Trends in recurrence of primary spontaneous pneumothorax in young population after treatment for first episode based on a nationwide population data.

The aim of this study is to identifying post treatment recurrence rates in pneumothorax patients under 35 and without any comorbidities according to the treatment types, gender, and age categories based on nationwide population data. Clinical information of pneumothorax patients was extracted from the Korean National Health Insurance Service (NHIS) database between January 2002 and December 2020. Enrolled patients were categorized into two groups; (1) Group I, those who underwent conservative management including pain relief, oxygen therapy, and closed thoracostomy, and (2) Group II, surgical intervention. Recurrence rates were compared according to age, gender, and type of treatment. Surgical intervention was performed in 25.6% patients as first treatment. The overall recurrence rate was 20.3%. Male patients showed a higher 5-year recurrence rate than female (20.8% vs. 10.9%, p < 0.001). Those with conservative management showed lower 5-year recurrence rates than those with surgical treatment (7.9% vs. 23.7%, p < 0.001). The 5-year recurrence rates of patients aged 14≤, and < 20 was higher than other age groups (29.2% vs. 4.5 and 11.9%, p < 0.001). Surgical intervention, male gender and aged under 20 showed association with higher recurrence rates.

Development of a Multi-Layer Skin Substitute Using Human Hair Keratinic Extract-Based Hybrid 3D Printing.

Large-sized or deep skin wounds require skin substitutes for proper healing without scar formation. Therefore, multi-layered skin substitutes that mimic the genuine skin anatomy of multiple layers have attracted attention as suitable skin substitutes. In this study, a novel skin substitute was developed by combining the multi-layer skin tissue reconstruction method with the combination of a human-derived keratinic extract-loaded nano- and micro-fiber using electrospinning and a support structure using 3D printing. A polycaprolactone PCL/keratin electrospun scaffold showed better cell adhesion and proliferation than the keratin-free PCL scaffold, and keratinocytes and fibroblasts showed better survival, adhesion, and proliferation in the PCL/keratin electrospun nanofiber scaffold and microfiber scaffold, respectively. In a co-culture of keratinocytes and fibroblasts using a multi-layered scaffold, the two cells formed the epidermis and dermal layer on the PCL/keratin scaffold without territorial invasion. In the animal study, the PCL/keratin scaffold caused a faster regeneration of new skin without scar formation compared to the PCL scaffold. Our study showed that PCL/keratin scaffolds co-cultured with keratinocytes and fibroblasts promoted the regeneration of the epidermal and dermal layers in deep skin defects. Such finding suggests a new possibility for artificial skin production using multiple cells.

Motility Improvement of Biomimetic Trachea Scaffold via Hybrid 3D-Bioprinting Technology.

A trachea has a structure capable of responding to various movements such as rotation of the neck and relaxation/contraction of the conduit due to the mucous membrane and cartilage tissue. However, current reported tubular implanting structures are difficult to impelement as replacements for original trachea movements. Therefore, in this study, we developed a new trachea implant with similar anatomical structure and mechanical properties to native tissue using 3D printing technology and evaluated its performance. A 250 µm-thick layer composed of polycaprolactone (PCL) nanofibers was fabricated on a rotating beam using electrospinning technology, and a scaffold with C-shaped cartilage grooves that mimics the human airway structure was printed to enable reconstruction of cartilage outside the airway. A cartilage type scaffold had a highest rotational angle (254°) among them and it showed up to 2.8 times compared to human average neck rotation angle. The cartilage type showed a maximum elongation of 8 times higher than that of the bellows type and it showed the elongation of 3 times higher than that of cylinder type. In cartilage type scaffold, gelatin hydrogel printed on the outside of the scaffold was remain 22.2% under the condition where no hydrogel was left in other type scaffolds. In addition, after 2 days of breathing test, the amount of gelatin remaining inside the scaffold was more than twice that of other scaffolds. This novel trachea scaffold with hydrogel inside and outside of the structure was well-preserved under external flow and is expected to be advantageous for soft tissue reconstruction of the trachea.

Comparison of Hemodynamic Energy between Expanded Polytetrafluoroethylene and Dacron Artificial Vessels.

