Keigo Yamashita

Rapid Restoration of Thrombus Formation and High-Molecular-Weight von Willebrand Factor Multimers in Patients with Severe Aortic Stenosis After Valve Replacement

Aim: Patients with severe aortic stenosis (AS) may have bleeding episodes due to the loss of high-molecular-weight (HMW) von Willebrand factor multimers (VWFMs). The absence of HMW-VWFMs and bleeding tendency are usually corrected after aortic valve replacement (AVR). To investigate the process of VWFM recovery and symptoms in patients with severe AS, we analyzed changes in VWF antigen (VWF:Ag), ADAMTS13 activity (ADAMTS13:AC), and platelet thrombus formation under high shear stress conditions. Methods: Nine patients with severe AS undergoing AVR were analyzed. Results: Evident deficiency of HMW-VWFMs was observed in six patients before surgery, which was rapidly restored within 8 days after AVR. Median levels of VWF:Ag before surgery, on postoperative days (PODs) 1, 8, 15, and 22, and one year after AVR were 78.1%, 130%, 224%, 155%, 134%, and 142%, respectively. In contrast, ADAMTS13:AC was 50.5%, 35.5%, 25.5%, 25.1%, 30.3%, and 84.6%, respectively. Preoperative thrombus formation but not surface coverage was significantly lower than that on POD 22, which was considered as normal level in each patient. Compared with preoperative levels, thrombus volume was significantly lower on POD 1, but rapidly increased by POD 8. Conclusion: Bleeding tendency and loss of HMW-VWFMs observed in patients with severe AS before surgery was rapidly corrected after AVR. Instead, patients were in a VWF-predominant state between POD 8 and 22.

Experimental use of crosslinked gelatin glue for arterial hemostasis in cardiovascular surgery.

BACKGROUND Anastomotic needle hole bleeding is a frequently encountered problem in cardiovascular surgeries. OBJECTIVE To examine the feasibility of crosslinked gelatin glue as an anastomotic needle hole sealant in comparison with fibrin glue. METHODS The in vitro burst water pressures were measured for gelatin and fibrin glue sealed needle holes of expanded polytetrafluoroethylene (ePTFE) or collagen coated woven polyester grafts. For in vivo investigations, abdominal aorta-ePTFE graft anastomoses of heparinized beagle dogs were sealed by gelatin or fibrin glue and hemostatic efficacy was judged. The implanted sites were re-examined 4 weeks postoperatively. RESULTS The in vitro burst water pressures of gelatin glue sealed needle holes of both grafts were higher than those sealed by fibrin glue. For in vivo canine studies, hemostasis was successful for all gelatin glue applied suture lines, but not two out of three fibrin glue treated sites when 3-0 polypropylene suture was employed. Although adhesions of surrounding tissues were intense for all sites 4 weeks postoperatively, inflammation was more severe for the fibrin glue group compared to those of gelatin glue. CONCLUSIONS Gelatin glue was found to be an effective and safe sealant for accomplishing hemostasis of anastomotic needle holes of vascular grafts.

Transcatheter Aortic Valve Implantation for Chronic Dialysis Patients in Japan

Aortic stenosis (AS) is one of the common cardiovascular diseases in dialysis patients. Calcification of the aortic valve is present in approximately 28–55% of dialysis patients, with an average age of onset that is 10–20 years lower than that of patients with normal renal function.2 Although surgical aortic valve replacement (AVR) has been the gold standard approach for patients with severe AS, it carries considerable risk for patients with advanced age, frailty, or high comorbidity. Okada et al3 retrospectively analyzed the clinical data from 89 dialysis and 317 nondialysis patients undergoing AVR in Japan. t is well-known that end-stage renal disease (ESRD) requiring chronic dialysis is associated with cardiovascular diseases. According to the report of the Japanese Society for Dialysis Therapy (JSDT), the number of patients requiring chronic dialysis in Japan increased from 36,397 in 1980 to 310,007 in 2012, representing a more than 8-fold increase over 30 years (Figure 1), and the leading cause of death is cardiovascular disease, including heart failure, cerebrovascular accident, and myocardial infarction (Figure 2).1 (The data depicted in the Figures were provided by the JSDT. The interpretation and reporting of these data are the responsibility of the authors and in no way should be seen as an official policy or interpretation of the JSDT.) I

Gelatin Sealing Sheet for Arterial Hemostasis and Anti-adhesion in Vascular Surgery: a Dog Model Study.

BACKGROUND The bilayer gelatin sealing sheet was developed as a safe, effective, easy-to-handle and low-cost hemostatic agent. OBJECTIVE To examine the feasibility of gelatin sealing sheets using a canine arterial hemorrhage model. METHODS In vivo degradation of gelatin sealing sheets was examined by implanting subcutaneously in rats. For the hemostatic and anti-adhesion efficacy investigations, femoral arteries of dogs were pricked with syringe needle to make a small hole and a gelatin (i.e. experimental group) or fibrin glue sealing sheet (i.e. control group) was applied on the hole to stop bleeding (n=8). After discontinuation of the bleeding, the skin incisions were closed and re-examined 4 weeks postoperatively. RESULTS From the degradation study, 4 h thermally treated gelatin sheet which degraded within 3 weeks in vivo was chosen for the further hemostatic study. In all cases of gelatin and fibrin glue sealing sheets, bleeding from the needle hole on canine femoral arteries was effectively stopped. Postoperative adhesions and inflammation at the site in the experimental group were significantly less than those in the control group (P<0.01 for adhesion scores). CONCLUSIONS The gelatin sealing sheet was found to be as effective as the fibrin glue sealing sheet as a surgical hemostatic agent, and more effective in preventing postoperative adhesions.

Isolated dissecting aneurysm of the brachiocephalic artery associated with contained rupture

A 79-year-old man with no history of trauma complained of a sudden onset of headache and backache. Computed tomography showed an isolated dissecting aneurysm 4 cm in diameter associated with contained rupture at the takeoff region of the brachiocephalic artery. Surgery was performed on an emergent basis. The proximal aortic arch was successfully replaced using antegrade selective cerebral perfusion. The patient was easily weaned from cardiopulmonary bypass and recovered uneventfully.

Circumferential Acute Type an Aortic Dissection with Intimo-Intimal Intussusception: The Efficacy of Central Aortic Cannulation

An 80-year-old woman suffered from acute chest pain and then exhibited cardiogenic shock. Transthoracic echocardiography revealed severe aortic regurgitation due to the intussusception of the intima. Computed tomography also showed the intussusception of the intima into the left ventricular outflow tract over the aortic valve and dissection involving the aortic root, aortic arch, and descending thoracic aorta. During surgery, echocardiography-guided central aortic cannulation was performed for the prompt establishment of cardiopulmonary bypass. The complete intimal tear was circumferentially located in the middle level of the ascending aorta. The proximal flap was inverted into the left ventricle, and the distal flap had been pushed into the aortic arch. Graft replacement of the ascending aorta was performed successfully, and the patient had an uneventful postoperative course.