Shear-dependent platelet aggregation size

Nonsurgical bleeding is the most frequent complication of left ventricular assist device (LVAD) support. Supraphysiologic shear rates generated in LVAD causes impaired platelet aggregation, which increases the risk of bleeding. The effect of shear rate on the formation size of platelet aggregates has never been reported experimentally, although platelet aggregation size can be considered to be directly relevant to bleeding complications. Therefore, this study investigated the impact of shear rate and exposure time on the formation size of platelet aggregates, which is vital in predicting bleeding in patients with an LVAD. Human platelet-poor plasma (containing von Willebrand factor, vWF) and fluorochrome-labeled platelets were subjected to a range of shear rates (0-10 000 s⁻¹) for 0, 5, 10, and 15 minutes using a custom-built blood-shearing device. Formed sizes of platelet aggregates under a range of shear-controlled environment were visualized and measured using microscopy. The loss of high molecular weight (HMW) vWF multimers was quantified using gel electrophoresis and immunoblotting. An inhibition study was also performed to investigate the reduction in platelet aggregation size and HMW vWF multimers caused by either mechanical shear or enzymatic (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13—ADAMTS13, the von Willebrand factor protease) mechanism under low and high shear conditions (360 and 10 000 s⁻¹). We found that the average size of platelet aggregates formed under physiological shear rates of 360-3000 s⁻¹ (200-300 μm²) was significantly larger compared to those sheared at >6000 s⁻¹ (50-100 μm²). Furthermore, HMW vWF multimers were reduced with increased shear rates. The inhibition study revealed that the reduction in platelet aggregation size and HWM vWF multimers were mainly associated with ADAMTS13. In conclusion, the threshold of shear rate must not exceed >6000 s⁻¹ in order to maintain the optimal size of platelet aggregates to “plug off” the injury site and stop bleeding.     

Optimal cannula positioning of HeartMate 3 left ventricular assist device

Cannula position in HeartMate II and HeartWare left ventricular assist devices (LVADs) is associated with clinical outcome. This study aimed to investigate the clinical implication of the device positioning in HeartMate 3 LVAD cohort. Consecutive patients who underwent HeartMate 3 LVAD implantation were followed for one year from index discharge. At index discharge, chest X-ray parameters were measured: (a) cannula coronal angle, (b) height of pump bottom, (c) cannula sagittal angle, and (d) cannula lumen area. The association of each measurement of cannula position with one-year clinical outcomes was investigated. Sixty-four HeartMate 3 LVAD patients (58 years old, 64% male) were enrolled. In the multivariable Cox regression model, the cannula coronal angle was a significant predictor of death or heart failure readmission (hazard ratio 1.27 [1.01-1.60], P = .045). Patients with a cannula coronal angle ≤28° had lower central venous pressure (P = .030), lower pulmonary capillary wedge pressure (P = .027), and smaller left ventricular size (P = .019) compared to those with the angle >28°. Right ventricular size and parameters of right ventricular function were also better in the narrow angle group, as was one-year cumulative incidence of death or heart failure readmission (10% vs. 50%, P = .008). Narrow cannula coronal angle in patients with HeartMate 3 LVADs was associated with improved cardiac unloading and lower incidence of death or heart failure readmission. Larger studies to confirm the implication of optimal device positioning are warranted.     

Castration-resistant prostate cancer without metastasis at presentation may achieve cancer-specific survival in patients who underwent prior radical prostatectomy

International Urology and Nephrology - Radical prostatectomy (RP) is relatively better oncological outcomes in patients with prostate cancer (PCa). However, the incidence of castration-resistant...     

Low reduction of prostate volume is a significant predictor of prostate cancer at subsequent biopsy in patients with dutasteride: A retrospective study

Appropriate decision of prostate biopsy in men with 5α-reductase inhibitor (5AR inhibitor) is still unclear to avoid unnecessary biopsy. We retrospectively investigated patients with initial PSA 4.0 ng/ml or more and underwent subsequent prostate biopsy following dutasteride treatment. From September 2009 to August 2018, 399 cases of benign prostate hyperplasia (BPH) were treated with dutasteride in our department. Of the total, 36 cases with elevated pre-treatment PSA (4.0 ng/ml or more) and underwent subsequent prostate biopsy were included into this study. We evaluated PSA kinetics and changing prostate volumes (PV), and detection of prostate cancer. Overall, average PSA reduced by half at 6 months from dosing. Pre-treatment biopsy was performed in 17 of 36 cases, and all were diagnosed as having no malignancy. After treatment, prostate cancer was detected in 15 cases by subsequent biopsy. Fourteen of 15 cases were clinically significant cancer (Gleason score 7 or more). Logistic regression analysis detected a nominal association between prostate cancer detection and three variants, PSAD, PV reduction (1–Before/After PV) and abnormal MRI findings. In addition to abnormal MRI findings and pre-treatment of high PSAD, the case with low reduction of PV after treatment should consider performing prostate biopsy.     

