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Biomedical subjects

M Toyama

Publications and source records attributed to M Toyama.

At least 55 records · Page 3Linked to original sources
PubMed1998

Relationship between normalization of negative T waves on exercise ECG and residual myocardial viability in patients with previous myocardial infarction and no post-infarction angina.

The usefulness of normalization of negative T waves in exercise ECG was investigated as an index of myocardial viability in patients with previous myocardial infarction with no symptoms or ischemic ST-segment change during exercise test. A total of 39 patients, 20 with T-wave normalization (POS group) and 19 without T-wave normalization (NEG group) on exercise ECG. were studied. Myocardial viability was evaluated by thallium-201 single-photon emission computed tomography (SPECT) during exercise or at rest. We also assessed left ventricular ejection fraction (LVEF) by contrast ventriculography before (n=39) and after percutaneous transluminal coronary angioplasty (PTCA) (n=17). SPECT detected myocardial viability in 16 (80%) of the 20 patients in the POS group and in 4 (21%) of the 19 patients in the NEG group (p<0.01). LVEF increased after successful PTCA in the POS group (from 53+/-13% to 63+/-8%, p<0.025), but fell in the NEG group (from 57+/-10% to 51+/-8%). It is concluded that normalization of negative T waves on exercise ECG is a useful, simple index of myocardial viability in patients with previous myocardial infarction with no symptoms or ischemic ST-segment change during exercise testing.

Adult↗
PubMed1997

Single-channel thin-fiber and Nd:YAG laser temporomandibular joint arthroscope: development and preliminary clinical findings.

This study evaluated the development and preliminary results of a single-channel thin-fiber and Nd:YAG laser temporomandibular joint arthroscope. No articular damage from the arthroscopic procedure and laser lysis was observed in any of the joints when the arthrotomy was performed. All three disk perforations found by the arthroscope were confirmed at the time of the arthrotomy, and in these joints the tip of the arthroscope could be advanced into the inferior joint. The nine joints, where only arthroscopic laser lysis was performed, were followed up and the results were satisfactory.

Aluminum Silicates↗
PubMed1997

Reoperation of coronary artery bypass with right gastroepiploic artery on a beating heart.

The case of a 67-year-old male with double-vessel coronary artery disease combined with a severely calcified ascending aorta, moderate aortic insufficiency, cholecystic stones, and unruptured intracranial aneurysm is presented. Successful coronary artery bypass reoperation is described using the right gastroepiploic artery through an additional left anterior thoracotomy on the beating heart.

Aged↗
PubMed1996

Effect of warming of exercising legs on exercise capacity in patients with impaired exercise tolerance.

OBJECTIVE: The purpose of this study was to determine whether warming of exercising legs improves exercise capacity in patients with cardiac disease and low exercise tolerance. BACKGROUND: Exercising muscle temperature reflects both muscle metabolic rate and muscle blood flow. Increase in muscle temperature in exercising legs is impaired in patients with chronic heart failure. We hypothesized that the mechanisms responsible for impairment of temperature increase in exercising muscle might be related to those responsible for low exercise tolerance. METHODS: We studied 17 patients with cardiac disease whose anaerobic threshold (AT) ranged from 6.6 to 14.8 ml/kg/min (mean 11.2 +/- 1.9 SD). Subjects performed symptom-limited sitting cycle ergometer exercise with or without warming of the thighs. Both thighs were warmed by use of hot packs fixed by supporters. To determine the effect of the supporters themselves on AT and peak VO2, the same ergometer exercise was performed by 7 patients with or without supporters. Peak VO2 and AT were determined by concomitant respiratory gas monitoring. RESULTS: 1) Warming of the thighs increased deep temperature in the thighs (1.0 approximately 2.8 degrees C). 2) AT and peak VO2 were significantly improved in the warming exercise compared with the non-warming exercise (p < 0.01, p < 0.01). 3) There was no significant difference in AT or peak VO2 between the exercise with and without supporters. CONCLUSION: The findings of this study indicate that warming of exercising legs improves exercise capacity in patients with cardiac disease and low exercise tolerance.

Aged↗
PubMed1996

[Successful surgical treatment of intraoperative aortic dissection complicating aortic valve replacement].

