Wall thickness after carotid endarterectomy in patients with paired vein and Dacron patch reconstruction.

Abstract

This is an analysis of early postcarotid endarterectomy (CEA) wall thickness in patients who have undergone bilateral operations with vein and Dacron patch reconstructions. In the past 5 years 23 patients had staged bilateral CEA within 2 months with an autologous greater saphenous vein patch on one side and a knitted Dacron patch on the other. Duplex scans with adequate B-mode resolution to measure common carotid bulb total wall thickness were performed in all 23 patients during the first post-CEA year and in 12 patients in the post-CEA second year. There were no hemodynamically detectable restenoses by Doppler velocity criteria. All peak systolic velocities were < or = 110 cm/sec. In the first post-CEA year the total wall thickness of the 23 vein patch CEA was 1.7 +/- 1.0 mm (mean +/- 1 SD; range, 0.6 to 5.5 mm), and the total wall thickness of the 22 Dacron patch CEA was 1.7 +/- 1.1 mm (range, 0.6 to 6.1 mm, p = 0.93). In the second post-CEA year wall thickness was 2.1 +/- 1.8 mm (range, 0.6 to 5.8 mm) in the vein patch arteries and 2.0 +/- 1.5 mm (range, 0.6 to 5.4 mm, p = 0.91) in the Dacron patch arteries. Although wall thickness of both vein and Dacron patch CEA varied widely between patients, the within-patient absolute difference between the two sides was quite small, 0.1 +/- 0.3 mm in the first year and 0.2 +/- 0.5 mm in the second. With a 5% chance of a type I statistical error (alpha = 0.05) to detect a 0.5 mm difference in wall thickness between Dacron and vein patch CEA, the power of the paired t test is > 0.999, and the probability of a type II error, beta, is < 0.001 (power = 1-beta) in the first year. In the second year beta = 0.34. Wall thickness was bilaterally eccentric in 17 patients. The minimum thickness was in the patch wall, and the maximum was in the opposite endarterectomized wall. It was circumferentially uniform in five patients with < 1 mm wall thickness. The single patient with significant bilaterally concentric wall thickness in the first year was the only one who had a marked increase in wall thickness between the first and second years. Wall thickness > 2 mm was associated with continued smoking (p = 0.03). Post-CEA wall thickening is highly patient-dependent but is patch material-independent. Knitted Dacron and saphenous vein patch reconstructed carotid arteries develop almost identical wall thickness in a given patient in the first 2 years after endarterectomy. These results support the use of knitted Dacron as an acceptable alternative to greater saphenous for a CEA patch.