Biomedical subjects

Toshiki Takahashi

Publications and source records attributed to Toshiki Takahashi.

At least 19 recordsLinked to original sources

PubMed2006

Pulmonary artery dissection complicating lung transplantation for primary pulmonary hypertension.

We report a case of pulmonary artery (PA) dissection complicating lung transplantation. A 30-year-old man with primary pulmonary hypertension underwent bilateral single lung transplantation. Thirty hours postoperatively he had signs of obstruction of the right main pulmonary artery develop due to dissection demonstrated on transesophageal echocardiography and pulmonary arteriography. Surgical repair of the dissection with reanastomosis of the pulmonary artery was successfully carried out, and the patient subsequently improved to a favorable condition. Pulmonary hypertension is a risk factor of pulmonary artery dissection; our case suggested that underlying chronic pulmonary hypertension might have led to this rare and life-threatening anastomotic problem after lung transplantation.

Adult↗

PubMed2006

Simple and easy method for chordal reconstruction during mitral valve repair.

We describe a simple reproducible method for chordal replacement using expanded polytetrafluoroethylene sutures during a mitral valve repair. With this technique, fine length adjustments of the new chordae are easy to make and it is possible to tie the two ends of the suture securely without slippage.

Chordae Tendineae↗

PubMed2006

Isolation and characterization of Streptococcus mutans in heart valve and dental plaque specimens from a patient with infective endocarditis.

Streptococcus mutans, known to be an aetiologic agent of dental caries, also causes infective endocarditis (IE), although a comparison of isolates from the oral cavity and infected heart valve of the same patient has not been reported. In the present study, infected heart valve and dental plaque samples from a patient with IE were analysed. Broad-range PCR with DNA sequencing revealed that 50 clones from the dental plaque isolates were composed of oral streptococci and periodontopathic bacteria, whereas only Streptococcus mutans was detected in 50 clones from the heart valve. Eighteen strains of Streptococcus mutans were isolated from dental plaque and seven from the heart valve, and the biochemical properties of each were in accordance with those of Streptococcus mutans. DNA fingerprinting analysis revealed that all the oral isolates of Streptococcus mutans had similar patterns, which were different from those of the isolates from the infected heart valve. Western blotting using glucosyltransferase (GTF)-specific antiserum showed that the seven strains from the heart valve lacked the three types of intact GTF. In addition, the sucrose-dependent adhesion rates of these isolates were significantly lower than those of the oral isolates (P<0.001). Furthermore, the isolates from the heart valve were less susceptible to erythromycin and kanamycin. These results indicate that the properties of the Streptococcus mutans strains isolated from the infected valve were different from those of typical oral strains, which may be related to the effects of IE.

Anti-Bacterial Agents↗

PubMed2006

Detection of cariogenic Streptococcus mutans in extirpated heart valve and atheromatous plaque specimens.

The involvement of oral bacteria in the pathogenesis of cardiovascular diseases has been the focus of attention in many studies, and several periodontal pathogens have been detected in diseased cardiovascular lesions, suggesting relationships between oral microorganisms and cardiovascular diseases. However, no information is available regarding the involvement of cariogenic pathogens such as Streptococcus mutans. The presence of oral streptococcal species and periodontitis-related bacteria in 35 heart valve and 27 atheromatous plaque clinical specimens, as well as 32 dental plaque specimens from the same subjects, was analyzed using a PCR method. Furthermore, broad-range PCR with DNA sequencing analysis was employed to identify the bacterial species in those samples. Streptococcus mutans was frequently detected in the heart valve (69%) and atheromatous plaque (74%) specimens, while other bacterial species, including those related to periodontitis, were detected with much lower frequencies. The bacterial composition in cardiovascular tissues was found to be markedly distinct from that in dental plaque, with only a limited number of species, including S. mutans, in the cardiovascular regions shown to have possibly originated from the oral cavity. Semiquantitative assay results revealed that S. mutans was detected in significant quantities in the heart valve (40%) and atheromatous plaque (48%) specimens, whereas the quantities of all other tested bacterial species, including several related to periodontitis, were negligible in the cardiovascular samples. These results indicate that S. mutans is a possible causative agent of cardiovascular disease.

