Detection of myocardial ischemia by transesophageal echocardiographically determined changes in left ventricular area in patients undergoing coronary artery bypass surgery

Survey of observer variation in transesophageal echocardiography: comparison of anesthesiology and cardiology literature

OBJECTIVE

Transesophageal echocardiographic examination tends to be somewhat observer and experience dependent, and observer bias can arise easily when data are calculated and interpreted by unskilled, nonblinded, or single observers. The study plan was to see whether authors have adequately described how observer bias is minimized in their studies. Thus, a study was conducted systematically reviewing methods reported in transesophageal echocardio graphy articles in peer-reviewed anesthesiology journals versus those reported in peer-reviewed cardiology journals.

INTERVENTIONS

After MEDLINE searches of the literature published from 1997 through 1999, the authors investigated 56 anesthesiology reports and 56 randomly selected, year-matched cardiology reports. An 8-item questionnaire was developed that examined several factors: the number of observers and their experience levels, whether observers were blind to clinical data, whether low-quality images were excluded, the use of on-line or off-line analysis, and observer variability.

MAIN RESULTS

The analysis revealed inadequacies in reporting of important information that relates to bias and quality in 91.1% of anesthesiology and 98.2% of cardiology articles. Observer variability was not reported in 50.0% of the anesthesiology reports and 67.9% of the cardiology reports; however, difference between the 2 bodies of literature was not significant. The journal impact factor was significantly higher for the cardiology literature than for the anesthesiology literature (2.42 [0.386-10.893] v 1.07 [0.664-3.439]; median [range], p < 0.001).

CONCLUSION

Articles reviewed had at least some inadequacies in reporting the methods to minimize observer bias in both the anesthesiology and cardiology literature. Reporting methodology standards in TEE examinations remain to be established.

Segmental wall motion abnormalities during telerobotic totally endoscopic coronary artery bypass grafting

In addition to single-lung ventilation (SLV), intrathoracic CO2 insufflation is mandatory for adequate exposure during totally endoscopic coronary artery bypass grafting. With transesophageal echocardiography, we investigated biventricular myocardial wall motion in 25 patients with isolated disease of the left anterior descending coronary artery who underwent totally endoscopic coronary artery bypass grafting with the "Da Vinci" robotic surgical system. At distinct time points during the operation, a cine loop of both ventricles was registered from a transgastric mid-short-axis view. Myocardial wall motion analysis was performed according to an established segmentation model of the left ventricle and to an established five-point scale for wall motion (1, normal; 5, dyskinesia). Significant alterations from preoperative baseline wall motion were visible in the septal, inferior, and anterior segments of the left ventricle at some time during the prebypass period, combined with a markedly decreased PaO2 under SLV and increased intrathoracic pressure. The same findings applied to the right ventricle; however, wall motion abnormalities were more pronounced here. After myocardial revascularization, weaning from cardiopulmonary bypass, CO2 deflation, and return to double-lung ventilation, myocardial wall motion recovered to baseline values. Clinically significant hemodynamic instability did not occur. The data suggest that robot-assisted coronary artery bypass grafting leads to significant prebypass alterations of biventricular segmental wall motion. On the basis of our data, it cannot be definitively stated whether the observed results were due to reduced oxygenation during SLV and thus "real" myocardial ischemia, intrathoracic CO2 insufflation with positive pressure leading to mechanical compromise of the heart, absolute or relative hypovolemia, or a combination of these factors. However, in this cohort, which consisted of patients with single-vessel disease and good ventricular function, these changes were of limited clinical relevance.

IMPLICATIONS

Segmental myocardial wall motion was evaluated with transesophageal echocardiography during robot-assisted totally endoscopic coronary artery bypass grafting. Significant biventricular segmental wall motion abnormalities occurred before cardiopulmonary bypass under single-lung ventilation and carbon dioxide insufflation. The changes in myocardial wall motion were of limited clinical relevance.

Low-dose dobutamine stress and left ventricular wall motion monitored with transesophageal echocardiography versus hemodynamic data derived from pulmonary artery catheterization in patients scheduled for CABG

BACKGROUND

The clinical acceptance of transesophageal echocardiography (TEE) as a monitoring technique for left ventricular function in open-heart surgery is now widely recognized. This technique's accurate imaging capabilities have been found to improve the information obtained by the pulmonary catheter (PAC) and thermodilution. TEE is also a less invasive technique than PAC. However, because it is costly, further comparisons between the techniques are worthwhile. This study compares hemodynamic data obtained with PAC and how these correspond to echocardiography data using TEE.

METHODS

Twenty-four anesthetized patients undergoing elective coronary artery bypass grafting (CABG) were studied. They were monitored with PAC and TEE. A low-dose dobutamine protocol for viability was used with doses of 5 and 10 microg x kg(-1) x min(-1). Endpoints for this stimulation included on-line visual change in left ventricle wall motion (LVWM), increased arterial blood pressure more than 40 mmHg, a heart rate (HR) increase of more than 20%, or ST depression on ECG exceeding 0.2 mV. Visual assessment of LVWM using the transgastric short-axis view was made off line by a blinded observer. Six segments were used and a wall motion score was made at each level of dobutamine stimulation.

RESULTS & CONCLUSION

Two patients reached the endpoint for elevated blood pressure with a dobutamine dose of 5 microg x kg(-1) x min(-1), and twenty-two patients were stimulated to 10 microg x kg(-1) x min(-1). There were significant increases in cardiac output (CO), stroke volume (SV), systolic arterial pressure (SAP), mean arterial pressure (MAP), diastolic arterial pressure (DAP), pulmonary capillary wedge pressure (PCWP) and left ventricle stroke work index (LVSWI), but not in HR and systemic vascular resistance (SVR). Moreover, the LVWM increased significantly, but not fractional area change (FAC). The main finding, however, was the increase in SV with an accompanying improvement in LVWM, suggesting that visual assessment of improved wall motion could substitute PAC and thermodilution monitoring in clinical settings which demand a quick estimate of left ventricular performance.