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Biomedical subjects

H Miyamura

Publications and source records attributed to H Miyamura.

At least 37 records · Page 2Linked to original sources
PubMed1996

A comparative study of the effect of autologous platelet-rich plasma and fresh autologous whole blood on haemostasis after cardiac surgery.

The effects of fresh autologous platelet-rich plasma and autologous whole blood on haemostasis after cardiopulmonary bypass were examined in adult cardiac surgery patients. Platelet count, adenosine diphosphate 10 microM maximum aggregation rate and clotting Factor VIII were greater in the platelet-rich plasma group (n = 11) than in the whole blood group (n = 8) after platelet-rich plasma or whole blood reinfusion. Blood loss after heparin neutralization was less in the platelet-rich plasma group than in the whole blood group. Blood loss from heparin neutralization to 12h after surgery was correlated with platelet count, fibrinogen and ADP aggregation rate. The number of patients who required homologous blood transfusion was less in the platelet-rich plasma group. In conclusion, the reinfusion of autologous platelet-rich plasma improves haemostasis after cardiopulmonary bypass, and may enable surgery to be performed without homologous blood transfusion.

Adenosine Diphosphate↗
PubMed1996

Spontaneous regression of peripheral pulmonary artery stenosis in Williams syndrome.

An infant girl diagnosed with multiple peripheral pulmonary artery stenosis and Williams syndrome was followed-up for 17 years. Three cardiac catheterizations performed over the follow-up period showed that spontaneous gradual regression of the stenosis occurred with time. The initial systolic pressure gradient of 77-79 mmHg at the stenoses had decreased to 23-29 mmHg when measured at 17 years of age. Contrary to the progressive nature of systemic artery stenosis in Williams syndrome, peripheral pulmonary artery stenosis appears to have the capacity for spontaneous improvement. Careful consideration is required to determine the indications for interventional catheterization for the dilation of peripheral pulmonary artery stenosis in cases of Williams syndrome.

Constriction, Pathologic↗
PubMed1996

Induction of right ventricular hypertrophy in neonatal guinea pigs by monocrotaline.

The purpose of this study was to develop an experimental model of neonatal right ventricular hypertrophy which was similar to human congenital heart disease associated with pulmonary hypertension. Monocrotaline (200 mg/kg), a pyrrolizidine alkaloid, was injected into neonatal Hartley guinea pigs on the day of delivery. The occurrence of pulmonary hypertension and right ventricular hypertrophy was confirmed by pressure studies and a determination of the right ventricular wet weight and myocyte diameter on the seventh day after delivery. Right ventricular systolic pressure was significantly increased at 7 days after monocrotaline treatment compared with the untreated control group. The ratio of right ventricular systolic pressure to left ventricular systolic pressure, an indicator of pulmonary hypertension, was significantly elevated from 0.32 +/- 0.02 in the controls to 0.59 +/- 0.03 in the monocrotaline group. Right ventricular wet weight was also significantly increased, indicating right ventricular hypertrophy. The diameter of cardiac myocytes was significantly increased in the right ventricle, and was decreased in the left ventricle and interventricular septum in the monocrotaline group. Neonatal guinea pigs developed pulmonary hypertension and marked right ventricular hypertrophy within 1 week after treatment with monocrotaline. This simple experimental model may have features similar to those of human congenital heart disease associated with pulmonary hypertension.

Animals↗
PubMed1996

Right ventricular systolic performance before and after surgery for tricuspid regurgitation associated with mitral stenosis.

The reversibility of right ventricular function in patients with mitral stenosis associated with secondary tricuspid regurgitation (TR) is as yet undetermined. We assessed the right ventricular systolic performance by cardiac catheterization before and 19 months after surgery in 18 patients who underwent DeVega's tricuspid annuloplasty plus mitral valve replacement (MS plus TR group) and in 9 with mitral valve replacement for isolated mitral stenosis (MS group). After surgery, the right ventricular systolic pressure decreased significantly in both groups (both p < 0.01). In the MS plus TR group, the postoperative right ventricular end-diastolic and end-systolic volume indices (RVEDVI and RVESVI, respectively) were significantly decreased compared with the respective preoperative values (both p < 0.001). No significant difference was noted between the groups with regard to the right ventricular peak-systolic pressure/end-systolic volume index ratio (RVPSP/ESVI) either before or after surgery. Various left ventricular indices were comparable between the groups both before and after surgery. Linear regression analysis revealed significant correlations between RVEDVI and the RVPSP/ESVI, and between RVPSP and the RVPSP/ESVI both before and after surgery. These results indicate that right ventricular systolic performance in patients with MS plus secondary TR became comparable to those that in patients with isolated MS after surgery, and that this was probably due to nearly equivalent right ventricular contractility before surgery.

