Search PubMed⌕ Search

Biomedical subjects

H Miyamura

Publications and source records attributed to H Miyamura.

At least 55 records · Page 3Linked to original sources
PubMed1994

Adjustment of pulmonary artery banding by mitral valve flow velocity.

In order to determine the tightness of the pulmonary artery band, Doppler echocardiography is used to assess mitral valve flow velocity, which is an indirect indicator of pulmonary blood flow. The band is tightened until the velocity decreases to 70% of the original maximal level. Additional adjustment of the constriction is then made to obtain reasonable arterial oxygen saturation, heart rate and ventricular contractility. Using this method, 12 consecutive patients underwent pulmonary artery banding with satisfactory results. This technique is simple but useful in obtaining optimum constriction of the pulmonary artery in congenital heart disease with excessive pulmonary blood flow.

Aorta, Thoracic↗
PubMed1994

[The protective effect and problem of retrograde cerebral perfusion].

In order to study the protective effect and problem of retrograde perfusion (RCP), cerebral hemodynamics and cerebral metabolism were evaluated in fourteen pigs weighing 25-30 kg. Intracranial pressure, carotid arterial flow and pressure, and internal jugular venous pressure as cerebral hemodynamics; pyruvate, lactate, and oxygen consumption as cerebral metabolism; and brain temperature were measured. The animal was cooled to electrical cerebral silence on electroencephalogram under cardiopulmonary bypass. Then, animals were divided into three groups: group I (n = 4); circulatory arrest; group II (n = 3); RCP through superior vena cava (SVC); group III (n = 7); RCP through bilateral internal jugular vein (IJV). Retrograde perfusion flow was regulated to maintain the SVC pressure or IJV pressure of 30 mmHg, for 90 minutes. The variations in brain temperature were least in group III. As perfusion flow increased, intracranial pressure, and inferior vena cava (IVC) pressure increased. But, cerebral perfusion pressure, which was calculated from the difference of intracranial arteriovenous pressure, did not increase and, SVC pressure and returned blood flow through the aorta did not increase in group III. In group II, there was no significant relation between pump flow, SVC pressure, and intracranial pressure, but SVC pressure had a positive correlation with the pressure gradient of SVC-IJV. The uptake of cerebral lactate, cerebral pyruvate, and lactate-pyruvate ratio, and cerebral oxygen consumption were superior in group III than other groups. In conclusion, RCP through IJV was advantageous to maintain hypothermia and aerobic metabolism of the brain during systemic hypothermic circulatory arrest.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[Successful primary correction for tetralogy of Fallot associated with total anomalous pulmonary venous drainage (type Ia)].

The surgical correction was performed successfully in a 3-year-old girl with tetralogy of Fallot associated with total anomalous pulmonary venous drainage (type Ia). The preoperative cardiac catheterization and angiography showed high systolic pulmonary artery pressure (58 mmHg) and small left ventricular volume (54% of normal). The early postoperative course was stormy because of the unstable circulatory state. During the early postoperative period, we estimated the volume of left ventricle by 2 D echocardiography. A significant increase of the volume was observed on the 8th postoperative day, when her circulatory state became stable. The cardiac catheterization before discharge revealed Pp/Ps of 0.38 and normal LV volume. We conclude that primary repair should be done for this combined cardiac anomaly, even if small left ventricle and pulmonary hypertension is present.

Female↗
PubMed1994

[The study on cerebral hemodynamics during selective cerebral perfusion].

This study was undertaken to clarify characterization on cerebral hemodynamics during deep hypothermic selective perfusion (SCP) in 18 pigs. Besides, the changes on cerebral hemodynamics were investigated with obstruction to venous drainage due to the clamp of superior vena cava (SVC) cannula. For SCP, blood was infused into aortic arch with the clamp of descending aorta, during 90 minutes at 20 degrees C. We measured regional cerebral blood flow (CBF), intracranial pressure (ICP), and carotid arterial flow (CAF), and carotid arterial pressure. The carotid arterial pressure as perfusion pressure was not significantly correlated with CAF, CBF and ICP. Although CAF increased as pump flow rate increased, the relationship between pump flow and CBF was not significant. Moreover, SVC pressure showed a tendency to increase, as CAF increased. Both ICP and internal jugular vein pressure (IJVP) were significantly (p < 0.01) increase, and CAF was significantly (p < 0.05) decrease with the clamp of SVC cannula. On the other hand, both ICP and IJVP were significantly decrease, and both CAF and CBF were increase, without unclamp of SVC cannula. The results suggest that cerebral autoregulation is intact during deep hypothermic SCP, and hyperperfusion cause the increase of shunt flow in extracranial area, and besides, the increase of ICP with obstruction to venous drainage cause decrease in cerebral blood flow.

