Role of Pulse Pressure and Geometry of Primary Entry Tear in Acute Type B Dissection Propagation

Abstract

The hemodynamic and geometric factors leading to propagation of acute Type B dissections are poorly understood. The objective is to elucidate whether geometric and hemodynamic parameters increase the predilection for aortic dissection propagation. A pulse duplicator set-up was used on porcine aorta with a single entry tear. Mean pressures of 100 and 180 mmHg were used, with pulse pressures ranging from 40 to 200 mmHg. The propagation for varying geometric conditions (%circumference of the entry tear: 15–65%, axial length: 0.5–3.2 cm) were tested for two flap thicknesses (1/3rd and 2/3rd of the thickness of vessel wall, respectively). To assess the effect of pulse and mean pressure on flap dynamics, the %true lumen (TL) cross-sectional area of the entry tear were compared. The % circumference for propagation of thin flap (47 ± 1%) was not significantly different (p = 0.14) from thick flap (44 ± 2%). On the contrary, the axial length of propagation for thin flap (2.57 ± 0.15 cm) was significantly different (p < 0.05) from the thick flap (1.56 ± 0.10 cm). TL compression was observed during systolic phase. For a fixed geometry of entry tear (%circumference = 39 ± 2%; axial length = 1.43 ± 0.13 cm), mean pressure did not have significant (p = 0.84) effect on flap movement. Increase in pulse pressure resulted in a significant change (p = 0.02) in %TL area (52 ± 4%). The energy acting on the false lumen immediately before propagation was calculated as 75 ± 9 J/m2 and was fairly uniform across different specimens. Pulse pressure had a significant effect on the flap movement in contrast to mean pressure. Hence, mitigation of pulse pressure and restriction of flap movement may be beneficial in patients with type B acute dissections.

Prevalence of Bovine Aortic Arch Variant in Patients with Aortic Dissection and its Implications in the Outcome of Patients with Acute Type B Aortic Dissection

“…These factors include thickness of the wall, the deformationestress relationship, the impact of the tissue that surrounds the artery, the homogeneous material properties, and the blood pressure, as well as the pulse wave reflections from the arterial branches, the pulsatile movement of the heart, the residual stress, and the grade of fixation of the aortic wall. 25,26 Although data on flow haemodynamics of the anatomic variations of the aortic arch are rare and the association between the presence of a BA and the development of an AD is not extensively elucidated, these findings can provide a reasonable explanation.…”

Biomechanical Material Characterization of Stanford Type-B Dissected Porcine Aortas

“…The percent circumferential length of the entry tear was calculated as 100X (perimeter of the flap/circumference of the vessel). The perimeter of the flap was calculated by measuring the average length of the two edges of the flap in an ultrasound image representing cross-section of the entry tear (Peelukhana et al, 2016 ; Canchi et al, 2017 ). Using a surgical blade, a cut was made in the inner lining of the vessel.…”

Editor's Choice – Fluid–Structure Interaction Simulations of Aortic Dissection with Bench Validation

“…Physiological flow and pressure were simulated using a pulse duplicator experimental loop (PD; BDC laboratories, Wheat Ridge, CO, USA) with the porcine aorta connected into the test set-up. 11 Experimental set-up. The PD set-up consisted of an electronically actuated pulsatile flow pump controlled by a software (Stasys PD, BDC laboratories, Wheat Ride, CO, USA).…”