Experimental Hemodynamics within the Penn State Fontan Circulatory Assist Device

Abstract For children born with a single functional ventricle, the Fontan operation bypasses the right ventricle by forming a four-way total cavopulmonary connection adapting the existing ventricle for the systemic circulation. However, upon adulthood, many Fontan patients exhibit low cardiac output and elevated venous pressure, eventually requiring a heart transplantation. Despite efforts to develop a Fontan pump or use an existing ventricular assist device for failing Fontan support, there is still no device designed or tested for subpulmonary support. Penn State University is developing a hydrodynamically levitated Fontan circulatory assist device (FCAD) for bridge-to-transplant or destination therapy. The FCAD hemodynamics, at both steady and pulsatile conditions for three pump operating conditions, were quantified using particle image velocimetry to determine the velocity magnitudes and Reynolds normal and shear stresses. Data were acquired at three planes (0 mm and ±25% of the radius) for the inferior and superior vena cavae inlets and the pulmonary artery outlet. The inlets had a blunt velocity profile that became skewed towards the collecting volute as fluid approached the rotor. At the outlet, regardless of the flow condition, a high-velocity jet exited the volute and moved downstream in a helical pattern. Turbulent stresses observed at the volute exit were influenced by the rotor's rotation. Regardless of inlet conditions, the pump demonstrated advantageous behavior for clinical use with a predictable flow field and a low risk of platelet adhesion and hemolysis based on calculated wall shear rates and turbulent stresses, respectively.

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Anaesthesia for Neurosurgery in the Sitting Position: A Practical Approach

Anaesthesia and Intensive Care ◽

10.1177/0310057x0503300307 ◽

2005 ◽

Vol 33 (3) ◽

pp. 323-331 ◽

Cited By ~ 33

Author(s):

C. M. Domaingue

Keyword(s):

Superior Vena ◽

Venous Pressure ◽

Vena Cava ◽

Air Embolism ◽

Transoesophageal Echocardiography ◽

Systemic Circulation ◽

Right Atrial ◽

Sitting Position ◽

Volume Loading ◽

Venous Air Embolism

Neurosurgery in the sitting position offers advantages for certain operations. However, the approach is associated with potential complications, in particular venous air embolism. As the venous pressure at wound level is usually negative, air can be entrained. This air may follow any of four pathways. Most commonly it passes through the right heart into the pulmonary circulation, diffuses through the alveolar-capillary membrane and appears in expelled gas. It may pass through a pulmonary-systemic shunt such as a probe patent foramen ovale (paradoxical air embolism); it may collect at the superior vena cava-right atrial junction. Rarely it may traverse through lung capillaries into the systemic circulation. Many monitors, such as the precordial Doppler, capnography, pulmonary artery catheter, transoesophageal echocardiography are useful for venous air embolism detection, with transoesophageal echocardiography being today's gold standard. Various manoeuvres, including neck compression and volume loading, are also useful in reducing the incidence of venous air embolism. Volume loading, in particular, is very helpful as it reduces the risk of hypotension. Other particular concerns to the anaesthetist are airway management, avoidance of pressure injuries, and the risk of pneumocephalus, oral trauma, and quadriplegia. Newer anaesthetic agents have made the choice of anaesthetic technique easier. An appreciation of the implications of neurosurgery in the sitting position can make the procedure safer.

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A closed-circuit heart-lung preparation.—Effect of alterations in the peripheral resistance and the capacity of the circulation

Proceedings of the Royal Society of London. Series B, Containing Papers of a Biological Character ◽

10.1098/rspb.1926.0015 ◽

1926 ◽

Vol 99 (697) ◽

pp. 306-325 ◽

Cited By ~ 3

Keyword(s):

