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Biomedical subjects

Y Sawa

Publications and source records attributed to Y Sawa.

At least 55 records · Page 3Linked to original sources
PubMed2001

Three-dimensional flow velocity quantification of Freestyle aortic stentless bioprosthesis by magnetic resonance imaging: surgical consideration.

The characteristics in flow dynamics of stentless bioprosthetic valve implanted in aortic position has been reported using Doppler echocardiography and beneficial results have been demonstrated in patients. Because some disturbed flow characteristics were seen clinically with existence of pressure gradient, the nature of flow-velocity characteristics was evaluated in patients receiving Freestyle stentless aortic bioprosthesis using new three-dimensional MRI method. In 19 patients after AVR with Freestyle bioprosthesis, flow-velocity study was conducted using velocity-encoding phase-contrast magnetic resonance imaging (MRI). Three-dimensional flow profiles were reconstructed. The implantation techniques were subcoronary (SC) in 10, root inclusion (Incl) in 6, and full root (FR) in 3 patients. These results were compared to 4 pts with stented bioprosthesis and 4 healthy volunteers. In 3-D flow velocity profiles, there were variations from almost normal pattern to some disturbed flow pattern. All patients of FR showed the parabolic flow pattern nearly equal to normal subjects. Over half of the patients with SC and Incl showed disturbed flow pattern with increased pressure gradient. Although hemodynamically acceptable, Freestyle aortic bioprosthesis showed some degree of flow disturbance in subcoronary or inclusion method with increased transvalvular velocity that may cause late problems, and these findings evaluated by 3-D method should be implicated in surgical consideration.

Aged↗
PubMed2000

Cardioprotective effect of diadenosine tetraphosphate (AP4A) preservation in hypothermic storage and its relation with mitochondrial ATP-sensitive potassium channels.

BACKGROUND: The preconditioning effect of diadenosine tetraphosphate (AP4A) was reported in ischemia/reperfused hearts, but its effect in heart preservation was unknown. According to the possible role of mitochondrial ATP-sensitive potassium channel (mK(ATP) channel) in the effect of ischemic preconditioning, the contribution of mK(ATP) channel to the effect of AP4A was tested. METHODS: Isolated rat hearts were arrested and preserved by Eurocollin's (EC) solution at 4 degrees C for 8 hr. AP4A (80 microM) or AP4A with the 5-hydroxydecanoic acid (100 microM), a selective inhibitor of the mK(ATP) channel, was added into the EC solution. The preischemic and postischemic cardiac functions were evaluated on a buffer-perfused Langendorff apparatus before storage and after 20 min of reperfusion. RESULTS: AP4A administration improved the recovery of poststorage cardiac functions (the rate-pressure production, left ventricular systolic pressure, heart rate, coronary flow rate, and derivative of left ventricular systolic pressure; P<0.05) and reduced the leakage of lactate dehydrate and creatine kinase during reperfusion, compared with EC alone. Those effects of AP4A were completely reversed by 5-hydroxydecanoic acid administration in combination subjects. CONCLUSION: AP4A administration protects the heart through opening of the mK(ATP) channel during hypothermic preservation. Thus, addition of AP4A into cardioplegia may be a novel method of ischemic preconditioning in the transplantation context.

Adenosine Triphosphate↗
PubMed2000

Early experience of aortic valve replacement with the Freestyle stentless aortic bioprosthesis in elderly patients.

