Apical transthoracic Doppler echocardiography can be useful for analysis of postoperative early function of the left internal thoracic artery

Assessment of internal thoracic artery patency with transesophageal echocardiography during coronary artery bypass graft surgery

OBJECTIVE

The purpose of this study was to evaluate intraoperative transesophageal echocardiography (TEE) for assessing patency of internal thoracic artery grafts.

DESIGN

A retrospective study.

SETTING

A university hospital.

PARTICIPANTS

Fifty-one consecutive patients who underwent coronary artery bypass graft (CABG) surgery using the left internal thoracic artery (LITA)-to-left coronary artery were examined postoperatively with coronary angiography (CAG).

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

The authors measured blood flow velocity using TEE after anastomosis of a LITA graft. Intraoperative TEE findings and routine CAG results were compared to evaluate the quality of TEE assessment. The LITA was detected in 45 of 51 patients (88%) intraoperatively with TEE. Peak and mean velocities and velocity time integral ratios were determined by dividing each diastolic value by its corresponding systolic value. The peak velocity ratio was 0.51 +/- 0.04 (range, 0.40-0.59) in the presence of stenosis and 1.14 +/- 0.10 (range, 0.58-3.87) in its absence (p = 0.0289), whereas mean velocity ratios were 0.62 +/- 0.05 (range, 0.45-0.72) and 1.27 +/- 0.10 (range, 0.66-4.08) (p = 0.0223), respectively, and velocity time integral ratios were 0.83 +/- 0.09 (range, 0.64-1.05) and 2.69 +/- 0.29 (range, 0.91-8.35) (p = 0.0224), respectively. The critical values for peak and mean velocities and velocity time integral ratios were 0.60, 0.73, and 1.06, respectively, whereas the sensitivity for each was 100% and the specificity was 92%, 94%, and 89%, respectively.

CONCLUSIONS

The authors concluded that the intraoperative assessment of LITA patency with TEE was a markedly useful and powerful tool for anesthesiologists during CABG surgery.

Midterm results of coronary artery bypass graft surgery with internal thoracic artery under low free-flow conditions

BACKGROUND

We use the left internal thoracic artery (LITA) even when flow is very low. In this study, we investigated midterm outcome of coronary artery bypass graft surgery with low free-flow LITA.

METHODS

One hundred patients undergoing coronary artery bypass graft surgery using LITA with a free flow of less than 20 mL/min were reviewed. The mean follow-up duration was 47.4 months, ranging from 1 to 65 months. Graft angiography was performed postoperatively. The diameter of the LITA was assessed angiographically. Cumulative graft patency, cardiac-related event-free rate, and actuarial survival rate were calculated by the Kaplan-Meier method.

RESULTS

An early postoperative Doppler study showed that the diastolic-to-systolic ratio in the LITA was 1.76 +/- 0.33. A 1-month postoperative angiography revealed LITA string sign in 2 patients. One had a percutaneous coronary intervention, whereas string sign was not detected in the second patient, and LITA patency showed a marked improvement in 1-year postoperative angiogram. One month postoperatively the LITA diameter was 1.6 +/- 0.4 mm, and significantly enlarged in the second angiogram (1.9 +/- 0.4 mm, p = 0.0003). There was a significant correlation between the diameter of the LITA and the left anterior descending coronary artery (r = 0.889, p = 0.0001). The cumulative graft patency rate at 1 and 4 years was 99.0% and 94.3%, respectively. The cardiac-related event-free rate at 1 and 5 years was 97.0% and 93.3%, respectively. The actuarial survival rate at 5 years was 97.1%.

CONCLUSIONS

Even with a very low LITA free flow, graft function improves with LITA growth, if there was no mechanical damage that impedes recovery.

Current State of Intraoperative Echocardiography

Intraoperative use of echocardiography is becoming more prevalent and is now considered an essential part of modern cardiac surgery. Echocardiography can be performed intraoperatively using transesophageal, epicardial or epiaortic, and substernal approaches. These techniques have a variety of applications in evaluating myocardial and valvular function, assessing aortic atheroma, and determining adequacy of various kinds of repair and reconstruction. Future applications will most likely involve more compact equipment, the implementation of epicardial and transesophageal real-time three-dimensional echocardiography, and better use of provocative methods of intraoperative testing.