Biomedical subjects

K Tabayashi

Publications and source records attributed to K Tabayashi.

At least 163 records · Page 9Linked to original sources

PubMed1993

Protection of the brain during hypothermic perfusion.

The adequacy of the circuits for brain perfusion has been explored by hemodynamic assessment using the ability of the brain to autoregulate blood flow as an indicator, and by morphologic observation using carbon black or Evans blue infusion into the brain perfused antegradely or retrogradely. It is concluded that the safe pressure of cerebral perfusion needed to maintain cerebral integrity is between 40 and 50 mm Hg in both normothermic and hypothermic perfusions, a pressure that can be generated by nonpulsatile pump flows through the pump greater than 40 mL.kg-1 x min-1. Morphologic studies revealed development of focal infarctions in the brain and destruction of the blood-brain barrier by retrograde cerebral perfusion. The retrograde approach, therefore, is definitely inferior to the antegrade method. Antegrade perfusion for 90 minutes, however, produced minimal cerebral edema, suggesting the need for further improvement even in techniques of antegrade perfusion.

Animals↗

PubMed1993

Protection from postischemic spinal cord injury by perfusion cooling of the epidural space.

To avoid devastating spinal cord injury during aneurysm operations, we evaluated the protective effects of epidural space perfusion cooling during occlusion of the descending thoracic aorta in a canine model. Sixteen dogs were divided into three groups: group 1 (n = 5) underwent 60 minutes of aortic occlusion without epidural space perfusion cooling; group 2 (n = 6), 60 minutes of occlusion with perfusion cooling; and group 3 (n = 5), 120 minutes of occlusion with perfusion cooling. The development of motor disturbance and its severity were examined 7 days after the procedure. In group 1, 1 dog was normal and 4 dogs showed spastic paraplegia with rigidly extended hind limbs. In group 2, 5 dogs were normal and 1 dog was unable to walk although it could move both of its hind legs slightly. In group 3, all 5 dogs were normal. Groups 2 and 3 had a significantly better neurologic outcome than group 1. Histologic examination of the spinal cord in dogs with paraplegia revealed degeneration of gray matter with macrophage infiltration. Histologic examination of the spinal cord in dogs without neurologic deficit showed enlargement of the central canal, light edema, and a small number of dark neurons. We conclude that epidural space perfusion cooling is effective in reducing the incidence of spinal cord injury after temporary occlusion of the descending thoracic aorta.

Animals↗

PubMed1993

Risk analysis of low cardiac output syndrome after valve replacement.

In order to obtain a better understanding of the pathogenesis of the postoperative low cardiac output syndrome (LOS), a multivariate regression analysis was performed, evaluating predictive risk factors quantitatively as a function of plural preoperative variables. A total of 145 cases including 76 MVR (MS 36 MR 40), 42 AVR and 27 DVR were analyzed in this study. Ten historical, 10 hemodynamic and 4 operative risk factors were collected to compose the data file with corresponding status of postoperative cardiac function which was classified as follows. Patients who were not associated with postoperative LOS (Score 1), associated with the LOS which required and responded to ordinal dosage of a catecholamine (Score 2) associated with the LOS which required and responded to maximal dosage of the catecholamine and/or mechanical circulatory support (Score 3), and died of LOS (Score 4). Variables with significant relationships to postoperative LOS, regression equation to LOS score and their multiple correlation coefficients (R) of each group were as follows. MVR group: technical trouble (TT), extracorporeal circulation time (ECCT), change of myocardial preservation methods, delta LVSWI/delta LVEDP, diseased duration, aortic cross clamping time, CTR, Y = -1.16 + 1.01 (TT) + 0.05(ECCT) + 0.16(delta LVSWI/delta LVEDP) + 0.02(CTR), R = 0.76. AVR group: LVMMI, ECCT, cardiac failure, NYHA, Y = -0.71 + 0.03(LVMMI) + 0.004 (ECCT) + 0.22(NYHA), R = 0.78. DVR group: delta LVWI/delta LVEDP, LVMMI, NYHA, LV diastolic eccentricity ratio, ECCT, Y = -0.50 + 0.60 (delta LVWI/delta LVEDP) + 0.003(LVMMI) + 1.18(NYHA) + 0.38(delta LVSWI/delta LVEDP) + 0.003(ECCT), R = 0.87. It was demonstrated that preoperative ergometer exercise study during cardiac catheterization was useful in prediction of postoperative outcomes, especially in the MVR (MS) group.

Adult↗

PubMed1992

Thoracic aortic operations in patients aged 70 years or older.

