Prahlad Menon | University of Pittsburgh (original) (raw)

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Papers by Prahlad Menon

ASME 2013 Conference on Frontiers in Medical Devices: Applications of Computer Modeling and Simulation, 2013

ABSTRACT Left ventricular assist devices (LVADs) are mechanical pumps that provide full or partia... more ABSTRACT Left ventricular assist devices (LVADs) are mechanical pumps that provide full or partial support of the circulation in patients with varying degrees of heart failure (HF). This simulation study explores the hemodynamic effects of a continuous flow pump deployed in the Ascending Aorta (AAo) specifically focusing on: (a) perfusion of the coronary arterial circulation and (b) the effect of induced non-physiologic, swirling flow discharged by the pump on perfusion to head-neck vessels of the aortic arch.

Journal of Cardiovascular Magnetic Resonance, 2014

The clinical assessment of abdominal aortic aneurysm (AAA) rupture risk is largely limited to qua... more The clinical assessment of abdominal aortic aneurysm (AAA) rupture risk is largely limited to quantification of maximum diameter over time to monitor growth. Recent studies have extended this paradigm to modeling biomechanical loading and wall stresses using computational hemodynamics or solid mechanics simulations, in efforts to reliably numerically predict aneurysm-specific wall motion. However, the numerical simulation of aneurysm wall motion is time and resource intensive, and inherently involves complex mathematical modeling of often unrealistic wall properties. In this study, we characterize AAA wall motion using shape-analysis to quantify detailed regional function by direct processing of 4D (3D + time) cine CMR data.

Journal of Biomechanics, 2013

During pediatric and neonatal cardiopulmonary bypass (CPB), tiny aortic outflow cannulae (2-3 mm ... more During pediatric and neonatal cardiopulmonary bypass (CPB), tiny aortic outflow cannulae (2-3 mm inner diameter), with micro-scale blood-wetting features transport relatively large blood volumes (0.3 to 1.0 L/min) resulting in high blood flow velocities (2 to 5 m/s). These severe flow conditions are likely to complement platelet activation, release pro-inflammatory cytokines, and further result in vascular and blood damage. Hemodynamically efficient aortic outflow cannulae are required to provide high blood volume flow rates at low exit force. In addition, optimal aortic insertion strategies are necessary in order to alleviate hemolytic risk, post-surgical neurological complications and developmental defects, by improving cerebral perfusion in the young patient. The methodology and results presented in this study serve as a baseline for design of superior aortic outflow cannulae. In this study, direct numerical simulation (DNS) computational fluid dynamics (CFD) was employed to delineate baseline hemodynamic performance of jet wakes emanating from microCT scanned state-of-the-art pediatric cannula tips in a cuboidal test rig operating at physiologically relevant laminar and turbulent Reynolds numbers (Re: 650-2150 , steady inflow). Qualitative and quantitative validation of CFD simulated device-specific jet wakes was established using time-resolved flow visualization and particle image velocimetry (PIV). For the standard end-hole cannula tip design, blood damage indices were further numerically assessed in a subject-specific cross-clamped neonatal aorta model for different cannula insertion configurations. Based on these results, a novel diffuser type cannula tip is proposed for improved jet flow-control, decreased blood damage and exit force and increased permissible flow rates. This study also suggests that surgically relevant cannula orientation parameters such as outflow angle and insertion depth may be important for improved hemodynamic performance. The jet flow design paradigm demonstrated in this study represents a philosophical shift towards cannula flow control enabling favorable pressure-drop versus outflow rate characteristics.

Journal of Biomechanical Engineering, 2014

The pathology of the human abdominal aortic aneurysm (AAA) and its relationship to the later comp... more The pathology of the human abdominal aortic aneurysm (AAA) and its relationship to the later complication of intraluminal thrombus (ILT) formation remains unclear. The hemodynamics in the diseased abdominal aorta are hypothesized to be a key contributor to the formation and growth of ILT. The objective of this investigation is to establish a reliable 3D flow visualization method with corresponding validation tests with high confidence in order to provide insight into the basic hemodynamic features for a better understanding of hemodynamics in AAA pathology and seek potential treatment for AAA diseases. A stereoscopic particle image velocity (PIV) experiment was conducted using transparent patient-specific experimental AAA models (with and without ILT) at three axial planes. Results show that before ILT formation, a 3D vortex was generated in the AAA phantom. This geometry-related vortex was not observed after the formation of ILT, indicating its possible role in the subsequent appea...