OBJECTIVES: Stentless bioprostheses have been gaining popularity in recent years as hemodynamically superior alternatives to conventional stented bioprostheses. METHODS: Between July 1996 and November 1998, 13 patients with aortic valve disease, 7 males and 6 females with a mean age (+/- SD) of 68 +/- 5 years, underwent an aortic valve replacement using the Medtronic Freestyle aortic bioprosthesis. The predominant lesions were stenosis in 8 patients and regurgitation in 5, while 2 patients had endocarditis. The operation was performed by a subcoronary technique in 9, root-inclusion technique in 3, and full root technique in 1 patient. RESULTS: Throughout the follow-up periods (with average follow-up period of 20.6 months), there was no hospital mortality, though there was one late death of unknown cause. The New York Heart Association class improved in all patients. The peak transvalvular gradient decreased from 18.4 +/- 9.8 to 12.6 +/- 9.6 mmHg, and the effective valve orifice area increased from 2.30 +/- 0.96 to 2.59 +/- 1.05 cm2 between the 1-month and the 6-month follow-up examinations. In patients with aortic regurgitation, the left ventricular end-diastolic/end-systolic volume index significantly decreased from 147 +/- 36/62 +/- 19 to 73 +/- 26/33 +/- 14 ml/m2 at 1 month after the operation. The left ventricular mass index also significantly decreased from 189 +/- 26 to 143 +/- 30 g/m2 in patients with aortic regurgitation and from 171 +/- 28 to 144 +/- 30 g/m2 in those with aortic stenosis. CONCLUSIONS: Although long-term follow-up is required for further evaluation, the early results appeared to indicate that the Freestyle aortic bioprosthesis was suitable for elderly patients requiring aortic valve replacement.

Aged↗
PubMed2000

Percutaneous cardiopulmonary support with heparin-coated circuits in postcardiotomy cardiogenic shock. Efficacy and comparison with left heart bypass.

OBJECTIVE: Percutaneous cardiopulmonary support, a simplified form of venoarterial bypass, using totally heparin-coated circuits, has recently come into clinical use. To clarify its efficacy in postcardiotomy cardiogenic shock to aid weaning from cardiopulmonary bypass, we compared results of percutaneous cardiopulmonary support with those of left heart bypass using a centrifugal pump. METHODS: We reviewed 18 patients treated between 1991 and 1998 who could not be weaned from cardiopulmonary bypass. Nine were aided by totally heparin-coated percutaneous cardiopulmonary support (PCPS group), and 9 supported by left heart bypass using a centrifugal pump (LHB group). In both groups, activated clotting time was controlled at 150-200 seconds using minimal doses of heparin as needed. RESULTS: Weaning and survival rates were higher in the PCPS group than in the LHB group (100% vs 55.6%, and 66.7% vs 22.2%). The PCPS group had a smaller amount of blood loss and needed a smaller amount of blood components in the immediate postoperative period. One percutaneous cardiopulmonary support patient required surgical re-exploration for postoperative bleeding (11.1%), but no clinical thromboembolic event occurred in the PCPS group. In the LHB group, 5 patients underwent surgical re-exploration for postoperative bleeding (55.6%), and 2 underwent thrombus extirpation in the left ventricle (22.2%). CONCLUSIONS: Although this study was retrospective and historical backgrounds could have been involved, our data suggest that totally heparin-coated percutaneous cardiopulmonary support system appears more effective as an aid to weaning from cardiopulmonary bypass and in short-term circulatory support for patients in postcardiotomy cardiogenic shock.

Adult↗
PubMed2000

Concomitant aortic root remodeling and coronary bypass in a patient with poor left ventricular function.

A 58-year-old man who had previously undergone rectal cancer surgery and who had poor left ventricular function underwent concomitant aortic root remodeling and coronary bypass for aortic root aneurysm with aortic regurgitation and severe coronary artery disease. Intermittent retrograde cold blood cardioplegia and leukocyte-depleted terminal blood cardioplegia were used for myocardial protection. Angiographic studies 1 month after surgery showed improved left ventricular function at an ejection fraction from 24 to 46%. During a 1-year follow-up, he has remained free of any cardiac event. Even though this report is limited to a case and follow-up, this technique is expected to be beneficial even in patients with severely depressed left ventricular function when the postoperative quality of life is considered.

Aortic Aneurysm↗
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

Coronary artery bypass graft in a renal transplant recipient.

A 47-year-old woman receiving predonine after renal transplantation underwent coronary artery bypass graft (CABG) surgery because of medically angina uncontrollable since 1996. Although she had an episode of acute renal rejection successfully treated with steroid pulse therapy, she had no angina or hemodialysis for over 2 years after CABG. We discuss postoperative management of renal recipient after cardiac surgery using lymphocyte-subpopulation monitoring.