Aged↗

PubMed2005

Thallium-201 single-photon emission computed tomography: quantitative assessment of left ventricular perfusion and structural change in patients with chronic aortic regurgitation.

BACKGROUND: Previously, perfusion defect in the left ventricle was detected by thallium-201 (201T1) single-photon emission computed tomography (SPECT) in aortic regurgitation (AR). The significance of 201T1 SPECT, however, has not been clarified. Limited information is available regarding the relationship between functional characteristics and scintigraphic findings. HYPOTHESIS: The purpose of this study was to elucidate the role of exercise 201T1 SPECT in assessing myocardial perfusion or structural change in chronic AR. We examined the correlation between 201T1 scintigraphic findings and left ventricular (LV) function parameters in 11 patients. METHODS: Defect volume ratio (DVR) in exercise 201T1 SPECT was used as a parameter of the range of abnormal thallium distribution. Left ventricular parameters were obtained by right and retrograde left cardiac catheterizations. The relationship between DVR and the parameters was analyzed. RESULTS: The DVR ranged from 1.0 to 28.3% (average 12.1 + 8.5 %). There was a significant correlation (r = 0.77, p < 0.05) between DVR and end-diastolic volume index (EDVI), a definite correlation (r = 0.66, p < 0.01) between DVR and end-systolic volume index (ESVI), and a good correlation (r = -0.77, p <0.05) between DVR and end-systolic wall stress (ESS)/ ESVI; however, no such correlation was found between DVR and ejection fraction. CONCLUSION: All patients showed abnormal defects in 201T1 accumulation scattered across the entire ventricle. A strong correlation between DVR and ESS/ESVI, an index of myocardial contractility, was a major finding of this study, suggesting a significant association between abnormal myocardial perfusion or structural alteration and reduction in myocardial contractility in chronic AR.

Adult↗

PubMed2005

Therapeutic angiogenesis induced by injecting hepatocyte growth factor in ischemic canine hearts.

PURPOSE: Therapeutic angiogenesis, induced by the direct injection of angiogenic growth factors or by transmyocardial laser revascularization (TMLR), has shown great potential as a new therapeutic strategy for end-stage coronary artery disease. However, no significant differences in angiogenic effects of TMLR and vascular endothelial growth factor (VEGF) have been reported. We compared the effects of the intramyocardial injection of hepatocyte growth factor (HGF), a novel angiogenic factor, with those of TMLR, by evaluating the improvement in regional blood flow and regional function in a canine heart model of chronic ischemia. METHODS: To create a model of chronic ischemia, we ligated the left anterior descending artery (LAD) in 15 beagles. We divided the dogs into three groups according to the treatment given 1 month after ligation. Four dogs were given an intracardial injection of human recombinant HGF (H group), six dogs were given TMLR (T group), and five dogs were used as a control (C group). We compared the degree of improvement in regional blood flow and regional function 1 month after the treatment. RESULTS: The regional myocardial blood flow and function were significantly better in the H group than in the T or C groups (P < 0.05). Histologically, there were significantly more von Willebrand factor-positive cells in the LAD region in the H group than in the T or C groups. CONCLUSION: The intramural injection of recombinant human HGF resulted in therapeutic angiogenesis with an intrinsic contractile state, and it may have greater advantages than TMLR for the treatment of chronic ischemic heart disease.

Animals↗

PubMed2004

Self-organization phenomena and decaying self-similar state in two-dimensional incompressible viscous fluids.

The final self-similar state of decaying two-dimensional (2D) turbulence in 2D incompressible viscous flow is analytically and numerically investigated for the case with periodic boundaries. It is proved by theoretical analysis and simulations that the sinh-Poisson state comega=-sinh (betapsi) is not realized in the dynamical system of interest. It is shown by an eigenfunction spectrum analysis that a sufficient explanation for the self-organization to the decaying self-similar state is the faster energy decay of higher eigenmodes and the energy accumulation to the lowest eigenmode for given boundary conditions due to simultaneous normal and inverse cascading by nonlinear mode couplings. The theoretical prediction is demonstrated to be correct by simulations leading to the lowest eigenmode of {(1,0) + (0,1)} of the dissipative operator for the periodic boundaries. It is also clarified that an important process during nonlinear self-organization is an interchange between the dominant operators, which leads to the final decaying self-similar state.

