The Arterial Wall Response to Intimal Injury in an Experimental Model

Repair of occult arterial injuries is advocated to prevent thrombosis, arteriovenous fistula, and pseudoaneurysm formation. However, recent clinical series describe the healing of arterial intimal injuries and recommend nonoperative therapy. To investigate the arterial wall response to intimal injury, we created intimal flaps in 46 canine femoral arteries. The intimal flaps were imaged by arteriography, angioscopy, and intravascular ultrasound acutely, and at one and three weeks and five months post-injury. Lumen area was measured using caliper techniques (arteriography) and computerized video planimetry (angioscopy, intravascular ultrasound). Intimal and medial thickness were measured by intravascular ultrasound prior to harvest for histologic evaluation by light microscopy. Analysis of 32 patent arteries was performed after exclusion of 14 thrombosed arteries. Residual lumen area (mm²) correlated closely among the imaging modalities at one week (8.7 ± 1.1, 7.3 ± 2.0, 6.9 ± 1.8), three weeks (4.2 ± 0.9, 2.9 ± 1.0, 2.7 ± 0.8), and five months (5.3 ± 0.9, 5.0 ± 0.5, 5.0 ± 0.9). Maximal intimal and medial thickness occurred three weeks post-injury, coincident with the maximal reduction in lumen area. Although intimal injuries can cause acute and delayed arterial thromboses, observation may be appropriate in selected cases. The evaluation of those patients chosen for nonoperative therapy should extend beyond three weeks, as this is the time of maximal arterial wall response with a continued potential for adverse clinical events.