Effect of Impeller Geometry on Lift‐Off Characteristics and Rotational Attitude in a Monopivot Centrifugal Blood Pump

The effect of the flow path geometry of the impeller on the lift‐off and tilt of the rotational axis of the impeller against the hydrodynamic force was investigated in a centrifugal blood pump with an impeller supported by a single‐contact pivot bearing. Four types of impeller were compared: the FR model with the flow path having both front and rear cutouts on the tip, the F model with the flow path having only a front cutout, the R model with only a rear cutout, and the N model with a straight flow path. First, the axial thrust and the movement about the pivot point, which was loaded on the surface of the impeller, were calculated using computational fluid dynamics (CFD) analysis. Next, the lift‐off point and the tilt of the rotational axis of the impeller were measured experimentally. The CFD analysis showed that the axial thrust increased gently in the FR and R models as the flow rate increased, whereas it increased drastically in the F and N models. This difference in axial thrust was likely from the higher pressure caused by the smaller circumferential velocity in the gap between the top surface of the impeller and the casing in the FR and R models than in the F and N models, which was caused by the rear cutout. These results corresponded with the experimental results showing that the impellers lifted off in the F and N models as the flow rate increased, whereas it did not in the FR and R models. Conversely, the movement about the pivot point increased in the direction opposite the side with the pump outlet as the flow rate increased. However, the tilt of the rotational axis of the impeller, which oriented away from the pump outlet, was less than 0.8° in any model under any conditions, and was considered to negligibly affect the rotational attitude of the impeller. These results confirm that a rear cutout prevents lift‐off of the impeller caused by a decrease in the axial thrust.     

Cytokine and clinical predictors for treatment outcome of visually guided temporomandibular joint irrigation in patients with chronic closed lock.

PURPOSE: This study investigates selected predictors for clinical outcome of temporomandibular joint (TMJ) irrigation in patients with chronic closed lock (CCL). PATIENTS AND METHODS: Fifty-six patients with unilateral CCL, who underwent a visually guided TMJ irrigation (VGIR), were enrolled in this study. They were divided into either successful (s-group; n = 38) or unsuccessful groups (u-group; n = 18), according to the clinical success criteria. The investigated predictive factors were age, gender, duration of symptoms before the VGIR, preoperative painless range of mandibular motion, preoperative self-evaluated TMJ pain on visual analog scale (VAS), severity of arthroscopically observed pathologies, and presence and concentrations of a set of pro- and anti-inflammatory cytokines (ie, tumor necrosis factor [TNF]-alpha, interleukin [IL]-1beta, IL-6, IL-8, IL-12, and IL-10) in the aspirated synovial fluid (A-SF). Several comparative analyses and logistic regression analyses were used for statistical studies. RESULTS: The preoperative VAS score, detection rate of IL-8, and concentrations of IL-6 and IL-8 in the A-SF were significantly higher in the u-group (P < .05). Conversely, the detection rate and concentrations of IL-10 were significantly higher in the s-group (P < .05). The multivariate adjusted odds ratio (OR) showed that the detectable IL-10 in the A-SF (OR, 10.882; P = .047) is significantly predictive for a successful VGIR. CONCLUSIONS: The presence of IL-10 in the A-SF is a significant predictor of successful outcome of TMJ irrigation for CCL. Severe TMJ pain and detectable IL-6 or IL-8 in the A-SF seem to indicate a poor outcome after TMJ irrigation.     

In vivo evaluation of the "TinyPump" as a pediatric left ventricular assist device

Pediatric patients with end-stage heart failure require mechanical circulatory support (MCS) just as adults do. In order to meet the special requirements for neonates' and infants' MCS, pediatric circulatory support devices must be compact with low priming volume, easily controllable with low flow, less traumatic for blood cells and tissues, and biocompatible with minimum anticoagulation. We have designed and developed a miniature rotary centrifugal blood pump, "TinyPump," with a priming volume of 5 mL, which has already demonstrated its controllable performance for low flow and durability in vitro. To evaluate the feasibility of the TinyPump as a left ventricular assist device (LVAD) suitable for neonates and infants, we have examined the biocompatibility and hemodynamic performance of the TinyPump in a pediatric animal model using Shiba goats. The TinyPump is a miniaturized centrifugal pump weighing 150 g comprising a disposable pump head with a 30-mm diameter impeller having six straight-vanes and a reusable motor driver. The impeller in the pump head is supported by a hydrodynamic bearing at its center and is driven by radial magnetic force coupled to the motor driver. TinyPump implantations were performed in 22 Shiba goats (17 female and 5 male), with body weights ranging from 8.4 to 27.2 kg. Under gas anesthesia, via left lateral thoracotomy, a 22 Fr inflow cannula was inserted through the left ventricular apex, while a 6-mm outflow graft was anastomosed to the descending aorta, which were then connected to a TinyPump mounted on the animal's back. Postoperative hemodynamic monitoring included heart rate, arterial and central venous pressure, pump flow, and rotation speed. Target pump flow in all animals was maintained at 0.9 ± 0.1 L/min, which is approximately half the normal pulmonary artery flow measured in control animals. Blood samples were collected to evaluate peripheral organ functions, hemolysis, and thrombosis. Goats were divided into three groups-acute phase (6 h; n = 4), subchronic phase (6 h 2 postoperative days [POD]; n = 11), and chronic phase (3 POD-16 POD; n = 8)-based on their survival duration. In the early experiments, hemolysis and thrombi formation at the impeller bearing resulted in termination of the study. Subsequent modifications of the bearing design, pump housing design, and magnetic coupling force helped to minimize the hemolysis and thrombi formation, prolonging the survival duration of the Shiba goats to 2 weeks with minimum adverse effects on the blood components and organ functions. With further experiments and improvements in pump durability and hemocompatibility, the TinyPump can serve as a suitable circulatory support device for neonates and infants bridging to heart transplantation as well as to heart recovery.     