Journal Article↗

PubMed2004

Successful surgical intervention for active infective endocarditis on a hemodialysis patient with cerebral infarction and disseminated intravascular coagulopathy.

A 48-year-old woman on hemodialysis developed congestive heart failure, neurologic deficits and disseminated intravascular coagulopathy (DIC) caused by methicillin resistant staphylococcus aureus infective endocarditis. Echocardiography showed large vegetation attached to the anterior leaflet of the mitral valve, severe mitral and aortic regurgitation, and poor left ventricular function. Computed tomography findings revealed recurrent embolic events including cerebral and splenic infarction, but no evidence of intracranial bleeding. Abnormal laboratory findings included DIC in addition to the administration of the daily dose of ticlopidine hydrochloride. Aortic and mitral valves were urgently replaced with bioprosthetic valves after the transfusion of fresh frozen plasma and platelet. During the follow-up period of one year, she was free from any cardiac events and infectious signs. Even though this report is limited to a case and its follow-up, it is sensible to conclude that only aggressive and timely surgical intervention can be the only lifesaving action for patients with highly infective endocarditis.

Aortic Valve↗

PubMed2004

Prophylactic effect of intravenous nicorandil on perioperative myocardial damage in patients undergoing off-pump coronary artery bypass surgery.

Nicorandil, ATP sensitive potassium channel opener, is shown to reduce coronary events for patients with stable angina. The present study was designed to examine the protective potential of nicorandil for patients undergoing off-pump coronary artery bypass grafting. Twenty-four patients undergoing off-pump coronary artery bypass grafting were randomly assigned to two groups, one receiving continuous infusion of nicorandil (1.0 microg.kg(-1).min(-1)) (n = 12) through anesthesia to next day and the other receiving no nicorandil for control (n = 12). For assessing myocardial injury, heart type fatty acid binding protein, troponin T, and creatine kinase MB isoform were determined during the first 15 hours after reperfusion. The concentration of heart type fatty acid binding protein in the nicorandil group was significantly lower than that in the control group. On the other hand, the concentrations of troponin T and creatine kinase MB isoform in the nicorandil group were lower than those in the control group, but the differences did not reach statistical significance. Furthermore, nicorandil did not affect the patients' hemodynamic variables. Our data suggest that the infusion of nicorandil provides small myocardial protection without affecting hemodynamic parameters during perioperative treatment of patients undergoing off-pump coronary artery bypass grafting.

Aged↗

PubMed2004

Sinus of valsalva aneurysm with congenital aortic stenosis and aortic coarctation.

A 52-year-old female was diagnosed with the extremely rare combination of sinus of Valsalva aneurysm, congenital unicuspid aortic valve stenosis, and coarctation of the aorta. She was successfully treated in a two-stage operation. The first operation consisted of a bypass graft to correct the coarctation. The second, performed 31 days later, included aortic valve replacement, patch closure of the aneurysm, and translocation of the right coronary artery.

Abnormalities, Multiple↗

PubMed2004

Early result of heart transplantation in Japan: Osaka University experience.

Since the new organ transplantation law was established in 1997, 17 heart transplantations have been performed in Japan, 7 of which were carried out at Osaka University Hospital. Recipient diagnosis was dilated cardiomyopathy in 2, dilated phase of hypertrophic cardiomyopathy in 4, and post-myocarditis cardiomyopathy in 1. Ages ranged from 8 to 49 years with a mean of 35.3 years. Five patients were bridged with a left ventricular assist device. The waiting period was 182-977 days (mean, 643 days). There was no early or late death during follow-up of 1-4.8 years. Under a standard triple-drug regimen using mycophenolate, there were 3 rejection episodes greater than grade 3 in 2 patients, and humoral rejection requiring plasmapheresis in one. A young boy whose donor was a hemodynamically compromised adult developed neurological sequelae after resuscitation following ventricular tachycardia. All patients were discharged and went back to work or their regular daily life. Although the donor shortage is still severe in Japan, the resumption of heart transplantation has been satisfactory, and left ventricular assist devices have played a crucial role.

