Aortic Medial Elastic Fiber Loss in Acute Ascending Aortic Dissection

Abstract

The cause of acute aortic dissection continues to be debated. One school of thought suggests that underlying aortic medial cystic necrosis is the common denominator. The purpose of the present study was to determine if there was loss and, if so, how much loss of medial elastic fibers in the ascending aorta in patients with acute aortic dissection with the entrance tear in the ascending aorta. We examined operatively excised ascending aortas in 69 patients having acute dissection with tears in the ascending aorta. Patients with previous aortotomy, healed dissection, and connective tissue disorders were excluded. The 69 patients' ages ranged from 31 to 88 years (mean 56); 49 were men and 20 were women. Loss of aortic medial elastic fibers was graded as 0 (no loss), 1؉ (trace), 2؉ (mild), 3؉ (moderate), and 4؉ (full thickness loss). Of these 69 patients, 56 (82%) had 0 or 1؉ elastic fiber loss; 13 patients (18%), 2؉ to 4؉ loss including 4 with 2؉, 6 with 3؉, and 2 with 4؉. Nearly all patients (97%) had a history of systemic hypertension and/or had received antihypertensive drug therapy. In conclusion, most patients (82% in this study) having acute aortic dissection with entrance tears in the ascending aorta have normal numbers or only trace loss of aortic medial elastic fibers. Thus, underlying abnormal ascending aortic structure uncommonly precedes acute dissection.

S100A12 Expression in Thoracic Aortic Aneurysm Is Associated With Increased Risk of Dissection and Perioperative Complications

“…The morphology of elastic fibers serves as a good marker of chronic aortic remodeling, such as replacement with fibrous tissue and deposits of mucoid material, and are easily discernable and the grading of elastic fiber loss is highly reproducible. This is in contrast to acute type A dissection, where abnormal ascending aortic elastic fibers uncommonly precede acute dissection (10,11). Supplement Figure 1 shows the frequency of elastic fiber degradation in elective TAA with regards to S100A12 protein expression.…”

“…However, it remains unknown if apoptosis of medial smooth muscle cells occurs prior to dissection as a primary event leading to weakening and rupture of the aortic wall, or if alternatively as suggest by Roberts et al the intraluminal arterial pressure in the false luminal channel compresses the adjacent media and induces cell death after , not before acute dissection (11). …”

“…Staining for S100A12 was semiquantified by two blinded investigators (DD, MAHB) as absent (0), mild (1+), moderate (2+) or intense (3+) in cells that either was positive or negative for myeloperoxidase staining. Loss of aortic medial elastic fibers were graded as 1 (trace), 2 (mild), 3 (moderate) and 4 (full thickness loss) as previously reported by Dr. W.C.Roberts (10,11). …”

Surgical treatment of bicuspid aortic valve disease: Knowledge gaps and research perspectives

“…In addition, other studies have demonstrated the lack of correlations between aortic diameter and degree of medial degeneration in the aortic wall of patients with BAV 62 as well as between the degree of elastic fiber fragmentation and the occurrence of acute dissection. 63 Hence, other important unanswered questions emerge: does the aortic diameter need to be integrated into a more complex system of stratification including other risk markers, so that its relative weight in the decision-making process can vary case by case according to other prognostic factors? And what should those other risk markers be (Table 1)?…”

Trying to overcome the ‘chicken or egg’ impasse in bicuspid aortopathy research

“…In this perspective, classical histology might be not reliable as a metric of aortopathy severity: for example, Roberts et al [7] reported that severe rarefaction of medial elastic fibres was rarely associated with acute type A aortic dissection. Moreover, Bechtel's score includes features of both medial degeneration and atherosclerosis, which may be misleading [8].…”