Surgical techniques for aortic valve xenotransplantation

Background Heart valve replacement in neonates and infants is one of the remaining unsolved problems in cardiac surgery because conventional valve prostheses do not grow with the children. Similarly, heart valve replacement in children and young adults with contraindications to anticoagulation remains an unsolved problem because mechanical valves are thrombogenic and bioprosthetic valves are prone to early degeneration. Therefore, there is an urgent clinical need for growing heart valve replacements that are durable without the need for anticoagulation. Methods A human cadaver model was used to develop surgical techniques for aortic valve xenotransplantation. Results Aortic valve xenotransplantation is technically feasible. Subcoronary implantation of the valve avoids the need for a root replacement. Conclusion Aortic valve xenotransplantation is promising because the development of GTKO.hCD46.hTBM transgenic pigs has brought xenotransplantation within clinical reach.

Erratum: Chest radiographs of cardiac devices (Part 1): Cardiovascular implantable electronic devices, cardiac valve prostheses and Amplatzer occluder devices

No abstract available.

When Aortic Stenosis Is Not Alone: Epidemiology, Pathophysiology, Diagnosis and Management in Mixed and Combined Valvular Disease

Aortic stenosis (AS) may present frequently combined with other valvular diseases or mixed with aortic regurgitation, with peculiar physio-pathological and clinical implications. The hemodynamic interactions between AS in mixed or combined valve disease depend on the specific combination of valve lesions and may result in diagnostic pitfalls at echocardiography; other imaging modalities may be helpful. Indeed, diagnosis is challenging because several echocardiographic methods commonly used to assess stenosis or regurgitation have been validated only in patients with the single-valve disease. Moreover, in the developed world, patients with multiple valve diseases tend to be older and more fragile over time; also, when more than one valvular lesion needs to address the surgical risk rises together with the long-term risk of morbidity and mortality associated with multiple valve prostheses, and the likelihood and risk of reoperation. Therefore, when AS presents mixed or combined valve disease, the heart valve team must integrate various parameters into the diagnosis and management strategy, including suitability for single or multiple transcatheter valve procedures. This review aims to summarize the most critical pathophysiological mechanisms underlying AS when associated with mitral regurgitation, mitral stenosis, aortic regurgitation, and tricuspid regurgitation. We will focus on echocardiography, clinical implications, and the most important treatment strategies.

Advisory Board conclusion following the discussion "Controversial issues of low molecular weight heparins use in obstetrics"

Antithrombotic therapy is often used during pregnancy for the treatment and prevention of venous thromboembolism, systemic embolism in patients with heart valve prostheses, for prevention of foetal loss in patients with antiphospholipid syndrome, placenta-mediated complications. In common, low molecular weight heparins (LMWHs) have largely replaced unfractionated heparin as the anticoagulant. However, in case of placenta-mediated complications it has off-label status. The effectiveness and safety of the LMWHs in pregnant women at an increased risk of placenta-mediated complications is discussed in this review. LMWH is effective, safety, easy to administer and associated with a low incidence of foetal and maternal complications.

The concept of automated functional design of heart valve prostheses

Aim. To develop an algorithm for the automated functional design of the heart valve leaflet apparatus.Methods. The geometry of the aortic valve leaflet was designed in the Matlab programming environment (MathWorks, Massachusetts, USA). Numerical modeling of the opening process was performed using Abaqus/CAE (Dassault Systemes, France).Results. We developed an algorithm, with the help of which a set of models of the leaflet apparatus was designed. 8 models were subjected to numerical modeling of the stress-strain state. The locking pressure simulation has shown that the smallest von Mises stress value was recorded for a sample with a larger surface area of the leaflet belly and it equals 0.422 MPa. The results obtained show that the value of the radius of curvature significantly affects the behavior of the entire valve, which leads to the conclusion that it is necessary to carefully select the design of the valve apparatus for its correct functioning.Conclusion. The study provides the primary confirmation that the concept of the algorithm is efficient for the automated functional design of the aortic heart valve leaflet apparatus.