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Biomedical subjects

R Shirakura

Publications and source records attributed to R Shirakura.

At least 163 records · Page 9Linked to original sources
PubMed1990

Experimental complete right heart bypass. Proposal of a new model and acute hemodynamic assessment with vasoactive drugs in dogs.

A new model of complete right heart bypass was devised in dogs. All systemic venous blood was directly led to the bilateral pulmonary arteries by end-to-side superior vena cava-right pulmonary anastomosis, diverting the inferior vena caval blood to the superior vena cava with a graft, ligating the inferior vena cava at its end and the pulmonary artery at its trunk, and shunting the coronary venous return from the right-ventricle to the left atrium. Nine consecutive dogs tolerated the procedures, and acute hemodynamic characteristics and responses to vasoactive drugs were observed for 5 hours throughout the following full studies. Cardiac output ranged from 66 to 102 ml/min/kg at a central venous pressure of 15 to 26 mm Hg. Norepinephrine, isoproterenol, and phentolamine were administered with the central venous pressure maintained constant at 18 mm Hg. Isoproterenol and phentolamine increased cardiac output while reducing pulmonary and/or systemic vascular resistance, with a possible concomitant inotropic effect in the former. Norepinephrine was detrimental, causing an increase in both pulmonary and systemic vascular resistance.

Animals↗
PubMed1990

[Gore-Tex grafts for replacement of the superior vena cava in 10 patients with intrathoracic malignant tumors].

Ten patients with lung cancer and mediastinal tumor invading the mediastinal structures underwent replacement of superior vena cava (SVC) with ringed Gore-Tex to resect malignant tumors. In patients with lung cancer sleeve pneumonectomy (3 patients), sleeve lobectomy (1 patients) and tracheal resection (one patient) were performed simultaneously. By resection of the VCS system, invasive thymomas were able to be resected completely in 2 of 3 patients. In 2 patients with mediastinal tumors, one with metastatic testicular chorio carcinoma and one with malignant lymphoma of non-Hodgkin type, aggressive chemotherapy was followed by resection of the residual tumors including VCS. Except for one patient, there was no sign showing disturbance of the venous return in the VCS system in the 5 to 43 months' postoperative follow up period. We conclude that ringed Gore-Tex graft permits the extended operation for intrathoracic malignancies invading the mediastinal structures.

Adenocarcinoma↗
PubMed1990

[Optimal perfusion criteria for deep hypothermic selective cerebral perfusion in patients with aortic aneurysm involving aortic arch].

Although selective cerebral perfusion (SCP) might be an useful supportive method for aortic arch surgery, its optimal perfusion criteria has not been established. We studied the relationship between the oxygen saturation of superior vena cava or internal jugular vein (SvO2) and the perfusion hemodynamics during deep hypothermic (DH) SCP in twenty patients (pts) (type A dissection; 10, arch aneurysm; 10). SCP was accomplished by perfusion to the brachiocephalic trunk (BCT) and the left common carotid artery (LCC) using separate pumps. Cardiopulmonary bypass and DHSCP time were 128-312 (222 +/- 43, mean +/- SD) minutes and 25-214 (122 +/- 49) minutes, respectively. The cerebral perfusion pressures (CPP) monitored at the bilateral temporal arteries were 20-60 (47 +/- 9) mmHg and cerebral perfusion flow (CPF) was 0.28-0.7 (0.43 +/- 0.10) L/min/m2. The cerebral perfusion score (CPS) defined as CPP X CPF was 7-39 (20 +/- 8). SvO2 ranged from 79 to 99 (94 +/- 7)%. Two operative deaths were encountered from unrelated causes to SCP in both cases. Cerebral infarction occurred in one patient possibly form prolonged low perfusion with low SvO2. When the safety range of SvO2 in DHSCP was defined as greater than 90%, essential criteria to keep this range was CPP greater than 40 mmHg. In 13 out of 15 pts with SvO2 greater than 90%, CPS were above 15. In conclusion, optimal perfusion criteria for DHSCP was defined as CPP greater than 40 mmHg and CPS(CPP X CPF) greater than 15 considering adequate cerebral oxygen consumption.

Adult↗
PubMed1990

Pulmonary artery pressure and resistance late after repair of tetralogy of Fallot with pulmonary atresia.

