Screening the thoracic aorta for atheroma: a comparison of manual palpation, transesophageal and epiaortic ultrasonography

Abstract

Accurate detection of atheroma within the thoracic aorta is an important part of most stroke prevention strategies in cardiac surgery. The thoracic aorta was divided into six zones corresponding to sites of surgical manipulation. Zones 1-3, proximal, mid and distal ascending aorta, zones 4-5, proximal and distal arch and zone 6, proximal descending aorta. This study compares the accuracy of atheroma detection by manual palpation, epiaortic (EPI) and transesophageal (TEE) ultrasonography in 70 patients.

Results: Using EPI as the reference method for zones 1-4, 14/70 patients were identified with moderate or severe atheroma. The frequency of atheroma was age related with the youngest at 55 years. Compared with EPI, manual palpation correctly detected moderate or severe atheroma in 7/14 patients (p=0.0058) and TEE in only 4/14 patients (p= 0.0002). For TEE, adequate imaging was only obtained in 41/70 in zone 3 and 30/70 in zone 4. Adequate imaging of zones 5-6 was obtained in all patients using TEE. Of 68 patients with adequate imaging of all zones, 36 had moderate or severe atheroma in zones 5-6. The positive predictive value for zones 1-4 based on atheroma in zones 5-6 was 39%. Of 32 patients with nil or mild atheroma in zones 5-6, only 1 had moderate or severe atheroma in zones 1-4 (negative predictive value 94%).

Conclusion: Manual palpation and TEE are inaccurate methods of atheroma detection in zones 1-4. Epiaortic ultrasonography is recommended for all patients undergoing cardiac surgery, although the yield will be low for patients < 50 years of age or if there is nil or mild atheroma detected by TEE in zones 5-6.