Biomedical subjects

C M Hwang

Publications and source records attributed to C M Hwang.

9 recordsLinked to original sources

PubMed2006

Development of a new pulsatile extracorporeal life support device incorporating a dual pulsatile blood pump.

A new pulsatile extracorporeal life support device (ECLS) has been developed, designed to sustain pulsatile blood flow during emergency cardiopulmonary resuscitations and cardiopulmonary operations. This device features two identical pulsatile pumps that operate alternately and can therefore provide blood inflow in a more uniform manner than similar systems featuring a single-pump configuration. In order to confirm the presumed benefits of this newly-developed dual pulsatile pump configuration, we have conducted a series of in vitro experiments designed to compare the properties of the new system with a single pump system, specifically with regard to pump delivery rate and active filling efficiency. Our results reveal that the dual pump configuration can, indeed, deliver a higher flow than can the single-pump system, and exhibits an active filling efficiency superior to that of the single-pump configuration. We performed a series of animal experiments to measure the pulsatility of the dual-pump configuration in terms of equivalent energy pressure (EEP). In order to measure EEP, we measured femoral arterial pressure and pump outflow. The results of our animal experiments revealed that the newly-developed pulstile ECLS exhibits sufficient pulsatility in terms of the EEP considerations.

Advanced Cardiac Life Support↗

PubMed2005

Study of undifferentiated spondyloarthropathy among first-degree relatives of ankylosing spondylitis probands.

OBJECTIVE: To estimate in a Chinese population the prevalence of undifferentiated spondyloarthropathy (USpA) among first-degree relatives (FDRs) of ankylosing spondylitis (AS) probands, and to compare the clinical features of familial USpA with those of sporadic USpA. METHODS: The FDRs of two separate cohorts of consecutive AS probands were evaluated for the prevalence of USpA, using the Modified New York criteria and the European Spondylitis Study Group criteria for AS and SpA, respectively. Sporadic USpA and FDRs of non-SpA rheumatic patient probands served as separate controls. RESULTS: Among the 301 FDRs of 102 AS probands, 7.0% were USpA. This was 1000 times higher than the 147 FDRs of 40 non-SpA probands (P = 0.00230). Within the AS families, USpA was less male-dominated than AS (33.3 vs 72.5%) (P = 0.006). The only feature distinguishing familial from sporadic USpA was that the percentages of HLA B27 were 100 and 50%, respectively (P<0.001). CONCLUSION: USpA and AS coexist in the same Chinese families, both being predisposed by HLA B27. In these families, a female gender favours the development of USpA rather than AS. A significant subset of sporadic USpA (HLA B27-negative group) has a different genetic predisposition compared with familial USpA.

Adult↗

PubMed2005

The effects of pulsatile versus non-pulsatile extracorporeal circulation on the pattern of coronary artery blood flow during cardiac arrest.

BACKGROUND: In sudden cardiac arrest, the effective maintenance of coronary artery blood flow is of paramount importance for myocardial preservation as well as cardiac recovery and patient survival. The purpose of this study was to directly compare the effects of pulsatile versus non-pulsatile circulation to coronary artery flow and myocardial preservation in a cardiac arrest condition. METHODS: A cardiopulmonary bypass circuit was constructed in a ventricular fibrillation model using fourteen Yorkshire swine weighing 25-35 kg each. The animals were randomly assigned to group I (n=7, non-pulsatile centrifugal pump) or group II (n=7, pulsatile T-PLS pump). Extracorporeal circulation was maintained for two hours at a pump flow of 2 L/min. The left anterior descending coronary artery flow was measured with an ultrasonic coronary artery flow measurement system at baseline (before bypass) and at every 20 minutes after bypass. Serologic parameters were collected simultaneously at baseline, 1 hour, and 2 hours after bypass in the systemic arterial and coronary sinus venous blood. The Mann-Whitney U test of STATISTICA 6.0 was used to determine intergroup significances using a p value of <0.05. RESULTS: The resistance index of the coronary artery was lower in group II and the difference was significant at 40 min, 80 min, 100 min and 120 min (p<0.05). The mean velocity of the coronary artery was higher in group II throughout the study, and the difference was significant from 20 min after starting the pump (p<0.05). The coronary artery blood flow was higher in group II throughout the study, and the difference was significant from 40 min to 120 min (p<0.05) except at 80 min. Serologic parameters showed no differences between the groups at 1 hour and 2 hours after bypass in the systemic and coronary sinus blood (p=NS). CONCLUSION: In the cardiac arrest condition, pulsatile extracorporeal circulation provides more blood flow, higher flow velocity and less resistance to coronary artery than non-pulsatile circulation.