Vascular System ◽

Superior Vena ◽

Venous Pressure ◽

Peripheral Resistance ◽

Vena Cava ◽

Systemic Circulation ◽

Arterial System ◽

Diastolic Filling ◽

Arterial Blood ◽

Lung Preparation

Investigations of “resistance” and “capacity” effects in relation to the control which they exert upon the vascular system have been carried out by many physiologists, notably by Weber (1), Volkmann (2), Donders (3), de Jager (4), Bayliss and Starling (5), and L. Hill (6, 7). According to Weber, the rise in arterial blood pressure due to arteriole vaso-constriction is caused by an increase in peripheral resistance and by a diminution in the capacity of the circulation. Bayliss and Starling (5) brought forward evidence in favour of this view and pointed out that the venous pressure was in part determined by a balance between these two factors. In opposition to Weber’s view, L. Hill and Barnard (6) hold that capacity changes have no effect on the venous pressure since the vascular system is not filled to distension. In a later paper L. Hill (7) states that reduction in the capacity of the splanchnic area is of importance in so far as it increases the diastolic filling, and so the output of the heart, but that the mean hydrostatic pressure cannot be considered to contribute to this result. The part played by constriction of the veins in altering the venous and arterial pressure is discussed in a paper by Connet (8) in which a full bibliography is given. In a paper published in the ‘ Journal of Physiology ’ (9) I described a modification of Starling’s heart-lung preparation, in which the blood circuit was converted to a closed system, so as to imitate more closely the conditions ruling in the animal body, while maintaining the various factors fully under control of the experimenter. The arrangement is shown in fig. 1. The blood from the aorta flows through a cannula placed in the brachio-cephalic artery (A), the velocity of flow being recorded by a Pitot tube (B) or by a Henderson’s cardiometer. The peripheral resistance is regulated by a compressible fingerstall (D), a second resistance (D') being inserted for studying the effects of shunt circuits. The blood then passes to the venous reservoir (K) which consists of a rubber bag of approximately 250 c.c. capacity. The distal end of the venous reservoir is connected to the superior vena cava. A finger-stall (C) joined by a side tube to the arterial system represents the elasticity of the arterial sytem ; this finger-stall and the venous reservoir K when enclosed in plethysmographs enable the experimeter to study alterations in the volume of the systemic circulation.

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In Vitro Study of Pulmonary Vascular Resistance in Fontan Circulation With Respiration Effects

ASME 2012 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2012-80888 ◽

2012 ◽

Cited By ~ 1

Author(s):

Marija Vukicevic ◽

Timothy A. Conover ◽

Jian Zhou ◽

Tain-Yen Hsia ◽

Richard S. Figliola

Keyword(s):

Pulmonary Vascular Resistance ◽

Vascular Resistance ◽

Heart Defects ◽

Superior Vena ◽

Fontan Procedure ◽

Fontan Operation ◽

Venous Pressure ◽

Pulmonary Arteries ◽

Pulmonary Regurgitation ◽

Vena Cava

The Fontan operation is the final stage of palliative surgery for children born with single ventricle heart defects. The most common configuration is called total cavopulmonary connection (TCPC), wherein the inferior vena cava and superior vena cava are anastomosed directly to the pulmonary arteries; therefore the pulmonary circulation is driven by venous pressure only. The Fontan procedure, although successful in the early postoperative period, with time can decrease in efficiency or even fail within several years after the operation. The reasons of different clinical outcomes for some of the Fontan patients are not clear enough, even though it is commonly accepted that certain factors such as low pulmonary vascular resistance and proper shape and size of the TCPC construction are crucial for the succesful long term outcomes. Accordingly, one of the major problems is the increase in pulmonary vascular resistance due to altered hemodynamics after the surgery, causing venous hypertension and respiratory-dependent pulmonary regurgitation [1]. The main pulmonary arteries may also see increased resistance due to congenital malformations, surgical scarring, or deliberate surgical banding. Thus, the consequence of the increased pulmonary vascular resistance at both proximal and distal locations with respect to the TCPC junction, and its effect on the systemic pressures and flow rates, is the main objective of this study.

