Pathophysiology of Subintimal Hematoma Formation During Retrograde Arteriography

Major complications of clinical retrograde arteriography arouse continuing concern (1–7). A toxic effect of the contrast medium has been implicated in the production of certain types of lesions (11), but in a substantial group of patients, technical or mechanical factors appear to be major determinants of ensuing disability. Gudbjerg and Christensen (6) found a remarkable incidence of aortic dissection following retrograde aortography in the investigation of arteriosclerotic disease in their series: 36 instances of aortic dissection in 126 patients. Because of these findings, some radiologists (1) have virtually abandoned retrograde aortic catheterization in arteriosclerotic patients, employing instead the direct translumbar approach for the investigation of atherosclerosis of the great vessels. Some years ago, Gaylis and Laws (4) pointed out that many of the common serious neurological, renal, and gastrointestinal complications following aortography are strikingly similar to those associated with spontaneously occurring dissecting aortic aneurysm; they felt that many of these complications were caused by unrecognized subintimal injection, resulting in subintimal hematoma formation and dissecting aneurysm. Boblitt et al. (7) subsequently reported 42 patients with recognized subintimal injection, 2 of whom died as the result of proved dissecting aneurysm. The pathophysiology of subintimal injection with hematoma formation may thus be of critical importance in understanding and preventing disastrous complications following retrograde aortography. Yet, to our knowledge there have been no previous studies of the mechanism of subintimal hematoma formation in this procedure. Guilfoil recently suggested (5) that the subintimal extravasation of opaque material might be a function of injection speed rather than of toxicity of medium, and he was reluctant to incriminate a specific toxic action of contrast material on the endothelium as the principal causative factor. Boblitt et al, believe that chemotoxicity plays a combined role with aortic dissection in the production of complications. According to Sutton (8) aortic dissection is a result of poor catheterization technic. Gillanders also recently expressed the opinion that “a faulty technique may produce intimal elevation and facilitate dissection” (1) and he suggested that a test injection in his case might have prevented the ensuing subintimal hematoma and aortic dissection. The present report represents an attempt to study the mechanism of formation of subintimal hematoma following retrograde arch aortography in the dog.