Animals↗
PubMed1994

Total circular annuloplasty with absorbable suture for the repair of left atrioventricular valve regurgitation in atrioventricular septal defect.

To obtain a better control of left atrioventricular valve regurgitation, we applied total circular annuloplasty with the use of absorbable sutures to 14 children with atrioventricular septal defect (six complete forms and eight incomplete forms). In the intraoperative period, a good coaptation of the leaflets was achieved and the regurgitation was minimized or disappeared. Follow-up studies with echocardiography for 13 survivors showed a gradual increase of annular size during the postoperative period. Ten patients of the survivor group (77%) maintained good valvular competency in a long-term period. Total circular annuloplasty is a simple and effective procedure to reduce the regurgitation and prevent the annular dilatation during the immediate postoperative period.

Cardiac Surgical Procedures↗
PubMed1993

The effect of bupivacaine hydrochloride on skeletal muscle fiber type transformation by low frequency electrical stimulation.

Bupivacaine hydrochloride (bupivacaine HCl) is known to induce the degeneration and regeneration of skeletal muscles. We examined the priming effect of chronic and continuous nerve stimulation (5 Hz) on regenerating pectoralis major muscle after a single injection of bupivacaine HCl (3 mg/kg). Pectoralis muscle stimulated for 24 days after bupivacaine HCl injection contained 55.4 +/- 8.2% type 1 muscle fibers (n = 4). Control pectoralis major muscle stimulated for 34 days without bupivacaine HCl injection, in contrast, contained 37.7 +/- 5.5% type 1 fibers (n = 5). Therefore, the stimulated pectoralis major muscle with bupivacaine HCl injection contained a significantly larger number of type 1 fibers than that without bupivacaine HCl injection. Undifferentiated myosatellite cells produced by bupivacaine HCl may be primed to differentiate into type 1 cells by chronic low frequency electrical stimulation.

Animals↗
PubMed1993

Long-term results of the intracardiac repair of tetralogy of Fallot: a follow-up study conducted over more than 20 years on 100 consecutive operative survivors.

A long-term retrospective and follow-up study was conducted on patients with tetralogy of Fallot to evaluate survival rates and quality of life following surgery. Intracardiac repairs were performed on 132 patients at our institute between January, 1965, and July, 1971, among whom 100 consecutive operative survivors, being 54 males and 46 females, were followed for 20-25 years. Late deaths were confirmed in eight patients (8%) six of which (6%) were considered cardiac deaths. The 20- and 25-year survival rates were 93.7 +/- 2.5% and 90.9 +/- 3.6%, respectively. Reoperations were performed on six patients for residuae or sequelae without mortality or morbidity, and 90.4% +/- 3.1% of the patients were free from late death or reoperation at 20 years and 83.9 +/- 5.3% at 25 years. Thirty-one of the 46 female patients were married and 28 had children. Forty-three live births were confirmed without any association of a congenital heart anomaly. Employment status was satisfactory in most of the patients, and 81%-89% of the patients in this series were considered to have a good quality of life. Less than half the patients had late symptoms, and all were related to cardiac arrhythmias. Late ventricular arrhythmias remain the major concern of the future, and therefore, the establishment of effective pre- and intraoperative management to prevent postoperative arrhythmias is essential.

Adolescent↗
PubMed1993

Extracorporeal membrane oxygenation for severe heart failure after Fontan operation.

A 10-year-old boy with tricuspid atresia and Glenn anastomosis underwent a modified Fontan operation. After the operation, the pressure in the inferior vena cava increased, leading to oliguria and ascites. After the creation of continuity between the superior vena cava and the inferior vena cava to reduce the pressure gradient, there remained an elevated right atrial pressure. Six days of extracorporeal membrane oxygenation effectively stabilized his hemodynamics and organ function and allowed an excellent outcome.

