Excision of left atrial myxoma under perfused ventricular fibrillation with hypothermia after coronary artery bypass grafting.

BACKGROUND: Redo heart surgery has become increasingly common but involves additional high surgical risk, especially redo surgery after coronary artery bypass grafting (CABG). CASE PRESENTATION: In this study, we report the case of a 57-year-old Chinese male with left atrium myxoma who had previously undergone CABG. Common surgical methods usually include aortic cross-clamping, administering cold cardioplegia perfusion to protect the myocardium, opening the heart, and then removing the tumor. However, for patients with previous CABG, redo thoracotomy and ascending aortic cross-clamping present a greater risk of damage to the grafted vessels. In this study, we chose a right lateral mini-thoracotomy incision and hypothermia-induced ventricular fibrillation to minimize damage and avoid any adverse effects on the bridge vasculature. The patient recovered uneventfully and was discharged seven days after surgery. CONCLUSIONS: For patients with previous CABG, minimally invasive right thoracotomy under perfused ventricular fibrillation with hypothermia is safe and reliable and can prevent potential damage to the ascending aorta and graft.

30-Day Outcomes of Transcatheter Tricuspid Annuloplasty With the K-Clip System: A Single-Center, Observational Study.

Background: Surgery for isolated functional tricuspid regurgitation (TR) poses a high risk. Several transcatheter approaches are being evaluated for the treatment of such patients. The K-Clip system is a percutaneous approach designed for functional TR; however, its utility remains unknown. Objectives: This study aimed to report the 30-day echocardiographic and clinical outcomes with the K-Clip system for severe TR, including changes in TR severity and NYHA functional class. Methods: Transcatheter tricuspid valve annuloplasty was performed in 39 patients with intermediate or high surgical risk who underwent the K-Clip system. The right internal jugular vein procedure was performed with annuloplasty guided by fluoroscopy and echocardiography. The primary outcomes were clinical success and all-cause mortality at the 30-day follow-up. Results: The K-Clip was successfully implanted in all cases, with 1 to 3 devices deployed. At the 30-day follow-up, none of the patients had died. TR severity was reduced by at least one grade in all patients. There were no severe procedural or 30-day adverse events, except for 1 new pacemaker implantation. The proportion of NYHA class III-IV patients decreased from 79.5% to 5.1%, and the ascites disappeared. The 6-minute walk distance increased by 78 m (P < 0.05), and the Kansas City Cardiomyopathy Questionnaire score improved by 11 points (P < 0.05). Conclusions: The K-Clip device is practical, safe, and effective for patients with severe TR. A 30-day reduction in TR and enhanced cardiac function and quality of life were associated with transcatheter tricuspid annuloplasty using the K-Clip device, according to short-term follow-up studies. (Confirmatory Clinical Study of Treating Tricuspid Regurgitation With K-Clip TM Transcatheter Annuloplasty System [TriStar]; NCT05173233).

Hybrid Nanocomposites of Cellulose/Carbon-Nanotubes/Polyurethane with Rapidly Water Sensitive Shape Memory Effect and Strain Sensing Performance.

In this work, a fast water-responsive shape memory hybrid polymer based on thermoplastic polyurethane (TPU) was prepared by crosslinking with hydroxyethyl cotton cellulose nanofibers (CNF-C) and multi-walled carbon nanotubes (CNTs). The effect of CNTs content on the electrical conductivity of TPU/CNF-C/CNTs nanocomposite was investigated for the feasibility of being a strain sensor. In order to know its durability, the mechanical and water-responsive shape memory effects were studied comprehensively. The results indicated good mechanical properties and sensing performance for the TPU matrix fully crosslinked with CNF-C and CNTs. The water-induced shape fixity ratio (Rf) and shape recovery ratio (Rr) were 49.65% and 76.64%, respectively, indicating that the deformed composite was able to recover its original shape under a stimulus. The TPU/CNF-C/CNTs samples under their fixed and recovered shapes were tested to investigate their sensing properties, such as periodicity, frequency, and repeatability of the sensor spline under different loadings. Results indicated that the hybrid composite can sense large strains accurately for more than 103 times and water-induced shape recovery can to some extent maintain the sensing accuracy after material fatigue. With such good properties, we envisage that this kind of composite may play a significant role in developing new generations of water-responsive sensors or actuators.

Controllable Crimpness of Animal Hairs via Water-Stimulated Shape Fixation for Regulation of Thermal Insulation.

Animals living in extremely cold plateau areas have shown amazing ability to maintain their bodies warmth, a benefit of their hair's unique structures and crimps. Investigation of hair crimps using a water-stimulated shape fixation effect would control the hair's crimpness with a specific wetting-drying process thereafter, in order to achieve the regulation of hair thermal insulation. The mechanism of hair's temporary shape fixation was revealed through FTIR and XRD characterizations for switching on and off the hydrogen bonds between macromolecules via penetration into and removal of aqueous molecules. The thermal insulation of hairs was regulated by managing the hair temporary crimps, that is, through managing the multiple reflectance of infrared light by hair hierarchical crimps from hair root to head.

A collagen-coated sponge silk scaffold for functional meniscus regeneration.

