Coronary artery bypass surgery in patients with impaired left ventricular function. Predictors of hospital outcome

This prospective study evaluates the surgical outcome of 75 consecutive patients with impaired left ventricular function, including an analysis of predictors of the short-term outcome following coronary artery bypass grafting (CABG). Seventy-five patients (mean age 64 +/- 13 years) with coronary artery disease and impaired left ventricular function (left ventricular ejection fraction [EF] < or = 40%) who underwent a coronary artery bypass surgery were prospectively studied. Echocardiography and thallium-201 myocardial scintigraphy were preoperatively performed to measure the left ventricular function and to assess myocardial viability. Postoperative echocardiography was done before discharge and six months later to evaluate recovery of left ventricular function. Five patients (6.7%) died in total: three deaths were cardiac related (4%) and two patients (2.7%) died due to other causes. The left ventricular ejection fraction improved immediately after the operation (from 32.2 +/- 6% to 39.5 +/- 8%, p = 0.01) and showed a sustained improvement at later follow-up (mean = 16.3 +/- 4.5 months) (44.0 +/- 4.0%, p = 0.01). The left ventricular wall motion score improved significantly only at later follow-up (from 12.2 +/- 1.8 to 9.4 +/- 2.0, p = 0.03). In 43 patients of whom a preoperative thallium-201 scintigraphy was available, the presence of extensive reversible defects was correlated with significant improvement in EF. On the other hand, a poor outcome was correlated with the presence of pathological Q waves in the preoperative ECG and with an increased left ventricular end-systolic volume index (> 100 ml/m2). Patients with marked left ventricular dysfunction can safely undergo CABG with a low mortality and morbidity. The presence of extensive reversible defects on preoperative thallium-201 scintigraphy is a strong predictor of postoperative recovery of myocardial function. A poor outcome of surgery can be expected in the presence of pathological Q waves on the preoperative ECG or when the left ventricular endsystolic volume index exceeds 100 ml/m2.     

Prediction of improvement in regional left ventricular function after coronary artery bypass grafting: quantitative stress-redistribution 201Tl imaging in detection of myocardial viability

BACKGROUND: This study investigated the usefulness of quantitative assessment of Thallium-201 stress redistribution myocardial scintigraphy combined with quantitative assessment of regional left ventricular function using the centerline method for predicting of recovery regional left ventricular function following myocardial revascularization. METHODS: Twenty patients with chronic total obstruction of the proximal portion of left anterior descending artery and/or right coronary artery were studied. Percent Tl-uptake method was used to evaluate myocardial viability before CABG. Regional LV function was evaluated before and after CABG with the centerline method. The territory of LAD was defined by chords 10 to 58 and that of RCA was defined by chords 59 to 80 in the centerline method. The parameter of regional left ventricular function was the mean (SF-Av.)/SD of each LAD and RCA territory. RESULTS: In cases showing a % uptake value under 50%, the preoperative value of (SF-Av.)/SD was -3.18+/-0.74 and postoperative value was -2.63+/-0.8 1. The difference between these values was not significant. When the %uptake value over 50%, the preoperative value of (SF-Av.)/SD was -2.80+/-0.49 and the postoperative value was -2.27+/-0.28. The postoperative value was significantly higher than the preoperative value(p=0.007). CONCLUSIONS: Even in cases of severe left ventricular dysfunction, regional left ventricular function improved if the value of % uptake in the redistribution Thallium imaging was 50% or over. Quantitative analysis of myocardial scintigraphy combined with quantitative analysis of left ventriculography is a useful method for predicting recovery of regional left ventricular function following myocardial revascularization.     

Myocardial perfusion as assessed by thallium-201 scintigraphy during the discontinuation of mechanical ventilation in ventilator-dependent patients

