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Biomedical subjects

K Tabayashi

Publications and source records attributed to K Tabayashi.

At least 127 records · Page 7Linked to original sources
PubMed1996

Inductions of Cu/Zn superoxide dismutase- and nitric oxide synthase-like immunoreactivities in rabbit spinal cord after transient ischemia.

The distributions and inductions of Cu/Zn superoxide dismutase (SOD), neuronal and endothelial nitric oxide (NO) synthase (nNOS and eNOS), and nitrotyrosine (NT) were immunohistochemically examined in rabbit spinal cords after 5 and 15 min of transient ischemia. The neurons in the anterior horns (AH) were selectively lost 7 days after 15-min ischemia as compared with those of sham-operated controls. In the normal spinal cords, a number of neurons in the AHs were positive for the nNOS, and only slightly positive for the Cu/Zn SOD and the eNOS. Immunoreactivities for the proteins were induced at 8-24 h both after 5- and 15-min ischemia. In contrast, NT-like immunoreactivity was negative both in the normal and postischemic spinal cords. These results suggest that Cu/Zn SOD- and nNOS-, and eNOS-like immunoreactivities are induced, but that, even though an interaction of Cu/Zn SOD with NO could be present, NT was not detected in the motor neurons in the rabbit spinal cords after transient ischemia. Other factors could be required for NT formation found in degenerative motor neuron death in humans.

Animals↗
PubMed1996

Aneurysm of a patent ductus arteriosus in an adult.

An adult patient with a spontaneous aneurysm of a patent ductus arteriosus was successfully treated. The lumen of the aneurysm communicated with the distal aortic arch and the pulmonary artery. Closure of the pulmonary arterial orifice of the ductus arteriosus and replacement of the inferior wall of the distal aortic arch and proximal descending aorta with prosthetic graft were performed under partial cardiopulmonary bypass using a centrifugal pump. The postoperative recovery was uneventful.

Diagnostic Imaging↗
PubMed1996

Successful surgical repair of left atrial dissection after mitral valve replacement.

A rare case of left atrial dissection after mitral valve replacement is reported. Low output syndrome developed in the immediate postoperative period. Cardiac catheterization showed marked elevation of the pulmonary wedge pressure, and left ventriculography revealed massive paraprosthetic leakage with left atrial dissection. At the reoperation, the dissecting cavity was successfully closed from inside the left atrium under cardiopulmonary bypass. We consider this complication another variation of an atrioventricular discontinuity after mitral valve replacement.

Aged↗
PubMed1996

Extracardiac conduit composed of gutter-shaped prosthesis and pedicled pericardial valved patch for pulmonary trunk reconstruction.

A conduit for reconstruction of the pulmonary trunk is presented. A Gelseal vascular prosthesis (Vascutek Ltd, Inchinnan, Scotland) was split longitudinally in two halves, and one half was used as a posterior wall of the conduit like a gutter. The anterior wall was constructed by a pedicled pericardial valved patch. Finally, the proximal anastomosis of the conduit was completed with a gusset cut from the Gelseal prosthesis. This conduit can be applied to patients who require the Rastelli procedure, and growth potential of the pedicled pericardial patch may be expected.

Blood Vessel Prosthesis↗
PubMed1996

Extracting 1/f fluctuation from the arterial blood pressure of an artificial heart.

We have studied the fluctuations of an artificial circulation for the analysis of the physiological aspects; however, the conventionally used fast Fourier transform (FFT) method cannot separate harmonic oscillations, such as respiratory and Mayer waves, from the 1/f fluctuation, which has been though to represent underlying fractal dynamics. Fractal structure was shown in the strange attractor with chaotic dynamics, which is thought to be a flexible and intelligent system. In this study, the coarse-graining spectral analyzing (CGSA) method was utilized to quantitatively evaluate the proportion of the 1/f fluctuation in the total power in the frequency domain and to analyze artificial circulation in the whole system. We implanted two pneumatically actuated ventricular assist devices as biventricular bypasses (BVBs) in chronic animal experiments using 4 healthy adult goats. To compare the natural and prosthetic circulation of each experimental animal, the BVB-type complete prosthetic circulation model with electrically induced ventricular fibrillation was adopted. All hemodynamic parameters of natural and prosthetic circulation were recorded under awake conditions and calculated with the use of a personal computer. With the use of the CGSA method, time-series data of the hemodynamics were analyzed and fractal percentages, extracting the 1/f fluctuation from a given time series, were calculated. Fractal percentages of the arterial blood pressure were 85.8 +/- 10.7% and 82.0 +/- 7.3% with natural and artificial circulation, respectively (not significant [NS]). 1/f fluctuation showed the characteristics of being fractal in a time series. The fractal structure showed robustness and error resistance in nonlinear dynamics. Therefore, our results suggest that the circulatory regulatory system of the artificial heart may have desirable characteristics such as error resistance.

Animals↗
PubMed1996

Left ventricular function following conventional mitral valve replacement in patients with chronic mitral regurgitation.

