Transthoracic colour Doppler ultrasonography in the evaluation of internal thoracic artery bypass graft patency

Pre-operative trans-thoracic doppler ultrasonography evaluation and intraoperative manual evaluation of the left internal thoracic artery in patients with type 2 diabetes with coronary artery disease

Patients with coronary artery disease, with (n = 25) and without (n = 59) type 2 diabetes, who were scheduled to undergo coronary artery bypass grafting were enrolled in this prospective study. The left internal thoracic artery (LITA) was assessed for graft suitability before surgery by trans-thoracic Doppler ultra sonography and during surgery by manual measurement. Significant differences were seen between preoperative and intra-operative LITA blood flow rates and LITA diameters, and the values of each at the two time points showed significant correlation, suggesting that pre-operative measurements largely related to intra-operative conditions. The pre-operative and intra-operative LITA blood flow rates and LITA diameters were not significantly different between patients with and without type 2 diabetes. Pre-operative LITA blood flow was monophasic in three patients without diabetes and the LITA grafts of these patients were deemed unsuitable for implantation during surgery. It is concluded that type 2 diabetes does not seem to have a negative effect on the suitability of LITA grafts. In addition, trans-thoracic Doppler ultrasonography is an easy, cost-effective, reproducible and non-invasive examination method, which may help in the evaluation of LIMA function and contribute to graft selection.

Noninvasive Dynamic Assessment With Transthoracic Echocardiography of a Composite Arterial Y-Graft Achieving Complete Myocardial Revascularization

BACKGROUND

Composite arterial grafts are increasingly used in coronary artery bypass surgery. We assessed with transthoracic echocardiography the composite radial artery and in situ left internal thoracic artery Y-graft.

METHODS

In 53 of 60 consecutive patients who underwent complete myocardial revascularization using only this composite arterial graft, good transthoracic echocardiographic images and pulsed Doppler signals of the Y-graft main stem were obtained at rest and early after standard exercise. Stress/rest 99mTc-sestamibi myocardial perfusion single-photon emission computed tomography (SPECT) was the gold standard for residual myocardial ischemia. The patients with negative SPECT were divided into groups according to the number of coronary artery systems grafted, and history of preoperative myocardial infarction.

RESULTS

Diastolic peak velocity, diastolic velocity-time integral, the diastolic-to-systolic ratio of the peak velocities and velocity-time integrals, and the stress-to-rest ratio of the diastolic peak velocities and diastolic velocity-time integrals in the negative-SPECT patients were significantly greater than in the 6 positive-SPECT patients. Sensitivity and specificity for ischemia of the stress-to-rest ratio of the diastolic peak velocities less than 1.5 were 100%. The stress-to-rest ratio of the diastolic velocity-time integrals in the patients with three coronary systems grafted, and in those without preoperative myocardial infarction, were respectively greater than in the patients with two systems grafted (p < 0.0001), and in those with preoperative myocardial infarction (p = 0.0048).

CONCLUSIONS

Noninvasive dynamic assessment with transthoracic echocardiography of a composite arterial graft, including in situ left internal thoracic artery, is feasible and correlates with myocardial perfusion SPECT. The Y-graft used was able to regulate its flow capacity to myocardial demand.