Adult↗
PubMed1996

[The study on the mechanism of brain damage due to high flow and pressure during selective cerebral perfusion].

It has been reported that the high flow and pressure perfusion produced the brain damage during selective cerebral perfusion. This time we studied the mechanism of this brain damage with mock circulation. We made the mock circulation system of brain with the hard shell reservoir as cranium, and with the triple soft bags as brain tissue, involving into reservoir. We designed the control group that intracranial pressure (ICP) was 0 mmHg at pump off, and the increasing intracranial pressure (IICP) group that ICP was 10 mmHg at pump off. We measured the flow-pressure relationship in the control and IICP group, and then stenosis in outflow. In results, the flow and pressure in both the inflow and outflow side increased significantly (p < 0.001) in control groups, as pump flow increased. The changes of the flow and pressure in IICP group showed a same tendency to the control group. Moreover, both the inflow volume into bag and the outflow volume from bag decreased as pump flow increased stepwisely. The pressure in both inflow and outflow side increased significantly and the volume of the inflow side in IICP group showed a tendency to decrease, compared with the control. The stenosis in the outflow side produced the significant increase in the pressure of both inflow and outflow side, and intracranium, with the same pump flow as the control without stenosis. In conclusion, the high flow perfusion produced the increase of the several pressure in intracranial and extracranial vessels. Moreover, the high flow perfusion produced the decrease of the intracranial blood volume cerebral blood flow. The high flow perfusion does not necessarily contribute to the cerebral tissue perfusion. The stenosis at the side of venous return produced relative high perfusion. This result suggests that the venous return should be taken care of during the selective cerebral perfusion.

Blood Pressure↗
PubMed1996

Blalock-Taussig operation with an assist of venovenous extracorporeal membrane oxygenation.

Three infants with congenital cyanotic heart disease encountered severe hypoxemia during a Blalock-Taussig shunt procedure using a right thoracotomy approach. Pericardiotomy was performed and venovenous extracorporeal membrane oxygenation was instituted using right atrial canulation. The shunt procedure was completed with good oxygenation and hemodynamic stability in all cases. Venovenous extracorporeal membrane oxygenation can be easily established in the right thorax, and is an effective support technique for unexpected hypoxemia encountered during systemic-to-pulmonary artery shunt operations.

Anastomosis, Surgical↗
PubMed1995

Closure of isolated ventricular septal defect with detachment of the tricuspid valve.

Detachment of the septal leaflet of the tricuspid valve is an alternative technique for obtaining complete visualization of a perimembranous ventricular septal defect (VSD) in cases where the VSD is obscured by the chordae tendineae or a pouch formation of the septal leaflet. This method presents theoretical concerns because it has the potential for causing postoperative valvular insufficiency. We therefore evaluated valvular function in patients who underwent VSD closure with detachment of the tricuspid valve. In a consecutive series of 153 patients who underwent VSD closure using a transatrial approach, 13 had incision of the tricuspid valve. Follow-up echocardiographic studies were performed on these patients at least 1 year following operation. There were no operative deaths. Color Doppler echocardiography revealed no residual shunt in any of these patients. Ten patients had no evidence of tricuspid stenosis or regurgitation. One patient had trivial tricuspid regurgitation. Moderate tricuspid regurgitation was observed in two patients of these, one patient was a small infant who had a VSD complicated by pulmonary hypertension. The other patient had a VSD with a mitral cleft, pulmonary hypertension, and Down's syndrome. The incised tricuspid valve was resuspended by solely running sutures. In conclusion, detachment of the tricuspid valve is a safe and useful method for adequate exposure of a VSD. However, this method should be avoided in patients with Down's syndrome and in small infants. Furthermore, repair of the incised valve should not be performed using only running sutures.

Adolescent↗
PubMed1995

Congenital coronary artery fistula--surgical results and late changes in coronary artery aneurysm.

Four pediatric cases of congenital coronary artery fistula were surgically treated and followed for 8 years. In the 3 cases of right coronary artery to right ventricle fistula, regression of coronary artery dilatation was observed postoperatively. In the 1 case of circumflex artery to right atrium fistula, aneurysmal dilatation of the abnormal vessel persisted for 8 years. A reduction in vessel size is expected if the fistula-related coronary artery has a normal course and normal branchings. When the aneurysmal vessel takes an abnormal course without branches, it should be removed surgically along with fistula closure.

Child↗
PubMed1995

[Cabrol's operation and the aortic arch replacement for Stanford type A dissecting aortic aneurysm].