Thirty-one patients over the age of 70 years (group A) and 72 patients less than 69 years (group B) underwent a variety of thoracic aortic surgical procedures. Early and long-term results and cerebral function were compared between the two groups. Preoperative and postoperative cerebral function was evaluated using mini mental state-Himeji and Wechsler adult intelligence scale tests. The operative mortality of groups A and B was 12.9% and 11.1%, respectively (not significant). There were no significant differences in postoperative complications between the two groups. The late mortality rates of groups A and B were 11.1% and 9.3%, respectively (not significant). There were no significant differences between the two groups in the mini mental state-Himeji test, digit symbol, vocabulary, and total Wechsler adult intelligence scale scores before and after operation. We conclude that thoracic aortic surgical procedures in patients over 70 years of age can be performed with acceptable mortality and morbidity risks. Most patients showed symptomatic improvement.

Adult↗

PubMed1992

Hemodynamic effects of oral amiodarone on left ventricular function before and after global ischemia.

We evaluated the hemodynamic effects of amiodarone on left ventricular (LV) function after global ischemia. Amiodarone was administered orally at 15 mg/kg/day for an average of 28 days to a group of 10 dogs. The concentration of amiodarone in serum and LV myocardium was 0.40 +/- 0.24 micrograms/ml and 44 +/- 27.0 micrograms/g, respectively. This experimental group and a control group of 10 dogs each underwent 120 min of aortic cross-clamping with cold crystalloid cardioplegia resulting in an average myocardial temperature of 15 degrees C. LV function measurements by pulse-transit sonomicrometry and Millar solid-state micromanometers were processed by a minicomputer. Compared to the nontreated control group, oral amiodarone for 28 days produced depression of LV contractility which was reflected by lower slope of the end-systolic pressure-volume relation (Evmax), percentage shortening of segment length, left ventricular pressure-segment length loop area, and slope of the end-systolic pressure-segment length relation (Esmax). After ischemia, percentage recovery of LV global function (Evmax and mean velocity of circumferential fiber shortening) and regional function (Esmax) was significantly better in the amiodarone group than in the control group. We conclude that oral amiodarone for 28 days results in a depression of LV contractility but the combination of amiodarone and ischemia does not act synergistically to further depress postischemic LV function.

Administration, Oral↗

PubMed1992

Changes in myocardial beta-adrenergic receptors during acute rejection of heterotopically transplanted rat hearts.

To evaluate changes of the myocardial beta-adrenergic receptors in acute cardiac graft rejection, the density and binding affinity value of the myocardial beta-adrenergic receptors in heterotopically transplanted rat isografts and allografts were analyzed. Hearts from Fisher rat donors were transplanted either to the Fisher rats (isografts) or to Lewis rats (allografts). Histologic examination of the allografts showed mild to moderate rejection on the seventh and fourteenth days and showed severe rejection on the twenty-first day after transplantation. The density values in the allografts and isografts similarly increased significantly (p < 0.05) above the normal level on the seventh and fourteenth days after transplantation. The density in allografts on the twenty-first day decreased significantly (p < 0.05) below the normal level, while that in isografts remained at the normal level. In contrast, the binding affinity value of myocardial beta-adrenergic receptors in both isografts and allografts did not change after transplantation. These results demonstrated that myocardial beta-adrenergic receptors presented upregulation in mild to moderate rejection, whereas these receptors presented downregulation in severe rejection. The data suggested that downregulation of myocardial beta-adrenergic receptors plays a major role in decreased cardiac contractility during severe rejection, but not during mild and moderate rejection.

Abdomen↗

PubMed1992

[Malfunction of prosthetic valves: pathogenesis and diagnostic measure].

Modality of the malfunction of prosthetic valve often reflects the specific features of its design and materials of the prosthesis. During past 17 years, a total of 499 cases of valve replacements were performed in our institute and among them, 50 cases received redo surgery, in which 52 prosthetic valves were replaced due to their malfunctions. Those replaced prosthetic valves were analyzed in terms of their pathogenesis, onset durations and diagnostic methods of each type of malfunction. The malfunctions included hemolytic anemia, thrombosis or tissue overgrowth and tissue failure of bioprostheses. Hemolytic anemia was experienced in 8 cases with Starr-Edwards (S-E) 2320 (n = 7) and Omni-Science (n = 1) both in the aortic position and those prostheses were replaced at 1-9.6 (mean 4.5) postoperative years (POY). The linearized rate of the complication with the S-E 2320 was 3.0%/patient-years (p-y) and its actuarial event free rate was 62% at 11 POY. Operative findings disclosed cloth wear in 5 and perivalvular leakage in 5 cases. Fourteen Hancock (H) and 3 Angell-Shiley (A-S) bioprostheses experienced tissue failure of valves and they were subjected to reoperation at 3.2-10.0 (mean 6.5) POY. The linearized rates were 4.1%/p-y for H and 4.5%/p-y for A-S with actuarial event free rates at 12 POY of 59 and 56%, respectively. Prosthetic valve thrombosis and/or tissue overgrowth were seen in 17 valves at 1.6-15.1 (mean 9.1) POY.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1992

[Result of surgical treatment of true or dissected thoracic aneurysm: determinants analysis in operative mortality and morbidity].

