Application of the Pulsatile Cardiopulmonary Bypass in Animal Model / 대한흉부외과학회지

BACKGROUND: Currently, the cardiopulmonary machine with non-pulsatile pumps, which are low in internal circuit pressure and cause little damage to blood cells, is widely used. However, a great number of experimental studies shows that pulsatile perfusions are more useful than non-pulsatile counterparts in many areas, such as hemodynamic, metabolism, organ functions, and micro-circulation. Yet, many concerns relating to pulsatile cardiopulmonary machines, such as high internal circuit pressure and blood cell damage, have long hindered the development of pulsatile cardiopulmonary machines. Against this backdrop, this study focuses on the safety and effectiveness of the pulsatile cardiopulmonary machines developed by a domestic research lab. MATERIAL AND METHOD: The dual-pulsatile cardiopulmonary bypass experiment with total extracorporeal circulation was conducted on six calves. Extracorporeal circulation was provided between superior/inferior vena cava and aorta. The membrane oxygenator, which was placed between the left and right pumps, was used for blood oxygenation. Circulation took four hours. Arterial blood gas analysis and blood tests were also conducted. Plasma hemoglobin levels were calculated, while pulse pressure and internal circuit pressure were carefully observed. Measurement was taken five times; once before the operation of the cardiopulmonary bypass, and after its operation it was taken every hour for four hours. RESULT: Through the arterial blood gas analysis, PCO2 and pH remained within normal levels. PO2 in arterial blood showed enough oxygenation of over 100 mmHg. The level of plasma hemoglobin, which had total cardiopulmonary circulation, steadily increased to 15.87+/-5.63 mg/dl after four hours passed, but remained below 20 mg/dl. There was no obvious abnormal findings in blood test. Systolic blood pressure which was at 97.5+/-5.7 mmHg during the pre-circulation contraction period, was maintained over 100 mmHg as time passed. Moreover, diastolic blood pressure was 72.2+/-7.7 mmHg during the expansion period and well kept at the appropriate level with time passing by. Average blood pressure which was 83+/-9.2 mmHg before circulation, increased as time passed, while pump flow was maintained over 3.3 L/min. Blood pressure fluctuation during total extracorporeal circulation showed a similar level of arterial blood pressure of pre-circulation heart. CONCLUSION: In the experiment mentioned above, pulsatile cardiopulmonary machines using the doual-pulsatile structure provided effective pulsatile blood flow with little damage in blood cells, showing excellence in the aspects of hematology and hemodynamic. Therefore, it is expected that the pulsatile cardiopulmonary machine, if it becomes a standard cardiopulmonary machine in all heart operations, will provide stable blood flow to end-organs.

Cadaver Fitting Test of Mechanical Circulatory Assist Device Including Korean Artificial Heart (AnyHeart) in Korea / 대한해부학회지

Preclinical cadaver fitting study is paramount in the development of various implantable medical devices. It helps to evaluate the fitness of the size, shape, structure of the devices in the human anatomy, to locate the most optimal site for implantation, and to develope the clinically available surgical techniques. The purpose of this study was to observe the anatomical feasibility of Korean artificial heart (AnyHeart) in 12 human cadavers after obtaining the permission from the Korea University Anatomical Research Committee. The observation was focused on proper position of the artificial heart in various thoracic incisions (median sternotomy, right thoracotomy, left thoracotomy, transsternal incision), localization of inflow as well and outflow tract, cannulation sites, and so on. Results showed that Korean artificial heart had excellent anatomical feasibility in the human body and that a novel surgical technique of right thoracotomy approach was proved to be clinically applicable. Conclusively, the above results will provide the rationales of clinical trial and demonstrate the significance of human cadaver study in development of implantable medical devices.

A Clinical Experience of Korean Artificial Heart(AnyHeart) / 대한흉부외과학회지

Korean artificial heart(AnyHeart) is a single-pieced and implantable bi-ventricular pulsatile pump adapting a moving actuator mechanism. The authors report a case of clinical application of AnyHeart as a life-saving device for the patients with end-stage heart disease combined with biventricular failure.

