Theoretical and experimental analyses of acoustic characteristics of fine-grain powder considering longitudinal vibration and boundary layer viscosity.

There was a previous study to derive the sound absorption coefficient of the powder layers comprising powder particles with a diameter of a few tens of µm. According to this previous method, the impact of air viscosity at the boundary layer generated in the pores between the powder particles is neglected. Therefore, precision is not guaranteed when the particle diameter is relatively large or when the density is relatively high. In the present study, to obtain the sound absorption coefficient of the powder layer more accurately, in addition to the above-described longitudinal vibration mode, the energy damping property of the boundary layer viscosity was calculated using the transfer-matrix method. As a result, when the longitudinal vibration mode and boundary layer viscosity were considered, the theoretical value tended to be closer to the experimental value than when only the longitudinal vibration was considered.

Decision making of iatrogenic coronary embolism after SAVR: a case report.

BACKGROUND: Acute coronary artery obstruction is a rare but lethal complication of surgical aortic valve replacement (SAVR), which may be caused by embolization of resected native tissue such as calcium plaque, thrombus, or perivalvular aortic tissue like fat embolus. Coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) are the main treatment modalities. PCI is less invasive, but it is difficult to determine its feasibility intraoperatively. CASE PRESENTATION: We report an 86-year-old woman who had asymptomatic severe aortic stenosis. She had scleroderma with an intractable left leg ulcer and bilateral leg varices. Considering the possibility of the spread of infection from the leg wound, SAVR was performed via right anterior thoracotomy to avoid complications such as mediastinitis. Coronary artery occlusion was suspected after weaning of cardiopulmonary bypass in the operation room due to asynergy with ST elevation and new severe mitral regurgitation. Transoesophageal echocardiography (TEE) helped diagnose coronary obstruction by embolus based on the degree of stenosis and the movement of the stenosis site. Percutaneous catheter intervention was performed successfully to restore coronary perfusion. CONCLUSION: TEE facilitated the diagnosis of coronary artery stenosis caused by an embolus and helped in determining the feasibility of percutaneous catheter intervention, thus allowing us to choose PCI over CABG as a less invasive surgery. This is especially invaluable in cases where obtaining a saphenous graft for CABG is difficult or where CABG would have required conversion from minimally invasive surgery (anterolateral approach) to median sternotomy.

Comprehensive Treatment of Total Arch Replacement in a Patient With Liver Cirrhosis: A Case Report.

A 78-year-old woman with liver cirrhosis due to chronic hepatitis C visited our department for treatment of a thoracic aortic aneurysm. Her Child-Pugh classification was class A, and her model for end-stage liver (MELD) disease score was 8. As she also had thrombocytopenia associated with splenomegaly and esophageal varices, endoscopic injection sclerotherapy and partial splenic embolization were performed before total arch replacement surgery for treating esophageal varices to reduce the bleeding risk during transesophageal echocardiography and for thrombocytopenia, respectively. After endoscopic injection sclerotherapy and partial splenic embolization, the platelet count increased; hence, total arch replacement surgery was performed. By combining partial splenic embolization and endoscopic injection sclerotherapy, we were able to safely perform transesophageal echocardiography and total arch replacement surgery in the perioperative period.

Intraoperative Blood Flow Evaluation Using Indocyanine Green Fluorescence Angiography for the Surgical Reconstruction of a Hilar Renal Artery Aneurysm.

Surgical reconstruction is one of the standard treatments for renal artery aneurysm. However, its intraoperative evaluation is sometimes difficult depending on the operative field, aneurysm morphology, and peripheral blood vessel distribution. This case demonstrated that after renal artery reconstruction, indocyanine green fluorescence angiography is used to evaluate the results of repairing. This method is useful in visceral aneurysm evaluation not only for assessing reconstructed blood flow but also for confirming tissue perfusion of the renal parenchyma.