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Biomedical subjects

N Hirata

Publications and source records attributed to N Hirata.

At least 37 records · Page 2Linked to original sources
PubMed2000

Quantitative ultrasonic tissue characterization can identify high-risk atherosclerotic alteration in human carotid arteries.

BACKGROUND: Recently, ultrasonic tissue characterization of the composition of plaques has been performed in a quantitative fashion on the basis of integrated backscatter (IBS) analysis, but most of those studies have used high-frequency ultrasound to obtain microscopic images. METHODS AND RESULTS: We performed B-mode measurement and IBS signal analysis with acoustic densitometry with a 7.5-MHz linear-array transducer in freshly excised human aortas (n=58) (normal, atheromatous, and fibrous tissue) obtained at autopsy. Atheromatous and fibrous tissue had a similar intima-media thickness (IMT), but the IBS value in atheromatous specimens was lower than that in fibrous specimens. We further applied this method to human carotid ultrasonography. The subjects were young (80 regions), middle aged with 1 or no coronary risk factors (low risk) (120 regions), middle aged with >/=2 coronary risk factors (high risk) (240 regions), or elderly (80 regions) or were patients with myocardial infarction (MI) with multivessel disease (90 regions). The IMT was similar in middle-aged, elderly, and MI subjects. In contrast, the IBS value was significantly higher in elderly subjects and lower in high-risk middle-aged and MI subjects compared with that in low-risk middle-aged subjects. The percent of regions diagnosed as atheromatous (IBS less than mean minus 2-SD value of IBS in young subjects) was 11% in low-risk middle-aged subjects, 29% in high-risk middle-aged subjects, and 63% in the MI group. CONCLUSIONS: In conjunction with conventional B-mode imaging, IBS analysis with carotid ultrasonography appeared to provide prognostic information to identify a high-risk group with systemic atherosclerosis, which could lead to coronary heart disease in individuals with early-stage disease.

Adult↗
PubMed2000

Treatment of acute right coronary artery occlusion during anesthesia.

PURPOSE: Perioperative coronary artery occlusion is a potentially dangerous complication causing myocardial infarction and circulatory collapse. We report a case showing severe ST segment depression in leads II and V5 during anesthesia. Diltiazem and nifedipine, but not nitroglycerine, partially improved the ST changes which were normalized by a percutaneous cardiopulmonary system (PCPS). CLINICAL FEATURES: A 71-yr-old man with cerebrovascular disease was scheduled for coronary artery bypass grafting (CABG). Past medical history included myocardial infarction due to right coronary artery (RCA) occlusion. Both the femoral artery and vein were cannulated percutaneously before operation and the PCPS was prepared as a back-up system. Depression of the ST segments in leads V5 and II was observed following heparinization. Although hemodynamic stability was maintained with continuous infusion of catecholamines, the ST changes were not improved by intravenous nitroglycerine. Intravenous diltiazem followed by nasal nifedipine partially improved the ST changes. The changes were normalized after induction of PCPS. No neurological complications were observed. The postoperative coronary angiography confirmed the total occlusion of RCA. CONCLUSION: Calcium channel blockers were more effective than nitroglycerine in treating perioperative ST depression. However, none of them produced complete reversal of the ischemic changes which were normalized with PCPS.

Acute Disease↗
PubMed2000

Minimally invasive removal of infected pacemaker lead.

A 37-year-old woman with sick sinus syndrome suffered complications with recurring local infection at the generator pocket. Repeated debridement and antibiotic therapy was ineffective. Several attempts to remove leads via the implantation vein by direct traction were unsuccessful. We operated using cardiopulmonary bypass and applied a minimally invasive lower ministernotomy to obtain pleasing cosmetic results. After a right atriotomy, leads were removed. The minimally invasive approach gave satisfactory results, especially cosmetically.

Adult↗
PubMed2000

Importance of preoperative marking for minithoracotomy and for internal thoracic artery harvesting in minimally invasive direct coronary artery bypass grafting.