Twenty-one patients underwent elective hemodynamic and cineangiographic studies 1 to 9 years after repair of tetralogy of Fallot and pulmonary atresia. They were a subset of 41 patients who underwent complete repair between Jan. 1, 1973, and 1988. The mean and systolic pulmonary arterial pressure, as well as the pulmonary vasculature resistance, were abnormally high in 60% of the patients. Thirty-three percent of the patients were found to have pulmonary arterial segments that were not connected to the central and unbranched hilar portions of the right and left pulmonary arteries. The mean pulmonary artery pressure and the pulmonary vasculature resistance were correlated (inversely) with the number of centrally connected pulmonary arterial segments. The pulmonary vasculature resistance per pulmonary arterial segment was also inversely correlated with the number of centrally connected pulmonary arterial segments. Inferences: The finding that abnormalities in the pulmonary vasculature of centrally connected pulmonary arterial segments become more severe as the number of centrally connected pulmonary arterial segments decreased has implications as to hemodynamic effectiveness of unifocalization operations. Since others have found these abnormalities in the pulmonary vasculature to be age related, the findings support beginning the appropriate surgical treatment of patients with tetralogy of Fallot and pulmonary atresia very early in life.

Adolescent↗
PubMed1989

Evaluation of prostacyclin analogue OP-41483 as an adjunct to crystalloid cardioplegia in infants and children.

A chemically stable prostacyclin analogue (PGI2-A, carbacyclin, OP-41483) was evaluated as an adjunct to potassium cardioplegia in infants (n = 13) and children (n = 32), in whom the current potassium cardioplegia may be limited in its effects. PGI2-A was added in a dose of 300 micrograms/L to the potassium cardioplegic solution. Postoperatively, peak levels of the myocardial-specific isoenzyme of creatine kinase (MB-CK) were compared for the PGI2 group and a control group (n = 65). In patients 1 year of age or older (n = 32 and 49 for the PGI2 and control groups, respectively), the MB-CK level was significantly lower in the PGI2 group only when compared between the subgroups with an aortic cross-clamp time of 120 minutes or more (n = 9 and 10; MB-CK level, 35.2 +/- 15.6 vs 68.3 +/- 32.4 IU/L;p less than 0.05). In patients less than 1 year of age, in whom aortic cross-clamp times were generally less than 120 minutes, the MB-CK level was also lower in the PGI2-A group than in the control group (n = 13 and 16; MB-CK level, 33.6 +/- 14.3 vs 61.6 +/- 36.3 IU/L;p less than 0.05). Infants less than 6 months of age (n = 18) underwent ultrastructural assessment of left ventricular myocardial biopsy specimens, and the PGI2-A group showed better results in mitochondrial and intracellular edema scores. This clinical trial showed beneficial effects of PGI2-A used with crystalloid potassium cardioplegia in infants and children.

Adolescent↗
PubMed1989

Autopsy findings 14 years after septation for single ventricle.

The autopsy findings of a patient who survived 14 years after ventricular septation for single ventricle are reported. Although the patient had been well for years, she suddenly died at 22 years of age. Her ventricular free walls had grown normally, but the ventricular septum did not. A crevice was found in the apex, and the ventricular septum consisted of only the Teflon patch. Microscopically, fibrosis was found only in the right atrium.

Adult↗
PubMed1989

Prevention of pulmonary edema developing in autoperfusing heart-lung preparation by leukocyte depletion.

We investigated the preventive effect of leukocyte depletion on the development of pulmonary edema in a 12 h autoperfusing heart-lung preparation (AHLP). Sixteen mongrel dogs were divided into two groups: control group (group C, n = 9) and leukocyte depleted group (group L, n = 7). In group L, leukocytes were depleted with a leukocyte removal filter prior to the preservation. Extravascular thermal volume (EVTV) was measured by thermal-dye dilution technique as a parameter of pulmonary edema during preservation. The white blood cell (WBC) count was measured before and during preservation. After the procedure, extravascular lung water (EVLW) was measured by a gravimetric technique. In group C, the WBC count significantly decreased soon after the start of preservation, and subsequently remained without significant changes. In group L, the WBC count was maintained at a low level during the entire course of preservation. In group C, EVTV increased significantly with the preservation time. In group L, a significant increase in EVTV was only found at 12 h to a smaller extent than in group C. EVLW was significantly smaller in group L than in group C. In conclusion, the development of pulmonary edema was apparently prevented in the 12 h canine AHLP model by leukocyte depletion, and pulmonary leukocyte sequestration was considered as a cause of pulmonary edema in AHLP.