Coronary Artery Bypass↗
PubMed2000

Cardioprotective effect of diadenosine tetraphosphate (AP4A) cardioplegia in isolated rat hearts.

Preischemic administration of diadenosine tetraphosphate (AP4A) has been shown to be cardioprotective. We evaluated the protective effect of AP4A when used as a cardioplegic adjuvant and tested contributions of the ATP-sensitive potassium channel (K ATP channel), adenosine receptor (AR), and purine 2y receptor (P2yR) to the effect of AP4A. Isolated buffer-perfused rat hearts were subjected to 23 min of ischemia (37 degrees C) followed by 20 min of reperfusion. Cardioplegia solution (St. Thomas Hospital solution) was infused during the first 3 min of ischemia. AP4A (10 microM) or AP4A with glibenclamide (K ATP channel blocker, 100 microM), 8-SPT (AR antagonist, 300 microM) or reactive blue (P2yR antagonist, 13 nM) were added to the cardioplegia solution. Compared with the cardioplegia solution alone, administration of AP4A with the solution significantly increased the recovery of rate-pressure production (75% +/- 11% vs 58% +/- 10%; P < 0.05) and dp/dt at the end of reperfusion, and reduced the leakage of creatine kinase (3.2 +/- 3.7 vs 13.2 +/- 10.1 IU/g; P < 0.05) during reperfusion. This effect was reversed by coadministration of glibenclamide or reactive blue but not 8-SPT. The addition of AP4A into the cardioplegia solution led to an added cardioprotective effect, either by opening the K ATP channel or by activating P2yR.

Adenosine↗
PubMed2000

Diadenosine tetraphosphate (AP4A) mimics cardioprotective effect of ischemic preconditioning in the rat heart: contribution of KATP channel and PKC.

Diadenosine tetraphosphate (AP4A) administration is reported to mimic the effect of ischemic preconditioning (PC) via purine 2y receptors (P2yR) and adenosine receptors. This study was designed to test the contributions of the ATP-sensitive potassium channel (KATP channel) and protein kinase C (PKC), two of the main regulator in PC, to the effect of AP4A. Isolated buffer-perfused rat hearts were subjected to 20 min of global ischemia (37 degrees C) and 20 min of reperfusion. Three cycles of 1-min ischemia and 3-min reperfusion induced PC. Chemicals were administrated for 2 min before 20 min of ischemia. AP4A (10 microM) administration was as effective as PC in improving the recovery of post-ischemic contractile function and reducing creatine kinase leakage after reperfusion, whereas adenosine (10 and 100 microM) have not effect. AP4A had not effect on reperfusion-induced arrhythmia, whereas PC significantly prevented it. These effects of AP4A and PC were reversed by co-administration of glibenclimade (KATP channel blocker, 100 microM) and GF109203X (PKC inhibitor, 10 microM); the effects of AP4A but not PC were reversed by co-administration of reactive blue (P2yR antagonist, 13 nM). AP4A appears to activate the KATP channel and PKC via P2yR mimic the effects of PC in part. The role of P2yR indicated that trigger mechanism of the effect of PC and AP4A administration might differ in rat hearts.

Adenosine Triphosphate↗
PubMed2000

Reduction in myocardial apoptosis associated with overexpression of heat shock protein 70.

