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Biomedical subjects

H Maeta

Publications and source records attributed to H Maeta.

At least 109 records · Page 6Linked to original sources
PubMed1992

[Hematologic and endocrinologic effects of pulsatile cardiopulmonary bypass using a centrifugal pump].

The effects of pulsatile and nonpulsatile flow during cardiopulmonary bypass (CPB) with of centrifugal pump (Sarns) and membrane oxygenator, on blood cells, hemodynamics, and hormonal response were studied. In the pulsatile group (group P) in which pulsatile flow was generated by centrifugal pump and a 20 Fr arterial cannula was used, hemolysis and reduction of platelet count during CPB were more marked than in the nonpulsatile group (group NP), in which the same type of circuit was used. When the 20 Fr arterial cannula was replaced with a 24 Fr cannula (group Pc), the rate of hemolysis during CPB was significantly reduced compared with that in group P (p less than 0.05). The rate of rise in plasma free hemoglobin from 10 to 70 minutes CPB in group Pc was 15.0 mg/dl/hr, this value did not exceed that in either group NP or in group Pr, in which a roller pump rather than centrifugal pump was used to generate pulsatile flow. These findings show that pulsatile CPB with a centrifugal pump produces no deleterious hematologic effect in clinical use. The rise in the level of angiotensin II in group P was significantly smaller than that in group NP (p less than 0.05), and the rise in plasma renin activity and levels of angiotensin I, adrenalin and noradrenaline were smaller than those in group NP, although these differences were no significance. These findings indicate that the centrifugal pump generates pulsatile flow effectively, although not so effectively as to prevent the rise in peripheral vascular resistance. During CPB, there was no change in levels of thyroid hormones, including free T3, free T4 and reverse T3, in either pulsatile groups P and Pc or nonpulsatile group. TSH level in group Pc was significantly elevated in contrast with that in the nonpulsatile group (p less than 0.05), in which no change in TSH level was seen. It is suggested that pulsatile perfusion using a centrifugal pump might maintain sufficient hypothalamic-pituitary function to permit secretion of TSH in response to various stimuli.

Aged↗
PubMed1990

Effect of exogenous surfactant on the development of bronchopulmonary dysplasia in a baboon hyaline membrane disease model.

To test the effect of exogenous surfactant on the evolution of histopathologic changes of bronchopulmonary dysplasia (BPD), we conducted a study in a premature baboon hyaline membrane disease model. One hundred mg/kg bovine surfactant sonicated in saline or 3 ml/kg saline placebo was instilled via the trachea at about 10 min of age. The clinical status and physiologic changes were monitored for 9 days, and pulmonary histopathology was evaluated after death. Compared to the control, the surfactant-treated animals showed a significant improvement in arterial/alveolar oxygen ratio and pulmonary compliance, facilitating rapid weaning from assisted ventilation. Lung histology revealed that pulmonary parenchyma expanded 70% to 95% without features of early BPD. Dysplastic maturation, air trapping, or cellular atypia was not seen. In contrast, lung histology in the control group revealed alveolar expansion less than or equal to 50%, basal cell hyperplasia in the bronchial and bronchiolar epithelium, dysplastic maturation with cellular atypia, extensive epithelial erosion, and type II cell hyperplasia, all features of early BPD. The results of this study suggest that in the premature baboon model, exogenous surfactant therapy improves pulmonary functional abnormalities and lessens the histologic features of BPD, perhaps because of rapid weaning and reduced barotrauma.

Animals↗
PubMed1990

Chest radiographic course after exogenous surfactant therapy in baboons with respiratory distress syndrome.

Exogenous surfactant materials have been used under a variety of treatment protocols in cases of neonatal respiratory distress syndrome (RDS). To evaluate the differences in radiologic changes that follow either an early or late therapy with exogenous bovine surfactant, we reviewed 189 serially obtained chest radiographs from 48 premature baboons with RDS studied under different treatment regimen. Twenty-six animals were controls (100 chest films), and 22 received 100 mg/kg bovine surfactant instilled via the trachea in three study protocols (89 chest films). Surfactant was given within 10 min of birth in one group and at 2 h of age in the other. In 25/26 controls, radiologic evidence of severe RDS was seen by 2 h of age; these changes persisted in 15 animals at 24 h. By contrast, a rapid clearing of radiologic features of RDS was seen following surfactant instillation in all 22 (100%) animals within 4 h, but one (4.5%) of these 22 deteriorated at 9 h of age. Pulmonary interstitial emphysema (PIE) was seen in 9/26 (34.6%) and pneumothorax in 5/26 (19.2%) control animals, while 1/22 (4.5%) surfactant-treated animals developed PIE, and none had pneumothorax. The presence of a shunt via the patent ductus arteriosus did not affect radiographic findings in 20 animals studied by contrast injection. Therapy for patent ductus arteriosus (PDA) also had no substantial influence on the radiographic findings, or with regard to the pulmonary course. Radiographic clearing of RDS occurred approximately 18 to 20 h prior to the improvement in pulmonary compliance.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[A case of ventricular septal perforation with bidirectional shunt and Hegglin like syndrome].

