4242 Evaluating the effect of a compliant stent-graft prototype on effective stiffness in a cadaveric aorta

OBJECTIVES/GOALS: High aortic stiffness is associated with increased cardiovascular morbidity and mortality. The purpose of this work is to demonstrate the potential of our compliant stent-graft design to therapeutically increase aortic compliance over a standard aortic stent-graft. METHODS/STUDY POPULATION: The aorta from a human cadaver will be excised and placed into a pulse duplicator circuit. The stiffness of the system will be estimated using the pulse wave velocity (PWV), which will be calculated using the time delay between pressure measurements at proximal and distal locations in the system. Baseline measurements with the unstented aorta will be compared to two cases: (1) with a standard stent-graft placed, and (2) with our compliant stent-graft prototype in the descending thoracic aorta. PWV is calculated as the distance between the pressure sensors divided by the time delay. Faster PWV is associated with a stiffer vessel, or lower aortic compliance. RESULTS/ANTICIPATED RESULTS: Prior work in vitro showed that the compliant stent-graft reduced peak and pulse pressures compared a standard, rigid stent-graft. We also expect the compliant device to exhibit lower PWV compared to a rigid stent-graft. Depending on the aortic tissue stiffness, the compliant stent-graft could raise or lower PWV compared to no stent. Mean pressure in the compliant case is likely to be slightly higher than the other two cases because the compliant stent-graft’s narrower lumen increases flow resistance. Although mean pressure will be higher, peak pressure should be lower than in the standard stent-graft because the added compliance decreases overall pressure swing between systole and diastole. DISCUSSION/SIGNIFICANCE OF IMPACT: Lower PWV in the compliant stent-graft over the standard stent-graft will indicate its potential to therapeutically lower aortic stiffness in patients needing aortic stenting. Positive outcomes from this study will be a step toward the eventual translation of a compliant stent-graft to clinical use.

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Two Methods to Assess Aortic Compliance Using Blood Pressure and Pulse-Wave Velocity

Journal of Engineering and Science in Medical Diagnostics and Therapy ◽

10.1115/1.4047575 ◽

2020 ◽

Author(s):

Noah Manring ◽

Mouayed Al-Toki

Keyword(s):

Blood Pressure ◽

Mean Arterial Pressure ◽

Arterial Pressure ◽

Pulse Wave Velocity ◽

Wave Velocity ◽

Pulse Wave ◽

Rubber Tube ◽

Aortic Compliance ◽

Cardiovascular Morbidity And Mortality

Abstract Aortic compliance has been well established as an independent predictor of cardiovascular morbidity and mortality. The current "gold standard" for assessing aortic compliance is to use the carotid-femoral pulse-wave velocity (PWV) as a surrogate; however, PWV alone has been discussed in the literature as being inadequate for assessing compliance, especially for elderly patients and others who have a stiff aorta. In this paper an equation for the aortic compliance is developed using two approaches: 1) lumped-parameter modeling based on blood-pressure data and 2) distributed modeling based on the PWV. In-vitro experiments are conducted using a silicone-rubber tube which simulates the aorta, and an actual aorta harvested from a 1-year old, Holstein heifer. For both the rubber aorta and the Holstein aorta, a comparison is made between the blood-pressure model and the PWV model. In conclusion it is shown that good agreement exists between the two models, suggesting that either model may be used depending upon the available data. Furthermore, due to differences in material properties, it is shown that the compliance of the rubber aorta increases with mean arterial-pressure, while the compliance of the Holstein aorta decreases with mean arterial-pressure. Clinical implications of this research are also discussed.

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Research Models for Studying Vascular Calcification

International Journal of Molecular Sciences ◽

10.3390/ijms21062204 ◽

2020 ◽

Vol 21 (6) ◽

pp. 2204 ◽

Cited By ~ 2

Author(s):

Jaqueline Herrmann ◽

Milen Babic ◽

Markus Tölle ◽

Markus van der Giet ◽

Mirjam Schuchardt

Keyword(s):

Animal Models ◽

Vascular Calcification ◽

Ex Vivo ◽

Systemic Disease ◽

Treatment Options ◽

Aortic Tissue ◽

Cardiovascular Morbidity And Mortality ◽

Culture Models

Calcification of the vessel wall contributes to high cardiovascular morbidity and mortality. Vascular calcification (VC) is a systemic disease with multifaceted contributing and inhibiting factors in an actively regulated process. The exact underlying mechanisms are not fully elucidated and reliable treatment options are lacking. Due to the complex pathophysiology, various research models exist evaluating different aspects of VC. This review aims to give an overview of the cell and animal models used so far to study the molecular processes of VC. Here, in vitro cell culture models of different origins, ex vivo settings using aortic tissue and various in vivo disease-induced animal models are summarized. They reflect different aspects and depict the (patho)physiologic mechanisms within the VC process.