In Vitro Comparative Assessment of Mechanical Blood Damage Induced by Different Hemodialysis Treatments

Gradual deterioration of red blood cells (RBCs) due to mechanical stress (chronic hemolysis) is unavoidable during treatments that involve extracorporeal blood circulation, such as hemodialysis (HD). This effect is generally undetectable and does not generate any acute symptoms, but it leads to an increase in plasma free hemoglobin (fHb). There are no absolute safety levels for fHb increase, indicating the need for an empirical evaluation using comparative testing. The increase in fHb levels was investigated in vitro by applying double‐needle double‐pump HD (HD‐DNDP), a new modality in which arterial and venous pumps both run continuously. fHb was measured during typical and worst‐case simulated dialysis treatments (double‐needle single‐pump HD [HD‐DNSP], hemodiafiltration [HDF‐DN], single‐needle double‐pump HD [HD‐SNDP], and HD‐DNDP) performed in vitro using bovine blood for 4 h. Hemolysis‐related indices (fHb%; index of hemolysis, IH; and normalized IH) were calculated and used for comparison. The increase in fHb during either HDF‐DN or HD‐SNDP with Artis and AK200 dialysis machines was similar, while the fHb at the maximum real blood flow rate (Qb_real) at the completion of the HD‐DNDP treatment on Artis was higher than that for HD‐DNSP using a Phoenix dialysis machine (fHb% = 1.24 ± 0.13 and 0.92 ± 0.12 for the Artis machine with HD‐DNDP at Qb_real = 450 mL/min and Phoenix with HD‐DNSP at Qb_real = 500 mL/min, respectively). However, the fHb levels increased linearly, and no steep changes were observed. The increases observed during HD‐DNDP were the same order of magnitude as those for widely used bloodlines and treatment modes for delivering dialysis treatments. The observed results matched literature findings, and thus the measured fHb trends are not predicted to have clinical side effects. HD‐DNDP treatment with Artis does not merit any additional concern regarding mechanical stress to RBCs compared with that observed for routinely used dialysis treatments, bloodlines and machines. Although the in vitro measurement of the fHb increase in bovine blood does not allow a prediction of the absolute level of blood mechanical damage or the possible effects in humans, such measurements are valuable for assessing hemolytic harm by performing tests comparing the proposed treatment with existing devices.     

Recurrent palmar dislocation of the distal radioulnar joint. A case report

Recurrent palmar dislocation of the distal radioulnar joint is not a common injury. We report one case in a 73-year-old female. This injury was incorrectly diagnosed at the first presentation because there has been no distinct deformity at the wrist and extension-flexion was normal. The need for proper physical examination and accurate radiographic positioning is stressed. Distal diaphysis resection combined with distal radioulnar arthrodesis (modified Sauve-Kapandji procedure) was the preferred method of treatment in an old patient. Two years after the injury, the patient was asymptomatic.     

Dominantly inherited motor and sensory neuropathy with excessive myelin folding complex

The two patients in a family having the clinical and electrodiagnostic features of hereditary motor and sensory neuropathy (HMSN) are described. The main histological features of sural nerve were segmental demyelination and remyelination with moderate to marked loss of myelinated fibers, and myelin folding complex along all of the large and small myelinated fibers. These features appeared morphologically similar to those observed in HMSN with excessive myelin outfolding, or globular neuropathy. Southern blot analysis suggests that there were neither duplication nor deletion of the peripheral myelin protein-22 gene in the patients. The presented two patients may be a rare form of dominantly inherited HMSN with myelin folding complex.Department of Neurology National Okinawa HospitalSupported by grant from the National Center for Nervous, Mental and Muscular disorders of the Ministry of Health and welfare, Japan