Adult↗

PubMed2004

Advantages of off-pump coronary artery bypass grafting in long-term hemodialysis patients: multicenter analysis.

OBJECTIVE: Long-term hemodialysis remains a major risk factor for coronary artery bypass grafting (CABG). Off-pump CABG (OPCAB) is expected to offer benefits for these high risk patients; however, this issue has not been clarified. To elucidate the issue, we conducted a multicenter retrospective review of long-term hemodialysis patients who underwent on- or off-pump CABG. PATIENTS: Between January 1998 and December 2002, 53 hemodialysis patients underwent elective CABG at 14 centers. Nineteen patients underwent OPCAB, and 34 patients underwent conventional CABG (CCAB). Preoperative and perioperative variables, morbidity, and mortality were compared in the 2 groups. There were no significant differences in preoperative variables between the 2 groups. RESULTS: The length of intensive care unit (ICU) stay (3.7 versus 5.9 days), the amount of blood loss (668 versus 1100 mL), and the amount of red cell transfusion (4.7 versus 12.2 units) were less in the OPCAB group. The perioperative morbidity was significantly lower in the OPCAB group (0.0% versus 26.5%). The hospital mortality was not significant but was low in the OPCAB group (0% versus 14.7%, P = .079). CONCLUSION: OPCAB significantly decreased blood loss, blood transfusion, ICU stay, and major perioperative morbidity compared with the values for CCAB. OPCAB may have advantages over CCAB in long-term hemodialysis patients.

Blood Transfusion↗

PubMed2003

Aneurysm of the ductus diverticulum in adults: the diagnostic value of three-dimensional computed tomographic scanning.

Ductus arteriosus aneurysm is rare in adults and preoperative diagnosis has not been usually done. We report 2 cases of adult type ductus arteriosus aneurysm. In both cases, 3D computed tomographic scanning showed a saccular aneurysm originating from the distal aortic arch toward the left pulmonary artery, which had a notching in the orifice of the aortic side. They were successfully treated surgically though one was a ruptured aneurysm to the left pulmonary artery. In these cases, 3D-CT scan was of great value in the preoperative diagnosis of the ductus arteriosus aneurysm.

Adult↗

PubMed2003

Leukocyte-depleted terminal blood cardioplegia provides superior myocardial protective effects in association with myocardium-derived nitric oxide and peroxynitrite production for patients undergoing prolonged aortic crossclamping for more than 120 minutes.

OBJECTIVES: This study was designed to examine the myocardial protective effect of leukocyte-depleted terminal blood cardioplegia in association with nitric oxide and peroxynitrite production, especially for patients undergoing prolonged aortic crossclamping. METHODS: Fifty-four patients (34 men, 20 women, mean age 56.7 +/- 12.7 years) undergoing aortic valve replacement were randomly allocated to one of two groups; group LDTC (n = 27) received 10 minutes of leukocyte-depleted terminal blood cardioplegic solution, and group CONT (n = 27) served as controls. Each group was subdivided into 2 groups: aortic crossclamping for less than 120 minutes in groups LDTC-S (n = 13) and CONT-S (n = 14); aortic crossclamping for 120 minutes or more in groups LDTC-L (n = 14) and CONT-L (n = 13). RESULTS: After aortic unclamping, group LDTC-L showed higher incidence of spontaneous defibrillation (78.6% vs 30.8%, P =.0213), higher plasma nitrate + nitrite in the coronary sinus effluent (32.5 +/- 4.1 vs 28.7 +/- 3.0 micromol/L, P =.0013), lower differences between coronary sinus effluent and arterial blood in the percentage ratio of nitrotyrosine to tyrosine (myocardium-derived peroxynitrite; 2.987% +/- 0.576% vs 3.951% +/- 0.952%, P =.0036), and plasma polymorphonuclear-elastase (113.9 +/- 21.3 vs 155.5 +/- 41.6 microg/L, P =.0029) and malondialdehyde (2.75 +/- 0.67 vs 4.02 +/- 0.96 micromol/L, P =.0005) than group CONT did. Postoperatively, group LDTC-L showed lower human-heart fatty acid-binding protein (111.4 +/- 25.2 vs 156.4 +/- 38.6 IU/L, P =.0013), lower creatine kinase-muscle and brain (19.2 +/- 4.7 vs 24.8 +/- 6.5 IU/L, P =.0120), and smaller requirement of catecholamine (5.44 +/- 2.29 vs 8.45 +/- 3.42 microg x kg(-1) x min(-1), P =.0122). There were no significant differences in these parameters between groups LDTC-S and CONT-S. CONCLUSIONS: This study demonstrated that leukocyte-depleted terminal blood cardioplegia provided superior myocardial protective effects and regulated myocardial-derived nitric oxide and peroxynitrite production only for patients undergoing aortic crossclamping for more than 120 minutes. The results suggest that prolonged aortic crossclamping deteriorates the tolerance to leukocyte-mediated myocardial injury accompanied by endothelial dysfunction associated with nitric oxide and peroxynitrite production.

