Objective Pressure ulcers are caused by prolonged mechanical loads deforming the underlying soft tissues. However, the mechanical loads for microcirculatory occlusion are unknown. The present study was designed to characterize the simultaneous response of microvascular and lymphatic structures under repeated mechanical loading. Methods The effects of two distinct loading/unloading cycles involving (a) incremental pressures 30, 60, and 90 mmHg and (b) three repeated cycles of 30 mmHg were evaluated on a cohort of able‐bodied volunteers. Microvascular response involved the monitoring of transcutaneous gas tensions, while dermal lymphatic activity was estimated from near‐infrared imaging. Responses were compared during each load and recovery cycle. Results Changes in microvascular response were dependent on the load magnitudes, with 30 mmHg resulting in a reduction in oxygen tension only, while 90 mmHg affected both oxygen and carbon dioxide values in most cases (54%). By contrast, lymphatics revealed near total occlusion at 30 mmHg. Although there were intersubject differences, temporal trends consistently revealed partial or full impairment under load, with recovery during off‐loading. Conclusions The pressure required to cause microcirculatory occlusion differed between individuals, with lymphatic impairment occurring at a lower pressure to that of microvascular vessels. This highlights the need for personalized care strategies and regular off‐loading of vulnerable tissues.
The rupture of atherosclerotic plaques in coronary and carotid arteries is the primary cause of fatal cardiovascular events. However, the rupture mechanics of the heterogeneous, highly collagenous plaque tissue, and how this is related to the tissue's fibrous structure, are not known yet. Existing pipelines to study plaque mechanics are limited to obtaining only gross mechanical characteristics of the plaque tissue, based on the assumption of structural homogeneity of the tissue. However, fibrous plaque tissue is structurally heterogeneous, arguably mainly due to local variation in the collagen fiber architecture.The mechano-imaging pipeline described here has been developed to study the heterogeneous structural and mechanical plaque properties. In this pipeline, the tissue's local collagen architecture is characterized using multiphoton microscopy (MPM) with second-harmonic generation (SHG), and the tissue's failure behavior is characterized under uniaxial tensile testing conditions using digital image correlation (DIC) analysis. This experimental pipeline enables correlation of the local predominant angle and dispersion of collagen fiber orientation, the rupture behavior, and the strain fingerprints of the fibrous plaque tissue. The obtained knowledge is key to better understand, predict, and prevent atherosclerotic plaque rupture events.
Objectives The ELANA® Heart Bypass creates a standardized sutureless anastomosis. Hereby, we investigate the influence of arteriotomy and graft size on coronary hemodynamics. Methods A computational fluid dynamics (CFD) model was developed. Arteriotomy size (standard 1.43 mm2; varied 0.94 – 3.6 mm2) and graft diameter (standard 2.5 mm; varied 1.5 – 5.0 mm) were independent parameters. Outcome parameters were coronary pressure and flow, and fractional flow reserve (FFR). Results The current size ELANA (arteriotomy 1.43 mm2) presented an estimated FFR 0.65 (39 mL/min). Enlarging arteriotomy increased FFR, coronary pressure, and flow. All reached a maximum once the arteriotomy (2.80 mm2) surpassed the coronary cross-sectional area (2.69 mm2, i.e. 1.85 mm diameter), presenting an estimated FFR 0.75 (46 mL/min). Increasing graft diameter was positively related to FFR, coronary pressure, and flow. Conclusion The ratio between the required minimal coronary diameter for application and the ELANA arteriotomy size effectuates a pressure drop that could be clinically relevant. Additional research and eventual lengthening of the anastomosis is advised. Graphical abstract
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.