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Biomedical subjects

Y Shimazaki

Publications and source records attributed to Y Shimazaki.

At least 109 records · Page 6Linked to original sources
PubMed1994

Neointima formation after vascular stent implantation. Spatial and chronological distribution of smooth muscle cell proliferation and phenotypic modulation.

Intravascular stents have proved useful as angioplasty devices, but intimal hyperplasia after stent implantation remains an unsolved problem. In the present study, we analyzed the spatial and chronological distribution of proliferation and phenotypes of smooth muscle cells (SMCs) in rabbit aortas during the process of neointima formation after stent implantation (Gianturco's Z type) by immunohistochemistry for proliferating cell nuclear antigen (PCNA) and myosin heavy chain isoforms (SM1, SM2, and SMemb). Stent implantation induced regional injury in the arterial wall. Medial SMCs then began to proliferate adjacent to the injured SMCs, maximally on day 4 (PCNA index in the media: 3.9 +/- 3.4% [mean +/- SD]), and were modulated to the embryonic phenotype (SMemb-positive and SM2-negative). They migrated into the intima and proliferated most frequently on day 7 (PCNA index in the intima: 20.3 +/- 5.5%) and subsequently led to fibrocellular neointima formation at 2 weeks and later. At 1 month after implantation and later, SMC proliferation was rare, and the phenotype of intimal SMCs was gradually returning to the adult type (SMemb-negative and SM2-positive). Thus, this stent implantation model demonstrates that the regional effect on arterial wall by stenting leads to neointima formation through transient and regional proliferation and migration of SMCs and their phenotypic modulations.

Animals↗
PubMed1994

Monitoring of hepatic venous oxygen saturation for predicting acute liver dysfunction after Fontan operations.

Acute liver dysfunction after Fontan operations may result from inadequate hepatic perfusion along with low cardiac output and high central venous pressure. We monitored hepatic venous oxygen saturation in 15 patients after Fontan operations to determine whether oxygen saturation predicts the occurrence and severity of acute liver dysfunction. We measured oxygen saturation from hepatic venous blood samples every 4 to 5 hours for at least 24 hours after the operation and used the mean hepatic venous oxygen saturation value for the first 24 hours after the operation to analyze the relationship between oxygen saturation and hepatic function. As indices of hepatic function, we measured serum alanine aminotransferase, total bilirubin, blood lactate (arterial, hepatic venous, and the difference between them), and the arterial ketone body ratio (the ratio of aceto-acetate to beta-hydroxybutyrate). For alanine aminotransferase and bilirubin, we used the maximal values during the first week in the analysis, and for blood lactate and ketone body ratio, we used the mean values for the first 24 hours after the operation. Significant broken-line regression relationship existed between mean hepatic venous oxygen saturation and hepatic function indices (alanine aminotransferase, total bilirubin, and blood lactate). The interpretation of these relationships is that hepatic indices are constant above the critical mean hepatic venous oxygen saturation values but are correlated with mean hepatic venous oxygen saturation below critical points in the range of 21% to 26%. Thus a hepatic venous oxygen saturation value below about 25% during the first 24 hours after a Fontan operation predicts the occurrence and the severity of acute liver dysfunction. We suggest that monitoring hepatic venous oxygen saturation is useful for management of critically ill patients after Fontan operations.

Adolescent↗
PubMed1994

[Ultrastructural assessment of postoperative lung injury--the effect of bronchial blood flow during cardiopulmonary bypass].

On the basis of the hypothesis that pulmonary blood flow during cardiopulmonary bypass (CPB) is related to postoperative pulmonary dysfunction, we divided following two groups in 17 patients with congenital cardiac disease; A group: bronchial blood flow (BF) during CPB < 10%, B group: BF during CPB > 25%. Lung specimens taken immediately after CPB were reviewed for ultrastructural changes using semi-quantitative grading of epithelial cell injury, endothelial cell injury, and measuring thickness of basement membrane (BMT) as the index of interstitial edema. And postoperative pulmonary function using AaDO2 were assessed. Ultrastructural grading of epithelial cell injury, BMT, and AaDO2 of A group (BP < 10) were higher than those of B group (BP > 25%). These results indicate that pulmonary blood flow during CPB somewhat may reduce pulmonary impairment for CPB.

