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Review of numerical methods for simulation of mechanical heart valves and the potential for blood clotting

Zakaria MS, Ismail F, Tamagawa M, Aziz AFA, Wiriadidjaja S, Basri AA, et al.

Med Biol Eng Comput, 2017 Sep;55(9):1519-1548.
PMID: 28744828 DOI: 10.1007/s11517-017-1688-9

Even though the mechanical heart valve (MHV) has been used routinely in clinical practice for over 60 years, the occurrence of serious complications such as blood clotting remains to be elucidated. This paper reviews the progress that has been made over the years in terms of numerical simulation method and the contribution of abnormal flow toward blood clotting from MHVs in the aortic position. It is believed that this review would likely be of interest to some readers in various disciplines, such as engineers, scientists, mathematicians and surgeons, to understand the phenomenon of blood clotting in MHVs through computational fluid dynamics.

Matched MeSH terms: Heart Valves/physiology*
Fulltext Gross age-related changes and diseases in human heart valves

Gumpangseth T, Mahakkanukrauh P, Das S

Anat Cell Biol, 2019 Mar;52(1):25-33.
PMID: 30984448 DOI: 10.5115/acb.2019.52.1.25

Cardiac valves are highly complex structures optimizing their function during the cardiac cycle. They open and close directed by blood flow under different pressure conditions in the dynamic environment in the heart. It is acknowledged that the aging process affects the structure and functions of the heart valves. With regard to morphometry, age-related changes of the heart valve can be found in valve circumference, thickness of the leaflet, luminal area at the sinotubular junction, valve diameter, orifice area, and leaflet size in circumferential and radial direction. In addition, there are differences between male and female hearts in some features. Moreover, there are studies the qualitative and quantitative assessment of histological compositions, echocardiography study to investigate the annular circumference and diameter in the human heart valves related with age. Studies into the detailed anatomy of the changes in heart valves with age are important and the correlation between valve morphology and age may be used as an age indicator. This study reviews the basic anatomical structure of the heart valves, age-related changes of valve morphometry, heart valve diseases, and general treatment of valvular diseases in humans. Detailed knowledge of the anatomical features of the morphology of the human heart valve is useful for any treatments of valve pathology.

Matched MeSH terms: Heart Valves
Fulltext Safety of Vitamin K in mechanical heart valve patients with supratherapeutic INR: A systematic review and meta-analysis

Sapapsap B, Srisawat C, Suthumpoung P, Luengrungkiat O, Leelakanok N, Saokaew S, et al.

Medicine (Baltimore), 2022 Sep 09;101(36):e30388.
PMID: 36086772 DOI: 10.1097/MD.0000000000030388

BACKGROUND: Patients who had mechanical heart valves and an international normalized ratio (INR) of >5.0 should be managed by temporary cessation of vitamin K antagonist. This study aimed to investigate the safety of low-dose vitamin K1 in patients with mechanical heart valves who have supratherapeutic INR.
METHODS: CINAHL, Cochran Library, Clinical trial.gov, OpenGrey, PubMed, ScienceDirect, and Scopus were systematically searched from the inception up to October 2021 without language restriction. Studies comparing the safety of low-dose vitamin K1 treatment in patients with placebo or other anticoagulant reversal agents were included. We used a random-effect model for the meta-analysis. Publication bias was determined by a funnel plot with subsequent Begg's test and Egger's test.
RESULTS: From 7529 retrieved studies, 3 randomized control trials were included in the meta-analysis. Pooled data demonstrated that low-dose vitamin K was not associated with thromboembolism rate (risk ratio [RR] = 0.94; 95% CI: 0.19-4.55) major bleeding rate (RR = 0.58; 95% CI: 0.07-4.82), and minor bleeding rate (RR = 0.60; 95% CI: 0.07-5.09). Subgroup and sensitivity analysis demonstrated the nonsignificant effect of low-dose vitamin K on the risk of thromboembolism. Publication bias was not apparent, according to Begg's test and Egger's test (P = .090 and 0.134, respectively).
CONCLUSION: The current evidence does not support the role of low-dose vitamin K as a trigger of thromboembolism in supratherapeutic INR patients with mechanical heart valves. Nevertheless, more well-designed studies with larger sample sizes are required to justify this research question.