BACKGROUND: Artificial grafts such as polyethylene terephthalate (Dacron) and expanded polytetrafluoroethylene (ePTFE) are used for various cardiovascular surgical procedures. The compliance properties of prosthetic grafts could affect hemodynamic energy, which can be measured using the energy-equivalent pressure (EEP) and surplus hemodynamic energy (SHE). We investigated changes in the hemodynamic energy of prosthetic grafts. METHODS: In a simulation test, the changes in EEP for these grafts were estimated using COMSOL MULTIPHYSICS. The Young modulus, Poisson ratio, and density were used to analyze the grafts' material properties, and pre- and post-graft EEP values were obtained by computing the product of the pressure and velocity. In an in vivo study, Dacron and ePTFE grafts were anastomosed in an end-to-side fashion on the descending thoracic aorta of swine. The pulsatile pump flow was fixed at 2 L/min. Real-time flow and pressure were measured at the distal part of each graft, while clamping the other graft and the descending thoracic aorta. EEP and SHE were calculated and compared. RESULTS: In the simulation test, the mean arterial pressure decreased by 39% for all simulations. EEP decreased by 42% for both grafts, and by around 55% for the native blood vessels after grafting. The in vivo test showed no significant difference between both grafts in terms of EEP and SHE. CONCLUSION: The post-graft hemodynamic energy was not different between the Dacron and ePTFE grafts. Artificial grafts are less compliant than native blood vessels; however, they can deliver pulsatile blood flow and hemodynamic energy without any significant energy loss.

Cellular channelopathy mediated by hypergravity: IL-6-mediated Nkcc1 activation and enhanced Trpm2 expression in rat atrium.

Although cardiac tissue is considered a target of gravitational force (g-force), the mechanism of hypergravity on the ion modulation or identification of ion transporters is still unknown. Thus, we determine the effect of hypergravity on a physical force-sensitive cytokine, IL-6 and its related channel activity to investigate rat cardiac function changes in response to accelerated g-force. Serum IL-6 levels and intracellular calcium levels of the right atrium were moderately increased under hypergravity stimulation (4g). IL-6 was involved in the modulation of sodium-potassium-chloride cotransporter (Nkcc) activity. Surprisingly, the right atrium under 4g revealed significantly enhanced Nkcc1 activity. The use of IL-6 on the NKCC1-overexpressed or native NKCC-expressing cells also showed enhanced NKCC1 activity. Hypergravity conditions were also involved in the oxidative stress activated Trpm2 channel and revealed an enhanced expression of the Trpm2 channel under 4g in the rat right atrium. In conclusion, hypergravity revealed that moderate increases in serum IL-6 and enhanced Nkcc1 activity was modulated by IL-6. In addition, enhanced Trpm2 channel expression could be involved in the increased intracellular calcium levels of the right atrium under hypergravitational force. We therefore address that enhanced physical force-sensitive cytokine and oxidative stress by the gravitational force mediate activation of the cotransporter involved in possibilities of edema and calcium loading in cardiac tissue.

Quantitative proteomic analysis of bile in extrahepatic cholangiocarcinoma patients.

Background and Aims: Extrahepatic cholangiocarcinoma (CCA) without liver-fluke is increasing. Multifactorial carcinogenesis makes it hard to find biomarkers related to CCA. Although there are a few studies of bile proteomics, these showed different protein profiles because of having heterogeneous groups of patients and different sampling methods. Our aim was to identify the specific bile proteins of extrahepatic CCA patients. Methods: We collected bile from 23 patients undergoing endoscopic nasobiliary drainage in Korea University Guro Hospital from May 2018 to January 2019. The CCA group included 18 patients diagnosed with extrahepatic CCA, and the control group included 5 patients with benign biliary conditions. We analyzed bile proteome using liquid chromatography mass spectrometry. We compared the relative abundance of various proteins in the CCA and control groups. Results: In all, we identified a total of 245 proteins in the bile of CCA and control patients. Increased top 14 proteins in CCA patients were immunoglobulin kappa light chain, apolipoprotein B, inter-alpha-trypsin inhibitor heavy chain H4, apolipoprotein E, Mucin 5B, inter-alpha-trypsin inhibitor heavy chain H1, apolipoprotein A-IV, intercellular adhesion molecule 1, complement C7, complement C5, apolipoprotein C-III, albumin, antithrombin-III, and apolipoprotein A-II. However, the significantly increased proteins in bile of CCA patients comparing with control patients were immunoglobulin kappa light chain, apolipoprotein E, albumin, apolipoprotein A-I, antithrombin-III, α1-antitrypsin, serotransferrin, immunoglobulin heavy constant mu, immunoglobulin J chain, complement C4-A, and complement C3 (p<0.05). Conclusions: In this study, we identified several proteins that were significantly increased in the bile of extrahepatic CCA. Further study is needed to validate them as potential tumor-associated proteins that may be potential biomarkers for CCA.