A 47-year-old man with ventricular septal perforation (VSP) was repaired successfully. His preoperative examinations revealed Hegglin like syndrome with fixed and split second heart sound due to early closure of aortic valve (QT-Q II A = 58 ms), and bidirectional shunt through the VSP. These abnormal phenomena occurred due to shortening of left ventricular ejection time and prolongation of right ventricular ejection time, and were completely abolished after the operation.

Cardiac Catheterization↗
PubMed1990

[Differences in loading condition and its effects for valve replacement between chronic aortic and mitral regurgitation].

In order to clarify the differences of left ventricular mechanics between chronic aortic and mitral regurgitation (AR and MR), 23 patients with AR and 17 patients with MR were studied by noninvasive techniques. There were no differences between two types of regurgitation in R/Th, LV dimension, LVEDVI, PWTd, LV mass I and mean blood pressure. However, the peak systolic wall stress (PSWS), ESVI and systolic blood pressure (sBP) of AR were significantly higher than that of MR. One month after valve replacement (VR), in AR all parameters decreased significantly expect increased PWTd. But in MR, blood pressure, LV systolic size and LV mass I were unchanged, although LVDd, LVEDVI, PSWS and R/Th decreased significantly. These results indicates that high PSWS in AR is diminished effectively after AVR by both effects of reduction of LV volume and sBP, although in MR, as a sBP is kept in low level, a drop of PSWS after MVR occurs only due to reduction of volume. Therefore, systolic function after MVR for MR with impaired myocardium may be more destroyed by relatively high afterload as it is difficult to diminish the volume, even if LV function was kept relatively in good condition before operation.

Adult↗
PubMed1989

Treatment of patent ductus arteriosus after exogenous surfactant in baboons with hyaline membrane disease.

The effect of early treatment of patent ductus arteriosus (PDA) on the acute course of hyaline membrane disease was tested in a primate model, after intratracheal administration of 100 mg/kg exogenous bovine surfactant phospholipids at mean ages between 2.3-2.4 h. Twenty-two premature baboons were divided into four groups: seven animals were controls (group A); five were treated with surfactant but PDA was not intervened (group B); in five surfactant treatment was followed by three doses of 0.2 mg/kg intravenous indomethacin beginning at a mean age of 5.5 h (group C); and in five surfactant treatment was followed by a surgical ligation of PDA between 5-5.5 h of age. After surfactant instillation in groups B, C, and D, a prompt and sustained improvement was noted in a/APO2, mean airway pressure, ventilator efficiency index and pulmonary compliance. However, no consistent differences were found in the respiratory variables within the surfactant treated groups during the 72-h experiment: the respiratory course in the animals treated for PDA (groups C and D) was generally similar to the animals in which PDA was not treated (group B). In animals treated with surfactant and indomethacin (group C) the mean aortic blood pressure was maintained more optimally as compared to the other three groups. These findings suggest that although a significant early ductal shunting does occur after exogenous surfactant therapy in this animal model, the expected pulmonary deterioration does not occur, and an early abrupt interruption of PDA does not seem to provide additional advantage to the immediate course of hyaline membrane disease.

Animals↗
PubMed1989

[A technique of end-to-side anastomosis of a prosthetic graft to the ascending aorta: reinforcement of the anastomosis with wrapping of the ascending aorta].

In temporary, permanent or extra-anatomic bypass grafting to the side of the ascending aorta, a technique of prosthetic fabric wrapping of the ascending aorta associated with reinforcement of the anastomosis is devised as a simple and useful method for aortic surgery. With this technique, dislodgement of the vascular forceps can be prevented completely, and the ascending aortic wall may be protected from injuries owing to the vascular forceps.

Anastomosis, Surgical↗
PubMed1989

[Surgical treatment of acute pulmonary embolism--report of two cases].

