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.     

Passive external cardiac constraint improves segmental left ventricular wall motion and reduces akinetic area in patients with non-ischemic dilated cardiomyopathy.

OBJECTIVE: To verify changes in left ventricular (LV) volumes and regional myocardial wall motion after implantation of a textile cardiac support device (CSD) for passive external constraint in non-ischemic dilated cardiomyopathy. METHODS: In nine male patients participating in a non-randomized clinical trial LV volumes were determined and the segmental LV wall motion was studied by contrast-enhanced electron-beam CT in a sectionwise manner at three ventricular levels (base, middle and apex of ventricle) before and 32+/-6 months after CSD implantation. In 16 myocardial segments ejection fraction and wall thickening were measured semiautomatically after drawing the myocardial contours. The wall motion score index was calculated based on semiquantitative visual grading in each segment. RESULTS: The global LV volumes decreased significantly from 304.3 +/- 90.9 to 231.5 +/- 103.9 ml at end-diastole and from 239.7 +/- 83.7 to 164.0 +/- 97.7 at end-systole (P<0.05). Overall ejection fraction increased from 14.8 +/- 8.2 to 25.7 +/- 17.1% (P<0.05). A segment-by-segment analysis demonstrated a significant increase of regional ejection fraction in the basal myocardium as well as in the mid-inferior, mid-inferolateral, and mid-anterolateral myocardium. Overall wall thickening increased from 16.4 +/- 13.3 to 24.2 +/- 18.1% (P<0.05), but without significant differences in a segment-by-segment comparison. The mean wall motion score index improved from 2.70 +/- 0.26 to 2.20 +/- 0.71 (P<0.05), with an increased wall motion in eight (89%) patients. A section-by-section analysis demonstrated significantly improved wall motion in the inferior and lateral segments at each ventricular level. Postoperatively, the number of akinetic and markedly hypokinetic segments decreased significantly (P<0.05) from 56 (39%) to 26 (18%) and from 76 (53%) to 56 (37%), respectively. CONCLUSION: CSD implantation improves segmental wall motion, predominantly in the inferior and lateral myocardium, and reduces the number of akinetic and hypokinetic segments.     

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.     

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.     

Quantitative echocardiographic assessment of regional wall motion and left ventricular asynchrony with color kinesis in cardiac surgery patients

Conventional echocardiographic interpretation of regional wall motion abnormalities is subjective and experience dependent. Delayed contraction in the ejection phase (tardokinesis) and regional systolic asynchrony, sensitive markers of myocardial ischemia, cannot be accurately assessed visually. We used color kinesis (CK), a technique that evaluates spatiotemporal patterns of endocardial motion, to objectively detect regional wall motion abnormalities in patients undergoing coronary bypass surgery, and we compared it with conventional assessment of grayscale images by less experienced reviewers; we used expert grading as the gold standard for comparisons. Quantitative CK analysis agreed more closely with expert grading than less experienced reviewers (kappa coefficients, 0.74 versus 0.52 and 0.5). Global tardokinesis, identified in 9 of 26 patients (2 with normal fractional area change), was associated with an increased index of systolic asynchrony. Regional tardokinesis was identified in 48 of 150 segments: 27 segments had a normal magnitude of wall motion, 18 were hypokinetic, and 3 were severely hypokinetic/akinetic. Mildly hypokinetic segments showed delayed systolic motion, whereas residual motion of severely hypokinetic/akinetic segments occurred in early systole, reflecting passive effects produced by adjacent myocardial contraction. Quantitative CK may be a useful supplement to visual assessment, particularly for less experienced readers. By diagnosing tardokinesis, common among cardiac surgical patients even with normal standard ejection phase indices, quantitative CK may improve the intraoperative detection of regional ischemic changes. IMPLICATIONS: Quantitative color kinesis allows for objective and sensitive intraoperative echocardiographic assessment of abnormal spatial and temporal patterns of regional ventricular wall motion, with potentially important implications for improving myocardial ischemia detection in patients undergoing cardiac surgery.     

Ball thrombus induced by hibernating myocardium in the left ventricle; report of a case

An 80-year-old man was admitted to our hospital for examination of a ball thrombus incidentally found in the left ventricle (LV). Coronary angiogram revealed severe triple vessel disease and LV dysfunction. Although LV wall motion in the septum and the apex was akinetic, there were no signs of myocardial infarction. It was diagnosed as an acute LV ball thrombus with hibernating myocardium due to ischemia of the left anterior descending coronary artery. Emergency coronary artery bypass grafting (CABG) and excision of the thrombus were performed. Two weeks after surgery, LV function improved and the patient was discharged from the hospital without any complication. A LV ball thrombus without myocardial infarction is rare, and thought to be caused by hibernating myocardium.     