Replacement of the aortic arch was performed simultaneously with Cabrol's operation utilizing modified selective cerebral perfusion (SCP) in a patient with a Stanford type A dissecting aortic aneurysm. Preoperative arteriography revealed that the dissection involved both common carotid arteries. For this reason, antegrade SCP was performed via the branches attached to the composite graft which were anastomosed to both of the common carotid arteries following clamping under deep hypothermia. The operation was successfully performed, and the patient's postoperative recovery was uneventful. This method of SCP is useful in the treatment of patients with prior difficulty or risk of cannulation.

Adult↗
PubMed1995

[The long-term result of atrioventricular valvuloplasty and surgical technique].

The long-term follow-up study was performed on various atrioventricular valvuloplasties, and our special technique of annuloplasty was also described. In mitral stenosis, 10 and 20 years actuarial survival rates were 82 and 78% in CMC and 92 and 83% in OMC with statistically better result. Reoperation free rates at 10 and 20 years were 86 and 74% in CMC, and 87 and 73% in OMC, although statistically better result was shown in OMC at 28 years. In mitral regurgitation, 140 patients underwent surgery from 1990 to 1994. MVP was successful on 33 patients and the remained 107 patients underwent MVR with St. Jude Medical valve. Actuarial survival rates at 5 and 10 years were 94 and 78% in MVP, and 92 and 88% in MVR. Complication free rates at these periods were 88 and 74% in MVP, and 78 and 69% in MVR, showing no statistical difference. In tricuspid regurgitation. 166 cases underwent DeVega's annuloplasty with excellent result of reoperation free rate of 97% at 10 years.

Follow-Up Studies↗
PubMed1994

Combined warfarin and antiplatelet therapy after St. Jude Medical valve replacement for mitral valve disease.

OBJECTIVES: The clinical effect of combined warfarin and antiplatelet therapy on the incidence of stroke and postoperative complications after mitral (plus aortic) valve replacement was studied and compared with that observed with warfarin therapy alone. BACKGROUND: It has been reported that combined warfarin and antiplatelet therapy may be effective but may be associated with an increased hemorrhagic risk. Therefore, definite benefits of the treatment in patients with an implanted prosthetic valve have not been clearly documented. METHODS: Between January 1980 and December 1992, 195 patients with a St. Jude Medical valve at the mitral (plus aortic) position were assigned to receive treatment with either warfarin alone (125 patients) or warfarin plus antiplatelet agents (70 patients), such as dipyridamole (150 or 300 mg daily, 14 patients) or ticlopidine (200 or 400 mg daily, 56 patients). A minimal dose of aspirin (10 to 40 mg) was added (29 patients) if the maximal platelet aggregation rate by collagen was not reduced. The target thrombotest level was 10% to 20%. RESULTS: The two treatment groups were similar with regard to gender and age distribution. The number of patients with atrial fibrillation, left atrial thrombus, history of previous stroke, simultaneous aortic valve operation and previously performed valve procedures were comparable in the two groups. Actuarial survival rate at 10 years was 98.3 +/- 1.7% (mean +/- SD) in the warfarin plus antiplatelet group and 90.3 +/- 3.2% in the warfarin group (p < 0.05 at 1 and 9 to 12 years). The actuarial stroke-free rate at 10 years was 95.3 +/- 3.4% and 84.3 +/- 3.8%, respectively (p < 0.05 by the generalized Wilcoxon test). The actuarial complication-free rate at 10 years was 89.4 +/- 4.3% and 67.9 +/- 4.8%, respectively (p < 0.05 by the generalized Wilcoxon test). No hemorrhagic complications were seen in the warfarin plus antiplatelet group. CONCLUSIONS: The results strongly indicate the effectiveness and safety of combined warfarin plus antiplatelet treatment after St. Jude Medical valve replacement for mitral (plus aortic) valve disease.

Actuarial Analysis↗
PubMed1994

Surgical excision of a broad-based left atrial myxoma: report of a case.

We report herein the case of a 72-year-old woman who underwent successful resection of an unusual type of broad-based left atrial myxoma. The tumor, which was attached to the fossa ovalis and anterior wall of the left atrium posterior to the aorta, was resected en bloc with the interatrial septum and the affected free wall of the left atrium. The defect in the left atrium and atrial septum was then reconstructed with an equine pericardial patch. To our knowledge, this type of cardiac myxoma, with a base extending from the septum to the atrial wall, has not been previously reported.

Aged↗
PubMed1994

Carney's complex in association with right atrial myxoma.