It is reported that ischemia-reperfusion induces apoptotic cell death in myocardium. It is also demonstrated that heat shock protein 70 (HSP70) enhances myocardial tolerance. Therefore, it is hypothesized that HSP70 may play a role in the attenuation of myocardial apoptosis. To elucidate this goal, HSP70-overexpressing and control-transfected rat hearts were prepared using gene transfection by intra-coronary infusion of the hemagglutinating virus of Japan-liposome. In vivo experiment Hearts of both groups were subjected to global ischemia, followed by reperfusion in situ. Shorter recovery time to spontaneous beating (HSP70-transfected vs. control-transfected; 46.7+/-4.6 vs. 67.5+/-7.0 s, p = 0.033) and lower serum CPK levels (415+/-27 vs. 533+/-36 IU, p = 0.027) were observed in the HSP70-transfected group. The HSP70-transfected group also showed a lower percentage of cardiac myocytes positively stained by nick end labeling after ischemia-reperfusion (17.5+/-4.9 vs. 40.0+/-5.1%, p = 0.010). In vitro experiment Cardiac myocytes isolated from the hearts of both groups (prepared separately from the in vivo experiment) were subjected to hypoxia-reoxygenation. Flow cytometry was used to identify the cells that showed sub-G1 DNA content as apoptotic cells. Apoptotic cells as a percentage of viable cells increased more in the control-transfected group after hypoxia-reoxygenation (13.0+/-0.77 vs. 21.9+/-1.18%, p<0.0001). In conclusion, we demonstrated that apoptosis after ischemia-reperfusion was decreased in the HSP70-overexpressing heart in vivo and in vitro, leading to the suggestion that HSP70 could be associated with the reduction in myocardial apoptosis.

Adaptation, Physiological↗
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

Clinical evaluation of leukocyte-depleted blood cardioplegia for pediatric open heart operation.

BACKGROUND: Blood cardioplegia (BCP) is widely used for myocardial protection during open heart operation. However, BCP may have a chance to induce neutrophil-mediated myocardial injury during aortic cross-clamping. We clinically evaluated the myocardial protective effect of leukocyte-depleted blood cardioplegia (LDBCP) for initial and intermittent BCP administration in pediatric patients. METHODS: Fifty patients undergoing open heart operation for congenital heart disease between January 1997 and March 1999 were reviewed. Twenty-five were administered LDBCP for myocardial protection during ischemic periods (LDBCP group), and the remaining 25 were given BCP without leukocyte depletion (BCP group). RESULTS: The difference in plasma concentrations of malondialdehyde between coronary sinus effluent blood and arterial blood just after reperfusion in the LDBCP group (1.68 +/- 0.56 micromol/L) was significantly lower than that in the BCP group (2.35 +/- 0.62 micromol/L; p < 0.01). The LDBCP group showed significantly lower plasma concentrations of human heart fatty acid-binding protein at 50 minutes after reperfusion (LDBCP group, 103.5 +/- 38.7 IU/L; BCP group, 144.8 +/- 48.8 IU/L; p < 0.01) and the peak value of creatine kinase-MB during the first 24 postoperative hours (LDBCP group, 17.0 +/- 8.5 IU/L; BCP group, 26.0 +/- 11.6 IU/L; p < 0.01) than did the BCP group. The maximum dose of catecholamine was significantly smaller in the LDBCP group (LDBCP group, 3.20 +/- 2.18 microg x kg(-1) x min(-1); BCP group, 5.60 +/- 2.83 microg x kg(-1) x min(-1); p < 0.01). CONCLUSIONS: These results suggest the usefulness of LDBCP for protection from the myocardial injury that can be induced by BCP administration during aortic cross-clamping.

Blood Transfusion, Autologous↗
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

Myocardial protection using diadenosine tetraphosphate with pharmacological preconditioning.

BACKGROUND: We have reported a similar cardioprotective effect and mechanism of diadenosine tetraphosphate (AP4A) and ischemic preconditioning in rat hearts. In this study, the applicability of AP4A administration to cardiac surgery was tested by using a canine cardiopulmonary bypass model. METHODS: Hearts underwent 60 minutes of cardioplegic arrest (34 degrees C) by a single dose of cardioplegia. Cardioplegia contained either AP4A (40 micromol/L; n = 6) or saline (n = 6). Beagles were weaned from cardiopulmonary bypass 30 minutes after reperfusion, and left ventricular function was evaluated after another 30 minutes by using the cardiac loop analysis system. RESULTS: Administration of AP4A significantly improved the postischemic recovery of cardiac function and reduced the leakage of serum creatine kinase compared with saline. Systemic vascular resistance, mean aortic blood pressure, and the electrocardiographic indices were not significantly altered by AP4A administration. CONCLUSIONS: Administration of AP4A was cardioprotective without apparent adverse effects. Because the cardioprotective mechanism may be similar to that of ischemic preconditioning, the addition of AP4A into cardioplegia may be a novel safe method for clinical application of preconditioning cardioprotection.