Animals↗

PubMed2003

Applications of the pulsatile flow versatile ECLS: in vivo studies.

INTRODUCTION: T-PLS (Twin-Pulse Life Support) is the first commercial pulsatile ECLS (Extra Corporeal Life Support) device (1). The dual sac structure of T-PLS can effectively reduce high membrane oxygenator inlet pressure and hemolysis. To verify both the use of T-PLS for ECLS and the advantages of T-PLS, we tested various models. METHOD AND RESULTS: In the partial CPB (cardio pulmonary bypass) model (swine), T-PLS (N = 6), and Biopump (N = 2), a single pulsatile pump (N = 2), were compared. In the case of single pulsatile flow, during pump systole, pressure increased to 700 - 800 mmHg at the inlet port of the membrane oxygenator. fHb, a hemolysis measurement value, was about 80 mg/dL at 3 hours. On the contrary, because of T-PLS's dual sac system, the pressure of T-PLS had a maximum value of about 250 mmHg and fHb was similar to that of the commercial centrifugal pumps. In the total CPB model (bovine, N = 6), the heart was stopped via cardioplegia (Kcl). T-PLS flow was maintained at 3.0-4.5 L/min. T-PLS functioned like a natural heart, having a pulse pressure of 26-43 mmHg and a pulse rate of 40-60 bpm (beats per minute). In the emergency case model (canine, N = 6), T-PLS was started 10 minutes after cardiac arrest from electronic shock. In spite of cardiac arrest for a period of 40 minutes, the heart was recovered after defibrillation. In the ARDS (Acute Respiratory Distress Syndrome) model (canine, N = 6), minimal ventilator parameters were set: tidal volume 130 ml, respiration rate = bpm, FiO2 = 10%. Three hours after starting T-PLS, PO2 of the carotid artery blood (after 2 hours: 195 +/- 89.4; after 3 hours: 258 +/- 99.3 mmHg) was above half the value of the femoral artery but was within normal range. CONCLUSION: It is suggested that a portable pulsatile ECLS like T-PLS may be used as a CPB device and as an alternative CPR (cardiopulmonary resuscitation) device in the case of cardiac arrest. Due to the pulsatile flow, oxygenated blood is delivered to the patient without overloading the ARDS patients heart.

Animals↗

PubMed2002

Application of the moving-actuator type pump as a ventricular assist device: in vitro and in vivo studies.

A moving actuator type pump has been developed as a multifunctional Korean artificial heart (AnyHeart). The pump consists of a moving actuator as an energy converter, right and left sacs, polymer (or mechanical) valves, and a rigid polyurethane housing. The actuator containing a brushless DC motor moves back and forth on an epicyclical gear train to produce a pendular motion, which compresses both sacs alternately. Of its versatile functions of ventricular assist device and total artificial heart use, we have evaluated the system performance as a single or biventricular assist device through in vitro and in vivo experiments. Pump performance and anatomical feasibility were tested using various animals of different sizes. In the case of single ventricular assist device (VAD) use, one of the sacs remained empty and a mini-compliance chamber was attached to either an outflow or inflow port of the unused sac. The in vitro and in vivo studies show acceptable performance and pump behavior. Further extensive study is required to proceed to human application.

