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In vitro 4D Flow MRI evaluation of aortic valve replacements reveals disturbed flow distal to biological but not to mechanical valves
Author(s) -
Oechtering Thekla H.,
Sieren Malte,
Schubert Kathrin,
Schaller Tim,
Scharfschwerdt Michael,
Panagiotopoulos Apostolos,
Fujita Buntaro,
Auer Christian,
Barkhausen Jörg,
Ensminger Stephan,
Sievers HansHinrich,
Frydrychowicz Alex
Publication year - 2019
Publication title -
journal of cardiac surgery
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.428
H-Index - 58
eISSN - 1540-8191
pISSN - 0886-0440
DOI - 10.1111/jocs.14253
Subject(s) - medicine , hemodynamics , aortic valve , ascending aorta , afterload , shear stress , blood flow , cardiology , aorta , anatomy , biomedical engineering , materials science , composite material
Background and Aim of the Study Aortic hemodynamics influence the integrity of the vessel wall and cardiac afterload. The aim of this study was to compare hemodynamics distal to biological (BV) and mechanical aortic valve (MV) replacements by in vitro 4D Flow MRI excluding confounding factors of in‐vivo testing potentially influencing hemodynamics. Methods Two BV (Perimount MagnaEase [Carpentier‐Edwards], Trifecta [Abbott]) and two MV (On‐X [CryoLife], prototype trileaflet valve) were scanned in a flexible aortic phantom at 3T using a recommended 4D Flow MR sequence. A triphasic aortic flow profile with blood‐mimicking fluid was established. Using GTFlow (Gyrotools), area and velocity of the ejection jet were measured. Presence and extent of sinus vortices and secondary flow patterns were graded on a 0 to 3 scale. Results A narrow, accelerated central ejection jet (Area = 27 ± 7% of vessel area, Velocity = 166 ± 13 cm/s; measured at sinotubular junction) was observed in BV as compared to MV (Area = 53 ± 13%, Velocity = 109 ± 21 cm/s). As opposed to MV, the jet distal to BV impacted the outer curvature of the ascending aorta and resulted in large secondary flow patterns (BV: n = 4, grades 3, 3, 2, 1; MV: n = 1, grade 1). Sinus vortices only formed distal to MV. Although physiologically configured, they were larger than normal (grade 3). Conclusions In contrast to mechanical valves, biological valve replacements induced accelerated and increased flow patterns deviating from physiological ones. While it remains speculative whether this increases the risk of aneurysm formation through wall shear stress changes, findings are contrasted by almost no secondary flow patterns and typical, near‐physiological sinus vortex formation distal to mechanical valves.