Using self -suture branching artificial vesssels in aortic arch surgery at Hanoi Heart Hospital

Background: For aortic arch surgery, the improvement of anastomosis technique, and the improvement of using self-suture branching artificial vessels have shortened the time and reduced the cost of surgery. The study aimed to evaluate the improved results of using self-suture branched artificial vessels in aortic arch surgery. Methods: A retrospective descriptive study of the use of self-suture branching artificial vessels in aortic arch surgery at Hanoi Heart Hospital from October 2018 to May 2021. Results: There were 33 cases of aortic arch replacement using self-suture branching artificial vessels. The rate of postoperative bleeding was 6.06%. The rate of artificial vessel infection is 0%. Conclusion: Using self-suture branching artificial vessels in aortic arch surgery is a safe and effective technique.

The effect of aortic esophageal fistula treatment after TEVAR with artificial vessel bypass（Single center clinical experience）

Objective: To investigate the effect of aortic esophageal fistula treatment after thoracic aortic endovascular repair (TEVAR) with artificial vessel bypass. Methods: The clinical data of 6 consecutive patients who received surgical treatment at Shanghai Deda Hospital from September 2019 to June 2021 due to aortic esophageal fistula after TEVAR were retrospectively analyzed. There were 6 males, aged (47.7±8.2) years old (range: 35-56 years old). All patients had recurrent fever, and 4 patients had positive blood cultures. According to the specific conditions of the patients, all patients underwent artificial blood vessel bypass and jejunostomy under general anesthesia without extracorporeal circulation. One case underwent artificially infected vascular segment resection and esophageal repair at the same time. 5 cases underwent artificial infection vascular resection, 4 of them underwent esophageal repair, and 1 case had a large intraoperative fistula and local resection of the esophagus. Sensitive antibacterial drugs were continued after the operation for 6 to 8 weeks. Results: There were 2 deaths in hospital, 1 case of large cerebral infarction early postoperatively, and 1 case of septic shock. The remaining 4 patients recovered well after the operation and were discharged. The follow-up period was 2 to 23 months. During the follow-up period, the remaining patients had no recurrence of infection and esophageal fistula. Conclusion ：In patients with aortic esophageal fistula after TEVAR, the establishment of artificial vascular bypass, the resection of the infected vascular segment, contemporaneous or staged esophageal repair, regular anti-infective treatment can obtain a good prognosis.

"Sleeve" Sinus of Valsalva Repair in Patients with Acute Type A Aortic Dissection

Purpose: The optimal surgical strategy of aortic root in acute type A aortic dissection (ATAAD) is controversial. The aim of this study was to evaluate the feasibility and safety of “Sleeve” Sinus of Valsalva repair for AAD limited to the non-coronary sinus or partial left and right coronary sinus without involvement coronary artery ostia. Methods: From September 2016 to March 2019, 20 patients with AAD involving non-coronary sinus or partial left and right coronary sinus Valsalva underwent “Sleeve” Sinus of Valsalva repair. A tailored Dacron patch was inserted into the dissected layers and two Dacron strips were placed inside and outside of the aorta, and the new five-layers root was sutured with 3/0 prolene continuous stitches. The artificial vessel was reversed about 1cm and anastomosed with the reconstructed root. Then, the reversed artificial vessel was pulled and anastomosed with the Dacron strip of the new proximal aorta. Results: There was no early death in hospital and one death occurred during the 30-day postoperative period. Re-thoracotomy due to bleeding was necessary in only one patient and no bleeding was related to the proximal anastomosis. The postoperative drainage was 390.5 ± 229.3 mL. During follow up, the echocardiography showed the normal sinus of Valsalva and aortic valvular function. Computed tomography angiography showed normal aortic root without endovascular leak or dissection around the sinus of Valsalva. All patients were free from reoperation. Conclusions: “Sleeve” Sinus of Valsalva repair with Dacron patch for aortic dissection limited to the non-coronary sinus or partial left and right coronary sinus without involvement coronary artery ostia was technically feasible and safe.