Between 1986 and 1990, 69 patients underwent surgery either for thoracic aneurysm (27 patients) or aortic dissection (42 patients). Sixty one patients (88%) survived and 8 patients (12%) died after surgery. Main determinants of deaths in 4 patients with true arch aneurysm were bleeding from the sites of aortic clamping or anastomosis and intraoperative severe LOS. Three patients with acute type A dissection died from bleeding due to clamp injury or myocardial ischemia. The cause of death in the patient with chronic type B dissection was associated with brain damage due to hypoxia developed during left heart bypass. Postoperative cardiac, pulmonary, hepatic and renal functions were analyzed in the operative survivors. Cardiac functions were maintained well in all patients except two patients with chronic type A dissection. Four patients, one with true arch aneurysm, 2 with chronic type A and one with chronic type B dissection, required tracheostomy. The mean of maximum total serum bilirubin exceeded 4 mg/dl in the patients with true arch aneurysm, acute and chronic type A dissection. The level of serum creatinine showed slight increase in all patients but prophylactic peritoneal dialysis was performed in one patient with chronic type A dissection. In conclusion, the cause of deaths in most patients with thoracic aneurysm was due to inappropriate operative techniques and circulatory supports during surgery. Without the complication described above, the patients could tolerate surgery well.

Aged↗

PubMed1992

[Postoperative respiratory dysfunction in patients with Stanford type A aortic dissection].

Between 1986 and 1990, 24 patients with Stanford type A dissection (acute; 14, chronic; 10) underwent surgery through median sternotomy. The patients were divided into two groups by a duration of postoperative ICU stay for respiratory care. Six patients in the long-period group stayed in ICU for more than 15 days and 18 patients in the short-period group stayed for less than 15 days after surgery. Acuity of disease, age, sex, operation time, pump time, aortic clamp time, lowest esophageal temperature, amount of blood transfusion, arch manipulation for cerebral perfusion with or without arch reconstruction, occurrence of phrenic nerve palsy and other postoperative complications, postoperative cardiac, hepatic and renal functions were compared between two groups. Conclusions are as follows: 1) Arch manipulation for cerebral perfusion with or without arch reconstruction, phrenic nerve palsy, other complications (pericardial and pleural fluid accumulation, recurrent nerve palsy, postoperative bleeding and coronary spasm) and high serum creatinine level were main factors for prolonged postoperative ICU stay for respiratory care and 2) arch manipulation in the patients with chronic type A aortic dissection induced high incidence of phrenic nerve palsy.

Adult↗

PubMed1992

[Separate perfusion of upper and lower body for ruptured thoracoabdominal aortic aneurysm--a case report].

A case of ruptured thoracoabdominal aortic aneurysm was presented. The patient had emergent replacement of thoracoabdominal aorta with an aid of separate perfusion of upper and lower body. The postoperative course was uneventful. It was suggested that separate perfusion of upper and lower body was useful in the patients who require extensive aortic replacement and who are at substantial risk for spinal cord injury.

Aorta, Abdominal↗

PubMed1991

[Serious complication of retrograde perfusion during repair of dissecting aneurysm: compression of the true lumen].

Between 1982 and 1990, 61 patients underwent the repair of dissecting aneurysm. Retrograde perfusion from the unilateral femoral artery were performed for 56 patients and the selective false lumen perfusion occurred in 3 patients. As for those 3 patients, compression of the true lumen and insufficient cerebral perfusion were suspected. Selective cerebral perfusion and antegrade systemic perfusion from the ascending aortic graft were performed. Although 2 patients took uneventful postoperative courses, 1 patient died of massive brain damage. It is very important to accomplish the means to maintain adequate cerebral circulation as soon as possible toward this fetal complication.

Adult↗

PubMed1991

[A case of total aortic replacement in a patient with Marfan's syndrome].

