Are the dynamic changes of the aortic root determinant for thrombosis or leaflet degeneration after transcatheter aortic valve replacement?

Abstract

The role of the aortic root is to convert the accumulated elastic energy during systole into kinetic flow energy during diastole, in order to improve blood distribution in the coronary tree. Therefore, the sinuses of Valsalva of the aortic root are not predisposed to accept any bulky material, especially in case of uncrushed solid calcific agglomerates. This concept underlines the differences between surgical aortic valve replacement, in which decalcification is a main part of the procedure, and transcatheter aortic valve replacement (TAVR). Cyclic changes in shape and size of the aortic root influence blood flow in the Valsalva sinuses. Recent papers have been investigating the dynamic changes of the aortic root and whether those differences might be correlated with clinical effects, and this paper aims to summarize part of this flourishing literature. Post-TAVR aortic root remodeling, dynamic flow and TAVR complications might have a fluidodynamic background, and clinically observed side effects such as thrombosis or leaflet degeneration should be further investigated in basic researches. Also, aortic root changes could impact valve type and size selection, affecting the decision of over-sizing or under-sizing in order to prevent valve embolization or coronary ostia obstruction.

Supporting the Ross procedure: preserving root physiology while mitigating autograft dilatation

“…The aortic root is a dynamic structure consisting of several component parts: the semilunar valve cusps, the ventriculoaortic junction, the sinuses of Valsalva and the sinotubular junction (STJ) [53]. A series of complex and asymmetric deformations during the cardiac cycle and the innate elasticity of the root optimize forward flow and minimize stress on the aortic cusps [54][55][56][57][58][59][60].…”

Effect of Sinotubular Junction Size on TAVR Leaflet Thrombosis: A Fluid-structure Interaction Analysis

“…Previously, a clinical study by Nappi et al has indicated that the dynamic variation of the STJ diameter during the cardiac cycle may play an important role in the risk of leaflet thrombosis and degeneration post- TAVR [14]. The STJ diameter has also been related to coronary obstruction, reporting a low STJ-to-TAVR diameter ratio to be a predictor of left main trunk obstruction [15].…”

The Year 2020 in Review: Coronavirus Disease 2019 Cloud and Its Impact Excelling the Clinical Practice

“…(2) intrinsic limitation of leaflet material. 13 Futuristically, more personalized and customized TAVR valves (size, design, and material) may be the correct answer rather than trying to find a "fit-all" anticoagulation strategy. As the authors mention, the studies on use of mechanical circulatory support devices for cardiogenic shock, acute respiratory distress syndrome (ARDS), and sepsis have shown that extracorporeal membrane oxygenation (ECMO) may have a more beneficial role to play than realized yet.…”

“…Taking a step back, compared with surgical-AVR, the TAVR valve is increasingly predisposed thrombosis and degeneration due to (1) neo-anatomy (axis of left ventricle outflow tract, annulus, and sinuses of Valsalva) and eccentric distortion over time leading to mechanical stress and fluid-dynamic effects on leaflets and stent; and (2) intrinsic limitation of leaflet material. 13 Futuristically, more personalized and customized TAVR valves (size, design, and material) may be the correct answer rather than trying to find a “fit-all” anticoagulation strategy. As the authors mention, the studies on use of mechanical circulatory support devices for cardiogenic shock, acute respiratory distress syndrome (ARDS), and sepsis have shown that extracorporeal membrane oxygenation (ECMO) may have a more beneficial role to play than realized yet.…”