Two surgical cases of acute pulmonary embolism with severe cardiocirculatory impairment were reported. In the first case, emergent open pulmonary embolectomy with cardiopulmonary bypass was not effective, and multiple and organized emboli were indicative. In the second case, complete pulmonary thromboembolectomy was accomplished under extracorporeal circulation with remarkable hemodynamic improvement. It was suggested that urgent pulmonary angiography was necessary for definitive diagnosis and medical treatment, and that indications for pulmonary embolectomy included all patients with massive emboli in the main branches of the pulmonary artery. Monitoring of pulmonary arterial pressure was important to assess the effect of thrombolytic therapy, and the system of emergent cardiopulmonary bypass was required for immediate and effective cardiopulmonary resuscitation.

Acute Disease↗
PubMed1989

[The importance of aortic compliance as a prognostic factor after aortic valve replacement].

A variety of clinical variables and physiological parameters have been discussed in relation to postoperative survival and symptoms in aortic regurgitation (AR). Many of them have been derived from left ventricular morphology and functions, but there has been no parameter from aortic functions. As the heart is united with the aortic tree to form a circulatory system and both heart and aorta affect each other, aortic functions also have an important prognostic value after aortic valve replacement (AVR). This study was performed to clarify the participation of aortic functions in determining the prognosis after AVR. Fifteen consecutive patients undergoing isolated AVR for AR were evaluated. Twenty-one preoperative hemodynamic and dimensional variables of both heart and aorta were analyzed to determine the risk factors for early postoperative morbidity. These variables were obtained from chest X-ray film, electrocardiogram, echocardiogram, cine-aorto-ventriculogram and pressure manometries. All patients were divided in two groups according to the postoperative course. Group I composed of 10 patients took relatively smooth postoperative course, except two patients suffering from cardiac tamponade. Group II composed of 5 patients suffered from low cardiac output syndrome (LOS) and/or dangerous arrhythmias postoperatively. Two out of them died of uncontrollable ventricular arrhythmias. There were no statistic differences between two groups in the factors derived from preoperative examinations, i.e. CTR, LVDsI, PWT, R/Th, %FS, EDVI, EF, CI, LVEDP, etc. Mean aortic compliance of group II, (3.8 +/- 2.1) X 10(-4) mmHg-1, was, however, significantly lower than that of group I, (21.7 +/- 4.8) X 10(-4) mmHg-1, (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[A case of cardiac myxoma associated with long-term lasting symptoms of mitral stenosis].

We reported a case of 70-year-old woman whose left atrial myxoma was resected. She had been suffered from low cardiac output due to mitral stenosis for 15 years or more. Resection of the myxoma corrected mitral stenosis completely. Cardiac output and pulmonary wedge pressure, however, were not improved following the operation. Postoperative echo- and angiocardiography revealed marked early closure of the mitral valve. These findings indicate that left ventricular compliance should be reduced if inflow stenosis continued for a long period and it is difficult to improve depressed ventricular function even if mitral stenosis is completely removed.

Aged↗
PubMed1988

Response to bovine surfactant (surfactant TA) in two different HMD models (lambs and baboons).

The responses of Surfactant TA instillation in two groups of premature lambs (Group I, 124.8 +/- 1.1 days and Group II, 132.2 +/- 1.2 days, mean +/- SD) and one group of premature baboons (140 +/- 1.6 days) were compared to study the effectiveness of the same surfactant in different animal models. The treatment group received Surfactant TA 100 mg/kg surfactant lipid at 1 to 2 h of age. Control lambs and baboons did not receive surfactant. Sequential measurements of arterial blood gas tension, acid base status, mean airway pressure (MAP) and oxygen requirement (FiO2) were carried out for 8 h after surfactant instillation. The results show that the Group I surfactant-treated lambs improved significantly following instillation. The a/APO2 improved from 0.08 +/- 0.02 before treatment to 0.31 +/- 0.12, and the MAP decreased from 15.8 +/- 0.9 cm H2O to 13.3 +/- 1.3 cm H2O 2.5 h after treatment. At 5.5 h after treatment, the lambs given surfactant deteriorated. Group II treated lambs showed sustained improvement throughout the study period, and improvement in the treated group was not significantly different from Group II control lambs. The surfactant-treated baboons, however, showed sustained and significant improvement in a/APO2 from the time of instillation to the end of the study. These data suggest that the differences in response to the same surfactant therapy between the lamb and baboon models were due to related differences in species, lung maturation, and the differences in response to surfactant, i.e., alveolar leak of protein.

Animals↗
PubMed1988

Effect of acute hypovolemic hypotension on cerebral metabolism in newborn piglets.

