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Biomedical subjects

Y Misawa

Publications and source records attributed to Y Misawa.

At least 55 records · Page 3Linked to original sources
PubMed1999

Conduction disturbances after superior septal approach for mitral valve repair.

BACKGROUND: The superior septal approach sacrifices the sinus node artery, and it requires more invasive incisions into the right and left atria. Therefore, postoperative rhythm disturbances could be troublesome in patients with SSA. In this study, we evaluated perioperative and midterm conduction disturbances in the cardiac rhythms of patients who had a SSA for mitral valve repair. METHODS: Fifty-two patients had mitral valve operations by the superior septal approach, and cardiac rhythm status was assessed. The mean follow-up period was 15 +/- 8 months. In patients with normal sinus rhythms preoperatively, serial changes in PR intervals were also assessed. Holter electrocardiograms were used 6 to 12 months postoperatively. Twelve patients who had mitral valve operations by conventional left atriotomy from the right side of the left atrium served as the control group. RESULTS: There were no operative deaths, but one patient in the experimental group died of cerebral hemorrhage 4 months postoperatively. No intractable arrhythmias occurred. Of the 25 patients who maintained sinus rhythms, preoperative PR interval on electrocardiogram was 155 +/- 20 milliseconds. Postoperative PR intervals increased for 1 week, had decreased within 2 weeks postoperatively, and returned to the normal range by 6 months postoperatively. Holter electrocardiograms of 17 patients did not show supraventricular arrhythmias exceeding 3% of the total beats. None of the patients needed pacemaker implantation. The PR intervals of 5 patients with normal sinus rhythms in the control group did not show significant changes perioperatively. CONCLUSIONS: The superior septal approach is excellent for mitral valve operations because it overcomes postoperative dysrhythmias.

Adolescent↗
PubMed1999

Chronic administration of docosahexaenoic acid improves reference memory-related learning ability in young rats.

Wistar rats were fed a fish oil-deficient diet through three generations. The young (five-week-old) male rats of the third generation were randomly divided into two groups. Over 10 weeks, one group was perorally administered docosahexaenoic acid dissolved in 5% gum Arabic solution at 300 mg/kg/day; the other group received a similar volume of vehicle alone. Five weeks after starting the administration, the rats were tested for learning ability related to two types of memory, reference memory and working memory, with the partially (four of eight) baited eight-arm radial maze. Reference memory is information that should be retained until the next trial. Working memory is information that disappears in a short time. Entries into unbaited arms and repeated entries into visited arms were defined as reference memory errors and working memory errors, respectively. Docosahexaenoic acid administration over 10 weeks significantly reduced the number of reference memory errors, without affecting the number of working memory errors, and significantly increased the docosahexaenoic acid content and the docosahexaenoic acid/arachidonic acid ratio in both the hippocampus and the cerebral cortex. In addition, the ratio demonstrated a significantly negative correlation with the number of reference memory errors. These results suggest that chronic administration of docosahexaenoic acid is conducive to the improvement of reference memory-related learning ability, and that the docosahexaenoic acid/arachidonic acid ratio in the hippocampus or the cerebral cortex, or both, may be an indicator of learning ability.

Animals↗
PubMed1999

Doppler aortic flow pattern in the recovering heart treated by cardiac extracorporeal membrane oxygenation International Society for Artificial Organs.

A 39-year-old man was admitted to our hospital because of chest pain and was diagnosed with severe heart failure due to viral myocarditis. Intraaortic balloon pumping (IABP) and cardiac extracorporeal membrane oxygenation (ECMO) were employed. Using Doppler echocardiography, we evaluated the descending aortic blood flow pattern. When cardiac ECMO was initiated from the right femoral artery, a strong backflow of blood generated by the pump was observed in the abdominal aorta because the forward flow from the native heart was weak. Two days later, the blood flow was reversed from the thoracic to abdominal aorta; the natural flow was strengthened because the native heart had improved. The observation of this phenomenon is helpful for determining the recovery of cardiac function under cardiac ECMO support.

Adult↗
PubMed1999

Dietary docosahexaenoic acid enhances ferric nitrilotriacetate-induced oxidative damage in mice but not when additional alpha-tocopherol is supplemented.