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Hot-Film Wall Shear Probe Measurements Inside a Ventricular Assist Device

Journal of Biomechanical Engineering ◽

10.1115/1.3108449 ◽

1988 ◽

Vol 110 (4) ◽

pp. 326-333 ◽

Cited By ~ 16

Author(s):

J. T. Baldwin ◽

J. M. Tarbell ◽

S. Deutsch ◽

D. B. Geselowitz ◽

G. Rosenberg

Keyword(s):

Shear Stress ◽

Wall Shear Stress ◽

Operating Conditions ◽

Plate Motion ◽

Shear Stresses ◽

Assist Device ◽

Ventricular Assist ◽

Standard Orientation ◽

Wall Shear ◽

Hot Film

Wall shear rates at eleven sites within the Penn State Electric Ventricular Assist Device (EVAD) were determined with the pump operating under conditions of 30 and 50 percent systolic duration and a mean flow rate of 5.8 L/min using a flush-mounted hot-film probe. Probe calibrations were performed with the hot-film in two orientations relative to the flow direction: a standard orientation and an orientation in which the hot-film was rotated by 90 deg from the standard orientation. The magnitude and direction of the wall shear stress at each site within the EVAD were estimated from ensemble averaged voltage data recorded for similar standard and rotated film orientations. The results indicate that, during diastole the wall shear stress direction around the pump’s periphery for both operating conditions is predominantly perpendicular to the inflow-outflow plane (in the direction of the pusher plate motion) and reaches a peak value of approximately 350 dynes/cm2. The highest wall shear stresses were found near the prosthetic aortic valve (inside the EVAD) under the 30 percent systolic duration condition and are estimated to be as high as 2700 dynes/cm2. Peak shear stress values of 1400 dynes/cm2 were observed in the vicinity of the prosthetic mitral valve under both operating conditions. The results suggested that the valve regions are substantially more hemolytic than other wall regions of the EVAD; the magnitudes of the wall shear stresses are sensitive to operating conditions; and that wall shear in the direction of pusher plate motion can be significant.

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LDA Measurements of Mean Velocity and Reynolds Stress Fields Within an Artificial Heart Ventricle

Journal of Biomechanical Engineering ◽

10.1115/1.2895719 ◽

1994 ◽

Vol 116 (2) ◽

pp. 190-200 ◽

Cited By ~ 72

Author(s):

J. T. Baldwin ◽

S. Deutsch ◽

D. B. Geselowitz ◽

J. M. Tarbell

Keyword(s):

Artificial Heart ◽

Laser Doppler Anemometry ◽

Operating Conditions ◽

Reynolds Stresses ◽

Assist Device ◽

Mean Velocity ◽

Ventricular Assist ◽

Penn State ◽

Entire Flow ◽

Flow Cycle

Laser Doppler Anemometry measurements of mean (ensemble average) velocities and turbulent (Reynolds) stresses at 140 locations within the left ventricle of the Penn State 70 cc electric artificial heart/ventricular assist device are reported at 8 times during the cardiac cycle. Mean velocity patterns indicate that the surfaces of the blood sac and valve tracts are exposed to significant levels of wall shear stress (good wall washing) during some portion of the flow cycle, and there is no location where the flow is stagnant over the entire flow cycle. This implies that thrombus deposition within the artificial heart should be suppressed. Turbulent stresses in the main pumping chamber and the outflow tracts of the tilting disk valves do not exceed 2000 dynes/cm2. The highest turbulent stresses (20,000 dynes/cm2) and smallest turbulent microscales (6 μm) are found in the regurgitant jets on the minor orifice side of the aortic valve during diastole and the mitral valve during systole. Taken together, the data suggest that improvements in artificial heart fluid mechanics will come through valve design and pump operating conditions, not pumping chamber design.

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Biventricular Assist Device by the Berlin Heart as Bridge to Transplant in a 9-Year-Old Boy with Dilated Cardiomyopathy and Multiorgan Failure

Zeitschrift für Geburtshilfe und Neonatologie ◽

10.1055/s-2006-943311 ◽

2006 ◽

Vol 210 (S 5) ◽

Author(s):

K Seibel ◽

P Berdat ◽

T Riedel ◽

B Wagner

Keyword(s):

Dilated Cardiomyopathy ◽

Multiorgan Failure ◽

Assist Device ◽

Bridge To Transplant ◽

Biventricular Assist Device ◽

Berlin Heart

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Experimental investigation of the influence of the hydraulic performance of an axial blood pump on intraventricular blood flow

The International Journal of Artificial Organs ◽

10.1177/03913988211013046 ◽

2021 ◽

pp. 039139882110130

Author(s):

