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.
Acceleration ; Compliance ; Constriction, Pathologic ; Flowmeters ; Glass ; Heart, Artificial ; Pulsatile Flow* ; Rubber

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.
Aorta ; Heart Failure* ; Heart Transplantation ; Heart* ; Heart, Artificial ; Heart-Assist Devices ; Hemodynamics* ; Humans ; Prognosis ; Pulmonary Wedge Pressure ; Seoul ; Stroke Volume ; Weaning

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.
Animals ; Aorta, Thoracic ; Atrial Appendage ; Catheterization ; Catheters ; Heart Atria ; Heart, Artificial* ; Models, Animal ; Pleural Cavity ; Pulmonary Artery ; Respiratory Insufficiency ; Sheep ; Thoracotomy* ; Thromboembolism ; Thrombosis ; Ventilators, Mechanical

No abstract available.
Blood Flow Velocity*

A 76-year-old female present to the emergency department with dysarthria, dizziness, dyspnea. The patient had hypertension and atrial fibrillation. Brain MRI revealed right cerebellar infarction. Transthoracic echocardiography showed a large round mass in the left atrium. Transesophageal echocardiography showed large complex echogenic round mass lesion attached on left atrial side of interatrial septum. Coronary angiogram revealed round movable mass lesion in left atrium with feeding arteries originated from right coronary artery. She underwent removal of mass and Maze operation, and pathologic finding was compatible with myxoma.
Aged ; Arteries ; Atrial Fibrillation ; Brain ; Coronary Vessels ; Dizziness ; Dysarthria ; Dyspnea ; Echocardiography ; Echocardiography, Transesophageal ; Emergencies ; Female ; Heart ; Heart Atria ; Heart Murmurs ; Humans ; Hypertension ; Infarction ; Myxoma

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 : p<0.05). NAA/Cho and NAA/Cr ratios were significantly lower inage-matched controls than in younger normal controls (1.39 +/-0.21 versus 1.76 +/-0.15, and 1.36 +/-0.13 versus1.79 +/-0.17, respectively : p<0.05). However, NAA/Cho and NAA/Cr ratios between age-matched controls and IPD werenot significantly different (p>0.05). 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.
Corpus Striatum ; Humans ; Lactic Acid ; Magnetic Resonance Spectroscopy* ; Neurons ; Parkinson Disease* ; Putamen ; Steam ; Supranuclear Palsy, Progressive*

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.
Adult* ; Brain* ; Frontal Lobe ; Humans ; Parietal Lobe ; Rabeprazole ; Temporal Lobe ; Volunteers

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.
Astrocytoma ; Brain Neoplasms ; Filtration ; Glioblastoma ; Glioma* ; Humans ; Lactic Acid ; Magnetic Resonance Spectroscopy* ; Neoplasms, Neuroepithelial ; Oligodendroglioma ; Population Characteristics