaging planes. For each segment, the response to dobutamine was dichotomized as improved or not improved from baseline and analyzed with logistic regression. The influence of covariates (ejection fraction, myocardial infarction, diabetes mellitus, and [beta] blockers) was also determined with logistic regression models. P < 0.05 was considered significant.

Results: Changes in myocardial function after low-dose dobutamine were highly predictive for early (P < 0.0001) and late (P < 0.0001) changes in myocardial function from baseline regional scores. The overall odds ratio for early and late improvement increased by 20.7 and 34.6, respectively, when improvement was observed after low-dose dobutamine was administered. The overall positive predictive value of improved regional wall motion after CABG did not vary with left ventricular ejection fraction, a history of myocardial infarction, or [beta] blocker use, and it varied little with diabetic status (range, 0.86-0.96) if regional wall motion improved with low-dose dobutamine before CABG. The overall negative predictive value was 0.70; however, the range varied with diabetic status (i.e., lowest in diabetic patients and highest in nondiabetic patients).     

Is there a long-term predictive value of intraoperative low-dose dobutamine echocardiography in patients who have coronary artery bypass graft surgery with cardiopulmonary bypass?

In patients with coronary artery disease, chronic regional left ventricular systolic dysfunction at rest may be caused by hibernating or by infarcted myocardium. Intraoperative low-dose dobutamine (LDD) echocardiography reliably predicts the immediate recovery of regional myocardial function after coronary artery bypass graft (CABG) surgery. We sought to determine whether intraoperative LDD echocardiography would also predict recovery of regional function after 1 yr. Twenty-five patients with coronary artery disease who underwent CABG surgery with intraoperative LDD echocardiography were evaluated 1 yr later with a follow-up transthoracic echocardiogram. The covariates of left ventricular ejection fraction, old myocardial infarction, and diabetes mellitus were considered in an analysis of regional wall motion (RWM). A 16-segment model and a 1-5-point scoring system were used to evaluate 350 myocardial segments. Multiple logistic regression analysis was performed to determine whether response to intraoperative LDD echocardiography (5 microg. kg(-1). min(-1)) predicted changes in regional function at 1 yr. A segment was defined as stunned if the RWM score obtained during LDD infusion deteriorated after cardiopulmonary bypass but recovered in the 1-yr follow-up echocardiogram. A response to intraoperative LDD predicted changes in regional function at 1 yr. The overall odds of improvement in regional function were 2.22 times greater (95% confidence interval = 1.29, 3.82; P = 0.0039) with a positive response to intraoperative LDD. The positive predictive value of intraoperative LDD echocardiography for improvement in myocardial function was 0.81 and the negative predictive value was 0.34. The predictive values did not vary with the examined covariates. Of segments with unexpected deterioration of RWM immediately after cardiopulmonary bypass, 87% recovered at the time of the 1-yr follow-up echocardiogram. Contractile reserve demonstrated by intraoperative LDD echocardiography predicts regional function at 1 yr; however, the test cannot predict which segment will not recover. Most of unexpected regional ventricular systolic dysfunction immediately after CABG surgery can be attributed to myocardial stunning. IMPLICATIONS: In patients undergoing coronary artery bypass graft surgery, intraoperative low-dose dobutamine echocardiography has only limited value for the prediction of regional myocardial function at 1 yr. Small-dose dobutamine echocardiography predicts regional myocardial function at 1 yr when baseline regional wall motion abnormalities improve with dobutamine; however, the test cannot be used to predict which segment will not recover at 1 yr.     

术中多巴酚丁胺负荷经食道超声心动图预测冠状动脉旁路移植术后心肌存活的评价

目的 评价术中多巴酚丁胺负荷经食道超声心动图(DSE)预测冠状动脉旁路移植术后心肌存活情况.方法 择期拟行冠状动脉旁路移植术病人24例,性别不限,年龄50～75岁,体重55～90 kg,NYHA分级Ⅱ或Ⅲ级,左室射血分数30%～55%.麻醉诱导后,采用食道超声按16节段法,观察左室节段室壁运动情况,行半定量评分.静脉输注多巴酚丁胺,初始速率5μg·kg~(-1)min~(-1),然后以1μg·kg~(-1)min~(-1)的速率递增,每一速率持续输注3 min.将舒张末室壁厚度>0.5 cm的节段、室壁运动异常评分较给药前降低≥1分的心肌定义为存活心肌.计算DSE预测心肌运动恢复的敏感度、特异度、准确率、阳性预测率和阴性预测率.结果 DSE预测心肌存活率(36.3%)低于术后心肌运动改善率(43.2%)(P<0.05).DSE预测心肌存活的敏感度、特异度、准确率、阳性预测率和阴性预测率分别为75.3%、92.7%、85.3%、88.4%和83.5%.结论 术中DSE可有效地预测冠状动脉旁路移植术后存活心肌及功能恢复.     

