False Lumen Flow Patterns and their Relation with Morphological and Biomechanical Characteristics of Chronic Aortic Dissections. Computational Model Compared with Magnetic Resonance Imaging Measurements

Figures

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  Fig 1. Typical false lumen flow patterns. Four representative false lumen flow patterns (assessed at the diaphragm) observed in our patients in follow-up. They can be classified based on the direction of flow in systole and diastole; BA: systolic biphasic flow and primarily diastolic antegrade flow; BR: systolic biphasic flow and primarily diastolic retrograde flow; MA: systolic monophasic flow and primarily diastolic antegrade flow; MR: systolic monophasic flow and primarily diastolic retrograde flow. Antegrade flows are positive and retrograde flows are negative.

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  Fig 2. Lumped-parameter computational model of an aortic dissection. (A) Diagram of the lumped-parameter model of an aortic dissection including the presence of abdominal side branches (sb) and the modeling of the thoracic (ThAo) and abdominal (AbAo) aorta; (B) Clinical appearance of an aortic dissection with magnetic resonance imaging and the equivalent dissection geometry proposed; (C) Imposed inflow curve; (D) Value of interluminal resistance plotted as a function of the cumulative tear area, resulting from the calibration of the lumped-parameter model to the experimental in-vitro one [17]. Each data point corresponds to the cumulative value of the tear resistances in the numerical model related to the cumulative tear area in the experimental model for a specific scenario SP,D; P, proximal tear diameter; D, distal tear diameter; FL, False lumen; TL, True lumen; PT, Proximal tear; DT, Distal tear.

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  Fig 3. Simulated intraluminal flow patterns along the dissection. Spatial variability of true lumen (TL; A) and false lumen (FL; B,D) flow patterns for the baseline case with 2 large tears and in the absence of any visceral side branches originating from them. The spatial variability of FL flow patterns for the scenarios with a larger proximal (C) and a larger distal (E) tear is also illustrated. Antegrade flows are positive and retrograde flows are negative. Yellow dash lines indicate the diaphragm level.

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  Fig 4. Effect of wall stiffness on intraluminal flows and pressures. Changes in flow patterns (Left) and pressure profiles (Right) with changes in wall stiffness. Antegrade flows are positive and retrograde flows are negative. TL, True lumen; FL, False lumen.

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  Fig 5. Effect of incidence of visceral arteries arising from the FL on intraluminal flows. Changes in flow patterns with changes in the percentage of abdominal side branches connected to the false lumen (FL). Antegrade flows are positive and retrograde flows are negative. TL, True lumen.

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  Fig 6. Effect of decrease in cumulative tear area on intraluminal flows and pressures. Variations in flow patterns (Left) and pressure profiles (Right) for a decrease in the cumulative tear area (from 300 to 25 mm2) and resultant true lumen (TL) vasodilatation. Antegrade flows are positive and retrograde flows are negative. FL, False lumen.

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  Fig 7. Effect of tear size distribution along the dissection on flows. Changes in intraluminal flow patterns with changes in the distribution of total communicating area between the proximal and distal tears. The color scale represents the percentage of total area distributed at the proximal site. Antegrade flows are positive and retrograde flows are negative. TL, True lumen; FL, False lumen.

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  Fig 8. Quantification of flow profiles derived from the parametric study. Percentage of total volume flow into the false lumen (FL) (%TVF), percentage of systolic (%RSFFL) and diastolic (%RDFFL) FL retrograde flow for changes in (A) wall stiffness of the dissected segment; (B) percentage of FL side branches; (C) distribution of total area between the proximal and distal tear; (D) increase and (E) decrease in cumulative tear area.

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  Fig 9. Comparison between in-vivo observations and model predictions. Comparison between the 4 characteristic FL flow patterns (BA, BR, MA, MR) identified in the study population and the findings from the parametric study. The different FL flow profiles at the level of the diaphragm can be explained by the percentage of visceral arteries arising from the FL and the location (before/after) of the dominant interluminal communication respect to the place of measurement. Signs illustrate the level of incidence of each property in each FL flow pattern determination: (-) absent property; (++) existent property; (+/-) possible existent property. Antegrade flows are positive and retrograde flows are negative.