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Evaluating the Effect of a Double-Walled Aortic Stent-Graft Prototype on Pulse Wave Velocity in an In Vitro Flow Loop

2020 Design of Medical Devices Conference ◽

10.1115/dmd2020-9085 ◽

2020 ◽

Author(s):

Shannen B. Kizilski ◽

Filippo Coletti ◽

Rumi Faizer ◽

Victor H. Barocas

Keyword(s):

Pulse Wave Velocity ◽

Wave Velocity ◽

Stent Graft ◽

Pulse Wave ◽

Arterial Compliance ◽

Pressure Sensors ◽

Needle Valve ◽

Flow Loop ◽

Aortic Stent Graft

Abstract The effect of a double-walled stent-graft (DWSG) design on arterial compliance was evaluated using pulse wave velocity (PWV) measurements in an in vitro mock arterial flow loop. The DWSG prototype was compared to a rigid stent-graft and to an unstented aorta model. The time delay between two pressure sensors a fixed distance apart was used to calculate PWV. Latex tubing simulated the compliant aorta, and a needle valve provided downstream resistance. A series of pulse rates and stroke volumes was applied to enable measurements at different mean pressures for the same system. PWV for the rigid stent-graft was higher than in the other two cases across all mean pressures. The DWSG exhibited behavior similar to the unstented model, demonstrating the capability of the DWSG to maintain aortic compliance in patients requiring an aortic stent-graft.

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In Vitro Evaluation of the Effect of Aortic Compliance on Pediatric Intraaortic Balloon Pumping

Journal of the American College of Cardiology ◽

10.1016/s0735-1097(97)84976-5 ◽

1998 ◽

Vol 31 (2) ◽

pp. 291A

Author(s):

L Minich

Keyword(s):

Intraaortic Balloon ◽

Aortic Compliance ◽

In Vitro Evaluation ◽

Intraaortic Balloon Pumping

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Betulinic Acid Protects DOX-Triggered Cardiomyocyte Hypertrophy Response through the GATA-4/Calcineurin/NFAT Pathway

Molecules ◽

10.3390/molecules26010053 ◽

2020 ◽

Vol 26 (1) ◽

pp. 53

Author(s):

Jung Joo Yoon ◽

Chan Ok Son ◽

Hye Yoom Kim ◽

Byung Hyuk Han ◽

Yun Jung Lee ◽

...

Keyword(s):

Heart Failure ◽

Cardiac Hypertrophy ◽

Natriuretic Peptide ◽

Betulinic Acid ◽

Cardiomyocyte Hypertrophy ◽

Ros Generation ◽

H9c2 Cells ◽

Myosin Light Chain 2 ◽

Cardiovascular Morbidity And Mortality

Cardiac hypertrophy is a major risk factor for heart failure and leads to cardiovascular morbidity and mortality. Doxorubicin (DOX) is regarded as one of the most potent anthracycline antibiotic agents; however, its clinical usage has some limitations because it has serious cardiotoxic side effects such as dilated cardiomyopathy and congestive heart failure. Betulinic acid (BA) is a pentacyclic-cyclic lupane-type triterpene that has been reported to have anti-bacterial, anti-inflammatory, anti-vascular neogenesis, and anti-fibrotic effects. However, there is no study about its direct effect on DOX induced cardiac hypertrophy and apoptosis. The present study aims to investigate the effect of BA on DOX-induced cardiomyocyte hypertrophy and apoptosis in vitro in H9c2 cells. The H9c2 cells were stimulated with DOX (1 µM) in the presence or absence of BA (0.1–1 μM) and incubated for 24 h. The results of the present study indicated that DOX induces the increase cell surface area and the upregulation of hypertrophy markers including atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), beta-myosin heavy chain (β-MHC), and Myosin Light Chain-2 (MLC2) in H9c2 cells. However, the pathological hypertrophic responses were downregulated after BA treatment. Moreover, phosphorylation of JNK, ERK, and p38 in DOX treated H9c2 cells was blocked by BA. As a result of measuring the change in ROS generation using DCF-DA, BA significantly inhibited DOX-induced the production of intracellular reactive oxygen species (ROS) when BA was treated at a concentration of over 0.1 µM. DOX-induced activation of GATA-4 and calcineurin/NFAT-3 signaling pathway were remarkably improved by pre-treating of BA to H9c2 cells. In addition, BA treatment significantly reduced DOX-induced cell apoptosis and protein expression levels of Bax and cleaved caspase-3/-9, while the expression of Bcl-2 was increased by BA. Therefore, BA can be a potential treatment for cardiomyocyte hypertrophy and apoptosis that lead to sudden heart failure.

