A review of magnet systems for targeted drug delivery.

Computational modeling of cardiac hemodynamics

https://www.magneticmicrosphere.com/ckfinder/userfiles/files/Riegler_leg_artery_targeting_stem_cells_2013.pdf

Superparamagnetic Iron Oxide Nanoparticle Targeting of MSCs in Vascular Injury

Toward patient-specific simulations of cardiac valves: state-of-the-art and future directions.

As the pulsatile cardiac blood flow drives the heart valve leaflets to open and close, the flow in the vicinity of the valve resembles a pulsed jet through a nonaxisymmetric orifice with a dynamically changing area. As a result, three-dimensional vortex rings with intricate topology emerge that interact with the complex cardiac anatomy and give rise to shear layers, regions of recirculation, and flow instabilities that could ultimately lead to transition to turbulence. Such complex flow patterns, which are inherently valve- and patient-specific, lead to mechanical forces at scales that can cause blood cell damage and thrombosis, increasing the likelihood of stroke, and can trigger the pathogenesis of various life-threatening valvular heart diseases. We summarize the current understanding of flow phenomena induced by heart valves, discuss their linkage with disease pathways, and emphasize the research advances required to translate in-depth understanding of valvular hemodynamics into effective patient ther...

Fluid Mechanics of Heart Valves and Their Replacements

Mitral valve dynamics in structural and fluid-structure interaction models.

This work presents a mathematical model of the metabolic feedback and adrenergic feedforward control of coronary blood flow that occur during variations in the cardiac workload. It is based on the physiological observations that coronary blood flow closely follows myocardial oxygen demand, that myocardial oxygen debts are repaid, and that control oscillations occur when the system is perturbed and so are phenomenological in nature. Using clinical data, we demonstrate that the model can provide patient-specific estimates of coronary blood flow changes between rest and exercise, requiring only the patient's heart rate and peak aortic pressure as input. The model can be used in zero-dimensional lumped parameter network studies or as a boundary condition for three-dimensional multidomain Navier-Stokes blood flow simulations. For the first time, this model provides feedback control of the coronary vascular resistance, which can be used to enhance the physiological accuracy of any hemodynamic simulation, which includes both a heart model and coronary arteries. This has particular relevance to patient-specific simulation for which heart rate and aortic pressure recordings are available. In addition to providing a simulation tool, under our assumptions, the derivation of our model shows that β-feedforward control of the coronary microvascular resistance is a mathematical necessity and that the metabolic feedback control must be dependent on two error signals: the historical myocardial oxygen debt, and the instantaneous myocardial oxygen deficit.

https://www.physiology.org/doi/pdf/10.1152/ajpheart.00517.2015

A Mathematical Model of Coronary Blood Flow Control: Simulation of Patient-Specific Three-Dimensional Hemodynamics during Exercise

Computational fluid dynamics (CFD) is a modeling technique that enables calculation of the behavior of fluid flows in complex geometries. In cardiovascular medicine, CFD methods are being used to calculate patient-specific hemodynamics for a variety of applications, such as disease research, noninvasive diagnostics, medical device evaluation, and surgical planning. This paper provides a concise overview of the methods to perform patient-specific computational analyses using clinical data, followed by a case study where CFD-supported surgical planning is presented in a patient with Fontan circulation complicated by unilateral pulmonary arteriovenous malformations. In closing, the challenges for implementation and adoption of CFD modeling in clinical practice are discussed.

Patient-Specific Modeling of Hemodynamics: Supporting Surgical Planning in a Fontan Circulation Correction

Fluid-structure interaction study of the edge-to-edge repair technique on the mitral valve.

Short-term fluctuations in arterial pressures arising from normal physiological function are buffered by a negative feedback system known as the arterial baroreflex. Initiated by altered biomechanical stretch in the vessel wall, the baroreflex coordinates a systemic response that alters heart rate, cardiac contractility and peripheral vessel vasoconstriction. In this work, a coupled 3D–0D formulation for the short-term pressure regulation of the systemic circulation is presented. Including the baroreflex feedback mechanisms, a patient-specific model of the large arteries is subjected to a simulated head up tilt test. Comparative simulations with and without baroreflex control highlight the critical role that the baroreflex has in regulating variations in pressures within the systemic circulation.

/pdf/simulation-of-short-term-pressure-regulation-during-the-tilt-4e76kninvz.pdf

KD Lau

Papers

Mitral valve dynamics in structural and fluid-structure interaction models.

A Mathematical Model of Coronary Blood Flow Control: Simulation of Patient-Specific Three-Dimensional Hemodynamics during Exercise

Patient-Specific Modeling of Hemodynamics: Supporting Surgical Planning in a Fontan Circulation Correction

Fluid-structure interaction study of the edge-to-edge repair technique on the mitral valve.

Simulation of short-term pressure regulation during the tilt test in a coupled 3D–0D closed-loop model of the circulation