Factors excercising an influence on recovery of hibernating myocardium after coronary artery bypass grafting.

OBJECTIVE: Coronary artery bypass grafting (CABG) in patients with endstage coronary disease (CAD) significantly improves symptoms and prolongs life expectancy. Left ventricular function is also improved in some patients, but not in others. Factors which influence functional recovery of hibernating myocardium after revascularization are at present under investigation. METHODS: From 3/2000 to 8/2002, we analyzed 41 patients with an ejection fraction (EF) of < or =30%, who underwent CABG, prospectively. All patients received low-dose dobutamine echocardiography (DE), dobutamine myocardial scintigraphy with SPECT, dobutamine magnetic resonance tomography (MRI), contrast-enhanced MRI and, when necessary, positron emission tomography (PET). Hibernating myocardium (area of interest) was identified with these diagnostic tools preoperatively and biopsy samples were taken intraoperatively. RESULTS: All patients received complete coronary revascularization. Early mortality was 2.4%. Three patients died during follow-up. Six months after the operation DE, MRI and SPECT were repeated. EF increased in 23 patients (group I) by at least >or =5%, and in 14 patients (group II) it did not improve. The wall motion score in the area of interest had increased during preoperative DE in group I significantly. The score did not change in group II. In addition the diastolic-systolic wall thickness increase in the area of interest rose >15% during DE in group I preoperatively; the increase was < or =15% in group II. MRI hyperenhancement of the left ventricle was significantly lower in group I compared to group II preoperatively. SPECT showed myocardial viability in the area of interest in all 37 patients. There were no significant differences between group I and II seen in SPECT. When the area of interest was located in the anterior wall the patients more frequently showed ventricular improvement postoperatively than patients with an area of interest located in the inferior, lateral or posterior wall. Light microscopy showed more severe myocardial cell hypertrophy (>19 microm) and less severe destruction of myocardial cell architecture in biopsies of group I compared to group II (myocardial cell hypertrophy < or =17 microm). Electron microscopy showed mitochondrial abnormalities in size and shape, lack of contractile material and large areas containing nonspecified cytoplasm, lipid droplets, and large glycogen-filled regions, but no significant differences between the two groups. Gene expresssion of the pro-apoptotic genes BAK and BAX was lowered compared to expression in 'normal' myocardium. The anti-apoptotic gene BCL-XL was significantly more expressed in the 'area of interest' of group II patients than in group I patients. CONCLUSIONS: We conclude that in patients with endstage CAD myocardial recovery after coronary revascularization can be predicted using DE and MRI preoperatively. Myocardial regions without any potential of functional recovery show less adaptation (less pronounced myocardial cell hypertrophy), a more severe degree of myocardial architecture destruction and a higher degree of anti-apoptotic gene expression. We recommend a myocardial biopsy when DE and MRI are not favorable in a patient with end stage coronary artery disease referred to us with the option of heart transplantation or coronary bypass.     

Deterioration of regional wall motion immediately after coronary artery bypass graft surgery is associated with long-term major adverse cardiac events