Animals↗
PubMed1989

Analysis of acute and chronic heart failure in view of hepatic oxygen supply-demand relationship using hepatic venous oxygen saturation.

The adequacy of hepatic circulation in terms of oxygen supply-demand relation was assessed by measuring hepatic venous oxygen saturation (Shvo2) in patients. Among those with congenital cardiac lesions (n = 11), Shvo2 during the early postoperative period was markedly low as less than 20% in Fontan operation group (n = 5) with subsequent clinical findings of acute hepatic dysfunction. Significant correlations were found between Shvo2 values early after surgery and subsequent peak values in serum hepatic enzymes. Serum total bilirubin and prothrombin time started to deteriorate when Shvo2 became below 30%. Cardiac index, hepatic perfusion pressure and mixed venous oxygen saturation showed positive linear correlations with Shvo2, and central venous pressure (CVP) with an inverse relation. In chronic valvular disease (n = 28), those with NYHA class IV patients showed lower Shvo2 (average; 47.4%) at cardiac catheterization than the others (class-I; 66.4%, class-II; 63.9%, p less than 0.05). These results indicate that Shvo2 monitoring appears to be useful to assess the hepatic perfusion in terms of oxygen supply-demand relation in acute and chronic heart failure, and Shvo2 of 30% seems to be a critical level.

Adult↗
PubMed1989

Surgery for aortic arch aneurysm with selective cerebral perfusion and hypothermic cardiopulmonary bypass.

Deep-hypothermic cardiopulmonary bypass with selective cerebral perfusion (SCP) was used in 34 consecutive patients with aneurysms involving the aortic arch or the adjacent part of the aorta. The ages ranged from 25 to 79 years (mean, 56 years). Atherosclerotic aneurysms were present in 14 patients, dissecting aortic aneurysms in 16, and other lesion types in four. Replacement of the ascending aorta was performed in 10 patients, replacement of the ascending aorta and arch in 12, replacement of the distal arch in two, and other procedures in 10. Perfusion techniques consisted of femoral artery perfusion and SCP to the brachiocephalic trunk and the left common carotid artery. The blood temperature was maintained at 16 degrees-20 degrees C. SCP time ranged from 25 to 214 minutes (mean, 123 minutes). Operative death occurred in three (9%) patients. Neurological sequelae occurred in one patient (cerebral infarction), but significant respiratory and hemorrhagic problems were not encountered. For the SCP protocols, we advise that perfusion pressures at bilateral superficial temporal arteries be kept at approximately 50 mm Hg and that venous oxygen saturation of the superior vena caval line or internal jugular vein be kept at above 90%. With appropriate monitoring, this method can be performed in aortic arch or related surgeries with low morbidity results.

Adult↗
PubMed1989

Extended operation for lung cancer invading the aortic arch and superior vena cava.

Extended operation for lung cancer and mediastinal carcinoma involving the aortic arch or superior vena cava was performed in six patients. In three patients with lung cancer invading the right side of the mediastinum, sleeve pneumonectomy (two patients) or sleeve lobectomy was followed by resection and reconstruction of the superior vena cava with ringed polytetrafluoroethylene grafts. One patient with squamous cell carcinoma and T4 N1 M0 disease was alive and free of disease more than 34 months after the operation. The other patients with adenocarcinoma (T4 N1 M0) and adenosquamous cell carcinoma (T4 N2 M0) died 18 and 5 months after the operation of systemic metastases. In two patients with invasion of lung cancer into the left side of the mediastinum, resection and reconstruction of the aortic arch and left common carotid artery were performed by a femoro-femoral bypass. These patients had adenocarcinoma (T4 N2 M0) and large cell carcinoma (T4 N1 M0) and died of systemic metastases and bleeding during reoperation 12 and 4 months after the initial operation. In one patient with mediastinal squamous cell carcinoma, resection and reconstruction of the aortic arch and left subclavian artery were performed by application of a temporary bypass graft between the ascending and descending aorta. This patient was alive and free of disease more than 17 months after the operation.

Adult↗
PubMed1988

The mechanism of discordant xenograft rejection.