A 74-year-old man underwent standard aortic valve replacement. The aortotomy was closed by use of strips of Teflon felt because of somewhat friable thin aortic wall. After the termination of cardiopulmonary bypass, aortic cannulation site was carefully sutured enforcing with a piece of pericardium, since some bleeding persisted. The intraoperative diagnosis of acute aortic dissection (Stanford type A) was made with transesophageal echocardiography. Since extension of the dissection toward the aortic root was hardly possible due to the Teflon felt enforced aortotomy closure, further surgical intervention was not considered at this time. Thiry-two hours later after admission to CCU, sudden bleeding through the mediastinal tube prompted the patient back to OR for exploration Bleeding was noted from the posterior wall of the ascending aorta. Ascending aorta and transverse arch were significantly enlarged with notable discoloration. With the aid of extracorporeal circulation and selective cerebral perfusion, the total graft replacement of the ascending aorta and aortic arch was performed. The intimal tear located at the aortic cannulation site. The postoperative course was uneventful. Prompt recognition and appropriate surgical management are necessary to improve patient outcome.

Aged↗
PubMed1996

[Coronary reoperation--selection of conduit material and management of stenotic vein graft].

We have operated upon 30 cases of coronary reoperation during the past 12 years. The mean interval between the two operations was 46 months. The mean follow-up after reoperation was 61 months. The major reasons for reoperation were graft failure from technical problems in early and time-related degeneration in graft and native coronary progression in late cases. We aggressively have replaced the stenotic and obstructed vein graft with the arterial graft at reoperation since 1990. Hypoperfusion syndrome is clinical entity reported secondary to inadequate flow via the internal thoracic artery. For patients with atherosclerotic vein grafts to the LAD, the minimal manipulation of the old vein graft, adding the IMA graft to the LAD and leaving the stenotic vein graft intact appear to be safe and better procedure for long-term results. There were no operative and hospital death. Five and 10 years survival rate were 100% and 90% respectively. Five and 10 years event free rate were 92.1% and 82.9% respectively. The outcome of reoperation was satisfactory.

Adult↗
PubMed1996

[Emergent coronary bypass grafting after acute myocardial infarction].

In an attempt to examine various factors affecting the short- and long-term results of emergent coronary bypass graft surgery (ECABG) after an acute myocardial infarction (AMI), all patients undergoing ECABG without associated procedures at our institution from January 1987 to July 1995 were reviewed. Forty eight patients underwent ECABG after AMI. The hospital mortality rate was 20.8%. The charts of these patients were reviewed with regard to sex, age, preoperative shock, location of AMI, type of infarction, coronary anatomy, presence of postinfarction angina, technique of myocardial preservation, use of saphenous vein graft (SVG) alone, time from AMI to operation and short and long-term outcome. Univariate analyses showed that three factors were significantly associated with increased hospital death: preoperative shock (p = 0.001), type of infarction (p = 0.01), use of SVG alone (p = 0.003). Follow-up was 100% complete at a mean time of 36.4 +/- 4.8 months. Of all patients 77.0% were alive at 5 years after operation. Univariate comparison of survival curves and coronary event free curves showed that use of SVG alone was associated with decreased survival (p = 0.0009) and event free (p = 0.02) rates. Patients with non-Q-wave infarction and without cardiogenic shock may undergo ECABG relatively safely at any time. The use of internal thoracic artery at ECABG without cardiogenic shock does not increase hospital mortality and improves both long-term survival and freedom from coronary events.

Adult↗
PubMed1995

Malignant hyperthermia in a patient with Becker muscular dystrophy: dystrophin analysis and caffeine contracture study.

We present a 17-year-old boy with Becker muscular dystrophy (BMD) who developed hyperthermia and heart failure after general anesthesia. He presented clinical features of malignant hyperthermia (MH), and had masseter spasm and elevated body temperature (38.7 degrees C) with very high serum CK activity (107,000 IUl-1). Dystrophin tests confirmed a clinical diagnosis of BMD in the patient, i.e. faint and patchy immunostaining pattern of skeletal muscle, truncated dystrophin protein and a deletion of exons 3 and 4 of the dystrophin gene. To inquire into the mechanism of MH associated in the patient, we tested caffeine contracture reaction by the skinned fiber method. We found an increased sensitivity to caffeine only in type 1 muscle fibers. The rate of Ca(2+)-induced Ca2+ release (CICR) was normal, suggesting that the mechanism of "MH" observed in our patient with BMD is not the same as that of classical MH. A possible mechanism might be related to derangements of the sarcoplasmic reticulum membrane in BMD, which sensitize the membrane to caffeine or other agents.