Conventional mitral valve replacement (MVR) for patients with chronic mitral regurgitation (MR) is usually associated with decrease in left ventricular (LV) ejection fraction (EF). This study investigated the effect of preoperative LV size on LV performance and examined loading conditions before and after conventional MVR. Echocardiographic study was performed on 13 and 9 patients with LV end-systolic dimension of less than 26 mm/m2 (group A) or greater than 26 mm/m2 (group B), respectively. Postoperatively, the LV end-diastolic dimension and EF decreased significantly in both groups. There was a decrease in end-systolic wall stress after MVR. Preoperative LV forward flow estimated by the normalized aortic peak velocity increased significantly in both groups after surgery. The decrease in EF after MVR is not the result of increased systolic loading, and LV performance may not decrease after conventional MVR. Preoperative echocardiographic evaluation can provide important prognostic information in patients with MR undergoing MVR.

Adolescent↗
PubMed1996

[Acute aortic dissection with leg ischemia].

From January of 1987 to July of 1994, 83 patients with acute aortic dissection were treated at our institution. Of these, 7 patients (8%) sustained acute leg ischemia. Angiography showed that one patient had arterial occlusion at the abdominal aorta, three had occlusion at the right common iliac artery, and one had severe right common iliac artery stenosis. Four patients with acute type A dissection underwent emergency replacement of the aortic arch and/or ascending aorta. Three of them were discharged, but one patient died due to renal failure and multiple organ failure. In three patients with acute type B dissection, one with aortic rupture was successfully treated by replacement of the descending thoracic aorta; of the other two who received bypass operations for leg ischemia, one died due to myonephropathic metabolic syndrome and sepsis which were caused by a delay in surgery. In conclusion, emergency thoracic aortic repair should be performed in acute type A dissection with leg ischemia, whereas bypass operation for ischemic leg should be considered in patients of acute type B dissection with leg ischemia when they are not complicated with rupture or visceral ischemia.

Acute Disease↗
PubMed1996

Strange hemodynamic attractor parameter with 1/R total artificial heart automatic control algorithm.

To evaluate the automatic control algorithm of the total artificial heart (TAH) as an entity, and not just as parts, a non-linear mathematical analyzing technique including chaos theory was utilized. Chronic experiments on the biventricular bypass type artificial heart implantation were performed in healthy adult goats after the natural ventricles were removed. Hemodynamic time series data were recorded under the awake standing condition with TAH 1/R and fixed driving. Time series data were recorded on a magnetic tape and analyzed on a personal computer system with an A-D converter. Using the nonlinear mathematical technique, the time series data were embedded into the phase space and the Lyapunov numerical method was carried out for the quantitative evaluation of the sensitive dependence on the initial condition of the reconstructed attractor. Calculation of the largest Lyapunov exponents suggested that the reconstructed attractor of the left pump output during TAH 1/R control was a larger dimensional strange attractor, a characteristic pattern of deterministic chaos. A total system indicating chaotic dynamics was thought to be a flexible and intelligent control system. Thus, our results suggest that 1/R TAH control may be suitable for the biventricular assist type total artificial heart.

Algorithms↗
PubMed1996

Spectral analysis of hemodynamics during left ventricular assistance.

In order to analyze the autonomic nervous system during left ventricular (LV) assistance, fluctuations in hemodynamic derivatives were evaluated by a spectral analyzing method using a fast fourier transform (FFT) methodology. After the left pleural cavity was opened through the fourth intercostal space under general anesthesia, a pneumatically driven ventricular assist system was implanted as in left heart bypasses in chronic animal experiments, using three healthy adult goats. Hemodynamic parameters with and without LV assistance were recorded on a magnetic tape in the awake condition then analyzed in a computer system through an A-D convertor. Power spectral analysis was performed on a beat-to-beat basis for the evaluation of the fluctuations. During copulsation mode LV assistance, Mayer wave fluctuations (0.1 Hz) were significantly increased compared with counterpulsation mode LV assist, suggesting an increase in sympathetic tone. Co-pulsation mode LV assist is reported to increase the afterload of the natural left ventricle, thus, the sympathetic tone may be increased to maintain a natural heart output.

Analysis of Variance↗
PubMed1996

Fluctuations of the hemodynamic derivatives during left ventricular assistance using oscillated blood flow.

To analyze the autonomic nervous system during left heart bypass with a vibrating flow pump (VFP), fluctuations in hemodynamic derivatives were evaluated by the spectral analysis method using fast fourier transform methodology. After the left pleural cavity was opened through the fourth intercostal space under general anesthesia, a VFP was implanted as the left heart bypass device in chronic animal experiments using 3 healthy adult goats. Hemodynamic parameters with and without VFP assistance were recorded on magnetic tape in awake animals and were analyzed by computer through an analog to digital convertor. Power spectral analysis was performed on a beat-to-beat basis for the evaluation of the fluctuations. During left heart bypass with the VFP, Mayer wave fluctuations were decreased significantly although respiratory waves were not changed significantly. These results suggest that sympathetic nervous system modulation was changed under the influences of the left heart bypass with VFP. By using this analysis methodology, truly physiologic ventricular assistance may be achieved.

