Bicuspid and tricuspid aortic valve do not have the same ascending aorta morphology

Synthesis of multidimensional pathophysiological process leading to type A aortic dissection: a narrative review

Objective

This review aims to synthesize the existing knowledge on the etiological process leading to type A aortic dissection (TAAD) and to clarify the relationship between mechanical, biochemical, and histopathological processes behind the aortic disease.

Background

Extensive research has previously identified several risk factors for TAAD as well as pathological mechanisms leading to TAAD. However, due to the complexity of the pathological process and limited knowledge on the relationships between distinct pathomechanisms leading to TAAD, the ability to identify the patients at high risk for TAAD has been poor.

Methods

PubMed (National Library of Medicine) database was searched for suitable literature. The most relevant articles focusing on anatomy, histopathology, physiology, and mechanics of ascending aorta and aortic diseases were reviewed.

Conclusions

Pathophysiology of the TAAD is related to biochemical and histological as well as mechanical and hemodynamic alterations leading to a degeneration of the aortic wall via inflammatory response. The degradative mechanisms of aortic wall structures and the mechanical forces, to which the wall is predisposed, are interrelated and influence one another. The relativity between the factors influencing aortic wall strength and healing capacity, and factors influencing mechanical stress on the aortic wall suggest that the risk of TAAD is not a linear but rather a dynamic phenomenon. Accounting for the dynamical property of the aortic disease in assessing the need for preventive surgical aortic reconstruction may provide a wider perspective in identifying patients at risk of TAAD and in planning preventive medical therapies.

Comparison of Clinical and Echocardiographic Features of Asymptomatic Patients With Stenotic Bicuspid Versus Tricuspid Aortic Valves

The clinical and imaging differences between bicuspid aortic valve (BAV) and tricuspid aortic valve (TAV) patients with medically managed asymptomatic moderate-to-severe aortic stenosis (AS) have not been studied previously. We aim to characterize these differences and their clinical outcomes in this study. A retrospective observational study was conducted on 836 consecutive cases of isolated asymptomatic moderate-to-severe AS, with median follow-up of 3.4 years. Clinical and echocardiographic characteristics were compared between BAV and TAV patients. Subgroup analysis stratified by AS severity were performed. Survival analysis of all-cause mortality was performed using Kaplan-Meier curves and Cox proportional hazards model. Compared to BAV patients, TAV patients were older (76 ± 11 vs 55 ± 16 years, p <0.001) and had more co-morbidities including hypertension (78% vs 56%; p <0.001), diabetes (41% vs 24%; p <0.001), and chronic kidney disease (20% vs 3%; p = 0.001). TAV patients had less severe aortic valve disease than BAV patients, with a higher aortic valve area index (0.71 ± 0.20 cm²/m² vs 0.61 ± 0.18 cm²/m², p <0.001) and less aortic dilation (sinotubular junction: 23.7 ± 4.0 mm vs 26.9 ± 4.8 mm, p <0.001; mid-ascending aorta: 31.4 ± 4.7 mm vs 36.3 ± 6.3 mm, p <0.001). TAV patients were more likely to have eccentric left ventricular hypertrophy and less likely to have a normal geometry (p = 0.003). Competing risk analysis identified increased age (hazard ratio 1.03, 95% confidence interval 1.02 to 1.05, p <0.001) and LVEF (hazard ratio 0.98, 95% confidence interval 0.97 to 0.99, p <0.001) as independent risk factors of all-cause mortality. Valve morphology was not a significant independent risk factor for aortic valve replacement or mortality. In conclusion, asymptomatic TAV patients had more cardiovascular risk factors, less severe aortic valve disease, less sinotubular and mid-ascending aortic dilation, more severe LV remodeling.