BACKGROUND: Patients undergoing coronary artery bypass graft (CABG) surgery frequently develop wall motion abnormalities diagnosed by intraoperative transesophageal echocardiography. However, the relation between deterioration in wall motion and postoperative morbidity or mortality is unclear. Therefore, the authors hypothesized that deterioration in intraoperative left ventricular regional wall motion immediately after CABG surgery is associated with a higher risk of adverse cardiac events. METHODS: With institutional review board approval, data were gathered from 1,412 CABG surgery patients. Echocardiographic wall motion score (WMS) was derived using a 16-segment model. Outcomes data were gathered for up to 2 yr after surgery. The primary outcome, major adverse cardiac event, was a composite index of myocardial infarction, need for subsequent coronary revascularization, or all-cause mortality during the follow-up period. RESULTS: Two hundred twenty-one patients (16%) had 254 primary outcome events during follow-up. Postbypass WMS did not change in 812 patients (58%), deteriorated in 219 patients (16%), and improved in 368 patients (26%). Kaplan-Meier analysis showed that patients with deterioration in WMS after CABG experienced significantly lower major adverse cardiac event-free survival than patients with either no change or improvement in WMS (P = 0.004). Cox proportional hazards regression modeling revealed a significant association between deterioration in WMS and the composite adverse outcome (hazard ratio, 1.47 [1.06-2.03]; P = 0.02). CONCLUSIONS: The authors confirmed their hypothesis that deterioration in wall motion detected by intraoperative echocardiography after CABG surgery is associated with increased risk of long-term adverse cardiac morbidity. Worsening wall motion after CABG surgery should be considered a prognostic indicator of adverse cardiovascular outcome.     

Hemodynamic and transesophageal echocardiographic analysis of global and regional myocardial functions, before and immediately after coronary artery bypass surgery

AIM: We investigated the effect of coronary artery bypass grafting (CABG) surgery on global and regional myocardial function; before and immediately after coronary artery bypass grafting and 1 month after the operation. METHODS: Twenty-five patients who were undergoing elective CABG were evaluated. Transesophageal echocardiography (TEE) was used to evaluate both global and regional myocardial function. Intraoperative TEE images of the left ventricle were obtained after cannulation but before cardiopulmonary bypass (CPB), 5 and 30 minutes after the termination of CPB. Same time, hemodynamic parameters were recorded. Transesophageal echocardiography evaluation was repeated one month after the operation. RESULTS: Global left ventricular function was significantly depressed 5 minutes after CPB. At the 30 minutes after CPB, left ventricular function has returned to pre-CPB baseline levels. Global left ventricular function was significantly increased at 30 days following CABG surgery. The myocardial segments that were normal before CABG had reduced contractile functions at 5 minutes after CABG but normal segments showed a significant improvement from 5 to 30 minutes. The function of this region could not reach its initial status. The segments that had severe impairments of contractile function before the revascularization showed significant improvements at 30 minutes following CABG. CONCLUSIONS: In conclusion, a successful coronary revascularization provides an improvement in contractility in cases with chronic regional left ventricular dysfunction that is not related to irreversible necrosis.     

Quantitative assessment of myocardial viability following coronary artery bypass grafting using exercise thallium-201 myocardial single photon emission computed tomography and left ventricular regional wall motion

Using exercise thallium-201 myocardial single photon emission computed tomography (SPECT) and % radial shortening (%RS), 58 patients were evaluated before and after coronary artery bypass grafting (CABG) to quantitatively assess myocardial viability and the effect of CABG. The patient was classified, according to redistribution pattern, as group I with only complete redistribution (20 cases) and group II with including incomplete redistribution (22 cases) and group III with no redistribution (16 cases). 1. Group I was expected complete improvement of ischemic myocardium after CABG but regional left ventricular wall motion was unchanged (sigma i%RS: 142.5 +/- 54.7----138.4 +/- 39.6, sigma a%RS: 201.2 +/- 51.1----238.2 +/- 68.2). 2. Group II was expected to diminish ischemic size after CABG and left ventricular regional wall motion was significantly improved (sigma i%RS: 68.8 +/- 25.9----154.9 +/- 42.6 p less than 0.01, sigma a%RS: 108.4 +/- 62.3----178.9 +/- 77.6, p less than 0.05). 3. Group III was no significant change of ischemic size and left ventricular wall motion after CABG (sigma i%RS: 67.8 +/- 24.1----83.9 +/- 19.2, sigma a%RS: 86.0 +/- 29.0----94.0 +/- 33.9). The present study suggests that quantitative assessment of myocardial viability using exercise thallium-201 myocardial SPECT and %radial shortening was useful method to determine the indication and to assess the effect of CABG.     

Deterioration of Regional Wall Motion Immediately after Coronary Artery Bypass Graft Surgery Is Associated with Long-term Major Adverse Cardiac Events

Background: Patients undergoing coronary artery bypass graft (CABG) surgery frequently develop wall motion abnormalities diagnosed by intraoperative transesophageal echocardiography. However, the relation between deterioration in wall motion and postoperative morbidity or mortality is unclear. Therefore, the authors hypothesized that deterioration in intraoperative left ventricular regional wall motion immediately after CABG surgery is associated with a higher risk of adverse cardiac events.