Bronchi↗
PubMed1994

[A case of ventricular septal defect and patent ductus arteriosus associated with absent right pulmonary artery, scimitar syndrome and severe pulmonary hypertension].

A 8 month-old female was diagnosed with ventricular septal defect and patent ductus arteriosus associated with absent right pulmonary artery and scimitar syndrome. Cardiac catheterization revealed severe pulmonary hypertension as follows; 72 mmHg of mean pulmonary artery pressure, 0.56 Qp/Qs and 1.73 Pp/Ps. Temporary closure of the ductus reduced the mean pulmonary artery pressure from 72 to 40 mmHg. PDA was ligated and VSD was closed successfully. However, 4 months after initial operation she was readmitted due to infection of the hypoplastic right lung. Removal of the hypoplastic right lung was performed and postoperative course was uneventful.

Ductus Arteriosus, Patent↗
PubMed1994

Evaluation of regional myocardial perfusion in areas of old myocardial infarction after revascularization by means of intraoperative myocardial contrast echocardiography.

Because myocardial revascularization to areas of old myocardial infarction brings about functional recovery to some extent to myocytes in those areas, the assessment of regional myocardial perfusion on those areas after myocardial revascularization may allow myocardial viability to be estimated. Using intraoperative myocardial contrast echocardiography by direct injection of 2 ml sonicated 5% human albumin into saphenous vein grafts, we assessed regional myocardial perfusion in 16 revascularized areas of old myocardial infarction. We estimated the myocardial viability of areas with respect to myocardial perfusion, and we compared these results to both the improvement of regional wall motion after myocardial revascularization (increase in segmental wall thickening during systole) and relative thallium 201 activity obtained by quantitative analysis of preoperative exercise myocardial thallium 201 distribution on delayed images. The background-subtracted peak peak intensity of myocardial enhancement and the ratio of endocardial to epicardial intensity were determined in each revascularized area. An inverse correlation existed between peak intensity (18 +/- 7) and the endocardial/epicardial ratio (0.88 +/- 0.17) (r = -0.63, p < 0.01). A good correlation was found between peak intensity and both the percent increase in segmental wall thickening (r = 0.73, p < 0.005) and the relative thallium 201 activity (r = 0.81, p < 0.005). These results suggested that regional myocardial perfusion after myocardial revascularization in areas of old myocardial infarction distributed better to the epicardial halves than to the endocardial halves, and that the peak intensity could be related to myocardial viability.

Aged↗
PubMed1994

Evaluation of leukocyte-depleted terminal blood cardioplegic solution in patients undergoing elective and emergency coronary artery bypass grafting.

Leukocyte depletion at reperfusion may have a role in myocardial protection when combined with terminal cardioplegia. We applied this method in a selected group of 68 patients with coronary artery bypass grafting either for elective surgical procedures (n = 38) or emergency surgical procedures with the use of a preoperative intraaortic balloon pump (n = 30) because of developing acute myocardial infarction. Basic cold potassium crystalloid cardioplegic solution was used. During delivery of leukocyte-depleted terminal cardioplegic solution, warm arterial blood delivered from cardiopulmonary bypass was passed through a leukocyte removal filter, mixed with potassium crystalloid cardioplegic solution, and administered to the aortic root for the first 10 minutes of reperfusion. Patients were randomized into three groups for reperfusion: whole blood, terminal cardioplegic solution, and leukocyte-depleted terminal cardioplegic solution reperfusion groups. In elective coronary artery bypass grafting, no significant difference was found in the clinical data. However, in emergency coronary artery bypass grafting, the leukocyte-depleted terminal cardioplegic solution group (n = 10) showed significantly lower peak creatine kinase MB levels (leukocyte-depleted terminal cardioplegic solution versus terminal cardioplegic solution versus whole blood: 27 +/- 11, 56 +/- 13, 74 +/- 18, respectively; p < 0.05) and maximum dopamine doses required at the weaning of cardiopulmonary bypass (6.3 +/- 1.1 versus 11.2 +/- 3.3 versus 9.2 +/- 2.2; p < 0.05) than did the terminal cardioplegic solution (n = 10) and whole blood groups (n = 10). Moreover, the leukocyte-depleted terminal cardioplegic solution group showed significantly lower difference of malondialdehyde between arterial and coronary sinus blood (0.15 +/- 0.09 versus 0.36 +/- 0.06 versus 0.06 +/- 0.12 nmol/ml, p < 0.05) than did the terminal cardioplegic solution or whole blood groups. These results showed that leukocyte-depleted terminal blood cardioplegic solution may have a role in attenuating reperfusion injury in patients with critical conditions such as preoperative myocardial ischemic injury.

