Preliminary report on a sonographic method to determine the location of the intimal breach in Stanford type B aortic dissection

Abstract

Using a defined angle T, which can be measured noninvasively using Doppler ultrasound, we aim to determine the location of the intimal breach in Stanford type B aortic dissection (AD) and estimate the risk of AD using that measurement. Our subjects included 86 healthy volunteers, 60 hypertensive patients, and 42 patients with Stanford type B AD. We used dual functional color Doppler ultrasound to locate the central point of the high-speed flow zone within the descending aorta, and then calculated the angle T, using the law of cosines. In addition, we measured the degree of distortion within the descending aorta using Line BD, defined as the distance from the lateral edge of the left subclavian artery (LSA) to the center of the breach in the intima in AD. The value of T was approximately 24° ± 3° and was constant across all 3 groups. In addition, the increase in BD distance corresponded to increased distortion in the descending aorta between the LSA and the region of aortic artery ligament (RAALE). We found that when the preoperative BD was less than 2.6 cm, the aortic arch could be straightened, using a stent-graft, to approximate the normal aorta. When the preoperative BD is less than 2.6 cm, the aortic arch can be corrected using a stent. In addition, since the T angle is constant, we speculate that it can be used to predict the risk of intimal breach and estimate its location using digital subtraction angiography (DSA) to guide surgery.