Surgical Technique for Korean Artificial Heart(AnyHeart) Implantation Using a Right Thoracotomy Approach / 대한흉부외과학회지

BACKGROUND: The surgical technique for biventricular assist device(BVAD) implantation has mainly consisted of cannulation procedures. A median sternotomy has been the technique of choice as it gives a surgeon an excellent exposure of the heart. However, considering that most patients require a future sternotomy or already have a previous sternotomy, sternotomy-related complication remains a major concern in BVAD implantation. Based on this consideration as well as the clinical experiences of conventional heart surgery, the authors have hypothesized that the cardiac chambers for BVAD cannulation can be approached from the right side of the heart. The purpose of this study to develop a novel surgical technique of right thoracotomy for BVAD implantation in an animal study. MATERIAL AND METHOD: For last two years, 16 (11 calves, 3 canines, and 2 sheep) out of 30 experimental animals with AnyHeart implantation underwent a right thoracotomy. The device was used as an implantable BVAD in 14 animals, a wearable BVAD in 1, and an implantable LVAD in 1. The chest cavity was entered through the 4th intercostal space or the 5th periosteal bed. As for the BVAD use, a right inflow cannula was inserted into the right atrial free wall and a right outflow cannula was grafted onto the main pulmonary artery. A left inflow cannula was inserted into the interatrial groove and a left outflow cannula was grafted on the innominate artery of the ascending aorta. The connecting tubeswere brought out through the thoracotomy wound and connected to the pump located in the subcutaneous pocket at the right flank. RESULT: Except for the 5 animals for a fitting test or during the early learning curve, all recovered smoothly from the procedures. The inflow drainage allowed the pump output 6.5 L/min at the maximum with 3-3.5 L/min in an average. Of the survivors, there noted no procedure-related mortality or morbidity. Necropsy findings demonstrated the well-positioned cannula tips in the each cardiac chamber. CONCLUSION: The technique of right thoracotomy approach in AnyHeart implantation is simple, safe, and reproducible. As it can avoid sternotomy-orresternotomy-related complications, the authors suggest a right thoracotomy approach as one of the techniques for BVAD implantation. The technique would also be suggested as an alternatitve for a median sternotomy in a certain group of patients with various VAD implantations.

Simulation of the Effects of Long-term Implantation of Biventricular Assist Device on the Hemodynamic Parameters in Heart Failure

BACKGROUND AND OBJECTIVES: Ventricular assist device(VAD) was developed for the bridge to cardiac transplantation, but the current research trends proceed to the purpose of bridge to cardiac recovery. We investigated the effects of long-term VAD implantation on the hemodynamic parameters related to the prognosis of heart failure by simulation to provide the preclinical and clinical applicability. MATERIAL AND METHODS: A moving-actuator type artificial heart developed by Seoul National University Artificial Heart Laboratory was used as a model of biventricular assist device. We set initial values of hemodynamic parameters according to the guideline of VAD implantation, and performed simulation of the change of hemodynamic variables related to successful device weaning and the prognosis of heart failure. RESULTS: Cardiac indices (CIs) at 1 hour and 6 months after VAD implantation were 2.98 l/min/m2 and 2.60 l/min/m2, respectively. Systolic/diastolic/mean aorta pressure were 121/84/99 mmHg at 6 months after VAD implantation. During pump-off state at 6 month, each value of hemodynamic parameters were as follows: CI 2.53 l/min/m2, pulmonary capillary wedge pressure 10 mmHg, left ventricular end-diastolic volume 105 ml, left ventricular ejection fraction 0.58, mean aorta pressure 84 mmHg, end-systolic wall stress 108 kdyn/cm2. Peak rate of change of power(peak dPWR(t)/dt) was 5.62x108 dyneXcm/s2 after 6-month VAD implantation. In a real VAD-implanted patient, simulation data were partly compatible with real hemodynamic data, especially in the aspects of predicting VAD weaning. CONCLUSION:Long-term VAD implantation partially improved the values of hemodynamic parameters related to the prognosis, and this simulation results will provide the basic concept and applicability of clinical trial for end-stage heart failure.

Application of th Total Artificial Heart as an Implantable Biventricular Assist Device by Left Thoracotomy in an Ovine Model / 대한흉부외과학회지

BACKGROUND: The purpose of this study was to investigate the possibility of using the moving-actuator type total artificial heart as a biventricular assist device(BVAD) and to establish a safe and effective animal model for the implantation of a BVAD. MATERIAL AND METHOD: Seven Corridale sheep were used in this study wherein left thoracotomy was performed. The left and right outflow cannulas were anastomosed to the descending thoracic aorta and the main pulmonary artery, and the left and right inflow cannulas were inserted to the left atrium and the right atrial appendage. The devices were positioned in the preperitoneal pocket in 4 sheep, in the left pleural cavity in 2 sheep, and externally in 1 sheep. The aPTT was maintained between the 2 and 2.5 times the range that of the baseline. RESULT: Cannulation was carried out successfully in all cases. There was no case of operative death or immediate postoperative death. Three sheep expired postoperatively on the 2nd day because of thromboembolism, an artificial ventilator accident, and device and respiratory failure. Three other sheep died postoperatively on the 4th day because of acute renal and respiratory failure following thromboembolism. One sheep survived for 28 days. Experimentation on this animal terminated due to an electrical short-circuit caused by motor wire erosion. Thrombi were found on the valves of 4 out of 7 animals, especially on the connection between valves and the device. However , there was no thrombus in the cannulas. CONCLUSION: In conclusion, left thoracotomy for insertion of 4 cannulas and placement of device in the preperitoneal space is the safe and effective operative technique in ovine for testing in-vivo biocompatibility of the BVAD. Furthermore, it may be possible to use a moving-actuator type total artificial heart as a BVAD if technical improvements for reducing thromboembolism are carried out.