Adult↗
PubMed1994

[Reoperation and balloon dilatation for stenosed xenograft valved conduits].

Follow-up has been achieved in 41 hospital survivals who received xenograft valved conduits in the pulmonary position. The interval after operation ranged 6 months to 13 years (average 5.2 +/- 3.7 years) (+/- standard deviation). There has been 8 late deaths, 3 of which were sudden. Of the 11 reoperations, 7 underwent graft replacement with no operative death. The actuarial reoperation free survival rate was 73% at 5 years, and 54% at 10 years. There was a significant correlation between the interval after operation (x years) and the pressure gradient across the conduits (y mmHg). (y = 20.7 + 9.7x, r = 0.74, p < 0.001). Balloon dilatation of the conduits was performed in 15 patients. The mean conduit gradient was significantly (p < 0.001) reduced from 85 +/- 29 to 54 +/- 22 mmHg. However, the effect was not satisfactory enough and 4 patients received graft replacement after the balloon dilatation. These results warrant the avoidance of xenograft valved conduits in the pulmonary position, the safety of the graft replacement, and the limitation of the balloon dilatation for the stenosed conduits.

Adolescent↗
PubMed1994

[Obstruction of the left ventricular outflow tract due to an anomalous muscle bundle and an accessory tissue on the mitral valve associated with mitral stenosis].

This paper details a rare cause of subaortic obstruction, a discrete membrane combined with an anomalous muscle bundle and an accessory tissue on the mitral valve. A 13-year-old boy was referred to our hospital for surgical relief of subaortic obstruction and mitral stenosis. He had received two additional operations, the first was for coarctation of aorta when 5 years old and the second was for discrete subaortic stenosis when 6 years old. Recatheterization at this time revealed an peak systolic gradient of 44 mmHg across the left ventricular outflow tract, and an peak diastolic gradient of 7 mmHg across the mitral valve. An echocardiogram revealed two longitudinally anomalous tissues in the left ventricular outflow tract. Excision of both anomalous tissue and mitral valve replacement were performed. The macroscopic findings and histological reports of the excised specimens showed that one was the accessory mitral valve tissue and another was the anomalous muscle bundle. Intraoperative epicardial echocardiography is beneficial for evaluating the obstructive status of the LV outflow tract before and after excision of the anomalous tissues in this case.

Adolescent↗
PubMed1994

[Reoperation for obstructed extracardiac conduit after Rastelli operation--an autogenous tissue reconstruction (Danielson) method].

Eight patients with a mean age of 13.0 years underwent reoperation for obstructed extracardiac dacron conduit with xenograft valve at a mean of 7 years after Rastelli operation. In two patients, infective endocarditis of the stenotic conduit was the main indication for the reoperation. Diagnoses included 3 tetralogy of Fallot with pulmonary atresia, 3 d-TGA (III), 1 truncus arteriosus, and 1 corrected TGA. The conduit was completely excised leaving the posterior half of the autogenous external peel of conduit as the new outflow bed and a monocusped patch was then placed. Operations were mostly carried out allowing the heart to continue to beat. One patient with c-TGA who underwent concomitant replacement of aortic and left A-V values died in the hospital 4 months postoperatively. In other 7 patients, systolic pressure gradient across the right ventricular outflow decreased from a mean of 80.3 mmHg to 16.0 mmHg. Postoperative pulmonary regurgitation by UCG were trivial in 3 and grade III in 3 patients. One patient required re-reoperation late postoperatively for re-stenosis due to contracture of Golaski outflow patch. Three patients did not require any homologous blood during either the operation or the rest of the hospital stay. The results suggests that this method is a simple and effective option for reoperation of obstructed extracardiac dacron conduits late after Rastelli operation.

Adolescent↗
PubMed1994

[Necrotizing tracheobronchitis following radical repair in tetralogy of Fallot with absent pulmonary valve--a case report].