Animals↗

PubMed2002

Changes in the clinical and laboratory features of lupus patients after the big earthquake in Taiwan.

In order to understand the impact of the massive earthquake on disease activity, 60 patients with systemic lupus erythematosus (SLE) living in the earthquake area (group 1) and 31 patients living away from the area (group 2) were enrolled in this study. A questionnaire was used to record demographic data and clinical manifestations before and 6 months after the earthquake. Laboratory tests, including serum C3, C4, creatinine, anti-DNA antibody, CBC and 24 h urine protein were taken. The results showed that nine patients in group 1 had obvious disease flare-up as evidenced by fever, arthralgia, malar rash and photosensitivity, increased protein loss or edema, and other symptoms. However, there were no significant changes in either group 1 or 2 patients. In contrast, the comparison of laboratory parameters in group 1 patients before and after the earthquake showed a significant decrease of C4 from 17.3 +/- 15.3 to 14.1 +/- 7.33 and a significant increase of creatinine from 1.20 +/- 1.54 to 1.27 +/- 1.70 (P < 0.05), respectively. No significant difference for either C4 or creatinine was found in group 2 patients. In conclusion, there was no striking change in the clinical aspects for lupus patients. However, some laboratory results became abnormal in group 1 patients after the earthquake, indicating that their lupus status may have worsened.

Adult↗

PubMed2000

Tissue-engineered heart valve leaflets: an effective method for seeding autologous cells on scaffolds.

BACKGROUND: A precondition for the successful formation of tissue-engineered heart valves is the generation of a proper matrix on biodegradable scaffolds over a limited period of time. The aim of this study was to find an effective method of seeding autologous cells on these scaffolds to create a new matrix for heart valves. METHODS: Myofibroblasts and endothelial cells were isolated and cultured from an ovine artery. A synthetic biodegradable scaffold consisting of polyglycolic and polylactic acids was seeded first with the myofibroblasts, then coated with endothelial cells. Three different methods of myofibroblast seeding were compared: I) daily seeding of myofibroblasts (1x10(6)) for ten days and culture for four days; II) seeding of myofibroblasts (1x10(7)) and culture for 14 days with the use of a simple medium; III) seeding of myofibroblasts (1x10(7)) with the use of a medium containing collagen and culture for 14 days. Light and electron microscopic analyses were performed. RESULTS: The group that used the medium containing collagen showed the best results in terms of seeding efficiency. CONCLUSION: Seeding autologous cells with a medium containing collagen onto the scaffold showed the largest cell population and might generate the best matrix on the scaffold.

Absorbable Implants↗

PubMed1996

Prenatal diagnosis of Hb Bart's hydrops fetalis in West Malaysia: the identification of the alpha thal 1 defect by PCR based strategies.

Haemoglobin Bart's hydrops fetalis is the result of complete absence of functional alpha-globin genes where the fetus is homozygous for the alpha 0-thal gene. Prenatal diagnosis can be made by analysis of fetal DNA from chorionic villus, amniotic cells and fetal blood. Earlier studies for analysing genomic DNA needed digestion with restriction enzymes and hybridisation to radiolabelled probes which took 2 weeks. We have used the polymerase chain reaction (PCR) and non-radioactive primers to identify specific target sequences with results available within 1-3 days for the diagnosis of haemoglobin Bart's syndrome. With fetal blood samples, complete absence of alpha-chain synthesis is confirmed by globin chain electrophoresis on cellulose acetate pH 6.0.

Base Sequence↗

PubMedDate not supplied

Biliary ascariasis: MR cholangiography findings in two cases.

We describe the imaging features of two cases of biliary ascariasis. Ultrasonography and CT showed no specific abnormal findings, but MR cholangiography clearly demonstrated an intraductal linear filling defect that led to the correct diagnosis. MR cholangiography is thus a useful technique for the diagnosis of biliary ascariasis.

Adult↗