Computer simulations of blood flow through mechanical heart valves could pave the way for more individualized prosthetic
Four types of heart valves in open (left) and shut (right) positions. Diseased valves can be replaced with prosthetic ones but they can lead to complications. Credit: MedicalRF.com/Corbis
Every year, over 300,000 heart valve replacement operations are performed worldwide. Diseased valves are often replaced with mechanical heart valves (MHVs), which cannot yet be designed to suit each patient's specific needs. Complications such as blood clots can occur, which can require patients to take blood-thinning medication.
To investigate why such complications occur, Vinh-Tan Nguyen at A*STAR's Institute of High Performance Computing, Singapore, together with scientists at the National University of Singapore and institutions across the USA, have developed a new computer model to simulate the dynamics of blood flow through MHVs.
"The current practice for heart valve replacement in patients is a one-size-fits-all approach where a patient is implanted with the best-fit valve available on the market," explains Nguyen. "The valves are well designed for general physiological conditions, but may not be suitable for each individual's particular heart condition."
The researchers focused on the blood flow dynamics in a prosthetic valve known as a bileaflet MHV. This type of MHV contains two mobile leaflets, or gates, which are held in place by hinges. The leaflets open and close in response to blood flow pressures through the valve. Little is known about the effect that the hinged leaflets have on blood dynamics, although such designs are suspected of causing blood clots.
The computer model developed by Nguyen and his team simulates pressure flows through bileaflet MHVs by representing blood vessels as a computational mesh, where calculations are performed for individual blocks of the mesh. Their crucial advance was in enabling this mesh to move and evolve in response to the leaflet movements.
The researchers validated their computer model through laboratory experiments with a full 3D reproduction of the heart's circulation system. Particle imaging equipment allowed them to visualize the fluid dynamics under different scenarios including pulsatile flow, which follows the pattern of a typical cardiac cycle.
"We obtained good agreement between our computer simulations and the experiments in terms of the magnitude and velocity of blood flow through the leaflets," states Nguyen. The researchers also found that leaflet hinges might play a vital role in clotting, because individual hinges have different tolerances that can disrupt normal blood flow and cause stress in the vein walls.
This research is a first crucial step in understanding the impact of MHVs on blood flow. "Ultimately we hope to provide doctors with a tool to evaluate blood flow dynamics and other related aspects in patients with newly implanted valves," says Nguyen.
More information: Nguyen, V.-T., Kuan, Y. H., Chen, P.-Y., Ge, L., Sotiropoulos, F. et al. Experimentally validated hemodynamics simulations of mechanical heart valves in three dimensions. Cardiovascular Engineering and Technology 3, 88–100 (2012). rd.springer.com/ar… 9-011-0077-z
- New design for mechanical heart valves Nov 22, 2011 | not rated yet | 0
- Heart valves implanted without open-heart surgery Jan 07, 2009 | not rated yet | 0
- Prosthetic vein valve designed to direct blood flow shows promising pre-clinical results Sep 15, 2008 | not rated yet | 0
- Heart valve replacement without opening the chest gives new option for non-operable patients Jun 24, 2011 | not rated yet | 0
- 4 out of 106 heart replacement valves from pig hearts failed Jun 29, 2009 | not rated yet | 0
- Motion perception revisited: High Phi effect challenges established motion perception assumptions Apr 23, 2013 | 3 / 5 (2) | 2
- Anything you can do I can do better: Neuromolecular foundations of the superiority illusion (Update) Apr 02, 2013 | 4.5 / 5 (11) | 5
- The visual system as economist: Neural resource allocation in visual adaptation Mar 30, 2013 | 5 / 5 (2) | 9
- Separate lives: Neuronal and organismal lifespans decoupled Mar 27, 2013 | 4.9 / 5 (8) | 0
- Sizing things up: The evolutionary neurobiology of scale invariance Feb 28, 2013 | 4.8 / 5 (10) | 14
gravity is std. therefore can we rate a 'mass at height' by watts?
2 hours ago For example.... wind turbines are primarily listed by their wattage (1.5MW etc.) Presumably their output is varied according to rotational speed, so...
Calculating on-axis elements of a solenoid
14 hours ago I wanted to mention that this solenoid has many winds over many layers. The thickness of the windings is 2.4 inches coming off of the engineering...
latitude & longitude & air pressure
15 hours ago Hi there, I have a peculiar question. Imagine that you are in a earth position, obtained by google, that gives you the latitude and longitude....
Differences of Classical Mechanics when learned with Calc vs algebra?
18 hours ago what are the differences? Every example I find usually has a derivative or integral or some kind of calculus defined concept that seems to make it...
what is the distance traveled
22 hours ago A rough sketch of experiment. Image: http://i43.tinypic.com/14t4sk5.png the red dots represent a side view of path traveled, F is downward force...
Image of a Convex Lens Cut in Half Horizontally
May 22, 2013 Hello everyone, A friend of mine came up with this question in class and I really do not have a good answer. Suppose you have a convex lens...
- More from Physics Forums - Classical Physics
More news stories
22 May 2013, Paris, France: The Lotus Valve, a second-generation transcatheter aortic valve implantation (TAVI) device, was successfully implanted in all of the first 60 patients in results from REPRISE II reported at EuroPCR ...
Cardiology 42 minutes ago | not rated yet | 0
Costs to treat stroke are projected to more than double and the number of people having strokes may increase 20 percent by 2030, according to the American Heart Association/American Stroke Association.
Cardiology 23 hours ago | not rated yet | 0
Blood thinners are the preferred treatment option to prevent heart attacks, blood clots and stroke, but they are not without risk, and not just because of their side effects. These high-risk drugs, known as anticoagulants, ...
Cardiology May 22, 2013 | not rated yet | 0
Results from a large observational study reported at EuroPCR 2013 today question whether bivalirudin is superior to heparin in the absence of GPIIb/IIIa blockade, showing similar 30-day mortality in patients with non-ST segment ...
Cardiology May 22, 2013 | 5 / 5 (1) | 0
The DESolve bioresorbable coronary scaffold system achieves good efficacy and safety with low rates of late lumen loss and major coronary adverse events at six months, show first results from the pivotal DESolve Nx trial ...
Cardiology May 22, 2013 | not rated yet | 0
A known difficulty in fighting influenza (flu) is the ability of the flu viruses to mutate and thus evade various medications that were previously found to be effective. Researchers at the Hebrew University of Jerusalem have ...
40 minutes ago | not rated yet | 0 |
Nervous about that upcoming job interview? You might want to take steps to reduce your jitters, especially if you are a man.
26 minutes ago | not rated yet | 0
Researchers at Lund University have succeeded in preventing very early symptoms of Huntington's disease, depression and anxiety, by deactivating the mutated huntingtin protein in the brains of mice.
14 minutes ago | not rated yet | 0
Frequent heartburn was positively associated with cancers of the throat and vocal cord among nonsmokers and nondrinkers, and the use of antacids, but not prescription medications, had a protective effect, according to data ...
13 minutes ago | not rated yet | 0
A potentially ground-breaking human drug trial is currently underway, which aims to discover whether blood pressure medication can slow or halt the progression of Alzheimer's Disease (AD). This is the latest ...
50 minutes ago | not rated yet | 0