A 32-year-old male with Marfan's syndrome was admitted to our Department in June, 1989 due to severe back pain that was diagnosed as type III-b dissecting aneurysm. His infrarenal abdominal aorta and bilateral iliac arteries had been replaced in another clinic in 1984 due to true aortic aneurysm. Two years later, Carbrol's operation was performed in our Department for the late development of DeBakey type II dissecting aneurysm. DSA and CT studies indicated the need for total replacement of the entire remaining aorta, since diffuse and extensive dilatation of the false lumen and the presence of an intimal tear at the origin of the left carotid artery were demonstrated. The arch and upper descending thoracic aorta were replaced in June, 1989, and replacement of the total remaining thoracoabdominal aorta was carried out under left heart bypass on September 26, 1989. Abdominal branch arteries and intercostal arteries of the 9th to 11th levels were reattached to the graft as onlay patches. Hoarseness of voice was the only complication. The patient recovered uneventfully and returned to his job after discharge. Although the native aorta had been completely replaced, ambulatory monitoring of the patient's pressure and ECG, performed two months after the operation, showed the normal reflex.

Adult↗

PubMed1991

[Treatment of aneurysms of the aortic arch].

Graft replacement therapy was employed in the treatment of 28 patients with aneurysms involving the aortic arch. Of the 28 patients, 14 had true aneurysms, 13 dissecting aneurysms, and 1 pseudoaneurysm. The operative mortality was 75% (6 of 8 patients) between 1979 and 1986, whereas it was 10% (2 of 20 patients) between 1987 and 1989. Temporary or permanent bypass with vascular graft or heparin coated tube were used in 10 patients (7 patients in the early period, 3 patients in the later period). In this group, 50% hospital mortality occurred. Cardiopulmonary bypass and separate cerebral circulation were used in 16 patients (1 case in the early period, 15 patients in the later period). Thirteen of 16 patients survived this technique. In 2 patients, both in later period, profound hypothermia and circulatory arrest were used. Two patients survived without neurological deficit. Operative mortality decreased since 1987 by the change of bypass technique and operative procedures.

Adult↗

PubMed1991

[Analysis of hepatic and renal dysfunction after surgery of thoracic aneurysm].

To analyze causes of postoperative hepatic and renal dysfunction in patients with thoracic aneurysm, we examined 31 patients who survived surgeries and 2 patients died of MOF. The patients were separated into three groups as follows; Cardiopulmonary bypass (CPB) was used for circulatory support in group A (n = 7), CPB and low flow perfusion during open distal anastomosis in group B (n = 13) and temporary bypass or left atrial distal aorta arterial bypass was used in group C (n = 11). Operation time was significantly longer in group A (9.8 hrs) compared with group C (6.1 hrs). Amount of intraoperative blood transfusion was greater in groups A (4980 ml) and B (4860 ml) compared with group C (2320 ml). Postoperative highest total bilirubin level was significantly greater in group A (7.8 mg/dl) than group C (2.5 mg/dl). LDH was higher in groups A (1322 IU/l) and B (1336 IU/l) than group C (991 IU/l). GOT was higher in group B (200 IU/l) than group C (64 IU/l). There were no significant differences in GPT, creatinine and BUN among the three groups. Operation time and amount of intraoperative blood transfusion were positively correlated with postoperative hepatic function parameters. Two patients died of MOF showed severe hepato-renal dysfunction associated with LOS. The results indicate that hypothermic low flow perfusion during open distal anastomosis do not induce hepatic or renal dysfunction, and postoperative hyperbilirubinemia is resulted from bilirubin overload which patients can tolerate well if they are not complicated with MOF.

Aged↗

PubMed1991

A clinical trial of allopurinol (Zyloric) for myocardial protection.

This study explored myocardial protective effects of allopurinol at various doses. Ninety patients undergoing coronary artery bypass or repair or replacement of cardiac valves were divided into three groups of 30 patients each in accordance with the amount of allopurinol administered to patients in each group. Patients in group I received no allopurinol, those in group II received low-dose allopurinol (total dose 1200 mg), and those in group III received high-dose allopurinol (total dose 2400 mg). Aspartate aminotransferase, cardiac isoenzyme of creatine kinase, and lactic dehydrogenase levels were measured up to 5 days after operation. Concentrations of allopurinol and oxypurinol were also measured before initiation of cardiopulmonary bypass and at the start and at the end of aortic crossclamping. Postoperative aspartate aminotransferase, creatine kinase, and lactate dehydrogenase 1 plus lactate dehydrogenase 2 levels in group III were significantly lower than those in groups I and II. Aspartate aminotransferase, creatine kinase, and lactate dehydrogenase 1 plus lactate dehydrogenase 2 levels in group II were lower than those in group I, without statistically significant differences. Plasma oxypurinol concentrations were significantly higher in group III than in group II. It was concluded that allopurinol had resultant high myocardial protective effects in dose-related fashion, but its effect might be attributed to oxypurinol levels formed by its degradation.