Methods: With institutional review board approval, data were gathered from 1,412 CABG surgery patients. Echocardiographic wall motion score (WMS) was derived using a 16-segment model. Outcomes data were gathered for up to 2 yr after surgery. The primary outcome, major adverse cardiac event, was a composite index of myocardial infarction, need for subsequent coronary revascularization, or all-cause mortality during the follow-up period.

Results: Two hundred twenty-one patients (16%) had 254 primary outcome events during follow-up. Postbypass WMS did not change in 812 patients (58%), deteriorated in 219 patients (16%), and improved in 368 patients (26%). Kaplan-Meier analysis showed that patients with deterioration in WMS after CABG experienced significantly lower major adverse cardiac event-free survival than patients with either no change or improvement in WMS (P = 0.004). Cox proportional hazards regression modeling revealed a significant association between deterioration in WMS and the composite adverse outcome (hazard ratio, 1.47 [1.06-2.03]; P = 0.02).     

Echocardiographic analysis of dysfunctional and normal myocardial segments before and immediately after coronary artery bypass graft surgery.

Echocardiography has revealed evidence of "subnormal" regional contraction patterns that result from myocardial ischemia and are often accompanied by nonadjacent "hyperkinetic" regions. Whether these regions of hyperkinetic wall motion persist unchanged or revert to normal after coronary artery bypass graft (CABG) surgery has not been studied in humans. Using echocardiography, we evaluated both dysfunctional and normal myocardial regions for changes in segmental wall motion and percent of systolic wall thickening that occurred immediately after CABG surgery in 32 patients. Segmental wall motion analysis before CABG surgery in these patients revealed that 170 (66%) of 256 myocardial segments were subnormal, of which 115 (67%) improved and 102 (60%) returned to normal immediately after CABG surgery. Eleven myocardial segments that were hyperkinetic before CABG surgery returned to normal after CABG surgery. Preoperatively, 162 (63%) of 256 myocardial segments had systolic wall thickening less than 30%, which increased from 11.8% +/- 8.9% to 24.3% +/- 14.3% (mean +/- SD) (P less than 0.01) postoperatively. Conversely, a reverse trend was found when systolic wall thickening was greater than 30% before CABG surgery: thickening decreased from 46.2% +/- 13.8% to 33.4% +/- 14.8% after CABG surgery (P less than 0.01). Thus, we conclude that immediately after CABG surgery, there is a recovery of function in some myocardial segments and a reduction in function in others. Furthermore, we conclude that the semiquantitative assessment of percent of systolic wall thickening is a more reliable (consistent) echocardiographic index of myocardial function compared with the qualitative assessment of segmental wall motion immediately after CABG surgery.     

Perioperative transoesophageal echocardiography with low-dose dobutamine stress for evaluation of myocardial viability: a feasible approach?

Background : The feasibility of low-dose dobutamine stress combined with transoesophageal echocardiography (TEE) to detect viable left ventricular myocardium was evaluated in 22 anaesthetised patients prior to sternotomy for elective coronary artery bypass grafting (CABG). Methods :After baseline measurements, a dobutamine infusion beginning with 5 μg . kg^-1 . min^-1 was started and eventually increased to 10 μg . kg^-1 . min^-1. Viability was assessed as visual improvement of left ventricular wall motion (LVWM). The criteria for discontinuation of the infusion were: 1. any changes in LVWM, 2. an increase in preanaesthetic blood pressure exceeding 40 MMHg, and/or a >20% increase in preanaesthetic heart rate compared to preanaesthetic levels. An off-line evaluation of LVWM was based upon visualisation of the left ventricle in a transgastric short-axis mid-papillary (mid-P) view, and the left ventricle was divided into anterior, septal, inferior, and lateral segments. Moreover, an off-line semiautomatic analysing system was used for assessing regional and global LVWM. With this analysis the effects on LVWM from changes in preload and afterload could be addressed. Results : 19 patients showed a decreased LVWM in one or several segments at baseline. A total of 36 segments exhibited decreased LVWM (an average of 1.9 segments/patient). Of these, 22 segments (61%) improved with dobutamine, while 12 segments (33%) did not, and 2 (6%) became more dysfunctional. Another 6 segments with normal motion at baseline became dysfunctional with dobutamine. According to the off-line semiautomatic analysing system for LVWM, there were no statistically significant changes with dobutamine stimulation. Only one patient showed an increased postoperative aspartateamino-transferase (ASAT) value (3.0 mmol . 1^-1) but no ECG changes. Conclusion : Since we regard the visual assessment of LVWM as being more applicable for this protocol than the semiautomatic analysis, we conclude that low-dose dobutamine stress echocardiography seems to be a feasible method for detecting viable myocardium in the anaesthetised patient scheduled for elective CABG surgery. However, the semiautomatic analysis complemented our findings, since the variations in pre- and afterload did not significantly change the size of the left ventricle, which hereby would imply LVWM changes.     

