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Sensor-Enabled 3D Printed Tissue-Mimicking Phantoms: Application in Pre-Procedural Planning for Transcatheter Aortic Valve Replacement
Published in Ayman El-Baz, Jasjit S. Suri, Cardiovascular Imaging and Image Analysis, 2018
Kan Wang, Chuck Zhang, Ben Wang, Mani A Vannan, Zhen Qian
The aortic valve is a heart valve situated between the left ventricle (LV) of the heart and the aorta. It functions like a one-way flow controller that allows blood from the LV to be pumped into the aorta but prevents the backflow of the blood. Aortic stenosis (AS), which is a narrowing of the aortic valve opening, is the most common valvular heart disease in developed countries [1]. Advanced age is a major risk factor of the development of AS. Some congenital heart defects, such as a bicuspid aortic valve, can also cause AS. The progression of AS involves a series of deteriorations of the cardiac function, including an elevated LV systolic pressure, LV concentric hypertrophy, an elevated LV diastolic pressure, and a decreased cardiac output. If untreated, AS patients ultimately develop heart failure.
Aortic Valve Mechanics
Published in Michel R. Labrosse, Cardiovascular Mechanics, 2018
J. Dallard, M. Boodhwani, M. R. Labrosse
Aortic stenosis (AS) refers to the narrowing of the AV opening during systole (Nishimura, 2002), producing an obstruction of the left ventricular outflow (Ketelsen et al., 2010). It can be caused by a congenital abnormality of the valve or by progressive calcification (Nishimura, 2002; ACC/AHA, 2006). The decrease in the GOA of the AV induces an overload for the left ventricle. Aortic stenosis is associated with elevated pressures in the left ventricle during systole, as the left ventricle attempts to produce the same cardiac output, despite the reduced GOA. This results in a hypertrophic process, whereby the left ventricular wall thickens (for more muscle), while the left ventricular volume is maintained.
Image decomposition-based sparse extreme pixel-level feature detection model with application to medical images
Published in IISE Transactions on Healthcare Systems Engineering, 2021
Geet Lahoti, Jialei Chen, Xiaowei Yue, Hao Yan, Chitta Ranjan, Zhen Qian, Chuck Zhang, Ben Wang
In medicine, image segmentation or feature detection is of particular importance (Bradshaw et al., 2013; Gaw et al., 2018; Wang, 2015). Consider aortic stenosis (AS), which is one of the most common yet severe valvular heart diseases. Transcatheter aortic valve replacement (TAVR) is a less-invasive treatment option for AS patients who have a high risk of open-heart surgery. TAVR procedure involves implanting a bioprosthetic aortic valve. Major post-procedural complications of TAVR are the paravalvular leakage (PVL), i.e. the blood flow leakage around the implanted artificial valve (Qian et al., 2017; Wang et al., 2018), and the over-stretching in the aortic tissues introduced due to the implant. For patients undergoing TAVR, computed tomography (CT) image (see Figure 1) is usually taken before the surgery, as an important visualization of the contrast-enhanced blood pool (i.e. the moderate intensity region in the CT image), the calcification (i.e. the high-intensity region), and the soft tissues (i.e. the low-intensity region).
The impact of calcification patterns in transcatheter aortic valve performance: a fluid-structure interaction analysis
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
Giulia Luraghi, Jose Felix Rodriguez Matas, Marta Beretta, Nicole Chiozzi, Laura Iannetti, Francesco Migliavacca
Aortic stenosis (AS) is the most common valvular disease, whose prevalence increases with age (Baumgartner et al. 2009). It is characterized by a reduction of the effective aortic valve area due to the presence of calcium deposits. This pathology is classified according to the measured aortic valve area in mild, moderate, and severe by means of Transthoracic Doppler echocardiography analysis (Kappetein et al. 2012). For severe AS, the disease entails morbidity and mortality. The initiating event of AS has been associated with endothelial damage of the leaflets, especially of the non-coronary leaflet (Dweck et al. 2012). The following inflammation event leads to the development of fibrous tissue and to the leaflet stiffening. The calcification onset is the key feature of this pathology and it can be detectable by noninvasive imaging techniques (Pawade et al. 2015).
In silico modelling of aortic valve implants – predicting in vitro performance using finite element analysis
Published in Journal of Medical Engineering & Technology, 2022
Robert Whiting, Elizabeth Sander, Claire Conway, Ted J. Vaughan
Aortic stenosis is a valvular heart disease, whereby calcification build-up on the native valve leaflets leads to restricted blood flow and increased left ventricular hypertrophy [1]. Severe aortic stenosis is treated with either surgical or transcatheter aortic valve replacement (TAVR), with over 300,000 valve replacements performed in the developed world each year [2]. This number is expected to increase in the coming years with ageing demographics [3]. Bioprosthetic heart valves (BHV) are now widely used and consist of either bovine or porcine tissue leaflets mounted on a metallic stent frame, with the distinct advantage that they can be delivered minimally invasively. While these devices have demonstrated good clinical outcomes [4], there is significant room for further design improvements to enhance structural durability and long-term hemodynamic performance. This is a problem particularly in younger patients where the onset of structural valve degeneration can occur 10 to 15 years post implantation, requiring reoperation [5–8]. Recently, there has been increasing interest in developing synthetic polymer leaflets as an alternative to bioprosthetic tissue leaflets in TAVR devices. While these polymeric valve devices are at an earlier stage of development, they have the potential to provide superior patient outcomes, as well as vastly improved efficiency in the manufacturability and reproducibility of TAVR devices [9,10]. In developing the next generation of aortic valve replacements, there are significant challenges that must be overcome to achieve suitable designs capable of withstanding the demanding functional requirements at the native aortic root. This applies to both bioprosthetic and synthetic leaflet-based aortic valve replacements (both surgical and TAVR), which must undergo stringent functional mechanical testing during the certification process.