Adolescent↗
PubMed1995

Hyponatremia and osmoregulation of vasopressin secretion in patients with intracranial bleeding.

To clarify the cause and pathophysiology of hyponatremia after intracranial bleeding, we analyzed the possible causative factors, and examined the response of vasopressin (AVP) secretion to osmotic stimulus in six patients. Despite hyponatremia, urinary sodium excretion persisted, with urinary osmolality exceeding plasma osmolality. Serum levels of urea nitrogen, creatinine, and uric acid were not elevated in any of them. PRA was normal or subnormal in four patients, and all had normal adrenocortical and thyroid functions. Although these laboratory findings may support the diagnosis of the syndrome of inappropriate antidiuretic hormone secretion, the cause of hyponatremia in our patients was attributed to excessive renal excretion of sodium, because water load performed in an euvolemic state showed no impairment in diuresis, and replenishment of sodium without water restriction improved hyponatremia as well as clinical conditions. Plasma AVP levels relative to plasma osmolality in these patients were constantly elevated. When challenged by an osmotic stimulus, AVP secretion increased with increasing plasma osmolality in one patient, but no consistent pattern of AVP secretion was observed in others. The potentiating effect of hypovolemia on osmotic secretion of AVP was not demonstrated in any of the patients. These results show that hyponatremia after intracranial bleeding with clinical features almost indistinguishable from those of syndrome of inappropriate antidiuretic hormone secretion may result from an impaired renal sodium-conserving mechanism of unknown cause. Persistent AVP secretion without an alteration in the sensitivity of the osmostat in this pathological state may be due to an incomplete suppression by plasma hypotonicity per se of the baroreceptor-mediated stimulation of AVP release.

Aged↗
PubMed1995

Effects of L- and DL-carnitine on patients with impaired exercise tolerance.

We designed this study to determine whether orally administered L- and DL-carnitine can improve exercise tolerance in a group of patients with exercise intolerance. Nineteen patients with cardiac disease were randomly divided into 2 groups, an L-carnitine treatment group (n = 9) and a DL-carnitine treatment group (n = 10). Eight additional age-matched patients served as an untreated control group. Subjects in both carnitine treatment groups underwent cardiopulmonary exercise testing on a cycle ergometer in order to determine peak exercise time, peak oxygen uptake (VO2), lactate threshold (LT) and ventilatory threshold (VT) before and after the oral administration of 900 mg/day of L- or DL-carnitine for 2 weeks. Basal values of peak exercise time, peak VO2, LT and VT did not differ significantly among the 3 groups. Peak exercise time and peak VO2 tended to be increased in the L-carnitine treatment group, and tended to be decreased in the DL-carnitine treatment group. Both LT and VT (ml/kg/min) were significantly improved (LT: from 9.7 +/- 0.6 to 10.8 +/- 1.0, p < 0.05; VT: from 9.8 +/- 0.8 to 11.8 +/- 1.9, p < 0.02) by the administration of L-carnitine, while LT was significantly decreased (from 11.0 +/- 2.0 to 9.6 +/- 1.2, p < 0.05) and VT tended to be decreased by the administration of DL-carnitine (from 11.6 +/- 2.0 to 10.8 +/- 2.4). In the untreated control group, no significant changes were observed in the values of exercise tolerance between the 2 series of exercise testings. In neither group did carnitine modify hemodynamic parameters at rest or during exercise. In conclusion, this study demonstrated that L-carnitine increases and DL-carnitine decreases exercise tolerance in patients with impaired exercise tolerance.

Administration, Oral↗
PubMed1995

Exercise-induced rise in arterial potassium is enhanced in patients with impaired exercise tolerance.

We assessed the changes in arterial potassium concentration during exercise and recovery in relation to exercise tolerance in patients with impaired exercise tolerance. Sixteen patients with cardiac disease were subjected to a cardiopulmonary exercise test on a cycle ergometer. Arterial potassium and lactate concentrations were measured every minute during and after exercise, and ventilatory threshold (VT) and lactate threshold (LT) were identified. Before exercise, arterial potassium concentration was 3.8 +/- 0.3 mEq/l. It increased to 4.1 +/- 0.3 mEq/l at LT (p < 0.002 versus at rest), to 4.2 +/- 0.3 mEq/l at VT, and to 4.8 +/- 0.5 mEq/l at peak exercise (p < 0.001 versus at LT, p < 0.001 versus at VT). At an exercise intensity equivalent to 30, 40, 50 or 60% of predicted maximum oxygen uptake, the increase in arterial potassium showed a negative and significant correlation with %LT (r = -0.62 approximately -0.72, p < 0.01 approximately 0.05) and %VT (r = -0.62 approximately -0.75, p < 0.001 approximately 0.05), where %LT and %VT represent the ratios of LT and VT to the predicted maximum oxygen uptake, respectively. There was a good correlation between the rate of fall in potassium concentration during recovery and its increase during exercise. It was concluded that in patients with impaired exercise tolerance, the greater the degree of exercise intolerance, the greater the increase in arterial potassium concentration during exercise, and the steeper the fall in potassium concentration during recovery. Because the rise in potassium concentration during exercise and its fall during recovery were greater when the exercise level exceeded the anaerobic threshold, exercise levels below the anaerobic threshold are recommended for patients with cardiac diseases.