Guang-Mao Liu ◽

Fu-Qing Jiang ◽

Xiao-Han Yang ◽

Run-Jie Wei ◽

Sheng-Shou Hu

Keyword(s):

Blood Flow ◽

Particle Image ◽

Swirling Flow ◽

Blood Stasis ◽

Systemic Circulation ◽

Operating Conditions ◽

Blood Pump ◽

Image Velocimetry ◽

Ct Data

Blood flow inside the left ventricle (LV) is a concern for blood pump use and contributes to ventricle suction and thromboembolic events. However, few studies have examined blood flow inside the LV after a blood pump was implanted. In this study, in vitro experiments were conducted to emulate the intraventricular blood flow, such as blood flow velocity, the distribution of streamlines, vorticity and the standard deviation of velocity inside the LV during axial blood pump support. A silicone LV reconstructed from computerized tomography (CT) data of a heart failure patient was incorporated into a mock circulatory loop (MCL) to simulate human systemic circulation. Then, the blood flow inside the ventricle was examined by particle image velocimetry (PIV) equipment. The results showed that the operating conditions of the axial blood pump influenced flow patterns within the LV and areas of potential blood stasis, and the intraventricular swirling flow was altered with blood pump support. The presence of vorticity in the LV from the thoracic aorta to the heart apex can provide thorough washing of the LV cavity. The gradually extending stasis region in the central LV with increasing blood pump support is necessary to reduce the thrombosis potential in the LV.

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New role of mechanical assist device as bridge to transplant

Current Opinion in Organ Transplantation ◽

10.1097/mot.0000000000000418 ◽

2017 ◽

Vol 22 (3) ◽

pp. 231-235 ◽

Cited By ~ 2

Author(s):

Ambreen Mohamed ◽

Natasha Mehta ◽

Howard J. Eisen

Keyword(s):

Assist Device ◽

Bridge To Transplant ◽

Mechanical Assist Device ◽

Mechanical Assist

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Improved infrared temperature mapping of elastohydrodynamic contacts

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1243/13506501jet499 ◽

2009 ◽

Vol 223 (8) ◽

pp. 1165-1177 ◽

Cited By ~ 17

Author(s):

T Reddyhoff ◽

H A Spikes ◽

A V Olver

Keyword(s):

Effective Means ◽

Field Measurements ◽

Operating Conditions ◽

Mapping Technique ◽

Shear Stresses ◽

Measured Temperature ◽

Ir Camera ◽

Full Field ◽

Group I ◽

Increased Sensitivity

An effective means of studying lubricant rheology within elastohydrodynamic contacts is by detailed mapping of the temperature of the fluid and the bounding surfaces within the lubricated contact area. In the current work, the experimental approach initially developed by Sanborn and Winer and then by Spikes et al., has been advanced to include a high specification infrared (IR) camera and microscope. Besides the instantaneous capture of full field measurements, this has the advantage of increased sensitivity and higher spatial resolution than previous systems used. The increased sensitivity enables a much larger range of testable operating conditions: namely lower loads, speeds, and reduced sliding. In addition, the range of test lubricants can be extended beyond high shearing traction fluids. These new possibilities have been used to investigate and compare the rheological properties of a range of lubricants: namely a group I and group II mineral oil, a polyalphaolephin (group IV), the traction fluid Santotrac 50, and 5P4E, a five-ring polyphenyl-ether. As expected, contact temperatures increased with lubricant refinement, for the mineral base oils tested. Using moving heat source theory, the measured temperature distributions were converted into maps showing rate of heat input into each surface, from which shear stresses were calculated. The technique could therefore be validated by integrating these shear stress maps, and comparing them with traction values obtained by direct measurement. Generally there was good agreement between the two approaches, with the only significant differences occurring for 5P4E, where the traction that was deduced from the temperature over-predicted the traction by roughly 15 per cent. Of the lubricants tested, Santotrac 50 showed the highest average traction over the contact; however, 5P4E showed the highest maximum traction. This observation is only possible using the IR mapping technique, and is obscured when measuring the traction directly. Both techniques showed the effect of shear heating causing a reduction in traction.

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