Tissue engineering is a promising solution for meniscal regeneration after meniscectomy. However, in situ reconstruction still poses a formidable challenge due to multifunctional roles of the meniscus in the knee. In this study, we fabricate a silk sponge from 9% (w/v) silk fibroin solution through freeze drying and then coat its internal space and external surface with collagen sponge. Subsequently, various characteristics of the silk-collagen scaffold are evaluated, and cytocompatibility of the construct is assessed in vitro and subcutaneously. The efficacy of this composite scaffold for meniscal regeneration is evaluated through meniscus reconstruction in a rabbit meniscectomy model. It is found that the internally coated collagen sponge enhances the cytocompatibility of the silk sponge, and the external layer of collagen sponge significantly improves the initial frictional property. Additionally, the silk-collagen composite group shows more tissue ingrowth and less cartilage wear than the pure silk sponge group at 3 months postimplantation in situ. These findings thus demonstrate that the composite scaffold had less damage to the joint surface than the silk alone through promoting functional meniscal regeneration after meniscectomy, which indicates its clinical potential in meniscus reconstruction.

Intratendon Delivery of Leukocyte-Poor Platelet-Rich Plasma Improves Healing Compared With Leukocyte-Rich Platelet-Rich Plasma in a Rabbit Achilles Tendinopathy Model.

BACKGROUND: Chronic tendinopathy is a commonly occurring clinical problem that affects both athletes and inactive middle-aged patients. Although some studies have shown that different platelet-rich plasma (PRP) preparations could exert various therapeutic effects in vitro, the role of leukocytes in PRP has not yet been defined under tendinopathy conditions in vivo. PURPOSE: This study compared the effects of the intratendon delivery of leukocyte-poor PRP (Lp-PRP) versus leukocyte-rich PRP (Lr-PRP) in a rabbit chronic tendinopathy model in vivo. STUDY DESIGN: Controlled laboratory study. METHODS: Four weeks after a local injection of collagenase in the Achilles tendon, the following treatments were randomly administered on the lesions: injections of (1) 200 µL of Lp-PRP (n = 8), (2) 200 µL of Lr-PRP (n = 8), or (3) 200 µL of saline (n = 8). Healing outcomes were assessed at 4 weeks after therapy with magnetic resonance imaging (MRI), cytokine quantification, real-time polymerase chain reaction analysis of gene expression, histology, and transmission electron microscopy (TEM). RESULTS: MRI revealed that the Lr-PRP and saline groups displayed higher signal intensities compared with the Lp-PRP group with T2 mapping. Histologically, the Lp-PRP group displayed significantly better general scores compared with the Lr-PRP ( P = .001) and saline ( P < .001) groups. Additionally, TEM showed that the Lp-PRP group had larger collagen fibril diameters than the Lr-PRP group ( P < .001). Enzyme-linked immunosorbent assay showed a significantly lower level of catabolic cytokine IL-6 in the Lp-PRP group compared with the Lr-PRP ( P = .001) and saline ( P = .021) groups. The Lp-PRP group displayed significantly increased expression of collagen I compared with the saline group ( P = .004) but not the Lr-PRP group. Both the Lp-PRP and Lr-PRP groups exhibited significantly lower matrix metalloproteinase (MMP)-1 and MMP-3 expression levels compared with the saline group. However, only the Lp-PRP group displayed significantly higher expression of TIMP-1 than the saline group ( P = .024). CONCLUSION: Compared with Lr-PRP, Lp-PRP improves tendon healing and is a preferable option for the clinical treatment of tendinopathy. CLINICAL RELEVANCE: PRP is widely used in the clinical management of chronic tendinopathy. However, the clinical results are ambiguous. It is imperative to understand the influence of leukocytes on PRP-mediated tissue healing in vivo, which could facilitate the better clinical management of chronic tendinopathy. Further studies are needed to translate our findings to the clinical setting.

Ectopic tissue engineered ligament with silk collagen scaffold for ACL regeneration: A preliminary study.

Anterior cruciate ligament (ACL) reconstruction remains a formidable clinical challenge because of the lack of vascularization and adequate cell numbers in the joint cavity. In this study, we developed a novel strategy to mimic the early stage of repair in vivo, which recapitulated extra-articular inflammatory response to facilitate the early ingrowth of blood vessels and cells. A vascularized ectopic tissue engineered ligament (ETEL) with silk collagen scaffold was developed and then transferred to reconstruct the ACL in rabbits without interruption of perfusion. At 2weeks after ACL reconstruction, more well-perfused cells and vessels were found in the regenerated ACL with ETEL, which decreased dramatically at the 4 and 12week time points with collagen deposition and maturation. ACL treated with ETEL exhibited more mature ligament structure and enhanced ligament-bone healing post-reconstructive surgery at 4 and 12weeks, as compared with the control group. In addition, the ETEL group was demonstrated to have higher modulus and stiffness than the control group significantly at 12weeks post-reconstructive surgery. In conclusion, our results demonstrated that the ETEL can provide sufficient vascularity and cellularity during the early stages of healing, and subsequently promote ACL regeneration and ligament-bone healing, suggesting its clinic use as a promising therapeutic modality. STATEMENT OF SIGNIFICANCE: Early inflammatory cell infiltration, tissue and vessels ingrowth were significantly higher in the extra-articular implanted scaffolds than theses in the joint cavity. By mimicking the early stages of wound repair, which provided extra-articular inflammatory stimulation to facilitate the early ingrowth of blood vessels and cells, a vascularized ectopic tissue engineered ligament (ETEL) with silk collagen scaffold was constructed by subcutaneous implantation for 2weeks. The fully vascularized TE ligament was then transferred to rebuild ACL without blood perfusion interruption, and was demonstrated to exhibit improved ACL regeneration, bone tunnel healing and mechanical properties.