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Mechanical heart valve replacement is the preferred alternative in younger patients with severe symptomatic aortic valve disease. However, thrombus and pannus formations are common complications associated with bileaflet mechanical heart valves. This leads to risks of valve leaflet dysfunction, a life threatening event. In this experimental study, we investigate, using time resolved planar particle image velocimetry, the flow characteristics in the ascending aorta in the presence of a dysfunctional bileaflet mechanical heart valve. Several configurations of leaflet dysfunction are investigated and the induced flow disturbances in terms of velocity fields, viscous energy dissipation, wall shear stress, and accumulation of viscous shear stresses are evaluated. We also explore the ability of a new set of parameters, solely based on the analysis of the normalized axial velocity profiles in the ascending aorta, to detect bileaflet mechanical heart valve dysfunction and differentiate between the different configurations tested in this study. Our results show that a bileaflet mechanical heart valve dysfunction leads to a complex spectrum of flow disturbances with each flow characteristic evaluated having its own worst case scenario in terms of dysfunction configuration. We also show that the suggested approach based on the analysis of the normalized axial velocity profiles in the ascending aorta has the potential to clearly discriminate not only between normal and dysfunctional bilealfet heart valves but also between the different leaflet dysfunction configurations. This approach could be easily implemented using phase contrast MRI to follow up patients with bileaflet mechanical heart valves.

From May 1976 to June 2001, 95 porcine heart valve bioprostheses (BPs) were explanted. Among them, 85 prostheses were available for an analysis of structural valve deterioration (SVD). There were 32 Hancock (H) BPs and 53 Carpentier-Edwards (CE) BPs, with a mean implantation duration of 12 +/- 3.5 and 11.0 +/- 4 years, respectively. There were two extraordinary complications. One was commissural dehiscence (CD) of the CEBPs in 10/53 cases (18.9%), with a mean duration of 12.7 +/- 2.7 years. This was not observed in the HBPs. The other was pannus formation in both BPs. In the mitral position, it was 25/32 (78.1%) in HBPs and 37/53 (69.8%) in CEBPs. In the aortic position, it was 4/32 (1.3%) in the HBPs and 11/53 (20.8%) in the CEBPs. We conclude that CD could not be diagnosed preoperatively and anticoagulation is therefore indicated to prevent pannus formation of such prostheses, particularly in those located in the mitral position.

The study investigated the hypothesis that plasma transforming growth factor type beta 1 (TGF-beta1) initiated pannus overgrowth in cases with aortic prosthetic valve dysfunction (PVD). Patients with obstruction of an aortic St. Jude Medical valve in 26 cases (PVD group) and without obstruction in 48 cases (control group) were studied. Plasma TGF-beta1, the intensity of the prothrombin time-international normalized ratio (PT-INR), and the interruption of an oral anticoagulant medicine were conducted. Plasma TGF-beta1 levels in the PVD group (87.7 +/- 29.2 ng/mL) were significantly higher (P < 0.05) than in the control group (73.7 +/- 25.2 ng/mL). The interruption of an oral anticoagulant medicine in 54% of the PVD group versus 12% of the control group was identified (P < 0.001). The mean value of the PT-INR in the PVD group (1.75 +/- 0.30) and control group (1.75 +/- 0.30) was not significantly different (P = 0.82). In conclusion, elevated levels of plasma TGF-beta1 may play a role in pannus overgrowth.

This study was conducted to determine the effect of thrombolytic therapy with tissue plasminogen activator (t-PA) for nonstructural malfunction of bileaflet cardiac valve prostheses. Twenty-seven patients with bileaflet prosthetic valve malfunction diagnosed by a combination of cineradiography and transthoracic echocardiography were treated with the administration of intravenous t-PA. The treatment resulted in complete success in 55.6% (15 of 27), partial success in 22.2% (6 of 27), and no change in 22.2% (6 of 27). In the complete success and partial success groups, the condition of the patients in 85.7% (18 of 21) of the cases improved within 24 h after the administration of t-PA. Six cases in whom thrombolytic therapy was instituted more than 1 month (ranged from 1 to 38 months, mean 14.7 months) after the diagnosis of prosthetic valve malfunction showed significantly less effectiveness of thrombolytic therapy with t-PA. Only one patient (3.7%) had a major complication (thromboembolism) after t-PA treatment. The results suggest that thrombolytic therapy with t-PA in patients with nonstructural malfunction of bileaflet cardiac valve prostheses is effective with low incidence of complication when the treatment is instituted early after the diagnosis.

A 59-year-old woman was admitted to our hospital because of heart failure. In 1988, she underwent aortic valve replacement with an Omnicarbon valve and mitral valve replacement with a bioprosthetic valve. She was doing well until July in 1996 when she developed heart failure. Echocardiography revealed massive mitral valve regurgitation, and cinefluoroscopy showed implanted Omnicarbon valve dysfunction with a leaflet opening angle of 35 degrees. At reoperation, it was revealed that pannus formation prevented the valve from functioning well. The pannus was resected through the major orifice, and the leaflet was rotated toward the right anterolateral orientation. The worn bioprosthetic valve was replaced with a mechanical one. Postoperative cinefluoroscopy of the rotated Ominicarbon valve showed the opening angle to be 61 degrees.

A Jarvik-7 type of pneumatic artificial heart, which was specifically designed to fit the anatomy and hemodynamic requirements of human patients, was implanted in a calf in an experiment to test the hemodynamic performance of the artificial heart. The experiment lasted for 221 days, longer than any animal had ever lived without its natural heart, despite the fact that the calf increased its body weight to 171 kg. The calf showed typical signs of low cardiac output before its death, but the direct cause of death was intestinal bleeding. At autopsy, it was discovered that the low cardiac output was due to severe pannus around the left inflow valve, as diagnosed earlier by changes in the pneumatic pressure wave form.

A 150-day experiment in a calf with an implanted total artificial heart, TNS-BRNO-II, is described. The Czechoslovak TAH-BRNO-II device is a hybrid; the outer housing is made of polymethylmethacrylate, the moving parts of segmented polyurethane. The blood flow through the device after the surgery gradually increased from 7 L/min to 12 L/min by the end of the experiment. Atrial pressures were automatically maintained at the same level, about one kPa on both sides. The left systolic time was automatically derived from the pump emptying phase; the right systolic time was maintained between 40% and 50%. After the surgery, normal values of blood gases, stabilization of respiratory activity, and normalization of gastrointestinal functions were reached very soon. Anticoagulant therapy was performed during the whole experiment, with several periods of increased bleeding tendency. The clinical state of the calf was essentially physiological until the 94th day of the experiment, when acute bronchopneumonia, with a high fever, over 41°C, initiated a series of complications (pseudomembranous enterocolitis, followed by sepsis lenta). The fatal complication was sudden impairment of the coagulation mechanisms on the 149th to 150th day of the experiment. This was the basic reason for the subsequent death of the animal, caused by acute cerebral anemic anoxia, which could not be prevented by immediate therapeutic procedures. In spite of these complications, the clinical state of this calf was relatively good until the end of the experiment. Autopsy revealed minimal thromboembolization at the valves. The outer surface of the diaphragm was covered with pseudoneointimal deposits and the inlet orifices were free of pannus or other connective tissue crescents. Macroscopic signs of infection were not seen, but bacteriological cultivation from internal organs confirmed Klebsiella infection. The state of the device at the time of autopsy, with simultaneous undisturbed function of the control and driving unit, showed the possibility of still longer survival.