Development of a heat labile antibiotic eluting 3D printed scaffold for the treatment of osteomyelitis.

In general, osteomyelitis is treated with antibiotics, and in severe cases, the inflammatory bone tissue is removed and substituted with poly (methyl methacrylate) (PMMA) beads containing antibiotics. However, this treatment necessitates re-surgery to remove the inserted PMMA beads. Moreover, rifampicin, a primary heat-sensitive antibiotic used for osteomyelitis, is deemed unsuitable in this strategy. Three-dimensional (3D) printing technology has gained popularity, as it facilitates the production of a patient-customized implantable structure using various biodegradable biomaterials as well as controlling printing temperature. Therefore, in this study, we developed a rifampicin-loaded 3D scaffold for the treatment of osteomyelitis using 3D printing and polycaprolactone (PCL), a biodegradable polymer that can be printed at low temperatures. We successfully fabricated rifampicin-loaded PCL 3D scaffolds connected with all pores using computer-aided design and manufacturing (CAD/CAM) and printed them at a temperature of 60 °C to prevent the loss of the antibacterial activity of rifampicin. The growth inhibitory activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), the representative causative organisms of osteomyelitis, was confirmed. In addition, we optimized the rifampicin-loading capacity that causes no damage to the normal bone tissues in 3D scaffold with toxicity evaluation using human osteoblasts. The rifampicin-releasing 3D scaffold developed herein opens new possibilities of the patient-customized treatment of osteomyelitis.

Simulated microgravity with floating environment promotes migration of non-small cell lung cancers.

A migration of cancer is one of the most important factors affecting cancer therapy. Particularly, a cancer migration study in a microgravity environment has gained attention as a tool for developing cancer therapy. In this study, we evaluated the proliferation and migration of two types (adenocarcinoma A549, squamous cell carcinoma H1703) of non-small cell lung cancers (NSCLC) in a floating environment with microgravity. When we measured proliferation of two NSCLCs in the microgravity (MG) and ground-gravity (CONT), although initial cell adhesion in MG was low, a normalized proliferation rate of A549 in MG was higher than that in CONT. Wound healing results of A549 and H1703 showed rapid recovery in MG; particularly, the migration rate of A549 was faster than that of H1703 both the normal and low proliferating conditions. Gene expression results showed that the microgravity accelerated the migration of NSCLC. Both A549 and H1703 in MG highly expressed the migration-related genes MMP-2, MMP-9, TIMP-1, and TIMP-2 compared to CONT at 24 h. Furthermore, analysis of MMP-2 protein synthesis revealed weaker metastatic performance of H1703 than that of A549. Therefore, the simulated microgravity based cancer culture environment will be a potential for migration and metastasis studies of lung cancers.

Simulated microgravity inhibits C2C12 myogenesis via phospholipase D2-induced Akt/FOXO1 regulation.

The skeletal muscle system has evolved to maintain body posture against a constant gravitational load. Mammalian target of rapamycin (mTOR) regulates the mechanically induced increase in the skeletal muscle mass. In the present study, we investigated mTOR pathway in C2C12 myoblasts in a model of mechanical unloading by creating a simulated microgravity (SM) using 3 D clinorotation. SM decreased the phosphorylation of Akt at Ser 473, which was mediated by mTOR complex 2 (mTORC2), in C2C12 myoblasts, leading to a decrease in the cell growth rate. Subsequently, SM inhibited C2C12 myogenesis in an Akt-dependent manner. In addition, SM increased the phospholipase D (PLD) activity by enhancing PLD2 expression, resulting in the dissociation of mSIN1 from the mTORC2, followed by decrease in the phosphorylation of Akt at Ser 473, and FOXO1 at Ser 256 in C2C12 myoblasts. Exposure to SM decreased the autophagic flux of C2C12 myoblasts by regulation of mRNA level of autophagic genes in a PLD2 and FOXO1-dependent manner, subsequently, resulting in a decrease in the C2C12 myogenesis. In conclusion, by analyzing the molecular signature of C2C12 myogenesis using SM, we suggest that the regulatory axis of the PLD2 induced Akt/FOXO1, is critical for C2C12 myogenesis.