Patients who cannot be separated from mechanical ventilation (MV) after an episode of acute respiratory failure often have coexisting coronary artery disease. The authors hypothesized that increased left ventricular (LV) wall stress during periods of spontaneous ventilation (SV) could alter myocardial perfusion in these patients. Using thallium-201 (201TI) myocardial scintigraphy, the authors studied the occurrence of myocardial perfusion abnormalities during periods of SV in 15 MV-dependent patients (nine women, six men; aged 71 +/- 7 yr, mean +/- SD). Fourteen of these patients were studied once with 201TI myocardial scintigraphy during intermittent mechanical ventilation (IMV) and again on another day, after at least 10 min of SV through a T-piece. One patient was studied during SV only. Thirteen of 14 of the patients (93%) studied during MV had abnormal patterns of initial myocardial 201TI uptake, but only 1 patient demonstrated redistribution of 201TI on delayed images. The remainder of the abnormalities observed during MV were fixed defects. SV produced significant alterations of myocardial 201TI distribution or transient LV dilation, or both, in 7 of the 15 patients (47%). Four patients demonstrated new regional decreases of LV myocardial thallium concentration with redistribution of the isotope on delayed images. The patient studied only during SV also had myocardial 201TI defects with redistribution. Five patients (3 also having areas of 201TI redistribution) had transient LV dilation during SV.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ventricular function after coronary artery bypass grafting: evaluation by magnetic resonance imaging and myocardial strain analysis

OBJECTIVE: Magnetic resonance imaging with radiofrequency tissue tagging permits quantitative assessment of regional systolic myocardial strain. We sought to investigate the utility of this imaging modality to quantitatively determine preoperative impairment and postoperative improvement in ventricular function in patients with ischemic heart disease. METHODS: Magnetic resonance imaging with radiofrequency tissue tagging was performed on 6 patients (average age 60.2 +/- 13.7 years) with coronary artery disease and 32 control subjects with no known heart disease. Patients with coronary artery disease underwent imaging before and 3 months after coronary artery bypass grafting. The ventricle was divided into 6 segments within a midventricular plane. Regional 2-dimensional left ventricular circumferential strain was calculated from tagged magnetic resonance images throughout systole. Circumferential strain results were compared in patients before and after and 3 months after coronary artery bypass grafting and also in control subjects. RESULTS: Before the operation circumferential strain identified 100% (10/10) of all regional wall motion abnormalities seen by preoperative ventriculography. Postoperatively, improvements were demonstrated in 56% (20/36) of the regions, and these improvements agreed with viability testing by single-photon emission computed tomography when available. Additionally, preoperative global circumferential strain for the ischemic group was significantly depressed relative to that in control subjects (0.11 +/- 0.05 vs 0.20 +/- 0.03, P <.001). Global circumferential strain correlated with ejection fraction by ventriculography (r = 0.84, P <.01) and improved after coronary artery bypass grafting (0.14 +/- 0.05 vs 0.11 +/- 0.05, P <.01). CONCLUSIONS: Magnetic resonance imaging with radiofrequency tissue tagging permitted circumferential strain calculation. This technology quantitatively demonstrated improvements in left ventricular wall motion after coronary artery bypass grafting for both individual regions and the entire ventricle. This noninvasive method may prove useful in preoperative evaluation and postoperative serial assessment of left ventricular wall motion.     

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.     

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.     

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.     

Prolonged ischemic heart disease and coronary artery bypass - relation to contractile reserve.

OBJECTIVE: A major effect of coronary artery bypass grafting (CABG) in patients with ischemic heart disease and impaired left ventricular (LV) contractile function is believed to be an improvement in LV function due to recovery of dysfunctional, but viable myocardium. However, recent studies have indicated a time limit for such a recovery. We therefore investigated the extent of viable myocardium in patients with impaired LV function due to ischemic heart disease after a prolonged strategy of medical treatment and its relation to changes in clinical variables after CABG. METHODS: Forty-five consecutive patients with a mean duration of ischemic heart symptoms of 9 years and LV ejection fraction (EF) <45% referred for CABG were included and LV extent of viable myocardium was measured preoperatively by glucose metabolism--blood flow positron emission tomography imaging and dobutamine stress echocardiography. Symptoms, exercise-capacity and LV function were evaluated before and 7 months after surgery in event-free survivors. RESULTS: LV extent of myocardial viability was <30% in most patients. In event-free survivors, LVEF decreased from 31+/-7 to 26+/-8% 7 months after CABG. The decrease in LVEF was correlated to the LV extent of myocardial metabolism--blood flow reverse mismatch. Most of the patients experienced an improvement in their angina pectoris, heart failure symptoms and exercise capacity after CABG; the overall 3-year survival was 77%. CONCLUSIONS: Patients with chronic ischemic heart disease and impairment of LV function, in whom an initial long-standing conservative treatment has been practiced, benefit from CABG, despite a lack of LV functional reserve.     

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.     