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Modeling Endoleaks and Collateral Reperfusion following Endovascular AAA Exclusion

Journal of Endovascular Therapy ◽

10.1177/152660280301000305 ◽

2003 ◽

Vol 10 (3) ◽

pp. 424-432 ◽

Cited By ~ 10

Author(s):

Chuh K. Chong ◽

Thien V. How ◽

Geoffrey L. Gilling-Smith ◽

Peter L. Harris

Keyword(s):

Stent Graft ◽

Aortic Pressure ◽

Type I ◽

Type Ii ◽

Pump System ◽

Type Ii Endoleak ◽

Type I Endoleak ◽

The Impact ◽

Mean Aortic Pressure

Purpose: To investigate the effect on intrasac pressure of stent-graft deployment within a life-size silicone rubber model of an abdominal aortic aneurysm (AAA) maintained under physiological conditions of pressure and flow. Methods: A commercial bifurcated device with the polyester fabric preclotted with gelatin was deployed in the AAA model. A pump system generated physiological flow. Mean and pulse aortic and intrasac pressures were measured simultaneously using pressure transducers. To simulate a type I endoleak, plastic tubing was placed between the aortic wall and the stent-graft at the proximal anchoring site. Type II endoleak was simulated by means of side branches with set inflow and outflow pressures and perfusion rates. Type IV endoleak was replicated by removal of gelatin from the graft fabric. Results: With no endoleak, the coated graft reduced the mean and pulse sac pressures to negligible values. When a type I endoleak was present, mean sac pressure reached a value similar to mean aortic pressure. When net flow through the sac due to a type II endoleak was present, mean sac pressure was a function of the inlet pressure, while pulse pressure in the sac was dependent on both inlet and outlet pressures. As perfusion rates increased, both mean and pulse sac pressures decreased. When there was no outflow, mean sac pressure was similar to mean aortic pressure. In the presence of both type I and type II endoleaks, mean sac pressure reached mean aortic pressure when the net perfusion rate was low. Conclusions: In vitro studies are useful in gaining an understanding of the impact of different types of endoleaks, in isolation and in combination, on intrasac pressure after aortic stent-graft deployment.

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Micromachined Pressure Sensors on Optical Fiber Tip

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.74.149 ◽

2009 ◽

Vol 74 ◽

pp. 149-152

Author(s):

X.M. Zhang ◽

M. Yu ◽

Silas Nesson ◽

H. Bae ◽

A. Christian ◽

...

Keyword(s):

Optical Fiber ◽

Pressure Sensor ◽

Linear Response ◽

Applied Pressure ◽

Pressure Sensors ◽

Outer Diameter ◽

Sensor Element ◽

Batch Fabrication ◽

In Vitro Measurements

This paper reports the development of a miniature pressure sensor on the optical fiber tip for in vitro measurements of rodent intradiscal pressure. The sensor element is biocompatible and can be fabricated by simple, batch-fabrication methods in a non-cleanroom environment with good device-to-device uniformity. The fabricated sensor element has an outer diameter of only 366 μm, which is small enough to be inserted into the rodent discs without disrupting the structure or altering the intradiscal pressures. In the calibration, the sensor element exhibits a linear response to the applied pressure over the range of 0 - 70 kPa, with a sensitivity of 0.0206 μm/kPa and a resolution of 0.17 kPa.

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In Vitro Evaluation of Facial Pressure and Air Leak with a Newly Designed Cushion for Non-Invasive Ventilation Masks

Healthcare ◽

10.3390/healthcare8040523 ◽

2020 ◽

Vol 8 (4) ◽

pp. 523

Author(s):

Hui-Ling Lin ◽

Yu-Chi Lee ◽

Ssu-Hui Wang ◽

Li-Ying Chiang ◽

Jui-Fang Liu

Keyword(s):

Contact Pressure ◽

Positive Airway Pressure ◽

Pressure Sensors ◽

Air Leakage ◽

Air Leak ◽

Non Invasive ◽

Bilevel Positive Airway Pressure ◽

Non Invasive Ventilation ◽

The Face

Background: The aim of this study was to evaluate the effect of a newly designed foam cushion on the air leakage and pressure when applied to the face. Methods: A teaching manikin connected to a bilevel positive airway pressure ventilator attached to four different brands of oronasal masks (Amara, Mirage, Forma, and Wizard) was used. The foam cushions of 5-mm and 10-mm-thickness were attached to the masks, and each mask was tested without a cushion. Six pressure sensors were placed on the manikin’s face, and data were recorded. Inspiratory volume and air leak flow from the ventilator were observed. Results: Air leakage was influenced by both the mask brand and the presence of a cushion. The presence of a cushion did not affect the Wizard mask in terms of leakage (p = 0.317) or inspiratory volume (p = 0.726). The Wizard and Amara masks generated the lowest contact pressure on the frontal forehead (p < 0.001) compared to the other five points. Conclusions: Utilisation of a cushion reduces air leakage and maintains greater inspiratory volume regardless of its thickness. The contact pressure varies depending on the brand of the mask, which would require a difference in the thickness of the cushion for pressure reduction.

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