Thrombosis of mechanical mitral valve prosthesis

Ramifications of Vorticity on Aggregation and Activation of Platelets in Bi-Leaflet Mechanical Heart Valve: Fluid-Structure-Interaction Study

Bileaflet Mechanical Heart Valves (BMHV) are widely implanted to replace diseased heart valves. Despite many improvements in design, these valves still suffer from various complications, such as valve dysfunction, tissue overgrowth, hemolysis, and thromboembolism. Thrombosis and thromboembolism are believed to be initiated by platelet activation due to contact with foreign surfaces and non-physiological flow patterns. The implantation of the valve causes non-physiological patterns of vortex shedding behind the leaflets. The present study signifies the importance of vorticity in platelet activation and aggregation in BMHV implants. A two-phase model with the first Eulerian phase for blood and the second Discrete phase for platelets are used here. The generalized cross model of viscosity has been used to simulate the non-Newtonian viscosity of blood. A Fluid-Structure-Interaction model has been used to simulate the motion of leaflets. The present study has also estimated Platelet Activation State (PAS), which is the mathematical estimation of the degree of activation of platelets due to flow-induced shear stresses that cause thrombus formation. The regions in the fluid domain with a higher vorticity field have been found to contain platelets with relatively higher PAS than regions with relatively lower vorticity fields. Also, this study has quantitatively reported the effect of vorticity on platelet aggregation. The densities of platelets in the fluid areas with higher vorticity fields are higher than densities in the fluid regions with relatively lower vorticity fields, which indicate aggregation of highly activated platelets in areas with somewhat higher vorticity.

Two Strategies for the Dosage of Acenocoumarol Co-Administered with Rifampicin in Staphylococcal Prosthetic Valve Endocarditis

According to current European Society of Cardiology guidelines, for staphylococcal prosthetic valve endocarditis, rifampicin should be one of the drugs used. However, there is a concomitant need for vitamin K antagonists in patients with mechanical prostheses. It is widely known that rifampicin interacts with vitamin K antagonists (VKA), and this interaction makes it difficult to maintain the INR (international normalized ratio) value in the therapeutic range. We present two clinical cases of staphylococcal prosthetic valve endocarditis patients. Two different strategies for dealing with adverse drug interactions have been applied. In the first case, the dose of warfarin was up-titrated until the optimal INR value was obtained. In the second case, due to the history of labile INR values, a decision was made to modify the dosage of warfarin, taking into account pharmacological aspects of drug interactions.

Afebrile Pannus-Induced Blood Culture-Negative Mechanical Valve Endocarditis

The diagnosis of prosthetic valve endocarditis may be challenging in patients with an atypical clinical presentation. Virtually all infections associated with mechanical prosthetic valves are localized to the prosthesis-tissue junction at the sewing ring and are accompanied by tissue destruction around the prosthesis. Because the orifice of the mechanical prosthetic valve is made of metal and pyrolytic carbon, which do not enable the adherence of microorganisms, any vegetation originating from the interior of the valve orifice is usually rare. Here we present a rare case of pannus-induced mechanical prosthetic valve endocarditis that was difficult to diagnose.

Mitral valve-sparing procedures and prosthetic heart valve failure: a case report

Prosthetic heart valve dysfunction due to thrombus or pannus formation can be a life-threatening complication. The present report describes a 47-year-old woman who developed valvular cardiomyopathy after chorda-sparing mitral valve replacement, and subsequently underwent heart transplantation for progressive heart failure. The explanted mitral valve prosthesis showed significant thrombus and pannus leading to reduced leaflet mobility and valvular stenosis. The present report illustrates the role of the subvalvular apparatus and pannus in prosthesis dysfunction.

Acute thrombosis in mitralic mechanical prosthesis: a case report

We describe a case of a man, 42 years old, submitted to successful fibrinolitic strategy with rTPA in acute mitralic prosthesis valve thrombosis and ipomobility of one emidisk. There aren't a consensus agreement in therapeutic strategy but we may support the approach of some authors that employ fibrinolisis in patients without absolute or relative controindications and if thrombus dimension is less than 1 cm otherwise they make use of heparin therapy in non obstructive thrombosis with successive transesophageal echocardiography evaluation for the efficacy and the later indication for thrombolisis or surgery treatment.

Thrombolytic treatment of thrombosis on the aortic valvular prosthesis complicated by brain embolism

The authors present a case of thrombosis on the St. Jude Medical 19 aortic valve prosthesis. The diagnosis was confirmed by transthoracic and transoesofageal echocardiography, cardiac fluoroscopy revealed restricted movement of the aortic valve prosthesis leaflet. Thrombolytic therapy was complicated with brain embolism that was successfully percutaneously removed from the cerebral artery by the mechanical device. The patient has fully recovered without any neurological residual symptoms. This case report should be instructive to other clinicians who encounter the same complications after thrombolytic treatment.