Early changes in the time course of myocardial contraction after correcting aortic regurgitation

BACKGROUND: Correcting aortic regurgitation causes significant changes in left ventricular loading conditions, but few observations have been made intraoperatively of early effects on myocardial function. METHODS: We studied 18 patients (mean age, 59+/-12 years; 14 men) in whom aortic regurgitation was corrected with a stentless biologic valve. Overall left ventricular function was studied by thermodilution cardiac output, ventricular filling pressure, and systemic arterial pressure. Regional myocardial function was assessed from intraoperative transesophageal M-mode echocardiography and high fidelity ventricular pressure recordings before cardiopulmonary bypass, and 0.5, 1, 3, 6, 12, and 20 hours after operation. Time course of contraction, and magnitude of left ventricular systolic wall stress, dimensional shortening, myocardial power, and stroke work were measured. RESULTS: Global hemodynamics: there was an immediate decrease in left ventricular stroke volume (58+/-31 mL versus 80+/-30 mL, p = 0.004) and stroke work index (250+/-86 mJ/m versus 401+/-198 mJ/m, p = 0.005), but systemic arterial pressure (79+/-11 mm Hg versus 65+/-10 mm Hg, p = 0.002), increased at constant heart rate and end-diastolic pressure. Regional myocardial function and timing: peak systolic wall stress, dimensional shortening rate, and myocardial power production were all unchanged with operation. However, myocardial stroke work decreased (3.0+/-1.3 mJ/cm versus 4.8+/-2.4 mJ/cm, p = 0.009), attributable to shortening of the duration of systole (475+/-91 ms versus 543+/-67 ms, p<0.001). Diastolic time increased from 34%+/-18% to 71%+/-33% of systolic pulse duration (p<0.001). CONCLUSIONS: Correcting aortic regurgitation causes an early decrease in regional and global stroke work and increases diastolic time, although systolic wall stress does not decrease immediately. These beneficial effects are achieved by reducing the duration rather than altering the peak intensity (power) of myocardial contraction.     

Revascularization of dysfunctioning myocardium: differential prognostic effects of coronary artery bypass grafting and percutaneous transluminal coronary angioplasty in patients with three-vessel disease and mostly viable myocardium

In patients with left ventricular dysfunction, multivessel coronary disease and viable myocardium, little is known on the differential prognostic effect of coronary artery by pass grafting (CABG) and percutaneous transluminal coronary angioplasty (PTCA). To this purpose, 177 patients with previous myocardial infarction, three-vessel coronary disease and an EF<0.40 underwent CABG (group A, 114 patients) or PTCA (group B, 63 patients). Viability was demonstrated by maintained Thallium-201 uptake in more than 70% of left ventricle in 95/114 and 51/63 patients of groups A and B, respectively. Revascularization was greater in the CABG group (2.9+/-1.2 graft/patient) as compared to the PTCA group (1.3+/-1.2 treated vessel, P<0.05). Intraoperative mortality was 6.7 and 6.3% in groups A and B, respectively. At 6 months, viability was highly predictive of improvement of symptoms and wall motion abnormalities. Survival at 4 years was 90% in CABG and 92% in PTCA patients with maintained viability, while cumulative hard event rates showed an event-free survival of 86 and 76% in groups A and B, respectively (log rank: 0.0035). In patients with three-vessel coronary disease, low EF and mostly viable myocardium, coronary revascularization was associated with a favourable 4-year survival, even if CABG was superior to PTCA in reducing cumulative events.     

Emergency coronary artery bypass grafting in patients with severe pump failure complicating acute myocardial infarction]

Thirty patients with severe pump failure (Killip's degree III or more) complicating acute myocardial infarction (MI) underwent emergency coronary bypass grafting (CABG). Average age was 66 years old and CABG was performed 2.6 days after the onset of MI. The patients were divided into two groups according to the mechanisms that can bring about severe pump failure: 19 patients had large MI alone (G-I). The other 11 patients had severe ischemia occurring either at areas distant from the site of coronary occlusion or in the previous area at risk (G-II). To estimate the ventricular wall motion quantitatively, the left ventricular wall was divided into 17 segments. Each segment was graded on a four-point scale: akinesis, 3; severe hypokinesis, 2; hypokinesis, 1; normal 0. Wall motion score was estimated by summing the number of asynergic segments score. In G-I, Cardiac index (CI (l/min/m2)) increased from 2.03 +/- 0.91 to 2.68 +/- 0.73 and pulmonary wedge pressure (PCWP (mmHg)) decreased from 28 +/- 5 to 15 +/- 5, 72 hours after the surgery (p < 0.01). In G-II, CI increased from 2.17 +/- 0.78 to 3.17 +/- 1.01 and PCWP decreased from 29 +/- 6 to 13 +/- 5 after the surgery (p < 0.01). There was no difference in preoperative and postoperative hemodynamics between two groups. The wall motion score at the risk area did not change postoperatively (from 16 +/- 7 to 17 +/- 9 in G-I, from 15 +/- 8 to 11 +/- 5 in G-II).(ABSTRACT TRUNCATED AT 250 WORDS)     

