Ascending aorta dissection in a new classification system: Clinicopathological features of 62 cases

Insights From the Histopathologic Analysis of Acquired and Genetic Thoracic Aortic Aneurysms and Dissections

OBJECTIVE

The purpose of this study was to apply contemporary consensus criteria developed by the Society for Cardiovascular Pathology and the Association for European Cardiovascular Pathology to the evaluation of aortic pathology, with the expectation that the additional pathologic information may enhance the understanding and management of aortic diseases.

METHODS

A scoring system was applied to ascending aortic specimens from 42 patients with heritable thoracic aortic disease and known genetic variations and from 86 patients from a single year, including patients with known genetic variations (n = 12) and patients with sporadic disease (n = 74).

RESULTS

The various types of lesions of medial degeneration and the overall severity of medial degeneration overlapped considerably between those patients with heritable disease and those with sporadic disease; however, patients with heritable thoracic aortic disease had significantly more overall medial degeneration (P = .004) and higher levels of elastic fiber fragmentation (P = .03) and mucoid extracellular matrix accumulation (P = .04) than patients with sporadic thoracic aortic disease. Heritable thoracic aortic disease with known genetic variation was more prevalent in women than in men (27.2% vs 9.8%; P = .04), and women had more severe medial degeneration than men (P = .04). Medial degeneration scores were significantly lower for patients with bicuspid aortic valves than for patients with tricuspid aortic valves (P = .03).

CONCLUSION

The study's findings indicate considerable overlap in the pattern, extent, and severity of medial degeneration between sporadic and hereditary types of thoracic aortic disease. This finding suggests that histopathologic medial degeneration represents the final common outcome of diverse pathogenetic factors and mechanisms.

Histopathological findings of diseased ascending aortae with clinicopathological correlation - A single-centre study of 160 cases

The most common reason for ascending aorta resection is an aneurysm or dissection. Aortic dissection is a life-threatening condition in which an aneurysm is a crucial risk factor. The essential criteria for aneurysm resection include the diameter, genetic predisposition, and aortic valve disease. This study aimed to compare the histological findings in aneurysms and dissections and correlate them with clinical parameters to determine whether histopathological findings correspond with the current clinical approach. A total of 160 ascending aorta surgical specimens, separate or with an aortic valve, were collected and divided into four groups: aneurysm-tricuspid (n = 40; median 67 y), aneurysm-malformed (n = 68; median 50 y), dissection-tricuspid (n = 48; median 65.5 y), and dissection-malformed (n = 4; median 52.5 y). Male preponderance was observed in all groups; the youngest patients were in the aneurysm-malformed group. None of the specimens showed normal aortic histology. The most common finding in the aortic samples was medial degeneration, which was the most severe and most common in dissection. The mildest findings were found in the aneurysm-malformed group. Atherosclerosis was predominant and most severe in the aneurysm-tricuspid group, while only mild in both dissection groups, suggesting its protective effect against this complication. Chronic aortitis was the least common pathology, found only in the aneurysm-tricuspid group. The aortic valve was resected and examined simultaneously with the ascending aorta in 76 cases, most commonly in the aneurysm-malformed group (n = 53). Myxoid degeneration was the major finding in the tricuspid aortic valves, with calcifications in the malformed. Comparing the histopathological results with the clinical aspects, aneurysms with a malformed aortic valve seem to be managed appropriately, with the findings not reaching the severity as in patients with a tricuspid valve. In contrast, in patients with a tricuspid valve, there were more dissections than aneurysms, with a significant subset of aneurysms showing histological findings almost identical to those of dissections. Supported by histological findings, patients with a diseased ascending aorta and tricuspid aortic valve represent an underdiagnosed risk group that would benefit from earlier diagnosis and intervention to prevent dissection. There is a need to find a marker for dissection risk other than the aortic diameter.

Medial degeneration and atherosclerosis show discrete variance around the circumference of ascending aorta aneurysms

Medial degeneration is the most common histological finding in ascending aortic aneurysms with lesser but significant involvement by atherosclerosis. The overall extent and severity can be potentially underrated because of their uneven distribution and macroscopic inconspicuousness of medial degeneration. This study aims to compare the distribution of degenerative and atherosclerotic lesions around ascending aorta circumference, also considering aortic valve cuspidity. We evaluated 88 cases of resected ascending aortae, 25 with a tricuspid aortic valve and 63 with a malformed aortic valve, oriented by a cardiac surgeon and sent for pathological examination. We applied the consensus documents from 2015 and 2016 for microscopic evaluation of aortic specimens. The medial degeneration and atherosclerosis were graded semi-quantitatively for each aortic quadrant: convexity, anterior wall, concavity, and posterior wall. Nearly all quadrants showed at least mild medial degeneration; more severe findings of medial degeneration and atherosclerosis were in the aneurysms associated with the tricuspid valve. In the aneurysms with the tricuspid aortic valve, there was more frequent and more severe atherosclerosis at the concavity than at the anterior wall (p = .046); the frequency and severity of medial degeneration did not differ significantly. The aneurysms with a malformed aortic valve showed more severe medial degeneration at the concavity compared to the convexity (p = .011); atherosclerosis was less common and did not show any significant differences. More than half of the samples also revealed at least a one-grade (mostly one-grade) difference among the quadrants in individual cases for both atherosclerosis and medial degeneration. Extreme differences were rare except for atherosclerosis in the tricuspid group. The results revealed only slight overall differences around the aortic circumference, with concavity being the most susceptible. Still, thanks to occurring inter- and intraindividual variability, the examination of all quadrants seems meaningful not to miss the most severe changes and to underscore the findings.