The association between myxomas, spotty pigmentation, and endocrine overactivity is referred to as Carney's complex. This report describes the case of a 24-year-old woman with right atrial myxoma who presented with this association. The patient had a previously excised myxoid tumor of the breast and uneven facial pigmentation was observed, but no evidence of endocrinopathy was detected. The myxoma originated from the right atrial wall adjacent to the junction of the inferior vena cava and right atrium, and was successfully excised. A brief review of Carney's complex is provided after discussion of this rare case.

Adrenal Cortex Diseases↗
PubMed1994

[The changes on cerebral hemodynamics during selective cerebral perfusion cooling].

We studied the influence on cerebral hemodynamics with 10 pigs, weighing 25 to 30 kg, when the temperature of perfusion blood changed in both rapid cooling and rewarming, and in slow them. As for the protocol of temperature, we decided that rapid change was the large temperature gradient of more than 0.5 degree C/min, and slow change was the small gradient of less than 0.3 degree C/min. Cardiopulmonary bypass (CPB) was established with a flow rate of 60 ml/kg/min, and core cooling was performed until the temperature of the returned blood from internal jugular vein reached 25 degrees C/min. For selective cerebral perfusion (SCP), blood was infused into aortic arch with the clamp of descending aorta at the temperature of less than 20 degrees C. We measured regional tissue cerebral blood flow (TCBF), intracranial pressure (ICP), carotid arterial flow (CAF), and carotid arterial pressure (CAP), and PCO2 in both CPB and SCP. Rapid cooling during CPB caused an elevation in CAP, and marked decrease in CAF, ICP, and PCO2. In contrast, rapid rewarming caused the significant increase in CAF, ICP. Slow change did not cause marked difference in CAP, CAF, and ICP, and PCO2. Moreover, TCBF was not significant in both rapid and slow changes. On the other hand, rapid change in SCP caused a significant decrease in CAP, significant difference in CAF, ICP. Slow change did not cause significant difference in them as same as in CPB. In conclusion, we presume that the influence on cerebral hemodynamics is less in slow cooling and rewarming than in rapid changes.

Animals↗
PubMed1994

[A new operative technique for pulmonary artery banding: adjustment of pulmonary artery bands by mitral valve flow velocity].

We developed a new technique to adjust the pulmonary artery band at surgery by monitoring the mitral valve flow velocity, which is indirectly indicative of the pulmonary flow. We employed this technique for 10 consecutive patients aged from 5 days to 5 months (mean, 1 months) weighing from 2.7 to 4.4 kg (mean, 3.3 kg). Underlying disease was aortic coarctation or interrupted+ventricular septal defect in 7 patients, single ventricule in 1 patients and miscellaneous defects in 2 patients. The pulmonary artery was exposed through a left lateral thoracotomy and a 3 mm wide Teflon tape was placed around the main pulmonary artery. The transducer of the Doppler echocardiography was placed along the left sternal border. The band was tightened gradually until the maximum velocity of the mitral valve flow decreased to around 70% of the previous level. During banding procedure, arterial oxygen saturation, heart rate and left ventricular contractility were monitored continuously. If bradycardia, unacceptable hypoxemia or ventricular dysfunction occurred, the band was released. The mitral valve flow velocity decreased rapidly by just a little additional tightness of the band between the range of 50% to 80% of the previous level. This technique enabled a very fine adjustment (less than 0.5 mm plication) and postoperative management has become very easy. Although there is a limitation of this technique that monitoring of the mitral valve flow velocity cannot be applied to the patients with significant interatrial shunt or mitral regurgitation, we conclude that this technique is simple and useful to obtain the optimum constriction of the pulmonary artery with excessive pulmonary blood flow.

Aortic Coarctation↗
PubMed1994

[Tetralogy of Fallot with a restrictive ventricular septal defect caused by a membranous flap].

A 5-year-old boy who had typical tetralogy of Fallot (TOF) with mild cyanosis was referred to us. Preoperative echocardiogram revealed that in addition to the TOF morphology, an abnormal piece of tissue attached to the right side of the ventricular septum was floating and obstructing flow through the ventricular septal defect (VSD) in systole. Preoperative cardiac catheterization showed suprasystemic right ventricular pressure with a gradient of 60 mmHg between the right ventricle and the aorta, and a right ventriculogram demonstrated a narrow radiolucent structure beneath the aortic valve in the right ventricle. During surgery a fibrous membranous tissue, with no relation to the tricuspid valve, was found to extend from the edge of the VSD to the aortic valve and to partially occlude the defect. This tissue was used as a suture anchorage for patch closure of the defect. Preoperative echocardiography is useful to detect such flaps and early surgical correction should be done to prevent right ventricular failure resulting from right ventricular pressure overload.

Child, Preschool↗