Minimally invasive direct coronary artery bypass has the potential to cause an anastomotic failure because of a limited exposure of the operative field and the difficulty of internal thoracic artery harvesting. In the present study, the importance of preoperative marking for an accurate minithoracotomy location and a successful internal thoracic artery harvest was assessed. A paperclip was placed on the left nipple and a chest X-ray was performed in the supine position. By aligning the position of the paperclip to the location of the left anterior descending coronary artery from a coronary arteriogram frontal view, the intercostal space for the minithoracotomy was thus determined. Marking the incisional intercostal space during preoperative left internal thoracic arteriography revealed the number and location of the internal thoracic artery branches at the beginning of the harvest. This preoperative marking technique allowed for a more adequate exposure of the operative field and an easier internal thoracic artery harvest which therefore contributed to an improvement in the operative results.

Aged↗
PubMed2000

Is median sternotomy invasive? A comparison between minimally invasive direct coronary artery bypass and off-pump bypass.

Although minimally invasive direct coronary artery bypass (MIDCAB) eliminates the need for median sternotomy and cardiopulmonary bypass, its indications are limited. Conversely, coronary artery bypass without cardiopulmonary bypass (off-pump bypass) enables complete surgical revascularization under an optimal surgical field established by median sternotomy, even if patients have multivessel disease. The present study was designed to determine the invasiveness of median sternotomy by comparing 11 patients who underwent MIDCAB and 5 who underwent off-pump bypass between May 1997 and April 1998. There were no significant differences between the MIDCAB group and the off-pump group in age, being 57 +/- 11 vs 66 +/- 8 years old, the operative time, being 321 +/- 149 vs 441 +/- 205 min, the number of grafts, being 1.0 vs 1.4/patient, peak creatine kinase (CK) values, being 662 +/- 436 vs 609 +/- 56 IU/l, the peak CK-muscle-brain values, being 12 +/- 9 vs 16 +/- 5 IU/l, and the postoperative blood loss, being 369 +/- 198 vs 541 +/- 204 ml. Although there was no significant difference in peak C-reactive protein, at 17 +/- 5 vs 20 +/- 2 mg/dl, the periods declining within the normal ranges were shorter in the MIDCAB group than in the off-pump group, at 7 +/- 1 vs 15 +/- 2 days (P > 0.01). The hospital stay was almost the same in both groups, at 16 +/- 8 vs 26 +/- 14 days. These findings suggest that off-pump bypass is more invasive than MIDCAB, which may be attributed to the median sternotomy.

Aged↗
PubMed2000

The long-term outcome of a surgical repair of sinus of valsalva aneurysm.

BACKGROUND: In order to clarify the long-term outcome after surgical repair of a sinus of Valsalva aneurysm, we retrospectively assessed the operative results for patients treated in our institute. METHODS: The subjects were 27 patients who had undergone an operation between 1958 and 1996. For associated aortic regurgitation (AR) aortic valve repair was performed in 13 patients, 12 of whom had a ventricular septal defect (VSD); and an aortic valve replacement was performed in 3 patients, 1 of whom had a VSD. RESULTS: Five of the 13 patients who had aortic valve repair needed aortic valve replacement because AR developed after a period of between 7 and 13 years; those cases were complicated by VSD. Another 2 patients with mild AR also complicated by VSD are currently under observation. CONCLUSIONS: Although the postoperative outcome of the aortic valve repairs was good, cases that were complicated by VSD plus associated AR tended to develop AR later after surgery. Therefore, careful observation of the postoperative course is necessary.

Adolescent↗
PubMed2000

The Vdelta1 T cell receptor repertoire in human nasal mucosa.