Myocardial restoration with embryonic stem cell bioartificial tissue transplantation.

BACKGROUND: The optimal cell-matrix combination for robust and sustained myocardial restoration has not been identified. The present study utilizes embryonic stem cells as the substrate of bioartificial myocardial tissue and evaluates engraftment in, and functional recovery of, the recipient heart. METHODS: Collagen type I was populated with undifferentiated green fluorescent protein (GFP)-positive mouse embryonic stem cells. An intramural left ventricular pouch was fashioned after ligation of the left anterior descending artery in an athymic nude rat heterotopic heart transplant model. The bioartificial mixture (0.125 ml) was implanted in the infarcted area within the pouch. Echocardiography was performed to assess fractional shortening in: Group I, infarcted rats that received cell-matrix implants; Group II, rats given matrix implant without cells; Group III, rats given no matrix or cells; and Group IV, rats receiving transplanted hearts without ligation (n = 5/group). Hearts were stained for GFP, cardiac markers (connexin-43, alpha-sarcomeric actin), hematoxylin-eosin (H&E) and trichrome. RESULTS: Embryonic stem cells formed stable intramyocardial grafts that were incorporated into the surrounding area without distorting myocardial geometry, thereby preventing ventricular wall thinning (anterior wall thickness was: Group I, 1.4 +/- 0.1 mm; Group II, 1.0 +/- 0.1 mm, Group III, 0.9 +/- 0.2 mm; and Group IV, 1.3 +/- 0.2 mm). The inoculated cells expressed connexin-43 and alpha-sarcomeric actin in vivo. Fractional shortening was better in embryonic stem cell-treated animals (Group I, 21.5 +/- 3.5%; Group II, 12.4 +/- 2.8%; Group III, 8.2 +/- 2.9%; Group IV, 23.2 +/- 4.2%). CONCLUSIONS: Embryonic stem cells are an efficient alternative substrate for myocardial tissue engineering and can prevent myocardial wall thinning and improve contractility after implantation into injured myocardium in a 3-dimensional matrix.     

Coronary artery bypass surgery in patients with severely impaired left ventricular function]

The efficacy and problem of coronary artery bypass grafting (CABG) in patients with severely impaired left ventricular function (left ventricular ejection fraction < or = 30%) were assessed in 27 patients of whom 17 (group 1) underwent emergent CABG and 10 (group 2) elective between Jan 1984 to Aug 1990. As a whole, history of myocardial infarction (24/27, 88.9%), large left ventricular volume with reduced ejection fraction (LVEDVI 126.08 +/- 25.91 ml/m2, LVESVI 93.04 +/- 21.02 ml/m2, LVEF 25.04 +/- 4.75%) and multiple vessel disease with at least one vessel total occlusion (20/27, 74.1%) were characteristically seen in these patients. The patients of group 1 were significantly older (mean 66.12 +/- 5.68 vs 57.10 +/- 8.08, p < 0.01) and needed more frequent preoperative support with IABP (17/17 vs 4/10, p < 0.01). Using Thallium-201 scintigraphy, in 10 patients of group 1 and 9 of group 2, myocardial viability in the proposed bypass area was evaluated before operations. Average 2.37 +/- 0.79 grafts were placed and continuous retrograde cold blood cardioplegia via the coronary sinus was employed for myocardial protection. Two mitral annuloplasty (MAP) for ischemic mitral regurgitation and 2 cryoablation for the treatment of ventricular tachycardia were performed concomitantly. Operative mortality was 47.1% in group 1 and none in group 2 (p < 0.05). Two cases of MAP died, but two cases of cryoablation survived. Postoperative LVEF was improved significantly only in group 2 (p < 0.05), but during the follow-up period of 7 months to 6 years, all 19 survivors expect one remains with NYHA class I or II.(ABSTRACT TRUNCATED AT 250 WORDS)     