Weaning mice were fed a diet supplemented with beef tallow (BT) or BT plus docosahexaenoic acid (DHA) containing 100 mg alpha-tocopherol/kg (alpha-Toc100) or 500 mg alpha-tocopherol/kg (alpha-Toc500) for 4 wk to modify membrane fatty acid unsaturation, and then were administered ferric nitrilotriacetate (Fe-NTA). The mortality caused by Fe-NTA was higher in the group fed the DHA (alpha-Toc100) diet than in the BT diet groups but the DHA (alpha-Toc500) diet suppressed this increase. Serum and kidney alpha-tocopherol contents were slightly influenced by the dietary fatty acids but not significantly. These results indicate that the increased unsaturation of tissue lipids enhances oxidative damage induced by Fe-NTA in mice fed DHA (alpha-Toc100) but not when additional alpha-tocopherol is supplemented. The apparent discrepancy between the observed enhancement by dietary DHA of oxidative damage and the beneficial effects of dietary DHA on the so-called free radical diseases is discussed in terms of strong bolus oxidative stress and moderate chronic oxidative stress.

Animals↗
PubMed1999

The hypotensive effect of docosahexaenoic acid is associated with the enhanced release of ATP from the caudal artery of aged rats.

Fish oils have been shown to lower blood pressure in hypertensive subjects. To determine the mechanism of this hypotensive effect, we examined the effects of docosahexaenoic acid (DHA), one of the (n-3) polyunsaturated fatty acids in fish oil, on blood pressure and on the release of adenyl purines, such as ATP, ADP, AMP and adenosine, from the caudal arteries of aged rats. Aged female Wistar rats (100 wk) were fed a high cholesterol diet and were administered intragastrically ethyl all-cis-4,7,10,13,16,19-docosahexaenoate [300 mg/(kg.d)] for 12 wk (DHA group) or vehicle alone (control group). Compared with the controls, rats supplemented with DHA had significantly greater (10.1%) DHA concentrations in the caudal arteries. This was associated with more total (n-3) arterial fatty acids, a greater unsaturation index of arterial fatty acids, 43.9% lower plasma noradrenaline levels and the repression of the elevation in blood pressure observed with advancing age. The amount of purines released, both spontaneously and in response to noradrenaline, from arterial segments of DHA-supplemented rats was significantly higher than that released from tissues of control rats. Regression analysis revealed significant negative relationships between the total amount of purines released from the artery and the systolic (SBP) and diastolic (DBP) blood pressures. These results suggest that in aged rats, supplementation with DHA alters the membrane fatty acid composition as well as the amount of ATP released from vascular endothelial cells and decreases plasma noradrenaline, and that these factors may ameliorate the rise in blood pressure normally associated with advancing age.

Adenosine Triphosphate↗
PubMed1998

Recovery from lymphocytopenia and prognosis after adult extracorporeal membrane oxygenation.

Extracorporeal circulation severely impairs the host immune system. Also decreases in circulatory lymphocytes correlate with greater degrees of surgical damage. In this study, the pattern of recovery from lymphocytopenia after extracorporeal membrane oxygenation was retrospectively evaluated from a prognostic viewpoint. The results showed that the circulatory lymphocyte count of survivors returned to normal levels within 5 days after their being weaned from extracorporeal membrane oxygenation, while the circulatory lymphocyte count of nonsurvivors remained at low levels. Because it is easy to measure the number of peripheral lymphocytes, the changing pattern of the circulatory lymphocytes might be a simple and reliable prognostic factor after extracorporeal membrane oxygenation.

Aged↗
PubMed1998

Surgical Correction and Prognostic Factors for Ascending Aortic Lesions Involving Coronary Arteries

The prognostic factors following aortic root reconstruction were studied in 19 patients including 13 with annuloaortic ectasia (AAE) and 6 without AAE (non-AAE). The preoperative diagnosis of six non-AAE patients was a dissecting aneurysm in five of the patients and supravalvular aortic stenosis associated with stenosis of the right coronary ostia in one patients. In the AAE group, the Bentall's method was initially selected in 11 patients and the Cabrol's method in the remaining 2 patients. In the non-AAE group, ascending aortic replacement was performed in 4 patients, patch plasty of the ascending aorta in 1 patient, and entry closure in the other patient. In this group, aorto-coronary bypass grafting using a saphenous vein graft was performed in 4 patients, ostioplasty of the right coronary artery (RCA) in 1, and the Bentall's method in 1. During the postoperative acute phase, one AAE patient died of acute myocardial infarction 3 days after surgery; the remaining 18 patients survived. In the follow-up study, 3 patients died of cardiac events which included two cardiac failures and one arrhythmia. The preoperative left ventricular diameter in the end-diastolic phase (LVDd) of 2 AAE patients who died of cardiac failure was 80 mm or larger and the left ventricular function remained unchanged after surgery. One non-AAE patient who underwent RCA ostioplasty suddenly died of arrhythmia. Postanastomotic leakage around the left coronary ostia associated with the patent Cabrol's trick occurred in 1 AAE patient and mitral valve regurgitation occurred in the other non-AAE patient. Reoperation using Cabrol's procedure and mitral valve replacement were performed for these 2 patients, respectively. Preoperative low cardiac function and large LVDd may influence the late results in AAE patients, therefore, earlier operations should be recommended.