Cardiomyoplasty improves contractile reserve after myocardial injury in mice: functional and morphological investigations with reconstructive three-dimensional echocardiography

Cellular cardiomyoplasty (CMP) is a novel therapeutic approach to myocardial injury (MI). Post-MI remodeling of the left ventricle (LV) comprises dilatation and impairment of systolic function and gives rise to progressive hemodynamic deterioration. We aimed to investigate: a) the impact of CMP on global and regional parameters of LV remodeling (LVR) as well as contractile reserve and b) the suitability and validity of different echocardiographic methods in this scenario. Murine ventricular cardiomyocytes (E13.5-E16.5) were transplanted into cryolesioned hearts of male HIM-OF1 mice. Echocardiography was performed at rest 4 and 14 days postoperatively. For quantification of akinetic myocardial mass and contractile reserve 2 weeks postoperatively additionally low-dose dobutamine stress echocardiography was conducted. Reconstructive 3D-echocardiography (r3D-echo) was compared to "plain" echocardiographic investigations and was compared to invasive measurements with conduction catheter. CMP significantly attenuated LV dilatation and reduced LV function decline on day 14, as obtained with all echocardiographic modalities and confirmed with conduction catheter measurements. In contrast to plain echocardiography and invasive testing, r3D-echo allowed noninvasive quantification of scar size and assessment of regional contractile reserve. Cell transplanted hearts demonstrated a significant decrease of akinetic myocardial mass (-CMP: 13 ± 2%; +CMP 7 ± 1%; p < 0.001) and increased regional contractile reserve, an indirect sign of myocardial viability. The present study demonstrates beneficial effects of CMP on global and regional parameters of LVR and contractile reserve after MI. In contrast to "simple" 2D echocardiography, r3D-echo allowed the assessment of regional contractile reserve and quantification of akinetic myocardial mass as additive functional and morphological measures of LVR.     

Long term left ventricular systolic function assessment following CABG. A prospective, randomised study. Blood versus cristalloid cardioplegia

BACKGROUND: In an effort to define the role of blood cardioplegia delivered in antegrade/retrogade fashion in patients with either good or poor left ventricular function undergoing elective coronary artery bypass surgery, we initiated a prospective randomised study in which postoperative hemodynamics besides clinical data were compared in patients administered antegrade/retrograde crystalloid cardioplegia. METHODS: To compare the efficiency of two methods of myocardial protection--cold crystalloid ante/retro cardioplegia and cold blood ante/retro cardioplegia in two groups of patients with high and low LVEF--we randomised 122 patients for CABG. The potential improvement in left ventricular systolic function assessed by echocardiography and the same clinical data were the end points of the study. Patients were divided into group I (47 patients, LVEF <40%) and group II (75 patients, LVEF >40%). Pathologic antecedents and preoperative clinical conditions were similar in both randomised subgroups Ia, IIa (crystalloid cardioplegia) and subgroups Ib, IIb (blood cardioplegia). The following parameters were measured: left atrium diameter (LA), left ventricular end diastolic diameter (LVEDD), left ventricular end systolic diameter (LVESD), left ventricular ejection fraction (LVEF), left ventricular wall motion score index (WMSI), and area asynergy (AA). All patients underwent echocardiography: A--prior the CABG, B--2-6 weeks postoperatively, C--3 months postoperatively, D--6 months postoperatively, E--1 year postoperatively. RESULTS: The results of clinical assessment in both groups showed improvement of quality of life. The constant improvement of LVEF and WMSI was observed in group I in contrast to group II. There were no significant differences in postoperative left ventricular systolic function between subgroups Ia and Ib or IIa and IIb. CONCLUSIONS: The use of blood cardioplegia, instead of crystalloid cardioplegia, when used in the ante/retrograde fashion during CABG has no influence on postoperative left ventricular systolic function. The improvement in left ventricular systolic function following CABG is greater in patients with low LVEF in contrast to patients with high LVEF.     

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.     

