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Advanced Methodology and Preliminary Measurements of Molecular and Mechanical Properties of Heart Valves under Dynamic Strain.

ABSTRACT: Mammalian heart valves are soft tissue assemblies with multi-scale material properties. This is because they are constructs comprising both muscle and non-contractile extracellular matrix proteins (such as collagens and proteoglycans) and transition regions where one form of tissue structure becomes another, significantly different form. The leaflets of the mitral and tricuspid valves are connected to chordae tendinae which, in turn, bind through papillary muscles to the cardiac wall of the ventricle. The transition regions between these tissue subsets are complex and diffuse. Their material composition and mechanical properties have not been previously described with both micro and nanoscopic data recorded simultaneously, as reported here. Annotating the mechanical characteristics of these tissue transitions will be of great value in developing novel implants, improving the state of the surgical simulators and advancing robot-assisted surgery. We present here developments in multi-scale methodology that produce data that can relate mechanical properties to molecular structure using scanning X-ray diffraction. We correlate these data to corresponding tissue level (macro and microscopic) stress and strain, with particular emphasis on the transition regions and present analyses to indicate points of possible failure in these tissues.

SUBMITTER: Madhurapantula RS

PROVIDER: S-EPMC7037596 | biostudies-literature | 2020 Jan

REPOSITORIES: biostudies-literature

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Advanced Methodology and Preliminary Measurements of Molecular and Mechanical Properties of Heart Valves under Dynamic Strain.

Madhurapantula Rama S RS Krell Gabriel G Morfin Berenice B Roy Rajarshi R Lister Kevin K Orgel Joseph P R O JPRO

International journal of molecular sciences 20200124 3

Mammalian heart valves are soft tissue assemblies with multi-scale material properties. This is because they are constructs comprising both muscle and non-contractile extracellular matrix proteins (such as collagens and proteoglycans) and transition regions where one form of tissue structure becomes another, significantly different form. The leaflets of the mitral and tricuspid valves are connected to chordae tendinae which, in turn, bind through papillary muscles to the cardiac wall of the vent ...[more]

PMID: 31991583

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Project description:Aims:Evidence is lacking regarding acute anticoagulation management in patients after intracerebral haemorrhage (ICH) with implanted mechanical heart valves (MHVs). Our objective was to investigate anticoagulation reversal and resumption strategies by evaluating incidences of haemorrhagic and thromboembolic complications, thereby defining an optimal time-window when to restart therapeutic anticoagulation (TA) in patients with MHV and ICH. Methods and results:We pooled individual patient-data (n = 2504) from a nationwide multicentre cohort-study (RETRACE, conducted at 22 German centres) and eventually identified MHV-patients (n = 137) with anticoagulation-associated ICH for outcome analyses. The primary outcome consisted of major haemorrhagic complications analysed during hospital stay according to treatment exposure (restarted TA vs. no-TA). Secondary outcomes comprised thromboembolic complications, the composite outcome (haemorrhagic and thromboembolic complications), timing of TA, and mortality. Adjusted analyses involved propensity-score matching and multivariable cox-regressions to identify optimal timing of TA. In 66/137 (48%) of patients TA was restarted, being associated with increased haemorrhagic (TA = 17/66 (26%) vs. no-TA = 4/71 (6%); P < 0.01) and a trend to decreased thromboembolic complications (TA = 1/66 (2%) vs. no-TA = 7/71 (10%); P = 0.06). Controlling treatment crossovers provided an incidence rate-ratio [hazard ratio (HR) 10.31, 95% confidence interval (CI) 3.67-35.70; P < 0.01] in disadvantage of TA for haemorrhagic complications. Analyses of TA-timing displayed significant harm until Day 13 after ICH (HR 7.06, 95% CI 2.33-21.37; P < 0.01). The hazard for the composite-balancing both complications, was increased for restarted TA until Day 6 (HR 2.51, 95% CI 1.10-5.70; P = 0.03). Conclusion:Restarting TA within less than 2 weeks after ICH in patients with MHV was associated with increased haemorrhagic complications. Optimal weighing-between least risks for thromboembolic and haemorrhagic complications-provided an earliest starting point of TA at Day 6, reserved only for patients at high thromboembolic risk.

Project description:BackgroundPatients with mechanical heart valves are usually maintained on anticoagulation therapy. However, after a spontaneous intracerebral hemorrhage event, administration of anticoagulants is temporarily ceased, and it remains unclear when to restart anticoagulation therapy.MethodsA cohort study was conducted to investigate the optimal time for restarting anticoagulation in patients with mechanical heart valves after spontaneous intracerebral hemorrhage. All patients with mechanical valves who experienced spontaneous cerebral hemorrhage and were admitted to the Second Affiliated Hospital of the Zhejiang University Medical School between 2013 and 2018 were retrospectively enrolled in this study. The patient electronic medical records were reviewed and the correlation between the time of restarting anticoagulation (within 3 days or more than 3 days after hemorrhage) and patient prognosis was assessed.ResultsA total of 40 patients with mechanical heart valves who experienced spontaneous cerebral hemorrhage were enrolled in this study. All patients were given oral warfarin anticoagulant therapy prior to admission (1.5-3.25 mg). After admission, patients were administered fresh frozen plasma and/or vitamin K1 to reverse anticoagulation. Out of the 16 patients (40%) who underwent surgical intervention, 4 died from cerebral hemorrhage deterioration during the hospital stay and did not restart anticoagulant therapy. Anticoagulant therapy was resumed within 3 days for 18 patients and more than three days after hemorrhage for the other 18 patients. After discharge, patients were followed up for 12 months or more. Unfortunately, during this period, 17% of patients (6/36) died.ConclusionsDefinitive hemostatic measures can be as an important factor in the clinical resumption of anticoagulation. Halting anticoagulant therapy for 3 to 7 days may be safe. It is recommended that low molecular heparin be administered within 3 days as a bridge treatment, combine with warfarin anticoagulant therapy within 1 week after hemorrhage.

Dataset Information

Advanced Methodology and Preliminary Measurements of Molecular and Mechanical Properties of Heart Valves under Dynamic Strain.

Publications

Advanced Methodology and Preliminary Measurements of Molecular and Mechanical Properties of Heart Valves under Dynamic Strain.

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