Journal Article↗
PubMed1998

Transventricular mitral valve replacement in a patient with a left ventricular aneurysm: report of a case.

Postinfarct left ventricular aneurysm associated with mitral valve regurgitation is resistant to medical treatment and often requires surgical repair. A transventricular approach to the mitral valve in such a patient can enable the surgeon to avoid incision of the right or left atrium, and can provide for safe and reliable surgical intervention. We report herein the case of a patient in whom left ventricular aneurysmectomy and concomitant mitral valve replacement were successfully performed using a transventricular approach via aneurysmectomy.

Coronary Aneurysm↗
PubMed1998

Successful graft replacement of the descending aorta after an extended reconstruction of the ascending and transverse aorta in a patient with Marfan's syndrome.

A 27-year-old man with Marfan's syndrome underwent a total aortic graft replacement in three separate stages. Initially the abdominal aorta was replaced, followed by the ascending aorta and aortic arch, and finally the residual portion. The extensive reconstruction of both the ascending and transverse aorta at the second operation, even though no dissection was present in the aortic arch, reduced the risk of the subsequent operation since the same surgical approach did not have to be used.

Adult↗
PubMed1998

Infectious mediastinitis after cardiac operations: computed tomographic findings.

BACKGROUND: Infectious mediastinitis after cardiac operations is of great concern to cardiac surgeons because of its poor prognosis. Prompt surgical interventions such as debridement and irrigation are the key to treatment of infectious mediastinitis. METHODS: We surveyed retrospectively the cases of 722 consecutive cardiac surgery patients at our hospital. Mediastinitis developed in 21 patients after the cardiac operation. We performed computed tomography in 11 of these patients before resternotomy and in 10 patients as the control 2 to 3 weeks after the cardiac operation. RESULTS: Mediastinal soft tissue swelling was seen in 7 patients, bilateral pleural effusion was found in 9 patients, sternal dehiscence or sternal erosion was observed in 8 patients, and subcutaneous fluid accumulation was found in 7 of the mediastinitis group. Unilateral pleural effusion was seen in 6 and bilateral effusion in 1, and mediastinal soft tissue swelling was seen in 1 patient of the control group. CONCLUSIONS: Our study showed that mediastinal soft tissue mass combined with bilateral pleural effusion can be a characteristic computed tomography finding in poststernotomy infectious mediastinitis, and that chest computed tomography is more sensitive to detecting sternal dehiscence, sternal erosion, and subcutaneous fluid accumulation.

Bacterial Infections↗
PubMed1998

Saphenous vein graft pseudoaneurysm rupture after coronary artery bypass grafting.

An elderly woman underwent coronary artery bypass grafting, which was followed 1 month later by pseudoaneurysmal rupture at the distal anastomosis of a saphenous vein graft. Emergency repair of the suture line dehiscence was made, and the postoperative course was uneventful. Pseudoaneurysm formation of a saphenous vein graft after coronary artery bypass grafting is a rare but potentially lethal complication requiring urgent operative intervention.

Aged↗
PubMed1998

Mechanisms of cardiomyoplasty: comparative effects of adynamic versus dynamic cardiomyoplasty.