The gamma/delta T cells play important roles as the first line of defence in mucosal immunity. Vdelta1 bearing T cells comprise the major population of gamma/delta T cells in the human nasal mucosa. Recently, it was reported that certain receptors are predominant at given anatomical locations. The purpose of this study was to elucidate the gamma/delta T-cell receptor repertoire in human nasal mucosa. Nasal epithelia were scraped and peripheral blood were obtained from three healthy volunteers. We performed reverse-transcription polymerase chain reaction (RT-PCR) analysis and characterized the junctional sequences of Vdelta1 T-cell receptor (TCR) transcripts. Vgamma and Vdelta gene usage in intraepithelial lymphocytes (IELs) in right and left nasal mucosa were almost the same, but they were different from those in peripheral blood lymphocytes (PBLs). The VDJ sequence of nasal Vdelta1 T-cell receptor transcripts showed diversity and were different for each individual. Vdelta1 in the IELs were rearranged to Jdelta1 and Vdelta1 in the PBLs were rearranged not only to Jdelta1 but also to Jdelta3. Vdelta1 sequences in the IELs in the nasal mucosa showed no overlap with those in the PBLs. These results indicate that gamma/delta T cells in the nose are organ specific lymphocytes.

Adult↗
PubMed2000

Human bronchial intraepithelial T lymphocytes as a distinct T-cell subset: their long-term survival in SCID-Hu chimeras.

Intestinal intraepithelial T lymphocytes (i-IELs) show features different from those of conventional T cells and play specific roles in the mucosal immunity. To investigate whether human bronchial intraepithelial T lymphocytes (IELs) are a distinct entity, we examined T cells in human bronchial xenografts transplanted on mice with severe combined immune deficiency (SCID). We transplanted human bronchi subcutaneously into mice with SCID, resected the xenografts after various incubation periods (7-174 d), and examined them for CD3(+), CD4(+), CD8(+), and CD45(+) cells by immunohistochemistry. The number of CD3(+) cells in the lamina propria decreased significantly in the first month (from 308.7 +/- 60.2 to 70.9 +/- 49. 4/mm(2); P < 0.05), and xenografts more than 5 mo of age had scant T cells in the lamina propria (5.2 +/- 2.0/mm(2)). However, there was no significant difference between the number of CD3(+) IELs in freshly isolated bronchi and in xenografts maintained for more than 5 mo. In freshly isolated bronchi, the number of CD4(+) IELs was significantly lower than that of CD8(+) cells (2.35 +/- 0.62 versus 4.56 +/- 1.32/mm basement membrane; P < 0.01). After transplantation, the mean CD4-to-CD8 ratio of all xenografts was significantly higher than that of freshly isolated bronchi (5.2 +/- 0.9 versus 0.6 +/- 0.2; P < 0.005). The IELs were positive for CD45, which is specific for human leukocytes, and they were eliminated by irradiation before the transplantation. Almost all IELs (99.5%) in the xenografts expressed alphabeta T-cell receptor, and 35.8% of IELs expressed alpha(e)beta7 integrin. Bronchial epithelial cells in the xenografts expressed interleukin (IL)-7, stem cell factor, intercellular adhesion molecule (ICAM)-1, and human leukocyte antigen-DR (HLA-DR). We conclude that in the SCID-Hu chimera model, human bronchial IELs survive for more than 5 mo, unlike the T cells in the lamina propria, and we suggest that human bronchial IELs may be stimulated by bronchial epithelial cells expressing IL-7, stem cell factor, ICAM-1, and HLA-DR.

Animals↗
PubMed2000

Efficacy of mitral valve replacement for patients with mitral regurgitation and a dilated left ventricle.

Mitral regurgitation is a significant complication of end-stage cardiomyopathy, and its existence predicts poor survival. In general, it is thought that mitral valve replacement (MVR) alone is ineffective; however, there are few detailed reports of the clinical course of patients who have undergone MVR. Five patients with mitral regurgitation whose preoperative left ventricular end-systolic volume index was more than 100 ml/m2 were studied. Although their prognosis late after MVR became poor, none of them died within 30 days of the operation. Postoperative cardiac catheterization was performed 6.3+/-1.1 months after surgery; the end-diastolic volume had reduced (before: 193+/-26 ml/m2; after: 166+/-34 ml/m2, p<0.05), but the end-systolic volume had not (before: 110+/-7 ml/m2; after: 112+/-32 ml/m2). The end-systolic wall stress was substantially elevated preoperatively (238+/-29 kdyne/cm2) and tended to increase after surgery (295+/-96 kdyne/cm2). All the patients were able to return to work at some stage postoperatively (their New York Heart Association functional class improved to I or II), but 3 of the 5 patients died suddenly of heart failure at 3.3+/-1.6 years after surgery and the New York Heart Association functional class of the others worsened to III again. Mitral valve surgery, including MVR, can manage severe end-stage heart disease with mitral regurgitation.