Prognostic imaging of iatrogenic and traumatic ureteral injury by near-infrared fluorescence.

BACKGROUND: Iatrogenic or traumatic ureteral injuries are life-threatening but difficult to diagnose early. Ureteral visualization is essential for both the prevention and diagnosis of iatrogenic or traumatic ureter injuries. In the present study, we evaluated the feasibility of near-infrared (NIR) with ZW800-1C as a diagnostic tool of iatrogenic or traumatic ureteral injury in addition to ureter visualization, compared to methylene blue. METHODS: With mice model, we compared the image quality of ZW800-1C with methylene blue for ureter visualization. We also made ureter perforation, obstruction, crushing injury, and transection model with mice and evaluated the feasibility of ZW800-1C for diagnostic tool for ureteral injuries. RESULTS: We could confirm the ureter in the ZW800-1C images in maximally 30 minutes after injection, and the ureter was visible until NIR imaging concluded at 180 minutes after injection. However, methylene blue failed to provide clear ureter imaging during the same period. ZW800-1C imaging successfully visualized ureters subjected to obstruction, transection, perforation, and crush injuries, although urinary leakage was not visible by eye. CONCLUSIONS: Our results indicate ZW800-1C is better suited for ureter visualization than methylene blue and that ZW800-1C has considerable potential for the early diagnosis of various ureteral injuries.

Development of a flexible 3D printed scaffold with a cell-adhesive surface for artificial trachea.

Trachea stents are widely used to treat stenosis arising from various trachea injuries. However, they are associated with inflammation, re-stenosis, and tracheal obstruction. Seeking to overcome these problems, the development of an artificial trachea using tissue engineering has been explored. However, the artificial trachea did not mimic the natural rigidity and flexibility of the trachea and provide the micro-environment necessary for re-epithelialization. In this study, we developed a thermoplastic polyurethane (TPU) trachea scaffold that possesses a restoration characteristic, using flexible 3D printed patterns, and an improved cell attachment performance, utilizing electrospun fibers. With the aim of enhancing flexibility, we compared two geometric tubes, one with a straight pattern (SP) and the other with a wave pattern (WP). Simulation results showed that the WP scaffold was more flexible than the SP scaffold. A tensile expansion and torsion experiment demonstrated lower tensile strength and elastic modulus, and higher elongation ratio and rotation angle of the WP scaffold. Addition of the electrospun layers increased the tensile strength and elastic modulus and decreased the elongation ratio and rotation angle of both the SP and WP scaffolds. The same trend was observed regardless of electrospinning. However, polycaprolactone (PCL)-based scaffolds displayed lower elongation ratio and rotation angle in simulations and experiments. Although the cell attachment capacity of TPU-based electrospun WP scaffolds was less than 10% that of PCL-based scaffolds, the former showed good initial cell attachment performance and their cell numbers increased by more than three times within a week. The improved biomechanical performance and cell affinity of the TPU trachea scaffold could be exploited in patient-customized grafts for trachea reconstruction.

Optimization of Electrospun Poly(caprolactone) Fiber Diameter for Vascular Scaffolds to Maximize Smooth Muscle Cell Infiltration and Phenotype Modulation.