Clinical evaluation of pressure-controlled intermittent coronary sinus occlusion: randomized trial during coronary artery surgery

Pressure-controlled intermittent coronary sinus occlusion (PICSO) was evaluated in a randomized trial in 30 patients undergoing bypass surgery. PICSO was applied for one hour during early reperfusion. Myocardial function was determined from short-axis cross-sectional views of intraoperative two-dimensional echocardiography. Changes of sectional and segmental wall motion during extracorporeal circulation were analyzed. Although sectional wall motion did not change significantly, hypokinetic segments were preserved better in PICSO-treated patients than in controls (-1.3 +/- 2.4 versus -9.1 +/- 2.6 delta% fractional area change; p less than 0.04). Although not significant, the same trend was found for normal and severely hypokinetic segments. Cumulative enzyme release was related to coronary sinus occluded pressure (r = 0.94; p less than 0.006), indicating washout of metabolites during PICSO. Three months after operation, functional classification was similarly favorable in both groups. Long-term effects of PICSO cannot be predicted because PICSO was applied only during early reperfusion. We conclude that PICSO is a safe procedure and that its short-term beneficial effects on myocardial function suggest a preservation of myocardial viability.     

Transesophageal echocardiography during coronary bypass surgery]

The early diagnosis of intraoperative myocardial ischemia is important because such ischemia can lead to myocardial infarction. Clinical effectiveness of transesophageal echocardiography (TEE) was evaluated for detecting intraoperative myocardial ischemia and for observing the recovery of cardial motion at the end of cardiopulmonary bypass (CPB) in 20 patients who had undergone CABG. After endotracheal intubation, the TEE transducer was introduced into the esophagus to obtain a short axis cross-sectional view of the left ventricle at the level of the papillary muscles. Global LV function was assessed by measuring end-diastolic and end-systolic areas, which were calculated automatically, and the fractional area change (FAC). Regional endocardial wall motion was also analyzed by subdivision into four anatomical segments. The mean FACs were 48% after intubation, 47% after skin incision and 48% after sternotomy. Thereafter it increased significantly to 59% 30 minutes after CPB and 56% at the end of the operation. Thus, global LV function was improved significantly by revascularization. TEE could detect myocardial ischemia more sensitively than ECG. In 9 patients, FAC decreased significantly and new regional wall motion abnormality (RWMA) appeared around the time of sternotomy, but no ECG changes were detected. In another 7 patients, new RWMAs were detected without either a decrease in the FAC or ECG changes. It was found that myocardial ischemia took place more frequently before the initiation of CPB than expected. The recovery of left ventricular wall motion from cardioplegic arrest was able to be monitored visually during the period of weaning from CPB and the TEE could facilitated prompt and exact judgement of weaning from CPB.(ABSTRACT TRUNCATED AT 250 WORDS)     

Beneficial effects of endoventricular circular patch plasty in patients with left ventricular systolic dysfunction and left ventricular dyskinetic or akinetic apical segment

Background  Available data on the efficiency of endoventricular circular patch plasty (EVCPP) especially from Asian Indians are limited. The objective of the present investigation was to evaluate the efficacy of endoventricular circular patch plasty along with coronary artery bypass grafting (CABG). Methods  Patients having ischemic left ventricular (LV) systolic dysfunction [LV ejection fraction (LVEF)≤25%] with left ventricular dyskinetic or akinetic apical segement [as depicted by two dimensional (2D) echocardiography] were enrolled in the study. They were evaluated for 2D echocardiography and color Doppler parameters as well as functional capacity before surgery and after one, three and six months of surgery. Results  39 patients (35 males; average age 59 years) were enrolled in the study. There was significant (P<0.05) increase in LV contractility measured in terms of LVEF with absolute rise of 8–14 digits from presurgery levels during time course of the study. EVCPP performed in addition to CABG produced significant reduction in LV end diastolic diameter (5–5.5 mm) and LV end systolic diameter (4.5–8.5 mm) at short-and intermediate-term following surgery. EVCPP plus CABG also produced significant improvement in functional capacity as a significant decrease in New York Heart Association class for heart failure was observed at all three stages of follow-up after surgery. Conclusion  EVCPP carried out along with CABG produces significant improvement in LV contractility, in reverting LV remodeling and functional status in Indian patients with LV systolic dysfunction and LV dyskinetic or akinetic apical segment at shor-term as well as intermediate-term following surgery.     

How should we measure global and regional left ventricular systolic function?

The assessment of left ventricular (LV) systolic function is frequently the most important task during the echocardiography examination. LV ejection fraction (EF) is the most commonly used measure to assess LV systolic function. EF is well established, with strong prognostic and therapeutic implications, but, nevertheless, it may not always be satisfactory in all patients. Other measures of myocardial contractility can provide valuable additive information in some patients. This is particularly true in patients with suspected heart failure but normal EF. The measurement of longitudinal function using M-mode and/or deformation analysis from tissue Doppler data or speckle tracking algorithms can be useful in this respect. Regional LV dysfunction can be difficult to detect using visual semi-quantitative assessment of regional wall motion. Contrast echocardiography can be most helpful in delineating the LV endocardial border and, thus, increasing sensitivity for detecting wall motion abnormalities. Deformation analysis can also be helpful for detecting subtle wall motion abnormalities, but these methods should be used with caution due to measurement variability and image quality dependence.     