Matched MeSH terms: Heart Valves
Optimization and development of Maghemite (γ-Fe2O3) filled poly-l-lactic acid (PLLA)/thermoplastic polyurethane (TPU) electrospun nanofibers using Taguchi orthogonal array for tissue engineering heart valve

Fallahiarezoudar E, Ahmadipourroudposht M, Idris A, Yusof NM

Mater Sci Eng C Mater Biol Appl, 2017 Jul 01;76:616-627.
PMID: 28482571 DOI: 10.1016/j.msec.2017.03.120

Tissue engineering (TE) is an advanced principle to develop a neotissue that can resemble the original tissue characteristics with the capacity to grow, to repair and to remodel in vivo. This research proposed the optimization and development of nanofiber based scaffold using the new mixture of maghemite (γ-Fe2O3) filled poly-l-lactic acid (PLLA)/thermoplastic polyurethane (TPU) for tissue engineering heart valve (TEHV). The chemical, structural, biological and mechanical properties of nanofiber based scaffold were characterized in terms of morphology, porosity, biocompatibility and mechanical behaviour. Two-level Taguchi experimental design (L8) was performed to optimize the electrospun mats in terms of elastic modulus using uniaxial tensile test where the studied parameters were flow rate, voltage, percentage of maghemite nanoparticles in the content, solution concentration and collector rotating speed. Each run was extended with an outer array to consider the noise factors. The signal-to-noise ratio analysis indicated the contribution percent as follow; Solution concentration>voltage>maghemite %>rotating speed>flow rate. The optimum elastic modulus founded to be 28.13±0.37MPa in such a way that the tensile strain was 31.72% which provided desirability for TEHV. An empirical model was extracted and verified using confirmation test. Furthermore, an ultrafine quality of electrospun nanofibers with 80.32% porosity was fabricated. The MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and cell attachment using human aortic smooth muscle cells exhibited desirable migration and proliferation over the electrospun mats. The interaction between blood content and the electrospun mats indicated a mutual adaption in terms of clotting time and hemolysis percent. Overall, the fabricated scaffold has the potential to provide the required properties of aortic heart valve.

Matched MeSH terms: Heart Valves
Dystrophic amyloidosis: a local complication of tissue damage with heterogeneous distribution

Looi LM

Histopathology, 1991 Aug;19(2):169-72.
PMID: 1757071

Seventeen consecutive patients with dystrophic amyloidosis are reported here (eight Chinese, three Indian, three Iban, two Malay and one Caucasian). Ten were females and seven males, with ages ranging from 12 to 80 years (mean of 48 years). Five instances of dystrophic amyloidosis occurred in areas of tissue damage in the cardiovascular system, including fibrotic cardiac valves and an atheromatous plaque. Three occurred in osteoarthritic joint tissue. Of note were three occurrences in endometriotic cyst walls, four in the fibrotic walls of epidermal cysts, one in a hernial sac and one at the edge of a skin ulcer. All deposits were congophilic and exhibited green-birefringence and permanganate-resistance. Immunohistochemistry did not reveal reactivity for AA protein or immunoglobulin lambda or kappa light-chains. AP protein was detected in 35% of cases. Our results show that, besides the usual sites of osteoarthritic joints and damaged heart valves, dystrophic amyloidosis can complicate other areas of chronic tissue damage and fibrosis such as walls of cysts and ulcers. While the pathogenesis and biochemical nature remain unresolved, immunohistochemistry indicates that neither AA nor AL proteins are present in the deposits, and suggests that a different amyloid protein is involved.

Matched MeSH terms: Heart Valves/pathology
Fulltext Pregnancy outcomes compared in women with mechanical heart valve replacements anticoagulated with warfarin and enoxaparin in pregnancy

Vijayan V, Rachel T

Med J Malaysia, 2012 Dec;67(6):591-4.
PMID: 23770951 MyJurnal

The anticoagulation of choice for mechanical heart valves is the oral anticoagulant warfarin. Warfarin is associated with increased risk of miscarriage, intrauterine fetal deaths and warfarin embryopathy. This longitudical cross-over study of 5 women observed all 5 having livebirths of healthy infants after heparin-managed pregnancies. Their earlier 8 pregnancies had all resulted in perinatal losses or miscarriages when on regimes based on warfarin.

Matched MeSH terms: Heart Valves