Due to the morphological resemblance between the electrospun nanofibers and extracellular matrix (ECM), electrospun fibers have been widely used to fabricate scaffolds for tissue regeneration. Relationships between scaffold morphologies and cells are cell type dependent. In this study, we sought to determine an optimum electrospun fiber diameter for human vascular smooth muscle cell (VSMC) regeneration in vascular scaffolds. Scaffolds were produced using poly(caprolactone) (PCL) electrospun fiber diameters of 0.5, 0.7, 1, 2, 2.5, 5, 7 or 10 µm, and VSMC survivals, proliferations, infiltrations, and phenotypes were recorded after culturing cells on these scaffolds for one, four, seven, or 10 days. VSMC phenotypes and macrophage infiltrations into scaffolds were evaluated by implanting scaffolds subcutaneously in a mouse for seven, 14, or 28 days. We found that human VSMC survival was not dependent on the electrospun fiber diameter. In summary, increasing fiber diameter reduced VSMC proliferation, increased VSMC infiltration and increased macrophage infiltration and activation. Our results indicate that electrospun PCL fiber diameters of 7 or 10 µm are optimum in terms of VSMC infiltration and macrophage infiltration and activation, albeit at the expense of VSMC proliferation.

Development of a 3D-Printed Drug-Eluting Stent for Treating Obstructive Salivary Gland Disease.

Most studies of obstructive salivary gland disease have reported only statistical aspects, surgical operations, and prescriptions and have simulated the phenomena occurring in the salivary glands and ductal tissues. However, no direct lesion treatments involving drug-eluting stents have been used to reduce salivary pooling induced by inflammation. In this study, a biodegradable polymer polycaprolactone (PCL)-based antibiotic-eluting stent was developed to treat recurrent obstructive salivary gland disease. The structure's diameter was designed after consideration of the human anatomical structure, and the data were processed in a form suitable for three-dimensional (3D) printing via computer-aided design and manufacturing. After the proper mixing conditions of the antibiotics and PCL were ensured, the optimized printing conditions were secured and the stent was successfully printed with the original lumen size diameter maintained. Amoxicillin and cefotaxime, the antibiotics loaded in this study, did not lose their original antimicrobial activity under the 3D printing process and were effectively released from the constructs for verification of the antimicrobial activity against the causative bacteria according to their concentrations. In addition, antibiotic-eluting stents fabricated in a mesh-like network form were proven stable and capable of sustained release, thereby demonstrating the possibility of treating recurrent obstruction salivary gland disease.

Development of arginine-glycine-aspartate-immobilized 3D printed poly(propylene fumarate) scaffolds for cartilage tissue engineering.

Poly(propylene fumarate) (PPF) has known to be a good candidate material for cartilage tissue regeneration because of its excellent mechanical properties during its degradation processes. Here, we describe the potential application of PPF-based materials as 3D printing bioinks to create macroporous cell scaffolds using micro-stereolithography. To improve cell-matrix interaction of seeded human chondrocytes within the PPF-based 3D scaffolds, we immobilized arginine-glycine-aspartate (RGD) peptide onto the PPF scaffolds. We also evaluated various cellular behaviors of the seeded chondrocytes using MTS assay, microscopic and histological analyses. The results indicated that PPF-based biocompatible scaffolds with immobilized RGD peptide could effectively support initial adhesion and proliferation of human chondrocytes. Such a 3D bio-printable scaffold can offer an opportunity to promote cartilage tissue regeneration.

Feasibility of a 3D Printed Patient-Specific Model System to Determine Hemodynamic Energy Delivery During Extracorporeal Circulation.

Although many have studied the effects of pulsatile flow on extracorporeal circulation, its advantages remain controversial. One reason for this situation is that in most studies, pulsatility was evaluated using an in vitro model system. The most serious disadvantage of such model systems is that they lack consideration of anatomical variations due to the use of a straight tubing line to mimic the aorta. In the current study, the authors constructed and tested the feasibility of a three-dimensional (3D) printed, patient-specific, silicone aortic model to determine whether aortic cannula tip positional changes affect energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE) in carotid arteries. Donovan model systems were connected to a pulsatile pump (Korea hybrid ventricular assist device [KH-VAD]; Korea Artificial Organ Center, Seoul, Korea) and a 3D printed silicone model of the ascending aorta. The KH-VAD mimicked the heart, and another pulsatile pump (Twin-Pulse Life Support [T-PLS]; Newheartbio Co., Seoul, Korea) was connected to an aortic cannula, which was inserted at three different tip positions. Using this 3D printed silicone model of the ascending aorta, it was found that EEP and SHE of both right and left carotid arteries were significantly affected by aortic cannula tip position. The authors suggest that the described 3D printed, patient-specific, aorta model provides a feasible option to measure hemodynamic energy accurately given the considerable anatomical differences of model circuits.