BACKGROUND: The apparent paradox seen in patients who have undergone dynamic cardiomyoplasty and shown substantial clinical and functional improvements with only modest hemodynamic changes may be due to inappropriate end points chosen for study, a result of incomplete understanding of mechanisms involved. The purpose of this study was to compare the relative role of the passive "girdling effect" and the dynamic "systolic squeezing effect" of the wrapped muscle in cardiomyoplasty. METHODS: The control group of 6 dogs underwent 4 weeks of rapid pacing (250 beats/min) to induce severe heart failure followed by 8 weeks of observation without rapid pacing. The trajectory of recovery in hemodynamics and cardiac dimensions was followed with echocardiography and Swan-Ganz catheters. In the "adynamic" cardiomyoplasty group (n=4), the left latissimus dorsi muscle was wrapped around the ventricles and allowed to stabilize and mature for 4 weeks. This was followed by rapid pacing and recovery as in the control group. In the "dynamic" cardiomyoplasty group (n=3), the same protocol for the adynamic group was followed except that a synchronizable cardiomyostimulator was attached to the thoracodorsal nerve of the muscle wrap. This allowed the latter to be transformed during the rapid-pacing phase and permitted dynamic squeezing of the muscle wrap to be generated by burst stimulation synchronized with cardiac contraction in a 1:2 ratio. RESULTS: Baseline data were comparable in all groups prior to rapid pacing. After 4 weeks of rapid pacing, the left ventricular ejection fraction was higher in the adynamic (27.0%+/-3.9%; p < 0.05) and dynamic (33.3%+/-2.3%; p < 0.02) cardiomyoplasty groups compared with controls (18.8%+/-8.3%). Similarly, ventricular dilatation in both systole and diastole was less in the adynamic (51.8+/-8.7 mL, [p < 0.002] and 38.2+/-7.2 mL [p < 0.001], respectively) and dynamic (62.0+/-7.2 [p < 0.02] and 41.3+/-3.5 mL [p < 0.005], respectively) cardiomyoplasty groups compared with controls. In the dynamic group, on and off studies were carried out after cessation of rapid pacing while the heart was still in severe failure, and they demonstrated a systolic squeezing effect in stimulated beats. Only this group recovered fully to baseline after 8 weeks. CONCLUSIONS: By reducing myocardial stress, both the passive girdling effect and the dynamic systolic squeezing effect have complementary roles in the mechanisms of dynamic cardiomyoplasty.

Animals↗
PubMed1998

Growth potential and left ventricular diastolic function in cardiomyoplasty.

BACKGROUND: Dynamic cardiomyoplasty is an experimental operation for advanced heart failure. Current clinical results bring the possibility of its application to children. This study was designed to obtain information about the relationship between cardiomyoplasty and growth of the heart. METHODS: Six beagles, 9 to 10 weeks old, underwent cardiomyoplasty without electric stimulation (cardiomyoplasty group), and another 5 beagles underwent median sternotomy and pericardiotomy (control group). Six months later, weights of hearts, wrapped latissimus dorsi muscles, and unwrapped right latissimus dorsi muscles and pressure-volume relationships were obtained. RESULTS: Wrapped latissimus dorsi muscles weighed 33 +/- 3 g (mean +/- standard deviation), and unwrapped muscles weighed 68 +/- 5 g. The heart weight was 82 +/- 3 g in the cardiomyoplasty group and 89 +/- 7 g in the control group. Left ventricular maximum elastance was 3.8 +/- 0.8 mm Hg/mL in the cardiomyoplasty group and 3.9 +/- 0.9 mm Hg/mL in the control group. End-diastolic pressure versus end-diastolic volume ratios were 0.52 +/- 0.03 and 0.54 +/- 0.05, respectively. Pathologic examination showed fat infiltration and muscle fiber atrophy in the cardiomyoplasty group. CONCLUSIONS: The wrapped latissimus dorsi muscle flaps were growing and the diastolic function was not impaired. This indicates a potentially safe clinical application of dynamic cardiomyoplasty for children.

Adipose Tissue↗
PubMed1998

Platelet protective effect of TAK-029, a novel glycoprotein IIb/IIIa antagonist: an in vitro study.

Previous studies have indicated that exposure of fibrinogen receptors associated with the glycoprotein IIb/IIIa complex contributes to platelet loss during cardiopulmonary bypass. TAK-029 is a newly developed reversible, nonpeptide inhibitor of platelet glycoprotein IIb/IIIa receptors. In this study, we tested the platelet preserving effect of TAK-029 in an in vitro model. The methods included the comparison of the release of beta-thromboglobulin (beta-TG) between a TAK-029 group (n = 5) and a control group (n = 5) in a mock circulation under a shear force generated by a centrifugal pump. To evaluate the degree of beta-TG release, deltabeta-TG/deltaT was calculated where deltabeta-TG is the increase in beta-TG and deltaT is the time. The results showed that the value of deltabeta-TG/deltaT in the TAK-029 group was significantly lower than it was in the control group (4.22 +/- 0.27 x 10(2) ng/ml vs. 7.33 +/- 0.66 x 10(2) ng/ml, respectively). In conclusion, TAK-029 reduced the platelet activation under the shear forces of an in vitro model, suggesting that TAK-029 is a potential candidate for platelet protection during cardiopulmonary bypass.

Blood Platelets↗