Coronary revascularization in end-stage coronary heart disease in relation to assessment of myocardial vitality]

From 4/1986-12/1990, 177 pts. with endstage coronary artery disease (CAD) and left ventricular ejection fraction 10-30% received coronary artery bypass grafting (CABG). Preoperatively myocardial infarction rate was 1.5 (mean). Presupposition for CABGs was myocardial ischaemia at present demonstrated in myocardial viability test. 66.1% of the pts. had signs of ischaemia at e.c.g. after work. Additionally 97.6% of the pts. had myocardial ischaemia defined as redistribution in myocardial scintigraphy. Angina pectoris was present in 93.8% of the pts. preoperatively. 1-5 (mean 2.9) CABG per pt. were performed. 35 pts. received an internal mammaria bypass to the left coronary artery also. Operative mortality was 11.3% (1986-1990) and in 1990 alone 7.3%. Actuarial survival rate was calculated after one year to 87.4% after two years to 86.1% and after three years to 84.8%. Postoperatively all pts. were free from angina pectoris. 5 months after the operation e.c.g. after work was performed. The physical stress bearing area was increased to 82.7 Watt (mean) compared to 51.7 Watt (mean) preoperatively (p less than 0.001 s.). In conclusion pts. with endstage CAD and left ventricular ejection fraction 10-30% appeared to be good candidates for CABG with good prognosis and significant symptomatic improvement when signs of myocardial ischaemia are present preoperatively.     

Regional differences in myocardial work of the left ventricle in patients with idiopathic dilated cardiomyopathy: Implications for the surgical technique used for left ventriculoplasty

OBJECTIVES: In this study we measured regional myocardial work of the left ventricle in patients with dilated cardiomyopathy and examined the existence of regional differences in myocardial work. BACKGROUND: Left ventriculoplasty aims to improve the ejection fraction by excluding a region with decreased wall motion and decreasing wall tension. If regional differences in myocardial work are present, left ventriculoplasty will be more effective when a region with decreased myocardial work is excluded. METHODS: The study group consisted of 10 patients with idiopathic dilated cardiomyopathy. Regional work of the ventricle normalized to a unit volume of myocardium (RWM) is given as follows: RWM = -integral sigma(d)[ln(1/H)], where sigma is mean wall stress, and H is wall thickness of the region. After right-sided catheterization, left ventricular pressure was measured with a 3F micromanometer catheter. Echocardiography was performed simultaneously, and a short-axis view of the left ventricle at the level of the papillary muscles was obtained. The derived M-mode image was recorded with left ventricular pressure. sigma-ln(1/H) relations for the ventricle were delineated, and regional work of the interventricular septum and posteroinferior wall were determined. Relationships between regional work of the myocardium and wall thickness, interventricular septal regional work of the myocardium and right ventricular systolic pressure, and right ventricular ejection fraction were also studied. RESULTS: Interventricular septal regional work ranged from -0.84 to 3.34 mJ/cm3 (0.74 +/- 1.51 mJ/cm3). Posteroinferior wall regional work ranged from 1.59 to 4.29 mJ/cm3 (2.77 +/- 0.86 mJ/cm3). In the study group, interventricular septal regional work was lower than posteroinferior wall regional work (P <.05). In 8 of these 10 patients, interventricular septal regional work was lower than posteroinferior wall regional work. In the other 2 patients, conversely, interventricular septal regional work was higher than posteroinferior wall regional work. CONCLUSIONS: The existence of differences in regional work between the interventricular septum and the posteroinferior wall suggests the importance of the evaluation of regional work in the selection of an effective treatment for dilated cardiomyopathy.     

Two-year assessment by exercise thallium scintigraphy of myocardial revascularization using bilateral internal mammary and gastroepiploic arteries.