Improvement of severely reduced left ventricular function after surgical revascularization in patients with preoperative myocardial infarction.

In recent years, two pathophysiological conditions--stunned and hibernating myocardium--have been described showing how function may be depressed in myocardium that remains viable. The aims of the present study were postoperative assessment of LV function at rest and during exercise after CABG in patients with established previous myocardial infarction and impaired preoperative LV function and evaluation of preliminary experience with positron emission tomography (PET) in the preoperative identification of reversible ischaemic myocardium and its predictivity in postoperative functional improvement. We studied 23 patients with preoperative LV function under 45%. Echocardiography and complete heart catheter were performed pre- and postoperatively. PET was performed in all patients preoperatively. In 21 patients with patent grafts, CABG significantly improved systolic and diastolic function during exercise and at rest. EF improved from 34% +/- 14% to 52% +/- 11% at rest and from 31% +/- 14% to 58% +/- 13% during exercise (P less than 0.01). Time constant of diastolic relaxation was significantly reduced after revascularization. In 2 patients with pathological findings on postoperative coronarangiography, EF remained unchanged. Both global and regional contractility improved following surgery. Regional analysis indicated that improved EF at rest occurred in regions developing ischaemia during exercise before CABG and in regions showing typical mismatch in 82Rubidium-2-fluoro-2-desoxyglucose suggesting the presence of hibernating myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Transmyocardial laser revascularization in combination with coronary artery bypass: Clinical, wall motion and perfusion effects

Background. Transmyocardial laser revascularisation (TMR) is increasingly used in the management of intractable angina in the absence of graftable vessels, however it’s role in combination with coronary artery bypass remains undefined. The aim of this pilot study was to investigate the impact of the combination therapy. Methods. Patients (20) undergoing elective coronary artery bypass surgery with one or more non-graftable coronary arteries were prospectively randomized to either have bypass graft surgery alone (CABG) or bypass graft surgery and transmyocardial revascularization with a holmium — YAG laser to non-graftable areas (CABG+TMR). All patients had exercise tolerance test preoperatively and at 6 and 18 months follow-up. Stress echocardiography was performed on 17 patients 18 months following surgery. Wall motion analysis (1=normal, 2=hypokinesis, 3=akinesis, 4=dyskinesis) using the 16 segment model of the left ventricle and rest and stress perfusion analysis were performed. Results. Both groups of patients were similar in preoperative demographics and operative data. There was no perioperative mortality. There was no difference between the two groups in angina scoring at 6 and 18 months follow-up. Exercise tolerance improved by a mean of 46.8±20.0 seconds per patient in the CABG group and by 199.2±66.5 seconds per patient in the CABG+TMR group (p<0.05) and this was maintained at 18 months (157±46.3 vs 61±39.2 seconds; p<0.05). Regional wall motion score index (WMSI) (total score/number of segments) was calculated in non-revascularizable myocardium treated with TMR and compared to areas that were not lased. Although the WMSI in TMR regions is lower at each stage of dobutamine stress, this does not reach statistical significance. Conclusion. The combination of coronary artery bypass and transmyocardial laser revascularization is safe and improves exercise tolerance in patients in whom complete revascularization cannot be achieved by bypass graft surgery alone. Competition paper presented at the 48th Annual Conference of IACTS at Chennai Feb. 2002     

Evaluation of intraoperative transesophageal two-dimensional echocardiography

Transesophageal two-dimensional echocardiography (TEE) was evaluated in 11 patients who underwent myocardial revascularization. The TEE transducer was positioned to view the left ventricular (LV) short-axis at the level of the papillary muscles (midcavity). Good quality echocardiographic images were obtainable in ten of 11 patients. Global LV function was assessed by measuring LV end-diastolic and end-systolic area and computing the fractional area change (FAC). Measurements of LV areas and FAC had excellent intraobserver reproducibility. Regional LV function was analyzed in two ways after dividing the short-axis view of the LV into four or five anatomic segments. Systolic wall thickening (SWT) of the myocardium was measured in each of four segments by digitization of the endocardial and epicardial borders of the LV and determining the fractional wall thickening. Measurements of SWT were not reproducible, primarily because of a difficulty in delineating the epicardial border of the LV accurately. In the second method, regional wall motion (RWM) in each of five segments was graded according to a previously developed scoring system. RWM analysis proved to be a measurement with excellent interobserver and intraobserver reproducibility. TEE was performed without complication and found to be a reproducible method for assessing global and regional LV function. Quantitative analysis is tedious and, therefore, currently not available on-line in the operating room.     