The mechanism of discordant xenograft rejection using the guinea pig-to-rat heart graft model was studied. In this model, we found that (A) Rejection occurred rapidly, in 17.5 +/- 8.3 min (mean +/- SD) (n = 8). (B) The graft survived longer when the recipient rat was pretreated with cobra venom facter (CVF). (C) Complement hemolytic titers in serum showed significant reduction of C3 in rejection without consumption of C4 and C2, suggesting complement activation through the alternative pathway. (D) No natural antibodies were detected in this combination. Complement-dependent cytotoxicity (CDC) titer, and hemagglutination (HA) titer were lower than x1. (E) Histological examination of the rejected heart xenograft revealed a large area of myocytolysis without interstitial cellular infiltration. (F) In vitro experiments showed that rat complement attacked guinea pig erythrocytes (Egp) via the alternative pathway. These findings indicate that rejection in this discordant xenograft model of guinea pig-to-rat was caused by primary activation of complement via the alternative pathway.

Animals↗
PubMed1988

Assessment of prostacyclin and thromboxane A2 release during reperfusion after global ischemia induced by crystalloid cardioplegia--comparison between warm and cold ischemia.

The metabolites of prostacyclin (PGI2) and thromboxane A2 (TxA2), 6-keto-PGF1 alpha and thromboxane B2 (TxB2), were investigated during reperfusion (RP) following warm (37 degrees C, 60 min, n = 9) or cold (15 degrees C, 120 min, n = 11) ischemia induced by cold (4 degrees C) or normothermic (30 degrees C) K+ cardioplegia (CP) in isolated canine hearts subjected to global ischemia and RP. 6-Keto-PGF1 alpha flux was significantly higher (p less than 0.025) in the warm group at 1, 5, and 10 min of RP (4,202 +/- 1,412, 2,475 +/- 1,875, and 1,255 +/- 633 pg/g.min, mean +/- SD) compared to those in the cold group (1,504 +/- 1,245, 434 +/- 641, and 370 +/- 329 pg/g.min). TxB2 flux was small in amount compared to 6-keto-PGF1 alpha in both groups. Regarding the coronary hemodynamics, the cold group alone showed statistically significant relationships of coronary sinus blood flow to TxB2 level and TxB2/6-keto-PGF1 alpha ratio in coronary sinus blood. Also, coronary vascular resistance showed linear relations to these two parameters of the metabolites. In a supplementary experiment only with cold ischemia for 180 min, 6-keto-PGF1 alpha was released at each coronary flush-out by CP and the incremental amount showed a gradual increase during ischemia. These results indicated that significant production and release of PGI2 occurred during ischemia and RP following CP arrest and these related to the degree of myocardial damage while the response of TxA2 seemed less significant. The role of PGI2 release during RP following cardioplegic arrest was discussed.

6-Ketoprostaglandin F1 alpha↗
PubMed1987

Preoperative left ventricular function: minimal requirement for successful late results of valve replacement for aortic regurgitation.

Postoperative survival and left ventricular function were studied in 62 patients who underwent aortic valve replacement for isolated, chronic aortic regurgitation between 1978 and 1985. The average follow-up period was 3.8 years. There were three in-hospital and six late deaths. Five (56%) of the nine postoperative deaths were of cardiac-related causes. The mean 7 year survival rate was 83 +/- 5%. Preoperative left ventricular end-systolic volume index was the most important indicator (p less than 0.001) for subsequent cardiac death. The 6.5 year survival rate was 92 +/- 4% for patients with an end-systolic volume index less than 200 ml/m2 compared with 51 +/- 16% for those whose index was greater than 200 ml/m2. None of the 48 patients with an end-systolic volume index less than 200 ml/m2 died of cardiac-related causes. Twenty-three of the 48 patients with an end-systolic volume index less than 200 ml/m2 (Group 1) and 6 of the 12 patients with a higher index (Group 2) underwent repeat catheterization 26 months postoperatively. Preoperative afterload, assessed by end-systolic wall stress, was elevated in both groups, but decreased postoperatively, becoming identical to the afterload in 20 normal control subjects. Although the preoperative ejection fraction was depressed in both groups, the great majority of patients in Group 1, compared with none in Group 2, exhibited normal ejection fraction postoperatively. Thus, in patients who recently underwent surgery for aortic regurgitation, satisfactory late results in both long-term survival and reversal of left ventricular dysfunction were obtained when the preoperative end-systolic volume index was less than 200 ml/m2.

Adolescent↗