To evaluate the temporal changes in cerebral energy metabolism in shock during the perinatal period, we studied cerebral blood flow (CBF) and other metabolic variables in newborn piglets subjected an acute hypovolemic hypotension (HVH). By 30 minutes following HVH, the cardiac output dropped 64%, but the CBF was maintained. Serum glucose rose 110% baseline, resulting in an increase in brain glucose delivery. Cerebral metabolic rate of glucose also increased 246%, while that of oxygen remained unaffected. Further, at 30 minutes of HVH, systemic arterial lactate levels increased 250%, but cerebrospinal fluid (CSF) lactate levels remained in the normal range. By contrast, at 60 minutes following HVH, the CBF dropped 60%, the cerebral metabolic rate for glucose dropped 45%, and that of oxygen 43% of the respective baseline values. A profound systemic lactatemia was noted (500% baseline value), with a concomitant rise in the CSF lactate levels to 190% baseline value. These findings suggest that post-hemorrhagic hypovolemia can be divided into two arbitrary, but distinct phases: 1) An initial phase of relative compensation lasting approximately 30 minutes, during which time the brain utilization of metabolic substrates is well preserved. 2) A later phase of decompensation by 60 minutes of HVH, during which time the CBF as well as brain utilization of metabolic substrates drop significantly. By this time a loss of blood-CSF or brain-CSF barrier for lactate can be seen. The findings of this study may have important implications in the treatment of hemorrhagic shock in the perinatal period.

Animals↗
PubMed1988

Role of red blood cells in the coronary microcirculation during cold blood cardioplegia.

The role of red blood cells during cold blood cardioplegia was studied using an intravital microscope in 13 isolated canine hearts perfused with diluted blood containing potassium chloride. The coronary microcirculation on the left ventricular epicardial surface was observed while the perfusate temperature was varied between 37 degrees C and 10 degrees C. Considerable sludging of red blood cells occurred during hypothermia. The percentage of capillaries perfused by red blood cells (percentage change) significantly decreased as perfusate temperature was reduced (100, 56, and 31% at 37, 20, and 10 degrees C respectively). This was caused by occlusion of microvessels due to sludging and by functional closure due to hypothermia. There was incomplete recovery of perfusion of capillaries at the end of rewarming (60%). The diameters of venules were reduced to 76% of control value at 10 degrees C because of the decrease in the numbers of feeding capillaries, but this value returned to 91% at the end of rewarming. Coronary vascular resistance (mmHg.ml-1.min-1 (kPa.s.litre-1] significantly decreased from 2.0(0.2) at 37 degrees C to 1.2(0.12) at 10 degrees C, but it increased to 2.4(0.24) at the end of rewarming. The finding in this study that sludging occurred which was slow to clear is a definite disadvantage of perfusion with red blood cells during hypothermia.

Animals↗
PubMed1988

[Extra-anatomic bypass operation of ruptured thoracoabdominal aortic aneurysm].

A successful surgical case of ruptured thoracoabdominal aortic aneurysm of Crawford type III was reported. The patient was a 40-year-old male suffering from cystic kidney, hypertension and dissecting aortic aneurysm. The operative procedure was implantation of a large Dacron graft between the ascending aorta and the common iliac arteries, with branches of small Dacron grafts anastomosed to the left common carotid, left subclavian, celiac, superior mesenteric and renal arteries, and exclusion of the aorta.

Adult↗
PubMed1988

Early and late surfactant treatments in baboon model of hyaline membrane disease.

Because the issue of optimal time for artificial surfactant therapy for hyaline membrane disease has not been established, the effects of treatment with a reconstituted bovine surfactant (surfactant TA) were compared at two time periods in a hyaline membrane disease model in a premature baboon. The baboons were delivered by cesarean section at 75% of gestation (139.5 +/- 1.5 days, mean +/- SD). One group was treated with surfactant TA within ten minutes after birth (ultraearly), another group was treated at two hours of age (late) and a third (comparison group) did not receive the surfactant. Both treatment groups had significantly higher compliance and ratio of arterial to alveolar Po2 ratio and lower mean airway pressure and oxygen requirement (Fio2) than the comparison group. At autopsy, the largest residual volume and hysteresis in pulmonary pressure-volume curves were noted in the ultraearly group, intermediate values were found in the late group, and least values were found in the comparison group. These data indicate that early surfactant therapy for hyaline membrane disease results in greater improvement in lung mechanics than delaying treatment, even for two hours. Delivery room treatment with surfactant of infants at risk for hyaline membrane disease is perhaps better than therapy for established hyaline membrane disease.

Animals↗