Plasma levels of atrial and brain natriuretic peptides as indicators of recovery of left ventricular systolic function after coronary artery bypass.

OBJECTIVE: The purpose of this study was to investigate the effectiveness of atrial and brain natriuretic peptides (ANP and BNP, respectively) as indicators of recovery of left ventricular (LV) function after coronary surgery. METHODS: We measured the concentrations of these peptides in 31 patients with poor LV function (ejection fraction, EF<35%) undergoing coronary artery bypass, and evaluated their correlation with the echocardiographic indexes of LV function. RESULTS: Pre-operatively, the plasma levels of both ANP and BNP were markedly higher in coronary patients than in normal control subjects, and strongly correlated with both EF (BNP: r=-0.8, P<0.001; ANP: r=-0.6, P<0.001) and wall motion score index (WMSI). At post-operative follow up, plasma levels of both natriuretic peptides were markedly reduced compared with pre-operative values in 21 patients. In addition, the post-operative-pre-operative differences of BNP (Delta(BNP)) and ANP (Delta(ANP)) plasma levels strongly correlated with the differences of both EF (r=-0.7, P<0.0001 vs. Delta(BNP); r=-0.6, P=0.0003 vs. Delta(ANP)) and WMSI (r=0.6, P=0.002 vs. Delta(BNP); r=0.6, P=0.04 vs. Delta(ANP)). Finally, by logistic regression analysis, BNP appeared a significant predictor of LVEF recovery after surgery. CONCLUSION: Plasma levels of ANP and BNP might be used in routine clinical practice as a support to echocardiography in detecting recovery of the LV function after coronary surgery.     

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.     

Occlusion versus shunting during MIDCAB: effects on left ventricular function and quality of anastomosis

BACKGROUND: Minimally invasive direct coronary artery bypass is an established clinical procedure for revascularization of the left anterior descending coronary artery. Mechanical stabilization and temporary occlusion is currently used to perform the anastomosis of the internal thoracic artery to the left anterior descending coronary artery. However, critical reduction of cardiac function can occur as a result of temporary ischemia. The purpose of this study was to evaluate whether ischemic sequelae can be avoided by using temporary intraluminal shunts and whether this alters early outcome. METHODS: Thirty-five patients underwent minimally invasive direct coronary artery bypass revascularization using a mechanical stabilizer. In group A (n = 20), the anastomotic site was temporarily occluded by tourniquets. In group B (n = 15), temporary intraluminal shunts were inserted into the anastomotic site without any occlusion of the left anterior descending coronary artery. Anastomosis of the internal thoracic artery to the left anterior descending coronary artery was performed in an identical fashion. A Swan-Ganz catheter was inserted, and transesophageal echocardiographic measurements were obtained for analysis of left ventricular (LV) function. Regional wall motion, cardiac index, stroke volume index, systolic and diastolic LV diameters, and fractional area change were measured during four periods: at the start of the operation (baseline), placement of the stabilizer (stabilization), left anterior descending coronary artery occlusion (occlusion) or insertion of temporary intraluminal shunts (shunt), and 30 minutes after reperfusion (reperfusion). Angiograms were obtained 4 to 6 days postoperatively. RESULTS: In group A, LV performance, cardiac index, stroke volume index, and fractional area change decreased during occlusion whereas systolic diameters increased. Almost two myocardial segments per patient developed severe hypokinesia in the perfusion area. These changes disappeared after 30 minutes of reperfusion, with increased LV function. In group B, LV function remained stable whereas hypokinetic wall motion was only detected in 2 patients. Early angiograms revealed 90% of the grafts were patent in group A versus 100% in group B. The need for percutaneous intervention during the first 6 months was 20% in group A versus 6.7% in group B. CONCLUSIONS: The use of temporary intraluminal shunts resulted in reduced acute ischemia and revealed wall motion abnormalities and maintained LV function. Furthermore, this technique suggests an improvement of early graft patency and a lower reintervention rate within the first 6 postoperative months. Thus, use of temporary intraluminal shunts appears to be superior to the occlusion technique early after minimally invasive direct coronary artery bypass procedures.