Simulated Microgravity Effects on Nonsmall Cell Lung Cancer Cell Proliferation and Migration.

BACKGROUND: Despite improvements in medical technology, lung cancer metastasis remains a global health problem. The effects of microgravity on cell morphology, structure, functions, and their mechanisms have been widely studied; however, the biological effects of simulated microgravity on the interaction between cells and its eventual influence on the characteristics of cancer cells are yet to be discovered. We examined the effects of simulated microgravity on the metastatic ability of different lung cancer cells using a random positioning machine. METHODS: Human lung cancer cell lines of adenocarcinoma (A549) and squamous cell carcinoma (H1703) were cultured in a 3D clinostat system which was continuously rotated at 5 rpm for 36 h. The experimental and control group were cultured under identical conditions with the exception of clinorotation. RESULTS: Simulated microgravity had different effects on each lung cancer cell line. In A549 cells, the proliferation rate of the clinostat group (2.267 ± 0.010) after exposure to microgravity did not differ from that of the control group (2.271 ± 0.020). However, in H1703 cells, the proliferation rates of the clinostat group (0.534 ± 0.021) was lower than that of the control group (1.082 ± 0.021). The migratory ability of both A549 [remnant cell-free area: 33% (clinostat) vs. 78% (control)] and H1703 cells [40% (clinostat) vs. 68% (control)] were increased after exposure to microgravity. The results of the molecular changes in biomarkers after exposure to microgravity are preliminary. DISCUSSION: Simulated microgravity had different effects on the proliferation and migration of different lung cancer cell lines.Chung JH, Ahn CB, Son KH, Yi E, Son HS, Kim H-S, Lee SH. Simulated microgravity effects on nonsmall cell lung cancer cell proliferation and migration. Aerosp Med Hum Perform. 2017; 88(2):82-89.

The Effect of Pulsatile Versus Nonpulsatile Blood Flow on Viscoelasticity and Red Blood Cell Aggregation in Extracorporeal Circulation.

BACKGROUND: Extracorporeal circulation (ECC) can induce alterations in blood viscoelasticity and cause red blood cell (RBC) aggregation. In this study, the authors evaluated the effects of pump flow pulsatility on blood viscoelasticity and RBC aggregation. METHODS: Mongrel dogs were randomly assigned to two groups: a nonpulsatile pump group (n=6) or a pulsatile pump group (n=6). After ECC was started at a pump flow rate of 80 mL/kg/min, cardiac fibrillation was induced. Blood sampling was performed before and at 1, 2, and 3 hours after ECC commencement. To eliminate bias induced by hematocrit and plasma, all blood samples were adjusted to a hematocrit of 45% using baseline plasma. Blood viscoelasticity, plasma viscosity, hematocrit, arterial blood gas analysis, central venous O2 saturation, and lactate were measured. RESULTS: The blood viscosity and aggregation index decreased abruptly 1 hour after ECC and then remained low during ECC in both groups, but blood elasticity did not change during ECC. Blood viscosity, blood elasticity, plasma viscosity, and the aggregation index were not significantly different in the groups at any time. Hematocrit decreased abruptly 1 hour after ECC in both groups due to dilution by the priming solution used. CONCLUSION: After ECC, blood viscoelasticity and RBC aggregation were not different in the pulsatile and nonpulsatile groups in the adult dog model. Furthermore, pulsatile flow did not have a more harmful effect on blood viscoelasticity or RBC aggregation than nonpulsatile flow.

Surgical Planning by 3D Printing for Primary Cardiac Schwannoma Resection.