Effects of coronary artery bypass grafting for patients with totally occluded left anterior descending arteries]

Between April, 1987 and March, 1991, 21 patients with totally occluded left anterior descending arteries (TOLAD) underwent coronary artery bypass grafting (CABG) in our institute. All of them were diagnosed as angina pectoris and 15 (71%) of them have had episodes of myocardial infarction. Graftability of TOLAD was 90% (19/21) and two of the TOLADs were not suitable for CABG because severe atherosclerosis of these arteries were observed intraoperatively. There was no operative death. Short term (1-2 months) patency was 64% (7/11) for saphenous vein grafts (SVG) and 100% (8/8) for left internal thoracic artery grafts (LITA). Left ventricular wall motion assessed by left ventriculography showed impaired regional wall motion in 63% segments of the segment #2, #3 and #6 preoperatively. However, the regional wall with impaired motion decreased to 31% after CABG. Thallium-201 scintigraphy showed impaired perfusion in 62% segments of the left anterior wall, apex and interventricular septum preoperatively. However, the regional wall with impaired perfusion decreased to 42% after CABG. Exercises tolerance assessed by treadmill test was improved from 3.8 +/- 0.7 Mets preoperatively to 6.5 +/- 0.7 Mets with patent coronary bypass grafts. These data suggested that CABG can improve the wall motion of the regions perfused by TOLADs and the LIMA is more suitable than the SVG for CABG to TOLAD.     

Alteration of the left ventricular contractile reserve in heart transplant patients: a dobutamine stress strain rate imaging study

BACKGROUND: Strain rate imaging (SRI), a recently developed Doppler-derived process, allows quantification of myocardial systolic function. We investigate whether SRI quantifies the contractile reserve during dobutamine stress tests in heart transplant patients (HT), when compared with normal individuals. METHODS: An incremental dobutamine test (5 to 40 microg/kg per minute) was performed in 10 HT and 15 control subjects, all of whom displayed normal coronary angiography. Gray-scale and color myocardial Doppler data were acquired in standard B-mode views at baseline, low-dose, peak, and recovery. Longitudinal SR was processed from the myocardial velocities for each segment. The changes in maximal systolic SR were used to quantify myocardial contractile reserve. RESULTS: Dobutamine infusion failed to induce clinical symptoms or electrocardiographic (ECG) changes in either group. Visually determined wall motion score was considered normal in all segments for each stage of the dobutamine stress. Heart rate was augmented similarly in both groups during dobutamine infusion. In controls, systolic SR increased gradually with incremental dobutamine dose and returned to baseline values upon recovery. Conversely, in HT patients, the increase in systolic SR was blunted at peak dobutamine, at which point it was significantly different vs controls. CONCLUSIONS: Quantitative assessment of myocardial function using SRI during dobutamine stress revealed an impaired contractile reserve in HT patients with normal coronary angiography. These subtle changes in regional myocardial function could not be identified using visual wall motion scoring. Additional studies are necessary to evaluate whether SR imaging detection of contractile reserve impairment will improve clinical efficiency or event prediction in this population.     

Myocardial perfusion correlates with improvement of systolic function of the left ventricle after CABG. Dobutamine echocardiography and Tc-99m-MIBI SPECT study.