A 3-month-old infant with tetralogy of Fallot and absent pulmonary valve developed necrotizing tracheobronchitis following a radical repair. Right ventricular reconstruction using an equine pericardial valved conduit and plication of the main pulmonary arteries relieved compression of the left main bronchus by the dilated pulmonary artery. However, respiratory distress increased when bronchitis developed. Eventually, both main stem bronchi became stenotic secondary to inflammation, and the patient died 154 days following surgery. Necrotizing tracheobronchitis is a potentially lethal complication in patients with tetralogy of Fallot and absent pulmonary valve.

Bronchitis↗
PubMed1994

[Palliation for univentricular hearts].

Palliative operations for 44 univentricular hearts have been evaluated as bridges to Fontan operation. Pulmonary artery banding was the first palliation for 13 patients (pts) with high pulmonary blood flow (HPF), and systemic to pulmonary shunt was that for 27 pts with low pulmonary blood flow (LPF). 8 of the 13 with HPF required additional operation of Bidirectional Glenn (BDG) and Fontan operation. 5 pts underwent Fontan operation and 8 (62%) were candidate of Fontan operation. On the other hand, 9 of the 27 died of low cardiac output, dehydration or increased atrioventricular regurgitation. 17 survived the first palliation had additional procedures including Blalock-Taussig shunt, BDG or Fontan operation. 7 had Fontan operation, and 10 were candidate for Fontan operation. Atrioventricular valvular regurgitation increased after systemic to pulmonary shunt compared to BDG (p < 0.01). These results suggested that BDG should be performed before A-V valvular regurgitation increased and be a good bridge for Fontan operation.

Fontan Procedure↗
PubMed1993

Fate of right ventricular hypertrophy in tetralogy of Fallot after corrective surgery.

To elucidate the reversibility of right ventricular (RV) myocardial hypertrophy in tetralogy of Fallot (TF), 30 patients underwent RV endomyocardial biopsies 1 to 25 years (mean 9.7 +/- 6.6) after corrective surgery. Myocardial cell diameter was evaluated by comparing histopathologic data with preoperative patients with TF and normal subjects. As a whole, postoperative cell diameter was smaller than that of age-matched preoperative patients with TF, and larger than that of age-matched normal subjects. In 7 patients without significant residual pulmonary stenosis whose preoperative data were also available, cell diameter significantly decreased after surgery (17.1 +/- 2.1 to 14.0 +/- 2.1 microns, p < 0.01). There was a positive correlation between postoperative cell diameter and age at study (p < 0.01). To negate the influence of age, cell diameter was expressed in terms of a percentage of age-matched normal values (percent cell diameter). There was no significant correlation between percent cell diameter and age at surgery, age at study or the follow-up periods. There were positive correlations between percent cell diameter and the following parameters: RV systolic pressure (p < 0.05), percent normal RV end-diastolic (p < 0.05) and end-systolic (p < 0.01) volumes. These results demonstrate that RV myocardial hypertrophy in TF can regress to some extent after corrective surgery if significant residual pulmonary stenosis is avoided.

Adolescent↗
PubMed1993

Mixed type of total anomalous pulmonary venous connection with hemi-pulmonary vein atresia.

This reports a successfully corrected case of an 8-day-old baby who had a rare mixed type of total anomalous pulmonary venous connection in which the left pulmonary vein connected to the portal vein and the right one was atretic as demonstrated by pulmonary artery wedge angiography. The left common pulmonary vein and right pulmonary veins were anastomosed to the left atrium, separately. The patient tolerated the operation and has been well. Early total repair after accurate diagnosis was successful for this rare combination of anomalous pulmonary venous connection.

Anastomosis, Surgical↗
PubMed1993

Long-term appraisal of coronary bypass operations in familial hypercholesterolemia.