Impact of turbulent blood flow in the aortic root on de novo aortic insufficiency during continuous-flow left ventricular-assist device support

Severe aortic insufficiency (AI) after implantation of continuous-flow left ventricular-assist device (LVAD) affects device performance and outcomes. However, the mechanism for the occurrence and progression of AI has not been elucidated. We investigated the impact of nonphysiological retrograde blood flow in the aortic root on AI after LVAD implantation. Blood flow pattern was analyzed in patients with and without AI (n = 3 each) who underwent LVAD implantation, by computational fluid dynamics with patient-specific geometries, which were reproduced using electrocardiogram-gated 320-slice computed tomographic images. The total volume of retrograde blood flow during one cardiac cycle (716 ± 88 mL) was higher and the volume of slow blood flow (<0.1 cm/s) (0.16 ± 0.04 cm³) was lower in patients with AI than in those without AI (360 ± 111 mL, P = .0495, and 0.49 ± 0.08 cm³, P = .0495, respectively). No significant difference in wall shear stress on the aortic valve was observed between the groups. Patients with AI had a perpendicular anastomosis at the distal ascending aorta and the simulation in the modified anastomosis model of patients with AI showed that the retrograde blood flow pattern depended on the angle and position of anastomosis. Computational fluid dynamics revealed strong retrograde blood flow in the ascending aorta and aortic root in patients with AI after LVAD implantation. The angle and position of LVAD outflow anastomosis might impact retrograde blood flow and de novo AI after LVAD implantation.     

Predictors of postoperative early recurrence of extrahepatic bile duct cancer

Resected bile duct cancers often relapse during postoperative follow-up. The aim of this study was to detect predictors of early recurrence in patients with extrahepatic bile duct cancer. Consecutive cases (n = 162) of extrahepatic bile duct cancer in which R0 or R1 resection was achieved in Kobe University Hospital between 2000 and 2016 were divided into three groups [early recurrence (ER), within 6 months of surgery, late recurrence (LR), and no recurrence (NR)] and their clinicopathological features were compared. Twenty-two patients (14%) developed ER and 69 (43%) developed LR after surgery. The rates of lymph node metastasis and residual cancer status were similar in all three groups. Liver metastasis was more common in the ER group than in the LR group (59% vs. 32%, p = 0.02). ER had a significantly worse prognosis than LR and NR (7% vs. 44% vs. 85% at 1 year, p < 0.01, respectively). Multivariate analysis showed that age > 75 years, serum CA19-9 > 1008 U/ml and perineural invasion were independent predictors of early recurrence. High serum CA19-9 values (> 1008 U/ml) were an independent predictor of early recurrence. Neoadjuvant therapy and aggressive adjuvant therapy may be beneficial for patients who show highly elevated CA19-9 values before surgery.     

Initial pulmonary metastasis after pancreatectomy for pancreatic ductal adenocarcinoma

Patients who undergo pancreatectomy for pancreatic ductal adenocarcinoma (PDA) develop relatively early recurrence, but pulmonary metastasis from PDA is rare. Between January 2008 and December 2016, a total of 120 consecutive patients underwent pancreatectomy for primary PDA at Osaka Medical College Hospital. Among these, 13 patients developed pulmonary metastasis and 6 patients underwent pulmonary metastasectomy. Among these patients, the median disease-free survival following initial pancreatic surgery was 26.1 months, and the median overall survival (OS) interval was 39 months. On the other hand, seven patients did not undergo pulmonary resection. The median OS interval of these patients was 33 months. The 1-, 3-, and 5-year OS rates were 100%, 80%, and 60%, respectively, for patients who underwent pulmonary metastasectomy and 100.0%, 42.8%, and 0%, respectively, for those who did not undergo the procedure. Our experience has shown that surgical resection may lengthen the survival time of patients who tolerate surgery.