The complexities of modern biomedicine are rapidly increasing. Thus, modeling and simulation have become increasingly important as a strategy to understand and predict the trajectory of pathophysiology, disease genesis, and disease spread in support of clinical and policy decisions. In such cases, inappropriate or ill-placed trust in the model and simulation outcomes may result in negative outcomes, and hence illustrate the need to formalize the execution and communication of modeling and simulation practices.
View Article and Find Full Text PDFRecent explorations of knee biomechanics have benefited from computational modeling, specifically leveraging advancements in finite element analysis and rigid body dynamics of joint and tissue mechanics. A large number of models have emerged with different levels of fidelity in anatomical and mechanical representation. Adapted modeling and simulation processes vary widely, based on justifiable choices in relation to anticipated use of the model.
View Article and Find Full Text PDFMedical device manufacturers using computational modeling to support their device designs have traditionally been guided by internally developed modeling best practices. A lack of consensus on the evidentiary bar for model validation has hindered broader acceptance, particularly in regulatory areas. This has motivated the US Food and Drug Administration and the American Society of Mechanical Engineers (ASME), in partnership with medical device companies and software providers, to develop a structured approach for establishing the credibility of computational models for a specific use.
View Article and Find Full Text PDFPhysiological closed-loop controlled medical devices automatically adjust therapy delivered to a patient to adjust a measured physiological variable. In critical care scenarios, these types of devices could automate, for example, fluid resuscitation, drug delivery, mechanical ventilation, and/or anesthesia and sedation. Evidence from simulations using computational models of physiological systems can play a crucial role in the development of physiological closed-loop controlled devices; but the utility of this evidence will depend on the credibility of the computational model used.
View Article and Find Full Text PDFProtecting and promoting public health is the mission of the U.S. Food and Drug Administration (FDA).
View Article and Find Full Text PDFPhysiological closed-loop controlled medical devices are safety-critical systems that combine patient monitors with therapy delivery devices to automatically titrate therapy to meet a patient's current need. Computational models of physiological systems can be used to test these devices and generate pre-clinical evidence of safety and performance before using the devices on patients. The credibility, utility, and acceptability of such model-based test results will depend on, among other factors, the computational model used.
View Article and Find Full Text PDFThe total product life cycle (TPLC) of medical devices has been defined by four stages: discovery and ideation, regulatory decision, product launch, and postmarket monitoring. Manufacturers of medical devices intended for use in the peripheral vasculature, such as stents, inferior vena cava (IVC) filters, and stent-grafts, mainly use computational modeling and simulation (CM&S) to aid device development and design optimization, supplement bench testing for regulatory decisions, and assess postmarket changes or failures. For example, computational solid mechanics and fluid dynamics enable the investigation of design limitations in the ideation stage.
View Article and Find Full Text PDFA "credible" computational fluid dynamics (CFD) model has the potential to provide a meaningful evaluation of safety in medical devices. One major challenge in establishing "model credibility" is to determine the required degree of similarity between the model and experimental results for the model to be considered sufficiently validated. This study proposes a "threshold-based" validation approach that provides a well-defined acceptance criteria, which is a function of how close the simulation and experimental results are to the safety threshold, for establishing the model validity.
View Article and Find Full Text PDFObjective: The purpose of this study was to review the available literature regarding the biomechanics of the superficial femoral artery (SFA) and popliteal artery (PA) in patients with peripheral arterial disease (PAD). Stents are one of many available therapies used to treat patients with PAD. Because stents are permanent implants, they undergo a variety of deformations as patients go about their daily activities such as walking, sitting in a chair, or climbing stairs.
View Article and Find Full Text PDFSimulation-based medicine and the development of complex computer models of biological structures is becoming ubiquitous for advancing biomedical engineering and clinical research. Finite element analysis (FEA) has been widely used in the last few decades to understand and predict biomechanical phenomena. Modeling and simulation approaches in biomechanics are highly interdisciplinary, involving novice and skilled developers in all areas of biomedical engineering and biology.
View Article and Find Full Text PDFObjectives: The purpose of this study was to compare the eligibility of men and women with infrarenal abdominal aortic aneurysms (AAAs) for on-label endovascular aneurysm repair (EVAR) as part of the clinician-Food & Drug Administration (FDA) collaborative effort, the Characterization of Human Aortic Anatomy Project (CHAP).
Methods: Computed tomography (CT) scans with 3D reconstruction from a single institution obtained between July 1996 and December 2009, including standardized measurements by a blinded third-party (M2S, West Lebanon, NH) were examined. For inclusion, abdominal aortic aneurysm (AAA) had to be infrarenal, unrepaired, and >5 cm, or 4 cm to 5 cm if the orthogonal sac diameter was more than twice the aortic diameter at the renal level.
Objective: We developed a novel method using anatomic markers along the thoracic aorta to accurately quantify longitudinal and circumferential cyclic strain in nondiseased thoracic aortas during the cardiac cycle and to compute age-related changes of the human thoracic aorta.
Methods: Changes in thoracic aorta cyclic strains were quantified using cardiac-gated computed tomography image data of 14 patients (aged 35 to 80 years) with no visible aortic pathology (aneurysms or dissection). We measured the diameter and circumferential cyclic strain in the arch and descending thoracic aorta (DTA), the longitudinal cyclic strain along the DTA, and changes in arch length and motion of the ascending aorta relative to the DTA.