Adult↗
PubMed2000

[A successful case of hybrid therapy for the left main trunk and triple coronary vessel lesions with acute myocardial infarction and cardiogenic shock].

A 86-year-patient who had acute myocardial infarction and critical cardiogenic shock was diagnosed to have the left main trunk (LMT) and triple vessel disease. Emergent coronary artery bypass grafting to the left anterior descending artery was performed using saphenous vein graft without cardiopulmonary bypass through median sternotomy. On the 41st postoperative day, catheter intervention was performed to the remaining lesions by stenting of LMT and percutaneous transluminal coronary angioplasty to the right coronary artery lesions. Tl scintigraphy showed remarkable reduction of myocardial ischemia. Hybrid therapy is the effective new strategy for critical cases which cannot be successfully and securely treated by medical or surgical approach alone.

Aged↗
PubMed2000

Assessment of perioperative predictive factors influencing survival in patients with postinfarction ventricular septal perforation. Classified by the site of myocardial infarction.

BACKGROUND: The present study was designed to identify the perioperative factors and to consider a counterplan for the improvement of surgical results, based on the site of myocardial infarction. METHODS: Sixteen patients with postinfarction ventricular septal perforation underwent surgical repair. The operation was performed 5+/-3 days after the onset of ventricular septal perforation using the same method, an infarctectomy and reconstruction of the septum and right and left ventricular walls with a single Dacron patch. The ventricular septal perforation was anterior in 11 patients and posterior in 5. Preoperative hemodynamics between survivors and non-survivors were compared. Left ventricular wall motion was estimated using echocardiography by wall motion score (divided into 17 segments and each segment was graded on a fourpoint scale: normal, 0; hypokinetic, 1; severe hypokinetic, 2; a- or dyskinetic, 3) and summed up. RESULTS: The operative mortality was 36% in 11 patients with anterior ventricular septal perforation. In non-survivors compared to survivors, wall motion score was greater (25+/-4 vs 18+/-4, p<0.01) and all values were over 20. The value of the cardiac index divided by Qp/Qs was lower (0.98+/-0.09 vs 1.44+/-0.31, p<0.02) and all were under 1.1. In 5 patients with inferior ventricular septal perforation, the operative mortality was 40%. In non-survivors compared to survivors, wall motion score was greater (18, 18 vs 7, 2, 12) and the right atrial pressure was greater (18, 19 vs 10, 9, 9 mmHg) due to a right ventricular infarction. CONCLUSIONS: The patients with poor left ventricular wall motion were lost for reasons unrelated to the site of myocardial infarction. Moreover, a cardiac index over Qp/Qs in anterior ventricular septal perforation and the existence of a right ventricular infarction in inferior ventricular septal perforation was predictive of operative mortality.

Aged↗
PubMed1999

Pulmonary blood flow distribution after the total cavopulmonary connection for complex cardiac anomalies.

In total cavopulmonary connection (TCPC), the anastomotic portion of the caval veins to the pulmonary artery (PA) is decided empirically based on personal experience. To compare the pulmonary flow distribution from both caval veins in various types of cavopulmonary anastomosis, intrapulmonary ventilation-perfusion distribution after TCPC was studied using lung scanning. We studied 11 patients, 2 to 37 years old, at 30-84 months after TCPC. Lung scanning was performed by administering 185 MBq of xenon-133 saline solution from their upper extremities and, after xenon-133 was washed out, from their lower extremities. Radionuclide counts on both lungs were obtained and intrapulmonary ventilation-perfusion distribution was assessed. In 4 patients whose superior vena cava (SVC)-PA anastomosis was on the right side of the inferior vena cava (IVC)-PA anastomosis, the blood flow distribution of the right and left lungs was 57.4%: 42.6%. In 3 patients whose SVC-PA anastomosis was on the left side of the IVC-PA anastomosis, the blood flow distribution of the right and left lungs was equal in both lungs (right, 53.1%; left, 46.9%). Systemic arterial oxygen saturation increased after TCPC (before TCPC, 85.3% +/- 2.7% and after TCPC, 89.8% +/- 2.3% (P < 0.05) in group R; before TCPC, 86.1% +/- 2.8% and after TCPC, 93.6% +/- 0.6% (P < 0.02) in group L). After TCPC, the value in group L had a tendency to be greater than that in group R (P < 0.04), in spite of the same values of systemic arterial oxygen saturation before TCPC and cardiac index (group R, 2.9 +/- 0.96; group L, 3.4 +/- 0.37). Lung scanning with xenon-133 revealed the distribution of pulmonary blood flow in the patients after TCPC quantitatively, and in the patients whose SVC-PA anastomosis was on the left side of the IVC-PA anastomosis, the right and left balance of the pulmonary blood flow distribution appeared to be more balanced compared with patients whose connection was done the opposite way.