OBJECTIVE: To assess the blood flow supply offered to the myocardium by surgical revascularization using bilateral internal mammary (IMAs) and gastroepiploic (GEA) arteries. METHODS: Two-year assessment by exercise thallium myocardial scintigraphy without medical treatment was performed in 122 patients (mean age 61 +/- 9 years) who underwent coronary artery bypass grafting (CABG) with exclusive use of IMAs and GEA. Usually, the right IMA was used to bypass the left anterior descending coronary artery, and the left IMA to bypass the diagonal and the marginal arteries as a sequential graft if required. The GEA was used to bypass the right coronary artery (RCA) in 50 patients and its posterior branches in 72 patients. RESULTS: During maximal or submaximal exercise stress testing, 119 patients (98%) were asymptomatic and 26 patients (21%) exhibited moderate ischemic ECG modifications which were correlated (P < 0.01) with incomplete revascularization and with the use of GEA to bypass the RCA. A third of patients had moderate ischemic thallium defects on exercise reversible after redistribution (anterior, 10; lateral, 2; inferior, 28). Silent residual myocardial ischemia detected by thallium scintigraphy was correlated (P < 0.001) with ECG modifications and incomplete revascularization; and inferior thallium defects were more frequent when GEA bypassed the RCA (P < 0.05). However, 26% of patients had residual ischemia despite a complete revascularization, and in at least 18% of cases for GEA and 8% for right IMA, arterial graft blood flow was insufficient at maximum exercise level and caused silent residual myocardial ischemia detected by thallium scintigraphy. CONCLUSIONS: Myocardial revascularization using bilateral IMAs and GEA offers a satisfactory myocardial perfusion in the majority of cases; however silent residual myocardial ischemia was detected in a third of patients and was related to incomplete revascularization and to insufficient blood flow supply probably due to small diameter of the arterial grafts.     

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 microgram. kg-1. 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). CONCLUSION: Intraoperative low-dose dobutamine is a reliable method to predict myocardial functional reserve and to determine functional recovery expected after coronary revascularization.     

Left ventricular function in uremia: echocardiographic assessment in patients on maintenance dialysis

Echocardiographic assessment of left ventricular function was performed in twenty-two unselected patients on stable, chronic maintenance dialysis. The statistically significant abnormalities were enlargement of the left ventricular cavity (end diastolic internal dimension or "diameter" 5.4 +/- 0.2 cm, normal 4.4 +/- 0.3 cm), thickening of the left ventricular wall (end diastolic thickness 1.1 +/- 0.05 cm, normal 0.9 +/- 0.03 cm) and a reduction in myocardial contraction (fractional shortening 28.2 +/- 2.0%, normal 35.7 +/- 0.9%). Myocardial impairment could not be attributed to the effects of hypertension or to ischemic heart disease. There was, however, a significant negative correlation between fractional shortening and total plasma catecholamines (r = 0.45, P less than 0.05) suggesting that excessive catecholamines may contribute to the decreased myocardial contraction seen in uremic patients.     

Role of myocardial perfusion single photon emission CT (Sepct) in predicting improvement of myocardial function following revascularisation in patients with poor left ventricular function

Background We used a combined rest-stress Tc-sestamibi redistribution imaging using SPECT scan to identify viable myocardium and predict improved left ventricular (LV) function after revascularisation in patients with severe LV dysfunction. Methods 57 patients were studied retrospectively with severe LV dysfunction Ejection Fraction (EF)<30%. Regional and global LV functions were evaluated preop and 12 weeks post-coronry artery bypass grafting (CABG) with radionucleide ventriculography. Preoperatively, patients were classified into those with eight or more viable segments (out of 15 segments) and those with seven or less viable segments. Results 31 out of 43 (72%) patients with more than eight viable segments had shown significant improvement in LVEF (from 0.29 ± 0.01 to 0.36 ± 0.06) postoperatively. Out of the remaining 12 patients, 3 had persistent akinesia with deterioration of symptoms whereas others had shown sympomatic improvement. In the other group, 11 out of 14 patients (78%) with seven or less segments viable had not shown any improvement in their LVEF. The imaging also identified the segments that improved function after CABG. Out of a total 285 segments in 57 patients, 238 segments were studied. Among these, 178 segments were hypokinetic, 48 segments akinetic and 12 dyskinetic. Preoperatively, 160 out of 178 (90%) with hypokinesia had shown viability whereas 26/48 (54%) in akinetic group and 9/12 dyskinetic segments had shown viability with rest showing no viability. Postoperative imaging had shown improvement in these groups as follows: hypokinetic 88% (141/160); akinetic 62% (16/26); dyskinetic 48% (4/9). Conclusions In patients with coronary artery disease (CAD)-and severely depressed LV function. preoperative imaging using SPECT identifies viability in many akinetic or dyskinetic myocardial segments, and these segments frequently improve function after CABG. The presence of numerous akinetic but viable myocardial segments before surgery correlated significantly with improvement in global LV function after bypass surgery.