Aged↗

PubMed1990

Aortic regurgitation: ventricular response after aortic valve replacement.

This study was designed to evaluate the usefulness of the ratio of the preoperative regurgitant stroke volume to left ventricular end-diastolic volume (RSV/LVEDV) for assessing the left ventricular function preoperatively. In 26 patients with aortic regurgitation (AR), the percent decrease in LVEDV was compared with the preoperative RSV/LVEDV, ejection fraction (EF), LVEDV, left ventricular end-systolic volume (LVESV) or left ventricular end-diastolic pressure (LVEDP). There was a significant correlation between the percent decrease in LVEDV and RSV/LVEDV. Patients with RSV/LVEDV of more than 0.26 had a significantly smaller postoperative left ventricular end-diastolic volume index (LVEDVI) and left ventricular end-systolic volume index (LVESVI), and a greater postoperative EF than patients with smaller RSV/LVEDV. All but one patient with RSI/LVEDVI larger than 0.0016 LVEDVI had normal postoperative LVEDVI. Based on these findings, it is concluded that the RSV/LVEDV is an useful indicator for preoperative evaluation of left ventricular functions in patients with AR. Surgical intervention for patients with AR should be recommended before the RSI/LVEDVI drops to less than 0.0016 LVEDVI, to expect good postoperative ventricular responses.

Adult↗

PubMed1990

Myocardial preservation: a comparison of oxygenated crystalloid and blood cardioplegia.

The purpose of this experiment was to compare myocardial protective effect after global ischemia using oxygenated crystalloid (CCcO2) and an oxygenated blood (BCcO2) cardioplegic solutions. Post-ischemic ventricular performance was studied in 2 equal (n = 7) groups of dogs subjected to 120 min of global ischemia induced at average myocardial temperatures of 8 degrees C in the CCcO2 group and 18 degrees C in the BCcO2 group. Left ventricular (LV) function included analysis of LV systolic function (global and regional function), LV diastolic function (chamber and myocardial stiffness) and LV relaxation was measured by sonomicrometry and Millar micrometers. Data were processed with a Dec PDP-11/23 computer. In vitro oxygen content (Vol%) measured 3.2 +/- 1.0 (CCcO2) and 9.5 +/- 0.3 (BCcO2). Percent recoveries of LV global function (LVSP, loop area, % shortening, LV dp/dt, mean VCF and E max) in the CCcO2 group were approximately the same as those in the BCcO2 group. There were no significant differences in LV regional function (loop area and % shortening) after ischemia between the two groups. The chamber and myocardial stiffness after ischemia in the CCcO2 group were almost the same as the baseline values. Values in the BCcO2 group were reduced significantly compared to the baseline level. There were significant differences in post-ischemic chamber and myocardial stiffness between the two groups. Post-ischemic maximum negative LV dp/dt in both groups decreased significantly compared to the baseline values. However, the time constant and diastolic interval after ischemia in both groups were approximately the same as the baseline values. We conclude that there were no significant differences in myocardial protective effect between the CCcO2 and BCcO2 groups, and both methods preserved the ischemic myocardium well.

Animals↗

PubMed1990

Long-term results after repair of tetralogy of Fallot.

One hundred sixty-six patients with tetralogy of Fallot including 15 pulmonary atresia repaired since 1971 were analyzed with respect to their physical activities, school or social life, hemodynamics, ECG, reoperation and late mortality. Follow-up period ranged from 1 to 19 years with an average of 9.1. There were 9 late deaths including 4 sudden deaths. Actuarial survival rates at 5 and 13 years were 96.4% and 90.5%, respectively. Eighty-five patients (72.0%) of 118 replied were in NYHA functional class I, 31 (26.3%) in class II and 2 (1.7%) in class III. Thirteen patients (7.8%) demonstrated right ventricular/left ventricular systolic pressure ratio over 0.80 because of inadequate relief of the pulmonary stenosis or obstruction, hypoplasia of the pulmonary artery or external conduit stenosis. Although the left ventricular ejection fraction was maintained at the normal range (0.65 +/- 0.09), that of the right ventricle was below the normal level (0.52 +/- 0.09). Two patients developed complete heart block postoperatively and underwent pacemaker implantations. Complete right bundle branch block was observed in 85 patients including 6 with left axis deviation. Most of the patients after correction of tetralogy of Fallot are in satisfactory conditions. However, some patients have limitations in school or social life because of residual lesions or postoperative complications. It is important to consider the proper operative procedures to avoid these problems.

Adolescent↗