OBJECTIVE: The aim of the study was to assess the effect of surgical revascularization [coronary artery bypass grafting (CABG)] on systolic function and perfusion of the left ventricle using dobutamine echocardiography (DE) and Tc-99m-MIBI SPECT (SPECT). METHODS: There were 32 patients mean age 52.2+/-7.2 years in whom DE and SPECT were performed before and 3-4 months after CABG using standard protocols. Wall motion score index (WMSI) and perfusion index (PI) were calculated. RESULTS: Significant improvement of WMSI at rest (1.44+/-0.46 vs 1.33+/-0.41; P=0.03) as well as after maximal dose of dobutamine (1.49+/-0.42 vs 1.39+/-0.44; P=0.02) was observed after CABG as compared to preoperative examination. Similar relation was observed during SPECT study. Perfusion index diminished significantly after revascularization during rest acquisition (2.19+/-0.71 vs 1.93+/-0.70; P=0.0008) and after Dipirydamole administration (2.73+/-0.73 vs 2.20+/-0.69; P=0.0001) as compared to preoperative examination. We found correlation between PI and WMSI at rest before CABG (R=0.46; P=0.01), PI after Dipirydamole and WMSI after maximal dose of Dobutamine before CABG (R=0.37; P=0.04), PI and WMSI at rest after CABG (R=0.39; P=0.03), PI after Dipirydamole and WMSI after dobutamine after CABG (R=0.38; P=0.03). CONCLUSIONS: Surgical revascularization significantly improves both perfusion and contractility. Increased perfusion after CABG correlates with improvement of systolic function of the left ventricle.     

Real time assessment of myocardial revascularization during coronary artery bypass surgery by means of ultrasonic integrated backscatter.

OBJECTIVE: The recovery of cyclic variation (CV) of ultrasonic integrated backscatter (IB) may provide a more sensitive predictor of the success of myocardial revascularization. This study was designed to elucidate the possibility of real time assessment of coronary artery bypass grafting (CABG) using CV of IB. METHODS: We studied 10 patients (61 +/- 4 years old) with the perfused areas by stenosed or occluded LAD without myocardial infarction. There were six ischemic dysfunctional areas, and four ischemic but non-dysfunctional areas. The CV of IB was measured before and just after extracorporeal circulation (ECC). Wall motion was analyzed by segmental wall thickening during systole at the same time of the IB analysis during CABG and at 3 weeks after CABG. Those 10 areas were completely revascularized. RESULTS: In the non-dysfunctional areas, wall thickening did not change and remained at normal values before and after ECC, and 3 weeks after CABG (31 +/- 3% 29 +/- 3% and 29 +/- 5%, respectively). The magnitude of CV of IB did not also change before and after ECC (8.0 +/- 1.6 dB and 7.8 +/- 1.3 dB). However, in the ischemic dysfunctional areas, while wall thickening did not change before and after ECC (21 +/- 5% and 20 +/- 5%), it increased and reached similar values as the non-dysfunctional regions at 3 weeks after CABG (26 +/- 7%, P < 0.01 vs. before and after ECC values). The magnitude of CV of IB increased even after ECC (3.71 +/- 0.4 dB vs. 7.4 +/- 3.5 dB, P < 0.05), and reached the same level as those in the non-dysfunctional areas. There was a significant relationship between wall thickening at 3 weeks after bypass grafting and magnitude of CV of IB after ECC (r = 0.67, P < 0.05). CONCLUSIONS: Improvement in wall motion was gradually attained after bypass grafting. On the contrary, an increase in the magnitude of CV of IB was obtained immediately after myocardial revascularization. Our data suggest that CV of ultrasonic IB method can provide close real time information regarding the effectiveness of bypass surgery.     

Autotransplantation of unmanipulated bone marrow into scarred myocardium is safe and enhances cardiac function in humans

Stem cell transplants into damaged myocardium may have the potential to improve cardiac function. We investigated the safety of transplanting unmanipulated autologous bone marrow into infarcted myocardium of patients undergoing coronary bypass surgery and assessed its efficacy to improve cardiac function. Fourteen patients with one or more areas of transmural myocardial infarction were studied. Autologous bone marrow was obtained by sternal bone aspirate at the time of surgery, diluted in autologous serum at a ratio of 1:2, and then injected 1 cm apart into the mid-depth of the left ventricular scar. There were no deaths, no perioperative myocardial infarctions, and no significant ventricular arrhythmias. Dobutamine stress echocardiography demonstrated overall improvement in the global and regional left ventricular function 6 weeks and 10 months after surgery. Of 34 infarcted left ventricular segments, 11 were injected with bone marrow alone, 13 were revascularized with a bypass graft alone, and 10 received bone marrow transplantation and a bypass graft in combination. Only the left ventricle segmental wall motion score of the areas injected with bone marrow and receiving a bypass graft in combination improved at low dose and at peak dobutamine stress. These findings suggest that transplantation of unmanipulated autologous bone marrow into scar tissue of the human heart is safe and enhances cardiac function only when used in combination with myocardial revascularization. This benefit can be seen after 6 weeks of the bone marrow transplant and is maintained after 10 months of follow-up.     