Aged↗
PubMed1994

Two cases of acute myocardial infarction associated with aplastic anemia during treatment with anabolic steroids.

Thrombosis is a rare complication in patients with aplastic anemia because of the presence of coincidental thrombocytopenia. We have recently treated two cases, a 61-year-old male and a 59-year-old female, with acute myocardial infarction associated with aplastic anemia. Although their platelet counts were lower than normal in spite of treatment with anabolic steroids for aplastic anemia, the coronary angiographic findings strongly suggested coronary thrombosis in both cases. Anabolic steroids, which have been commonly used for the treatment of aplastic anemia, are a possible risk factor for coronary thrombosis because they have an accelerating effect on thrombus formation. We report two very rare but clinically important cases.

Anabolic Agents↗
PubMed1993

[Evaluation of factors aggravating and delaying recovery from postoperative hypercoagulable state in patients operated on for esophageal cancer].

When a living body is invaded to a high degree, a hypercoagulable state develops. The radical operation for esophageal cancer is known as a very high risk operation. The purpose of this study is to evaluate in detail the postoperative changes in platelet, coagulation and fibrinolytic systems, in 34 patients operated on for esophageal cancer, and to clarify the factors contributing to both the aggravation and delay of recovery from the postoperative hypercoagulable state. Operating time and blood loss during surgery were factors aggravating the postoperative hypercoagulable state. The mechanism of coagulation progressed significantly in those patients requiring 500 minutes or more operating time and having a blood loss of 600 ml or more during surgery. Age was seen as an important factor delaying recovery, as the recovery of the coagulative parameters was delayed significantly in patients aged 70 or above. Hepatic function was the most important of post operative organ functions. Renal, cardiac and respiratory functions were unrelated to the postoperative hypercoagulable state.

Blood Coagulation↗
PubMed1992

Effects of pentobarbital on heterosegmentally activated dorsal root depolarization in the rat. Investigation by sucrose-gap technique in vivo.

Slow positive cord dorsum (P-) potentials activated by segmental stimulation are believed to reflect primary afferent depolarizations and have been shown to be augmented by barbiturates. However, there have been no data to confirm whether heterosegmentally activated P-potentials also represent primary afferent depolarizations and are similarly affected by barbiturates. We therefore tested whether heterosegmental P-potentials reflect primary afferent depolarizations and how these heterosegmental potentials are affected by barbiturates. Heterosegmentally activated dorsal root (DR) depolarizations (depolarizations evoked in DRs of lumbar segments in response to afferent volleys to cervical segments produced by electrical stimulation of the forepaw) and P-potentials were simultaneously recorded, adapting the sucrose-gap technique for recording DR depolarization in vivo in the rat. Forepaw (heterosegmental) stimulations produced a large depolarization in the DRs of L5-S1 as well as a slow P-potential in the lumbosacral enlargement. Transection of the spinal cord at the level of C1-C2 abolished both the P-potential and DR depolarization activated by heterosegmental stimulation as well as the second component of segmentally (hind-paw) activated P-potential. Bicuculline (100 micrograms/kg, intravenous) augmented the P-potential and DR depolarization produced by heterosegmental stimulation, but larger doses, 400-600 micrograms/kg, eventually suppressed these. However, the drug, in a dose-dependent manner, suppressed both the P-potential and DR depolarization produced by the segmental stimulation. Pentobarbital (10-40 mg/kg, intravenous) suppressed in a dose-dependent manner both the heterosegmental P-potential and heterosegmental DR depolarization and prolonged their peak latencies. By contrast, pentobarbital augmented and prolonged the segmental P-potential and segmental DR depolarization.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