A Study of Doppler Waveform Using Pulsatile Flow Model

PURPOSE: Through the construction of a pulsatile flow model using an artificial heart pump and stenosis to demonstrate triphasic Doppler waveform, which simulates in vivo conditions, and to evaluate the relationship between Doppler waveform and vascular compliance. MATERIALS AND METHODS: The flow model was constructed using a flowmeter, rubber tube, glass tube with stenosis, and artificial heart pump. Doppler study was carried out at the prestenotic, poststenotic, and distal segments; compliance was changed by changing the length of the rubber tube. RESULTS: With increasing proximal compliance, Doppler waveforms show decreasing peak velocity of the first phase and slightly delayed acceleration time, but the waveform itself did not change significantly. Distal compliance influenced the second phase, and was important for the formation of pulsus tardus and parvus, which without poststenotic vascular compliance, did not develop. The peak velocity of the first phase was inversely proportional to proximal compliance, and those of the second and third phases were directly proportional to distal compliance. CONCLUSION: After constructing this pulsatile flow model, we were able to explain the relationship between vascular compliance and Doppler waveform, and also better understand the formation of pulsus tardus and parvus.

1H MR Spectroscopy in Parkinson's Disease and Progressive Supranuclear Palsy: Preliminary Study

PURPOSE: To determine whether 1H magnetic resonance spectroscopy (MRS) is useful in differentiating idiopathic Parkinson's disease (IPD) from progressive supranuclear palsy (PSP), based on metabolite ratios. MATERIALS AND METHODS: Using a 1.5 T MR Unit, single voxel 1H MRS using STEAM with a TR of 2000ms and a TE of 135ms was performed in seven PD and eight PSP patients. Five age-matched volunteers(mean age, 63 years) andanother five younger healthy volunteers(mean age, 30 years) were studied as normal controls. The regions of interest were the putamen and pallidum, with a size of 2 X 2 X 2cm. After measuring the spectral intensities ofeach metabolite (N-acetylaspartate=NAA, choline=Cho, creatine=Cr and lactate), relative peak height ratios ofNAA/Cr, Cho/Cr and Naa/Cho, and lactate levels among four groups were compared. ESULTS: NAA/Cho and NAA/Crratios were statistically lower in the PSP group than the IPD group (1.21 +/-0.26 versus 1.45 +/-0.20, and 1.26 +/-.23 versus 1.38 +/-0.19, respectively : p0.05). Cho/Cr ratios were not different among four groups. Lactate was not detectedin any patients. CONCLUSION: NAA/Cho and NAA/Cr ratios in the corpus striatum were significantly lower in the PSP group than in the age-matched control and IPD groups. These results suggest that loss of neuron cells in thecorpus striatum is more prominent in PSP than in IPD, and that NAA/Cho and NAA/Cr ratios may help in differential diagnosis of IPD and PSP.

1H MR Spectroscopic Patterns of Normal Adult Brain

PURPOSE: To evaluate regional differences of 1H magnetic resonance(MR) spectral patterns in normal adulthuman brains. MATERIALS AND METHODS: A total of 44 1H MR spectra in 25 volunteers aged 27-45 were obtained infive regions including the frontal lobe(10), parietal lobe(10), temporal lobe(5), basal ganglia(10) and thalamus(9). 1H MR spectroscopy(MRS) was performed using a PRESS sequence with a TR of 2000ms and a TE of 270msfrom a volume of cm on a 1.5T clinical MR unit. Relative metabolite ratios of NAA/Cho, NAA/Cr and CR/Cho in eachregion were measured and compared. RESULTS: A total of 44 reliable spectra were successfully obtained in allregions. NAA/Cho, NAA/Cr and Cr/Cho ratios varied considerably, ranging from 1.09 +/-0.2 to 2.46 +/-0.25, from1.72 +/-0.35 to 2.45 +/-0.25 and from 0.64 +/-0.1 to 1.01 +/-0.12, respectively. Significant regional difference sin metabolite ratios were observed; higher NAA/Cho and NAA/Cr ratios in the parietal lobe, lower NAA/Cho ratios inthe temporal lobe, and lower Cr/Cho ratios in the temporal lobe compared to those of other regions(p<0.05). Differences in metabolite ratios between the right and left frontal lobes, and between the right and left basalganglias were not significant. CONCLUSION: 1H MR spectra of the normal adult human brains using in vivo singlevoxel 1H MRS represented significant regional differences in metabolite ratios of NAA/Cho, NAA/Cr and Cr/Cho. Our1H MR spectroscopic results are a useful ueference for assessing the 1H MRS pattern of various intracranial diseases.

