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Background and Aim of the Study: Stentless biological valves have proven advantages in hemodynamic performance and left ventricular function compared to stented biological valves. Following a marked postoperative fall in the platelet count of patients after implantation of the Freedom SOLO valve, the study aim was to confirm clinical observations that this effect was more severe in patients receiving Freedom SOLO valves than in those receiving St. Jude Medical (SJM) mechanical aortic valves., Methods: Preoperative and postoperative platelet counts were compared in two groups of patients who underwent aortic valve replacement (AVR) without any concomitant procedures between January and December 2007. Patients received either a Freedom SOLO valve (n = 28) or a SJM mechanical valve (n = 41). Mean values of platelet counts were compared using three multiple linear regression models., Results: Platelet counts were significantly lower in the Freedom SOLO group than in the SJM group from the first postoperative day (POD 1) up to POD 6 (p <0.001). In three patients of the Freedom SOLO group the platelet count fell below 30x10(9)/l, while the lowest level in the SJM group was 75x10(9)/l. Based on multiple linear regression models, the type of valve implanted had a statistically significant influence on postoperative platelet counts on POD 1, POD 3, and POD 5 (p <0.001)., Conclusion: Whilst the reason for this phenomenon is unknown, the use of consistent monitoring should prevent severe falls in platelet count from becoming dangerous for the patient. Further studies are required to investigate the phenomenon since, despite a shorter cardiopulmonary bypass time, the fall in platelet count was more profound in the Freedom SOLO group.

Background and Aim of the Study: The study aim was to monitor serum troponin and plasma lactate concentrations in conventional aortic valve replacement compared to a beating-heart technique, perfused via the coronary sinus., Methods: In this prospective, non-randomized study, which was conducted between 2003 and 2009, a total of 35 patients was allocated to two groups, based on the method of myocardial protection. The groups did not differ significantly in terms of preoperative parameters. Levels of lactate were measured in all 35 patients, and of troponin I in 20 patients, in consecutive samples during and after surgery., Results: There was no in-hospital mortality and no serious complications among patients. The cardiopulmonary bypass and aortic cross-clamp times were each significantly shorter and lactate and troponin I concentrations higher, in the beating-heart group. No perioperative myocardial infarction was observed., Conclusion: Although good clinical results were observed in patients operated when using the beating-heart technique with retrograde coronary sinus perfusion, postoperative serum levels of troponin I were higher than in patients operated on using a conventional technique. Although troponin I is considered a prognostic factor for postoperative mortality, this parameter applies only to selected patients rather than for widespread use.

Background and Aim of the Study: It is well established that there are geometric differences between ischemic and dilative mitral regurgitation (MR), yet data on the hemodynamic consequences of these differences are scarce. The study aim was to determine whether mitral regurgitant flows in ischemic MR differ from those in dilative MR., Methods: A left heart simulator was developed to evaluate possible differences in regurgitant flows between two pathological mitral valve configurations, ischemic and dilative. Ischemic MR was simulated by increasing the baseline intercommissural diameter (CC) by 10%, the baseline septolateral (SL) diameter by 30%, and by displacing the posteromedial papillary muscle (PM) to the apical posterolateral position. Dilative MR was simulated by increasing the baseline SL and CC diameters by 30%, and by a symmetrical displacement of both PMs. Mitral regurgitant flow measurements were carried out under transmitral pressures ranging from 40 to 140 mmHg (increments of 15 mmHg). Camera snapshots of the mitral annulus were used to accurately determine mitral annular geometry by measuring the SL and CC diameters., Results: A total of 24 measurements was made on four porcine mitral valves; 14 to evaluate ischemic MR, and 10 to evaluate dilative MR. In ischemic MR, a constant regurgitant flow was observed throughout the pressure range tested. In dilative MR, increasing the transmitral pressure caused the regurgitant flows to decrease exponentially. The mitral annulus snapshot analysis showed that displacement of the posteromedial PM in ischemic MR caused the regurgitation orifice to appear at the tented side of the valve. An additional regurgitation orifice was formed through bulging (prolapse) of the leaflets at the contralateral commissure. The phenomenon was not observed in the dilative mitral valve configuration, where a central regurgitation orifice appeared with symmetrical PM displacement., Conclusion: These data suggest that geometric differences between ischemic and dilative MR translate into significantly different hemodynamic properties of insufficient mitral valves.