Adolescent↗

PubMed2002

Beating coronary bypass with right-heart bypass. A safer option in patients at high risk for stroke.

Two patients with bilateral obstructive carotid artery disease underwent beating heart coronary bypass including revascularization of the circumflex branch using right-heart bypass in a stable hemodynamic state. Without this mechanical support, lifting the left ventricle for the exposure of the posterior wall could impair the hemodynamic state of the patient. Right-heart bypass in addition to aortic no-touch technique can be a safer option for complete coronary revascularization in patients at high risk for neurological complications.

Aged↗

PubMed2002

Arch-first technique for aortic arch aneurysm repair through median sternotomy.

We describe a modified arch-first technique for total arch replacement through median sternotomy. This technique involves a short period of circulatory arrest (less than 30 minutes) and subsequent anterior cerebral perfusion. It does not require cannulation of the carotid vessels, which can cause cerebral thromboembolism, and it enables anterior cerebral perfusion to be resumed after a relatively short period of circulatory arrest. This appears to be a useful technique to reduce cerebral complications in complicated arch reconstruction operation for patients with severely atherosclerotic carotid vessels.

Aorta, Thoracic↗

PubMed2002

Intraoperative transfection of vein grafts with the NFkappaB decoy in a canine aortocoronary bypass model: a strategy to attenuate intimal hyperplasia.

BACKGROUND: The nuclear transcriptional factor NFkappaB is reported to play an important role in the expression of genes for neutrophil and macrophage chemotactic factors, adhesion molecules, and cell cycle-regulating proteins. In aortocoronary bypass surgery, the saphenous vein often develops vein graft disease. Here, we investigated whether transfection of a cis element decoy oligodeoxynucleotide of NFkappaB (NFkappaB decoy) into the vein graft wall suppresses neointimal hyperplasia and the differentiation of medial smooth muscle cells. METHODS: We established a canine aortocoronary bypass grafting model that has a saphenous vein graft between the left anterior descending coronary artery and the descending aorta. Pressure-mediated transfection of a scrambled (SD group; n = 5) or NFkappaB decoy (ND group; n = 5) into the graft wall was performed intraoperatively. The grafts were gently harvested at 4 weeks postoperative, and the middle portion of the graft was examined histopathologically. RESULTS: The average neointimal area of the ND group was significantly suppressed (SD group, 2.63 +/- 1.00 mm2 vs ND group, 0.88 +/- 0.66, p < 0.05), and the differentiation and proliferation of the medial smooth muscle cells in the ND group were also suppressed (proliferating cell nuclear antigen index: SD group, 56 +/- 24 vs ND, 13 +/- 4, p < 0.05). CONCLUSIONS: These results demonstrated the efficacy of intraoperative transfection of the NFkappaB decoy into the vein graft wall for attenuation of neointima formation.

Animals↗

PubMed2002

Modified aortic root remodeling for annuloaortic ectasia with abnormal coronary take-off.

The abnormality of coronary arterial take-off is a limiting factor for a successful aortic valve sparing procedure. We present a 13-year-old boy, with Marfan syndrome and annuloaortic ectasia, whose coronary take-off was found to be abnormal during surgery. Two adjacent coronary orifices were located in the left coronary sinus and very close to the right-left commissure. A modified aortic remodeling procedure was successfully performed without translocation of the coronary artery.

Adolescent↗