An extended pulse wave propagation model to predict (patho-)physiological coronary pressure and flow patterns

A patient-specific model describing the primary relations between the cardiac muscle contraction and coronary circulation might be useful for interpreting coronary hemodynamics and deciding on medical treatment in case multiple types of coronary circulatory disease are present. For this purpose we present the use of a microstructure-based heart contraction model and a micro-structure based fiber reinforced arterial wall model as the basis of a 1D wave propagation model to describe coronary pressure and flow waves. We conclude that this extended pulse wave propagation model adequately can predict coronary hemodynamics in both normal and diseased state based on patient-specific clinical data

A 1D wave propagation model of coronary flow in a beating heart

Due to recent developments in miniaturized sensors on guide-wires, assessment of coronary artery disease with intracoronary pressure and flow measurements has become available. However, direct quantification is still limited to the large epicardial vessels, which means that microvascular disease can only be determined from upstream measurements using an appropriate model of the vessels and their interaction with the cardiac muscle

A Novel Flexible Thermoelectric Sensor for Intravascular Flow Assessment

To accurately assess the severity of coronary artery disease, intracoronary pressure and flow measurements are required. In this paper, a novel flexible flow sensor, intended to be mounted on a medical guidewire, is tested experimentally. The device consists of a heating element and two thermopiles embedded in polyimide to measure flow-dependent heat transfer. The main aim of this paper is to determine whether constant temperature (CT) operation of the heater is feasible and is an improvement of the sensor response in unsteady flow compared with constant power (CP) operation. Thus, the flexible devices are glued to a surface and subjected to steady and unsteady water flows. From the relation between the sensor output and the applied shear rate it is shown that CT operation is superior over CP operation. Subsequently, a quasi-steady relation is identified and tested for coronary shear rate dynamics and found to be very accurate when the heater is operated at a CT difference of only 5 K, with an average error of 5%

Mechanical properties of the porcine coronary artery

Knowledge of the mechanical properties of arteries is important to understand vascular function during disease and the effect of interventions, such as PTCA treatment. A mechanical model of the vascular tree would facilitate the improvement of (balloon-)catheters and stents. The aim of this research is to propose general parameter values for the fiber-reinforced material model as proposed by Driessen et al. (2005) that can describe the arterial wall behavior of the porcine left anterior descending coronary artery (LAD, fig. 1a) at physiological axial stretch

A 1D wave propagation model of coronary flow in a beating heart

Due to recent developments in miniaturized sensors on guide-wires, assessment of coronary artery disease with intracoronary pressure and flow measurements has become available. However, direct quantification is still limited to the large epicardial vessels, which means that microvascular disease can only be determined from upstream measurements using an appropriate model of the vessels and their interaction with the cardiac muscle

Mechanical properties of the porcine coronary artery

Knowledge of the mechanical properties of arteries is important to understand vascular function during disease and the effect of interventions, such as PTCA treatment. A mechanical model of the vascular tree would facilitate the improvement of (balloon-)catheters and stents. The aim of this research is to propose general parameter values for the fiber-reinforced material model as proposed by Driessen et al. (2005) that can describe the arterial wall behavior of the porcine left anterior descending coronary artery (LAD, fig. 1a) at physiological axial stretch

A generic constitutive model for the passive porcine coronary artery

Constitutive models describing the arterial mechanical behavior are important in the development of catheterization products, to be used in arteries with a specific radius. To prove the possible existence of a constitutive model that, provided with a generic set of material and geometric parameters, is able to predict the radius-specific mechanical behavior of a coronary artery, the passive pressure–inner radius (P–r i ) and pressure–axial force change (P–¿F z ) relations of seven porcine left anterior descending coronary arteries were measured in an in-vitro set-up and fitted with the model of Driessen et al. in J Biomech Eng 127(3):494–503 (2005), Biomech Model Mechanobiol 7(2):93–103 (2008). Additionally, the collagen volume fraction, physiological axial pre-stretch, and wall thickness to inner radius ratio at physiological loading were determined for each artery. From this, two generic parameter sets, each comprising four material and three geometric parameters, were obtained. These generic sets were used to compute the deformation of each tested artery using a single radius measurement at physiological loading as an artery-specific input. Artery-specific P–r i and P–¿F z relations were predicted with an accuracy of 32 µm (2.3%) and 6 mN (29% relative to ¿F z -range) on average compared to the relations measured in-vitro. It was concluded that the constitutive model provided with the generic parameters found in this study can well predict artery-specific mechanical behavior

Thermal flow sensors on flexible substrates for minimally invasive medical instruments

\u3cp\u3eWe present a flexible polyimide-based calorimetric thermal flow sensor featuring two thermopiles and a heating element perpendicular to the flow direction, connected to a rigid silicon chip containing the bondpads for standard wire bonding. After measurement of the temperature coefficient of resistance of the heater (TCR) and the Seebeck coefficient of the thermopiles of the sensor, the devices are mounted on a printed circuit board (PCB) flow channel and tested in constant power (CP) mode under both steady and dynamic flow conditions. The obtained results are in good agreement with previous research on similar, less flexible, flow sensors. The presented device can then potentially be wrapped around catheters or guidewires for intravascular blood flow assessment. \u3c/p\u3