Long-term results of coronary artery bypass grafting (CABG) in consecutive 32 patients with familial hypercholesterolemia, 6 homozygotes and 26 heterozygotes between 1976 and 1990, were analyzed. Seventeen patients in the early series underwent CABG with vein grafts alone. Subsequently, 15 patients underwent CABG with internal mammary artery grafting to the left anterior descending artery and received intensive lipid-lowering treatments early after CABG. All homozygotes and 1 heterozygote received intermittent low-density lipoprotein apheresis after CABG. There was only one late noncardiac death (3%), and the actuarial rates of freedom from cardiac events (myocardial infarction, cardiac death, and angina pectoris) were 60% at 5 and 10 years for homozygotes, and 87% and 73% for heterozygotes. The cardiac event-free curve for the heterozygous familial hypercholesterolemia group was comparable with that for the random age-matched subset of patients without familial hypercholesterolemia who underwent CABG during the same period. Two of 3 homozygotes and 4 of 14 heterozygotes in the early series had one or more cardiac events, whereas no patients in the late period had cardiac events. The patency rate of internal mammary artery grafts to the left anterior descending artery from 1 to 3 years after CABG was significantly higher than that of vein grafts to the left anterior descending artery (92 versus 45%; p < 0.05). Abdominal aortic aneurysm developed postoperatively in 2 homozygotes and 2 heterozygotes without sufficient cholesterol reduction. In conclusion, internal mammary artery grafting in combination with postoperative intensive lipid-lowering treatments, including low-density lipoprotein apheresis, may provide acceptably good long-term results of coronary revascularization in patients with FH.

Actuarial Analysis↗
PubMed1993

Synthesis of 3-hydroxyretinal in the cytosol of the butterfly compound eye.

The metabolism of 3-hydroxyretinoids in the cytosol of the compound eyes of a species of butterfly, Papilio xuthus, was investigated. The cytosol was found to contain 25-30% of the total 3-hydroxyretinal and 70-82% of the total 3-hydroxyretinol in the eye. These percentages of 3-hydroxyretinoids in the cytosol were found to be constant regardless of whether the eyes are light-adapted or dark-adapted. 3-Hydroxyretinal can be newly synthesized in the cytosol of light-adapted eyes. Blue light specifically increases the amount of 11-cis and all-trans 3-hydroxyretinal ca 2.5 and 1.8 times respectively, compared to pre-irradiation. When 3-hydroxyretinal was synthesized, 3-hydroxyretinol was decreased or disappeared in the cytosol. When retinol (non-native chemical) was added to the cytosol, it was converted into retinal. This result indicates that an oxidative system exists in the compound eye which can convert 3-hydroxyretinol to 3-hydroxyretinal.

Adaptation, Ocular↗
PubMed1993

Pulsed Doppler echocardiographic assessment of portal venous flow patterns in patients after the Fontan operation.

OBJECTIVE: To assess the effect of the condition of the right heart after the Fontan operation on portal venous flow, and to determine whether the characteristics of portal venous flow were different when there was an atriopulmonary connection with atrial septal closure rather than an atriopulmonary or total cavopulmonary connection with intra-atrial routing. PATIENTS AND METHODS: After the Fontan operation six patients with an atriopulmonary connection (group 1), three patients with an atriosubpulmonary connection (group 2), four patients with intra-atrial routing and an atriopulmonary connection (group 3), and five patients with a total cavopulmonary connection (group 4) were studied by pulsed Doppler echocardiography. The flow signals were recorded for the pulmonary artery, hepatic vein, and intrahepatic portal vein in each patient. Postoperative cardiac catheterisation was performed in 16 of the 18 patients. The Doppler findings were compared with those of 14 controls. RESULTS: The portal flow was pulsatile in 13 patients and constant in five patients. Reversed flow was shown at or just after the QRS wave after hepatic venous regurgitation in two group 1 patients. The flow signal was interrupted in two group 1 patients and two group 2 patients. Decrease in velocity of flow was recorded in two group 1 patients, one group 2 patients, three group 3 patients, and one group 4 patient. Portal flow was constant in one group 3 patient and four group 4 patients. The pulsatility ratio ranged from -0.46 to 0.49 (mean (SD), 0.03 (0.32)) in the patients from group 1 and 2, from 0.41 to 0.76 (0.54 (0.15)) in group 3, and from 0.70 to 0.80 (0.75 (0.04)) in group 4. The ratio in the controls ranged from 0.29 to 0.83 (0.61 (0.13)). The ratio was significantly lower in groups 1 and 2 than in group 3 (p < 0.01), group 4 (p < 0.01), or the controls (p < 0.005). There was no significant difference in the ratio between group 3 and group 4 and no correlation between the pulsatility ratio and the cardiac index (r = 0.26), mean right atrial pressure (r = 0.25), or pulmonary vascular resistance (r = 0.17). CONCLUSION: The larger hepatic venous regurgitation caused by atrial contraction in patients with an atriopulmonary connection correlated with the higher portal pulsatility and a total cavopulmonary connection reduced portal pulsatility.

Atrial Function, Right↗