Adenosine↗
PubMed2000

Ecto-5'-nucleotidase plays a role in the cardioprotective effects of heat shock protein 72 in ischemia-reperfusion injury in rat hearts.

OBJECTIVE: Heat shock protein 72 (HSP72) is involved in the myocardial self-preservation system under several conditions such as ischemia-reperfusion injury or late preconditioning. However, its mechanism is not fully understood. Ecto-5'-nucleotidase is a key enzyme for synthesizing adenosine and plays an important role in ischemic preconditioning. In this study, we tested the hypothesis that ecto-5'-nucleotidase plays a role in the cardioprotection of HSP72. METHODS: Rat hearts (H group, n=6) were transfected with HSP72 gene by an intracoronary infusion of hemagglutinating virus of Japan (HVJ)-liposome complex. Control hearts (C group, n=6) were transfected with the beta-galactosidase gene. Following 30 min of normothermic ischemia, grafts were reperfused using Langendorff apparatus. RESULTS: The activity of ecto-5'-nucleotidase was significantly higher in H group than C group both before and after ischemia-reperfusion (H vs. C; 0.51+/-0.05 vs. 0.29+/-0.06, and 1.41+/-0.15 vs. 0.85+/-0.11 nmol/mg protein/min, P<0.05). H group also showed significant better functional recoveries than C group (P<0.05), as well as less creatine phosphokinase leakage (4.4+/-2.8 vs. 14.2+/-3.4 mU/min, P<0.05) and higher adenosine release (247.5+/-35.1 vs. 54.3+/-1.7 pmol/min, P<0.05). Administration of alpha,beta-methylene adenosine diphosphate (AMP-CP), an inhibitor of ecto-5'-nucleotidase, significantly diminished the tolerance to ischemia-reperfusion injury in H group (P<0.05). CONCLUSION: These results demonstrated that ecto-5'-nucleotidase activated by an overexpression of HSP72 attenuated ischemia-reperfusion injury in the rat myocardium. They suggest that ecto-5'-nucleotidase plays a role in the cardioprotective effects of HSP72 in rat hearts.

Adenosine Diphosphate↗
PubMed2000

Differential expression of proteoglycans biglycan and decorin during neointima formation after stent implantation in normal and atherosclerotic rabbit aortas.

Proteoglycans decorin and biglycan, which bind to TGF-beta, are thought to participate in regulation of extracellular matrix accumulation in arterial intimal hyperplasia. To investigate the correlation of these proteoglycans with the cellular localization and phenotypic modulation of smooth muscle cells (SMCs), we analyzed the spatial and chronological distribution of these proteoglycans and two cytokines, TGF-beta and IL-1beta, in the process of neointima formation after stent implantation in the aortas of rabbits fed a high-cholesterol diet (atherosclerotic group) or a regular diet (control group). We implanted metallic stents in the rabbit aortas and harvested the aortas 4-56 days later for immunohistochemical and mRNA in situ hybridization analyses. In the control group, TGF-beta and biglycan expression was in correspondence with the chronology and localization of embryonic SMCs. In the atherosclerotic group, TGF-beta and biglycan expression was sustained throughout the experimental period, which was in accord with the prolonged expression of embryonic SMCs. Decorin, which did not occur in neointima in the control group, appeared in the atherosclerotic aortas in the confined area of vascular SMCs surrounding the macrophages around the stent wire. These results indicate that biglycan and decorin kinetics during neointima formation after arterial injury are distinct, despite their similar construction; biglycan synthesis correlates with embryonic SMCs.

Animals↗