We report herein a case of benign cardiac schwannoma in the interatrial septum. A 42-year-old woman was transferred from a clinic because of cardiomegaly as determined by chest X-ray. A transthoracic echocardiography and chest computed tomography examination revealed a huge mass in the pericardium compressing the right atrium, superior vena cava (SVC), left atrium, and superior pulmonary vein. To confirm that the tumor originated from either heart or mediastinum, cine magnetic resonance imaging was performed, but the result was not conclusive. To facilitate surgical planning, we used 3D printing. Using a printed heart model, we decided that tumor resection under cardiopulmonary bypass (CPB) through sternotomy would be technically feasible. At surgery, a huge tumor in the interatrial septum was confirmed. By incision on the atrial roof between the aorta and SVC, tumor enucleation was performed successfully under CPB. Pathology revealed benign schwannoma. The patient was discharged without complication. 3D printing of the heart and tumor was found to be helpful when deciding optimal surgical approach.

Heart monitoring using left ventricle impedance and ventricular electrocardiography in left ventricular assist device patients.

BACKGROUND: Patients who develop critical arrhythmia during left ventricular assist device (LVAD) perfusion have a low survival rate. For diagnosis of unexpected heart abnormalities, new heart-monitoring methods are required for patients supported by LVAD perfusion. Ventricular electrocardiography using electrodes implanted in the ventricle to detect heart contractions is unsuitable if the heart is abnormal. Left ventricular impedance (LVI) is useful for monitoring heart movement but does not show abnormal action potential in the heart muscle. OBJECTIVES: To detect detailed abnormal heart conditions, we obtained ventricular electrocardiograms (v-ECGs) and LVI simultaneously in porcine models connected to LVADs. METHODS: In the porcine models, electrodes were set on the heart apex and ascending aorta for real-time measurements of v-ECGs and LVI. As the carrier current frequency of the LVI was adjusted to 30 kHz, it was easily derived from the original v-ECG signal by using a high-pass filter (cutoff: 10 kHz). In addition, v-ECGs with a frequency band of 0.1 - 120 Hz were easily derived using a low-pass filter. Simultaneous v-ECG and LVI data were compared to detect heart volume changes during the Q-T period when the heart contracted. A new real-time algorithm for comparison of v-ECGs and LVI determined whether the porcine heartbeats were normal or abnormal. Several abnormal heartbeats were detected using the LVADs operating in asynchronous mode, most of which were premature ventricle contractions (PVCs). To evaluate the accuracy of the new method, the results obtained were compared to normal ECG data and cardiac output measured simultaneously using commercial devices. RESULTS: The new method provided more accurate detection of abnormal heart movements. This method can be used for various heart diseases, even those in which the cardiac output is heavily affected by LVAD operation.

Evaluation of the Performance and Safety of a Newly Developed Intravenous Fluid Warmer.

To evaluate the performance and safety of a newly developed blood warmer (ThermoSens), we tested its heating capability under various conditions using isotonic saline and hemolysis analysis with swine blood. The following two in vitro tests were performed: (i) To investigate the performance of the device, the inflow and outflow temperatures were measured at various flow rates (30, 50, and 100 mL/min) using cold (5°C) and room temperature (20°C) isotonic saline (0.9%). Several parameters were measured including the highest temperature of the outlet, the time required to reach the highest temperature, and the temperature of the intravenous line. (ii) To investigate the safety of the device, a hemolysis test was performed using swine blood. We obtained 320 mL of whole blood from swine and refrigerated the blood for 35 days at 3°C. In order to replicate the clinical situation, blood flow by gravity and pressure (300 mm Hg) was used. Before and after the heating test, blood samples were obtained and a comparison was made between these samples. Hemoglobin, hematocrit, lactate dehydrogenase, and plasma hemoglobin were used for red blood cell (RBC) damage analysis. The highest outlet temperatures obtained using flow rates of 30, 50, and 100 mL/min were 39.10 ± 0.59, 39.25 ± 0.69, and 37.63 ± 1.03°C, respectively, with cold saline, and 39.40 ± 0.40, 39.66 ± 0.36, and 39.49 ± 0.49°C, respectively, with room temperature saline. Hemolysis tests showed no significant changes in hemoglobin, hematocrit, lactate dehydrogenase, or plasma hemoglobin (P > 0.05) between before and after heating for both gravity and pressure blood flow. The ThermoSens blood warmer warms isotonic saline effectively, reaching temperatures up to 36°C under various conditions. Hemolysis tests showed no RBC damage. Therefore, the newly developed ThermoSens has good heating performance and is safe for RBC products.