Adolescent↗
PubMed1999

Analysis of the elephant trunk method in patients with extensive thoracic aortic aneurysm.

We assessed the appropriate length of an elephant trunk prosthesis based on our experience with 9 patients experiencing extensive thoracic aneurysms. There were 3 patients with a true aneurysm, 5 patients with a dissecting aortic aneurysm, and 1 patient with a true plus dissecting aortic aneurysm. The subjects were 4 men and 5 women and, at the time of operation, were from 38 to 74 years old. The second-stage operations were performed on 6 patients from 9 days to 6 months after the first-stage operation. In the first-stage operation, one patient died of pneumonia during the hospital stay and another died of multi-organ infarction after 15 months. In the second-stage operation, two patients died of brain hemorrhage in the chronic stage after the operation. The length of the elephant trunk prosthesis was 3 cm in the three early patients, and in one of them the elephant trunk could not be utilized due to its insufficient length. In the next three patients, the length was extended to 5 cm, but one of patient experienced an expansion of the aneurysm in the descending aorta due to a graft of insufficient length which could not decompress the aneurysmal wall. Therefore, in the last three patients, the length was further extended to 10 cm, and the second-stage operation was performed uneventfully on the 64th, 9th and 45th day, respectively after the first-stage operation within a continuous hospital stay. Neither expansion of the aneurysm nor thromboembolism was found during the waiting period for any of the second-stage operations. Accordingly, we recommend using a 10 cm elephant trunk prosthesis.

Adult↗
PubMed1999

Hepatic subcapsular hematoma after extracorporeal shock wave lithotripsy (ESWL) for pancreatic stones.

We present a patient with complication of huge hepatic subcapsular hematoma after extracorporeal shock wave lithotripsy (ESWL) for pancreatic lithotripsy. The hematoma measured 78-110mm. Angiography showed a subcapsular hematoma, rather than a hematoma in the liver. In the arterial phase, the distal end of the small vessel showed spotty opacification similar to microaneurysma, suggesting that it was an injury caused by separation of the liver and its capsule, caused by the shock waves. The portal vein and hepatic vein were normal. After 8 weeks of conservative therapy, the hematoma was gradually absorbed and the patient was discharged. Eight months after the accident, the hematoma had decreased to 40mm in size. After 20 months, it was completely absorbed. The reported rate of renal subcapsular hematoma after ESWL for renal or ureter stones is 0.1%-0.7%. To date, however, only five cases of hepatic subcapsular hematoma after right renal stone disintegration have been reported. This is the first report of hepatic subcapsular hematoma after ESWL for pancreatic stones.

Adult↗
PubMed1999

The Freestyle stentless bioprosthesis for prosthetic valve endocarditis.

We report a case of methicillin-resistant Staphylococcus aureus-induced prosthetic valve endocarditis, which was successfully treated with aortic valve replacement using the Freestyle stentless bioprosthesis. The total root and stentless design of this bioprosthesis allows for more radical removal of infected tissue and easier treatment for annular abscess, while requiring less prosthetic materials than a conventional prosthesis. This bioprosthesis thus seems to be a valuable option for active endocarditis.

Abscess↗