Improved perfusion and contractile reserve after transmyocardial laser revascularization in a model of hibernating myocardium

Background. Transmyocardial laser revascularization (TMR) has been demonstrated effective for relieving angina, although prior studies have yielded inconsistent results regarding postoperative myocardial perfusion and function. This study evaluated long-term changes in myocardial perfusion and contractile reserve after TMR in a model of hibernating myocardium.

Methods. Miniswine had subtotal left circumflex coronary artery occlusion to reduce resting blood flow to 10% of baseline. After 2 weeks in the low-flow state, positron emission tomography and dobutamine stress echocardiography were performed to document ischemic, viable (hibernating) myocardium in the left circumflex distribution. Animals then had sham redo thoracotomy (n = 4) or TMR (n = 6). Six months later the positron emission tomography and dobutamine stress echocardiography studies were repeated.

Results. Myocardial blood flow in the left circumflex distribution as measured by positron emission tomography was significantly reduced in all animals after 2 weeks in the low-flow state. In animals that had TMR, there was significant improvement in myocardial blood flow to the lased regions 6 months postoperatively. No significant change in myocardial blood flow was seen in sham animals at 6 months. Dobutamine stress echocardiography after 2 weeks of low-flow demonstrated severe hypocontractility at rest in the left circumflex region of all animals, with a biphasic response to dobutamine consistent with hibernating myocardium. In animals that had TMR, there was a trend toward improved resting function and significantly improved regional stress function in the lased segments 6 months postoperatively, consistent with a reduction in ischemia. Global left ventricular wall motion at peak stress improved significantly as well. There was no change in wall motion 6 months postoperatively in sham-operated animals.

Conclusions. This study found improvements in myocardial perfusion and regional and global contractile reserve 6 months after TMR in a porcine model of hibernating myocardium. This improved perfusion and function likely accounts for the clinical benefits of the procedure.     

Mid-term results of combined transmyocardial laser revascularization and coronary artery bypass

BACKGROUND: Transmyocardial laser revascularization is increasingly used to treat intractable angina in the absence of graftable vessels; however, its role in combination with coronary artery bypass grafting remains undefined. The aim of this pilot study was to investigate the outcome of the combination therapy at mid-term follow-up. METHODS: Patients (n = 20) who had elective coronary artery bypass with one or more nongraftable coronary arteries were prospectively randomized to have either coronary artery bypass grafting alone or combination coronary artery bypass grafting plus transmyocardial laser revascularization with a holmium:YAG (yttrium-aluminum-garnet) laser to nongraftable areas. All patients had an exercise tolerance test preoperatively and at 6, 18, and 36 months follow-up. Stress echocardiography was performed on 17 patients at 18 months postoperatively, and regional wall motion score index was calculated in lased and nonlased nonrevascularizable myocardium of the left ventricle at rest and with dobutamine stress. RESULTS: Both groups of patients were similar in preoperative demographics and operative data. There was no perioperative death. There was no difference between the two groups in angina scoring at 6, 18, and 36 months follow-up. Exercise tolerance improved by a mean of 46.8 +/- 20.0 seconds in the coronary artery bypass grafting group versus 199.2 +/- 66.5 seconds per patient in the coronary artery bypass grafting plus transmyocardial laser revascularization group (p = 1.8 x10(-6)) at 6 months; this benefit was maintained at 18 months (157 +/- 46.3 versus 61 +/- 39.2 seconds; p = 4 x10(-4)) but was lost at 36 months (57.2. +/- 42.1 versus 68.1 +/- 46.7 seconds; p = 0.70). The mean values for wall motion score index in the lased and nonlased regions at each stage of dobutamine stress at 18 months after surgery were not statistically significant. CONCLUSIONS: The combination of coronary artery bypass and transmyocardial laser revascularization improved exercise tolerance in patients in whom complete revascularization could not be achieved by bypass grafting alone in the short term, but this benefit was lost by 36 months postoperatively. The transient improvement in exercise tolerance cannot be explained by changes in contractility in the lased areas.     