Animals↗
PubMed1995

Experimental study of physiological advantages of assist circulation using oscillated blood flow.

To estimate the effect of oscillated blood flow on hemodynamics in an awake condition, left ventricular assist circulation using oscillated blood flow was performed on 3 adult goats as chronic animal examination. A vibrating flow pump (VFP) was used for generating high-frequency oscillated flow. The blood flow rate of assisted circulation was approximately 1.0 L/min, and the driving frequency of VFP was 25 Hz. Systemic vascular resistance and arterial impedance were calculated in this study. Systemic vascular resistance during assist circulation was decreased compared with that without assistance. Oscillated blood flow may be effective in decreasing vascular resistance. Moreover, it was suggested from the study of arterial impedance that motive characteristics of the vascular wall against changing blood pressure may keep their normal reaction. Therefore, oscillated blood flow may be used for left ventricular assist circulation as concluded from the study of the characteristics of blood vessels.

Animals↗
PubMed1995

[Supra-annular mitral valve replacement for a patient with prosthetic valve endocarditis].

Supraanular mitral valve replacement with a 29 mm CarboMedics prosthetic valve was performed for a 58-year-old patient of prosthetic valve endocarditis. He has received mitral valve replacement 2 years ago, and was admitted because of high fever and severe heart failure diagnosed mitral regurgitation due to valve dehiscence. An annular abscess was observed and the new 29 mm CarboMedics prosthetic valve was sutured to the left atrial wall approximately 10 mm above the original annulus in order to secure the firm suturings for valve implantation and to left the infected annulus intact. The patient, however, underwent reoperation because of valve dehiscence from atrial wall 6 months after surgery. Infectious abscess at the native mitral annulau was observed to be completely cured, and a mitral prosthesis was implanted at the annulus. The patient is discharged under satisfactory condition.

Endocarditis↗
PubMed1995

[Surgical management of vascular ring in 5 cases].

Five cases of vascular ring are presented. Three cases have double aortic arch and two cases have right aortic arch with aberrant left subclavian artery. Other congenital heart diseases are complicated in four cases. MRI was useful for the evaluation of tracheal and esophageal compression.

Abnormalities, Multiple↗
PubMed1995

[A case of visceral ischemia associated with acute type IIIb aortic dissection].

The case was a 61-year-old man who was transported to our hospital with complaining of severe chest and back pain of sudden onset and diagnosed as acute type IIIb aortic dissection. Inspite of intensive medical treatments, severe abdominal pain with abdominal distension and progressive metabolic acidosis appeared at around 11 hours after admission. Aortogram revealed obstruction of both superior and inferior mesenteric arteries suggesting visceral ischemia associated with acute type IIIb aortic dissection. Emergent operation consisting of bypass grafting for the superior and the inferior mesenteric arteries with saphenous vein, partial resection of small intestine, left hemicolectomy and construction of artificial anus was immediately carried out. The patient had no particular trouble after the operation and returned to the previous job.

Acute Disease↗
PubMed1995

[Separate perfusion of upper and lower body under mild hypothermia during operation on the thoracoabdominal aorta].

During last 7 years, we performed 24 operations on the thoracoabdominal aorta. There were 9 true and 15 dissecting aneurysms. There were two cases of ruptured aneurysm and thoracoabdominal replacement was performed as a last stage operation for total aortic replacement in 4 cases. Three cases with aortic dissection died within 30 days after surgery. Femoro-femoral bypass was used in 4 cases (1 case died of brain damage, paraplegia and MOF), left heart bypass in 5 cases and separate perfusion of upper and lower body (SPULB) under deep hypothermia in 7 cases (2 cases died of LOS and cerebrovascular accident occurred at 2 weeks after operation) and SPULB with mild hypothermia in 8 cases for circulatory support. There was one case of renal dysfunction and transient mild liver dysfunction occurred in 7 cases. There was no evidence on relationship between surgical outcome and methods of circulatory supports, but we recently prefer SPULB under mild hypothermia for thoracoabdominal surgery since intraoperative massive bleeding and cardiac arrest can be easily treated and major organs can be protected by introducing hypothermia in this perfusion technique.

Adult↗
PubMed1995

[Aortitis syndrome with left coronary ostial occlusion and aortic regurgitation: a case report].

A 22-year-old woman with left coronary ostial occlusion and aortic regurgitation due to aortitis syndrome was reported. The coronary artery bypass grafting, using saphenous vein and aortic valve replacement were performed. The distal anastomosis of saphenous vein was performed to left anterior descending artery (Seg. 6), just distal to the origin of circumflex artery. The postoperative course was uneventful. There was no peri-prosthetic valvular leakage and bypass graft was patent.

Adult↗