Crosslinking porcine aortic valve by radical polymerization for the preparation of BHVs with improved cytocompatibility, mild immune response, and reduced calcification

Over one million artificial heart valve transplantations are performed each year due to valvular stenosis or regurgitation. Among them, bioprosthetic heart valves (BHVs) are increasingly being used because of the absence of the need for lifelong anticoagulation. Almost all of the commercial BHVs are treated with Glutaraldehyde (GLUT). As GLUT-treated BHVs are prone to calcification and structural degradation, their durability is greatly reduced with a service life of only 12–15 years. The physiological structure and mechanical properties of the porcine aortic valve (PAV) are closer to that of a human heart valve, so in this study, PAV is used as the model to explore the comprehensive properties of the prepared BHVs by radical polymerization crosslinking method. We found that PAV treated by radical polymerization crosslinking method showed similar ECM stability and biaxial mechanical properties with GLUT-treated PAV. However, radical polymerization crosslinked PAV exhibited better cytocompatibility and endothelialization potential in vitro cell experiment as better anticalcification potential and reduced immune response than GLUT-treated PAV through subcutaneous animal experiments in rats. To conclude, a novel crosslinking method of non-glutaraldehyde fixation of xenogeneic tissues for the preparation of BHVs is expected.

Original method of posterior aortoplasty for aortic valve replacement in surgical treatment of combined mitral-aortic valve diseases

Objective. To research of possibilities of reconstruction of aorta`s ostium and ascending aorta during aortic valve replacement and simultaneous correction of mitral valve defects at patients with narrow aorta`s ostium. Materials and methods. The study group consisted of 46 patients with mitral-aortic heart diseases and combination with a narrow aortic mouth, who were operated on at the A Amosov National Institute of Cardiovascular surgery for the period from January 1, 2006 to January 1, 2020. All patients underwent reconstruction of the aortic root and ascending aorta according to the original method of posterior aortoplasty. There were 26 men (56.5%) and 20 women (43.5%). The age of patients ranged from 23 to 72 years (average - 58.4±7.3 years). 8 (17.4%) patients belonged to class III NYHA, 38 (82.6%) - to class IV. Results. Of the 46 operated patients at the hospital stage (30 days after surgery), 4 died (hospital mortality 8.7%). No fatalities were associated with surgical technique. The dynamics of echocardiographic parameters at the hospital stage was as follows: the systolic gradient on the aortic valve was before surgery 112.1 ± 15.2 mm Hg, on the aortic prosthesis at discharge - 23.2 ± 6.4 mm Hg; end-systolic index (ESI) of the left ventricle (ml/m²) - 59.1 ± 7.6 (before surgery) and 48.3 ± 5.9 (after surgery); left ventricle ejection fraction (EF) - 0.45 ± 0.04 (before surgery) and 0.53 ± 0.04 (after surgery). Conclusions. The proposed original technique of posterior aortoplasty allows to effectively expand the mouth of the aorta for further implantation of an artificial heart valve of larger diameter. The technique is quite safe. At the hospital stage there are no complications directly related to the technique of operations. At the early postoperative period, the morphometric parameters of the left ventricle (EF and ESI) improved. The technique can be successfully used for the correction of combined mitral-aortic valve defects.

Developing an Intelligent System for Prediction of Optimal Dose of Warfarin in Iranian Adult Patients with Artificial Heart Valve

Introduction: Artificial intelligence (AI) research within medicine is growing rapidly. AI is poised to transform medical practice. AI has been studied in several areas of healthcare and medical practice, including diagnosing, treating and caring of patients. Warfarin is one of the most commonly prescribed oral anticoagulant. Among all anticoagulants, warfarin has long been listed among the top ten drugs causing adverse drug events. Due to narrow therapeutic range and significant side effects, warfarin dosage determination becomes a challenging task in clinical practice. The purpose of this study was to determine exact dose of warfarin needed for patients with artificial heart valve using artificial neural networks (ANN).Development: To achieved the best model, some multi-layer perceptron ANNs were constructed with different structures. The dataset used included 846 patients who had been referred to the PT clinic in Tehran heart center in the second six months of the year 2013. Finally, the best structure of ANN for warfarin dose was investigated and used for prediction system developments. In this paper the implementation of ANNs and proposed system in MatLab environment are described.Application: The effectiveness of ANNs were evaluated in terms of classification performance using 10fold cross-validation procedure and the results showed that the best model is a network that has 7 neurons in its hidden layer with an average absolute error of 0.1, disturbance rate of 0.33 and regression of 0.87. Conclusion: The achieved results reveal that ANN-based system is a suitable tool for warfarin dose prediction in Iranian patients with an artificial heartvalve. However, no system can be guaranteed to achieve 100% accuracy, but using such methods can reduce medical errors and thereby improve health care and patient safety.

Lactobacillus Endocarditis-Associated Glomerulonephritis Complicated by anti-Coagulant Nephropathy and Renal Amyloidosis

Kidney injury is a well-known sequelae of infectious endocarditis. Various types of kidney injury can be seen, including endocarditis-associated glomerulonephritis, and may affect nearly half of the patients with infectious endocarditis. Lactobacillus species are an infrequently documented cause of endocarditis. We present a case of Lactobacillus endocarditis-associated glomerulonephritis in a patient with a complex medical history including Lactobacillus infection of an artificial heart valve. To our knowledge, this is the first reported case of development of endocarditis-associated glomerulonephritis secondary to Lactobacillus species organisms. Furthermore, the patient’s renal biopsy revealed several frequently overlooked concomitant findings including anti-coagulant nephropathy and renal amyloidosis.

Pressure sensor emulator to improve longterm stability of heart valve testing systems

Fluid mechanical characterization of artificial heart valve prostheses requires reliable measurement of temperature, flow and pressure at normal heart rate. In vitro fatigue test procedures of artificial heart valve prostheses can take several months with up to 400 million cycles to assess valve performance and durability under simulated cardiac conditions at increased pulse frequency. In both cases, a minimum of user interventions for recalibration are required. In these tests, pressure data are collected for hydrodynamic heart valve characterization and for closed-loop control of pressure loading. In our study, the improvement of commercial heart valve testing systems (Vivitro Pulse Duplicator, Vivitro Labs Inc. and VDT-3600i, BDC Laboratories) is considered by substituting the built-in disposable pressure sensors (lifetime: one week) by longterm stable sensors. The selected highly accurate sensors (86A, TE Connectivity Corp.) provide amplified, linearized, calibrated and temperature compensated analog output signals. Their stainless steel construction allows for high media compatibility with corrosive liquids. Due to different sensitivity characteristics, these sensors are not fully compatible to the testing devices. To overcome this limitation, application-specific emulator interfaces were developed to connect the new sensors to the data acquisition part of the validated valve testing systems. To stay consistent with manufacturer’s device and software specification, we utilized fast analog signal conditioning, including scaling, offset calibration, out of range alarm and status indication. Compared to the originally equipped pressure sensors, emulator parameters, such as pressure range, precision, resolution and accuracy remained unchanged or even improved. For system verification the response characteristic, long-term stability and dynamic properties were examined in comparative studies