In Vivo Single Voxel 1H MR Spectroscopy in Cerebral Glioma

PURPOSE: To assess the metabolite ratios in gliomas to determine whether the metabolic information obtained by using by using in vivo single vexel 1H magnetic resonance spectroscopy(MRS) can be used as a marker for the grading of malignancy. MATERIALS AND METHODS: A total of 28 1H MR spectra from brain tumors in 27 patients with pathologically-proven gliomas were recorded. Seven patients had low grade gliomas (grade II astrocytoma in three, oligodendroglioma in three and mixed glioma in one), six had anaplastic gliomas (grade III astrocytoma in three and oligodendroglioma in three), and 14 had glioblastoma multiformes (grade IV), 1H MRS was performed on a 1.5T MRunit using PRESS sequence with a TR of 2000ms, a TE of 270 or 135ms and a voxel size of cm for all spectra. Relative lactate levels, NAA/Cho, NAA/Cr and Cho/Cr ratios were measured based on the peak heights of each resonance and compared among gliomas. RESULTS: Most tumors demonstrated decreased NAA, elevated Cho and lactate. Relatively high lactate and Cho levels and markedly decreased NAA level were more frequently observed in the high grade gliomas than in low grade gliomas. Marked elevation of lactate level in the solid component of the tumor was mostly observed in high grade gliomas. In a patient with gliomatosis cerebri, 1H MRS demonstrated a spectral pattern of tumor in filtration in an area that on MR images was apparently normal. However, NAA/Cr, NAA/Cho and Cho/Cr ratios did not significantly correlate, however, with the histologic grading of malignancy. Because of the partial volume effect, the heterogeneity of tumors containing solid and cystic or necrotic components within avoxel limited the interpretation of 1H MRS data for the grading of malignancy. CONCLUSION: The results suggest that in some patients in vivo single voxel 1H MRS may be useful for grading the malignancy of gliomas and evaluating the exact extent of tumors. In solid gliomas, the relative level of lactate appears to be a good markerfor the grading of malignancy.

Left ventricular blood flow velocity line analysis in normal person;a color M-mode digitizing study

No abstract available.

The Effects of Air Bubble on Damping of Arterial Pressure Waves during Monitoring of Mean Arterial Pressure Waves during Monitoring of Mean Arterial Pressure / 대한마취과학회지

By virtus of the development of monitoring system and increasing tendency of critically ill patients. We have performed cannulation of radial artery after Allen's test for the continuous monitoring of arterial pressure. It is very important to measure blood pressure, it gives un many informations in the poor risk patients. During monitoring of blood pressure for several years, we have had much troubles because of damping of arteiral pressure waved due to air bubbles. In this study, we used P25Db pressure tranducer and Spaculab Alpha System for monitering of blood pressure, following cannulation of radial artery. Air bubbles of 0.5ml, 1.0ml, 1.5ml and 2.0ml were inserted into monitering system, i.e. fluid filled catheter respectively. The statistical analysis by paired student T-test showed following results. 1) Systolic blood pressure were decreased significantly from 140+/-14.4 torr of control group to 105+/-15.9 torr, 102 +/-16.1 torr, 99+/-16.2 torr and 99+/-15.2 torr in 0.5ml, 1.0ml, 1.5ml and 2.0 ml air groups respectively. 2) Diastolic blood pressure were increased from 70+/-12.4 torr of control group to 72+/-13.8 torr, 76+/-13.9 torr, 78+/-14.3 torr and 81 +/-13.1 torr in each cases respectively. 3) Pulse pressure were decreased from 40+/-13.3 torr of control group to 33+/-15.4 torr, 26 +/-13.6 torr, 22+/-13.0 torr and 18+/-12.0 torr in each cases respectively. 4) But mean arterial pressure showed no significant changes except in 2.0ml air group. Where showed slight change.