Acute effects of aortocoronary bypass surgery on left ventricular function and regional myocardial mechanics: a clinical study.

The acute effects of myocardial revascularization on overall left ventricular performance and on myocardial segmental wall motion were assessed intraoperatively in 22 patients who had unstable (11 patients) or stable angina pectoris (11 patients). Segmental contraction patterns were evaluated using an ultrasonic transit-time method. In 9 patients with unstable angina pectoris, notable improvement in segmental wall motion was observed as the short-term response to coronary bypass grafting. Hypokinetic patterns were rendered normal after revascularization. Despite marked changes in segmental myocardial function, overall left ventricular performance was not altered notably. In contrast, reperfusion did not lead to acute effects on either segmental wall motion or total left ventricular function in patients with stable angina pectoris. The results indicate that aortocoronary bypass grafting may improve segmental wall motion in patients with unstable angina.     

Perioperative enoximone infusion improves cardiac enzyme release after CABG

OBJECTIVE: To assess whether routine postoperative enoximone infusion compared with dobutamine improved clinical and biochemical results after coronary artery bypass grafting with cardiopulmonary bypass. DESIGN: Prospective nonrandomized study. Data collection was blinded to the choice of inotrope. SETTING: Double-institutional clinical investigation. PARTICIPANTS: Two hundred sixteen consecutive patients undergoing myocardial revascularization between May 2000 and December 2002. INTERVENTIONS: Seventy-two patients underwent myocardial revascularization and were treated with enoximone, 5 microg/kg/min (group A). They were compared in a ratio of 1:2 to 144 patients treated with dobutamine at the same dose (group B) after aortic cross-clamp removal. The groups proved to be homogenous in preoperative and intraoperative characteristics. MEASUREMENTS and MAIN RESULTS: Hospital outcome, electrocardiogram, echocardiography, further inotropic support, and biochemical markers of ischemia were compared. Subsets of patients with comorbidities and total arterial revascularization were analyzed. Perioperative myocardial infarction, postoperative low-output syndrome, intra-aortic balloon pump, atrial fibrillation, ST-segment changes, postoperative echocardiographic findings, and intensive care and hospital durations were similar between groups. In the postoperative course, more patients belonging to group A maintained low-dose inotropic support, whereas more patients belonging to group B required higher doses. Troponin I and creatine kinase-MB values were higher in patients of group B, especially when subgroups with diabetes, left ventricular hypertrophy, or total arterial revascularization were included. CONCLUSION: Postoperative enoximone reduced troponin I release and need for inotropic support in patients undergoing on-pump myocardial revascularization. Subgroup data were confirmed in diabetes, left ventricular hypertrophy, and total arterial revascularization.     

Left anterior descending coronary artery: long-term angiographic results of CABG with endarterectomy

AIM: The procedure of coronary bypass grafting (CABG) with coronary endarterectomy (CE) is controversial. However, in the setting of severely calcified coronary arteries CE may enable complete revascularization. Complete revascularization, especially of the left anterior descending artery (LAD), is important for long-term outcome. In this study we assessed long-term LAD graft patency and anterior wall function after CABG with CE of the LAD. METHODS: Between 1984 and 1992, 283 patients underwent CABG with CE of the LAD. In 50 patients (47 men), aged 59+/-7.6 (40-77), clinical reassessment and surveillance angiography were performed. In all patients complete revascularization had been achieved with 3.5+/-1 (1-5) grafts/patient with 1-3 CE/patient. The LAD was grafted either with a saphenous vein segment (N=38) or with left intern thoracic artery (N=12). A graft obstructed less than 50% in diameter was defined as patent. RESULTS: At follow-up 39 patients (78%) were in CCS class I/II and had improved significantly (P<0.000). Control angiography after 7.6+/-2.5 (3.5-11.7) years after CABG revealed a patent LAD graft in 30/50 patients (60%). Actuarial graft patency was 100%, 96%, and 56% after 2, 5, and 10 years and was lower in patients with diabetes (P=0.001). Deterioration of anterior wall motion was observed in 17 patients (34%) and was more frequent if anterior wall motion was preoperatively normal (P=0.002), irrespective of LAD graft patency. CONCLUSION: Clinical status and long-term graft patency of grafts on endarterectomized LAD is considerable. However, patients with preoperatively normal anterior wall function are at increased risk for myocardial damage in the long-term.