Centrifugal blood pumps are playing a key role in circulatory mechanical assist systems including cardiopulmonary bypass (CPB), right and left ventricular assist devices (RVAD and LVAD), percutaneous cardiopulmonary support (PCPS), and extracorporeal membrane oxygenation (ECMO). Each of these circulatory assist systems requires specific flow and pressure conditions. In vitro hemolysis tests were performed using five compact mock loops with flow and pressure set equivalent to clinical conditions. These studies determined the hemolytic characteristics and clinical applicability of the pivot bearing-supported Gyro centrifugal pump with an eccentric port (C1E3) compared with the Bio-Medicus pump (BP-80). Normalized index of hemolysis (NIH) values of the C1E3 were less than those of the BP-80 under all conditions; in particular, they were significantly less in the CPB, LVAD, and RVAD conditions. In addition, linear correlation was observed between NIH values, rotational pump speed (RPM), total pressure head (delta P), and flow rate (Q) with both the C1E3 and BP-80: NIH = a(RPM/Q) + b, NIH = c(delta P/Q) + d. However, the slopes (a and c) of these equations were smaller with the C1E3 than those with the BP-80, which suggests that the C1E3 has decreased hemolytic characteristics when increasing the RPM and delta P. In other words, the increase of RPM and delta P results in less shear stress with the C1E3 than with the BP-80. One cause of these decreased hemolytic characteristics of the C1E3 is thought to be less pump power loss against an increase of RPM and delta P than with the BP-80. Furthermore, the average exposure time is shorter with the C1E3 than with the BP-80 because the priming volume of the C1E3 (30 ml) is smaller than that of the BP-80 (80 ml). From the point of both shear stress and exposure time, the C1E3 has less hemolytic features than the BP-80.

The maze procedure may be performed in combination with valve operations to treat chronic atrial fibrillation associated with valve dysfunction. Although we initially used the modified Cox maze III procedure, a more limited partial maze procedure is now preferred because the left atrium might be considered as the electrical impetues for atrial fibrillation. In this study we compared the results of 30 patients (group I) who underwent the full biatrial modified Cox maze III and 20 (group II) patients the partial maze procedure. While the rates of restored sinus rhythm were the same in both groups at 6‐month follow‐up (I: 83.3%, vs II: 80%), the following advantages were noted in the patients undergoing the partial maze procedure: shorter operative times, lesser elevations of creatine phosphokinase, lower rate of blood transfusion, lower rate of junc‐tional rhythm soon after the operation, and a higher P wave in those patients with restored sinus rhythm. The effectiveness of the partial maze procedure seems equal to that of the biatrial modified Cox maze III procedure for atrial fibrillation associated with valve disease. The partial maze procedure is simple and less invasive, and thus might be applied more frequently as an additional procedure to valve operations without additional risk.

Since 1991, in our laboratory, a pivot bearing-supported, sealless, centrifugal pump has been developed as an implantable ventricular assist device (VAD). For this application, the configuration of the total pump system should be relatively small. The C1E3 pump developed for this purpose was anatomically compatible with the small-sized patient population. To evaluate antithrombogenicity, ex vivo 2-week screening studies were conducted instead of studies involving an intracorporeally implanted VADs using calves. Five paracorporeal LVAD studies were performed using calves for longer than 2 weeks. The activated clotting time (ACT) was maintained at approximately 250 s using heparin. All of the devices demonstrated trouble-free performances over 2 weeks. Among these 5 studies, 3 implantations were subjected to 1-month system validation studies. There were no device-induced thrombus formations inside the pump housing, and plasma-free hemoglobin levels in calves were within the normal range throughout the experiment (35, 34, and 31 days). There were no incidents of system malfunction. Subsequently, the mass production model was fabricated and yielded a normalized index of hemolysis of 0.0014, which was comparable to that of clinically available pumps. The wear life of the impeller bearings was estimated at longer than 8 years. In the next series of in vivo studies, an implantable model of the C1E3 pump will be fabricated for longer term implantation. The pump-actuator will be implanted inside the body; thus the design calls for substituting plastic for metallic parts.

The Baylor C-Gyro Pump Eccentric Inlet Port Models (C1E) have been developed aiming for a long-term centrifugal ventricular assist device (VAD) as well as a cardiopulmonary bypass pump. The eccentric inlet port models are characterized by their unique inlet port and secondary impeller vanes. An inlet female pivot bearing, which was fixed to a supporting bar in the prototype model, is directly embedded into the ceiling of the pump casing. An inlet port is then placed off-center to avoid the bearing area, and it is angled between 0 to 90 degrees from the upright position. In addition, small secondary vanes were incorporated into the impeller bottom to accelerate the washout flow behind the impeller. These features attained design objectives proposed for higher antithrombogenicity: a seal-less pump chamber, no stationary parts in the blood path, and acceleration of the secondary flow behind the impeller. The first in vivo experiment using C1E pumps showed excellent antithrombogenicity for up to 18 days when the experiment ceased due to severe infection in the calf.

The 1992 AAMI SP-10 standards offer a thorough evaluation of the oscillometric sphygmomanometer by enforcing more stringent criteria on (1) agreement between two observers, (2) wide spectrum of blood pressure from hypertensive (above 180 mm Hg) to hypotensive, and (3) data analysis. The oscillometric blood pressure monitor evaluated in this study meets the specifications of the new AAMI SP-10 standards and can offer an accurate, automatic, and noninvasive measure of both systolic and diastolic blood pressure in adults and children. It can safely replace the manual or automatic auscultatory system in various clinical settings.