A Study of Coronary Artery Disease in the Left Circumflex Artery via Artificial Vessel Restoration

Diagnosis, risk analysis, and treatment of coronary artery disease (CAD) can be improved with a better understanding of cardiovascular flows. Numerical simulations can assist in achieving this understanding. The objective of this study is to compare the dynamics of blood flow in a diseased left circumflex artery (LCX) and its artificially restored counterpart representing its healthy state. This comparison is made to identify flow characteristics in the restored vessel that contribute to the development of CAD. The diseased LCX geometry was derived from computed tomography angiography data. The stenosed region of the diseased LCX was repaired by manually redefining cross-sections of the vessel, creating the restored geometry. To account for inaccuracies, variations of the restored LCX were made by dilating the repaired surface. Numerical simulations were conducted on all geometries and the results were compared. Alongside expected low wall shear stress, a region of high vorticity was present in all of the restored vessels near the location where CAD developed in the diseased vessel. Therefore, this research suggests that flow vorticity is relevant in assessing the risk for CAD, potentially improving the accuracy of non-invasive, computational diagnosis. Such improvements can also help avoid unnecessary invasive diagnosis methods and minimize risk.

Functional Nanofibers with Multiscale Structure by Electrospinning

Electrospinning can produce nanofibers with extremely high surface-to-volume ratio and well tunable properties. The technique has been widely used in different disciplines. To fabricate fibers with required properties, parameters of fabrication should be well controlled and adjusted according to specific applications. Modification of electrospinning devices to align fibers in highly ordered architectures could improve their functions. Enhanced efficiency have also been obtained through the upscaling modification of spinnerets. With the outstanding efficiency, electrospinning has exhibited huge potentials to construct various nanostructures, such as artificial vessel, membrane for desalination and so on.

The Effect of Pulsatile Flow on bMSC-Derived Endothelial-Like Cells in a Small-Sized Artificial Vessel Made by 3-Dimensional Bioprinting

Replacement of small-sized vessels is still challenging. This study is aimed at investigating the possibility of small-sized artificial vessels made by 3-dimensional bioprinting and the effect of pulsatile flow on bMSC-derived endothelial-like cells. Cells were harvested from rabbit bone marrow and primary cultured with or without growth factors. Endothelial differentiation was confirmed by the Matrigel tube formation assay, Western blot, and qRT-PCR. In addition, embedment of endothelial-like cells in an artificial vessel was made by 3-dimensional bioprinting, and the pulsatile flow was performed. For pumped and nonpumped groups, qRT-PCR was performed on CD31 and VE-cadherin gene expression. Endothelial-like cells showed increased gene expression of CD31 and VE-cadherin, and tube formation is observed at each week. Endothelial-like cells grow well in a small-sized artificial vessel made by 3-dimensional bioprinting and even express higher endothelial cell markers when they undergo pulsatile flow condition. Moreover, the pulsatile flow condition gives a positive effect for cell observation not only on the sodium alginate hydrogel layer but also on the luminal surface of the artificial vessel wall. We have developed an artificial vessel, which is a mixture of cells and carriers using a 3-dimensional bioprinting method, and applied pulsatile flow using a peristaltic pump, and we also demonstrated cell growth and differentiation into endothelial cells. This study suggests guidelines regarding a small-sized artificial vessel in the field of tissue engineering.

Contribution of Titanium, Chromium and Carbon Buffer Interlayers to Bio-Tribological Properties of Multilayer Composites

Research studies on bio-tribological protective coatings of titanium, chromium and carbon based have been performed. Thin films were fabricated by hybrid PLD technique (PLD supported by magnetron sputtering). Coatings consisted of two parts; the inner part (first from the substrate) in each case was formed by titanium or chromium/titanium nitride or chromium nitride (Ti/TiN or Cr/Cr2N). The outer part was formed by pure DLC or multilayer DLC/Ti or Cr. No delamination was found at the interface. Titanium or chromium metallic layer was deposited as a first layer directly on the metallic substrate to avoid delamination. All individual layers were built of columnar nano-crystallites. Mechanisms of the mechanical wear of analyzed systems were presented, focusing on the cracking propagation in ball-on-disc tests using an 1 N and 5 N applied loads for 5 000 cycles. Complex microstructure analysis of presented nano-multilayer coatings, before and after mechanical tests, were performed by means of transmission electron microscopy (TEM). The highest stress concentration during mechanical uploading was moved through the multilayer coating by breaking only one layer at the time. The microstructure characterization revealed that cracking propagating in the outer part of the coating was stopped at the interface. In the case of the inner part of the coating Ti/TiN; Cr/Cr2N, ceramic layers showed brittle cracking, while metallic (Ti or Cr) ones deformed plastically. Fabricated coatings were subjected under the analysis in the biomechanical system optimized to test for the direct contact with a human whole blood. The study considered physiological conditions mainly related to the temperature and humidity and the frequency of cyclic deformation of the artificial vessel into which the tested sample was introduced.