Angiography↗
PubMed1993

Force and histochemical changes in rabbit pectoral muscle induced by chronic electrical stimulation for use in cardiac assistance.

Before the application of skeletal muscle in a cardiac-assist device, a preconditioning procedure is required in order to overcome the easy fatigability of this muscle. We evaluated the effect of preconditioning muscles while keeping their collateral blood supply. In 15 male rabbits, a skeletal muscle ventricle (SMV) was constructed from silicone and pectoralis major muscle with minimal dissection. In six rabbits, the muscle was electrically preconditioned. The pressure generated by the SMV was measured under various conditions. Histochemical fiber grouping was performed using myosin ATPase staining. The pressure rose with preconditioning despite an increase in slow-twitch fibers. The cross-sectional area of both slow-twitch and fast-twitch fibers increased significantly. The rise in pressure is attributable to muscle hypertrophy. The use of muscles with minimal dissection may avoid or shorten the vascular delay because of a well maintained blood supply and nearly isometric preconditioning.

Animals↗
PubMed1993

Does recombinant human erythropoietin accelerate erythropoiesis for predonation before cardiac surgery?

This study was performed to determine the effect of recombinant human erythropoietin (rEPO) on preoperative autologous blood donation in patients undergoing elective coronary bypass or valvular operations. Nineteen patients received 200 u/kg of rEPO intravenously 3 times a week, and 210 mg/day of iron sulfate orally, for 2 weeks before surgery (EPO group). Seven matched patients only took the same dose of iron sulfate (control group). Bone marrow was aspirated from the sternum during surgery, and the Myeloids/Erythroids ratio was calculated in 13 patients of the EPO group. The total donated blood mass was 853 +/- 231 g in the EPO group, and 657 +/- 140 g in the control group (p < 0.05). The average increase in hemoglobin (Hb) mass from admission to the day before surgery was 87 +/- 33 g in the EPO group, and 24 +/- 13 g in the control group (p < 0.001). Furthermore, the logarithm of the ratio of "increased Hb mass/Hb mass at admission" was significantly correlated to the Myeloids/Erythroids ratio (r = -0.9130, p < 0.01). These results strongly indicate that rEPO is a very useful agent for predonation of autologous blood for cardiac operations.

Adult↗
PubMed1993

Direct thrombolytic revascularization of the occluded basilar artery.

Successful direct revascularization in a 54-year-old man with embolism of the basilar artery following St Jude Medical valve replacement for mitral regurgitation 6 years earlier is reported. He arrived at the hospital in a deep coma. Computed tomography showed no new lesions, but subsequent angiography revealed occlusion of the basilar tip, bilateral posterior cerebral arteries and right superior cerebellar artery. Direct thrombolytic therapy was performed using 420,000 units urokinase through an infusion catheter placed in the basilar artery. The patient immediately regained consciousness, with only slight diplopia. Direct thrombolytic therapy is considered to be an effective treatment for thromboembolism following prosthetic valve replacement in certain selected cases.

Basilar Artery↗
PubMed1993

[A successful insertion of the prosthetic valve in supraannular position concomitant with pericardial enlargement of the aortic root in a child: a case report].

A 4-year-old boy admitted to our hospital due to congestive heart failure one year after the intracardiac repair of tetralogy of Fallot. Echocardiography and cineangiography revealed severe aortic regurgitation. The aortic valve replacement was performed with a prosthesis larger than the aortic annulus. Operative findings showed that the cause of aortic regurgitation was infective endocarditis. The aortic root was enlarged with pericardial patch and a 21 mm St. Jude Medical valve prosthesis was inserted in supraannular position. This technique was very useful for insertion of a prosthetic valve one or two sizes larger than the aortic annulus without risk of distorting the mitral valve or left ventricular function.

Aortic Valve↗
PubMed1993

[Nutritional improvement after operation of valvular heart diseases with protein-calorie malnutrition].

We evaluated the nutritional states before and after operation in patients with severe valvular heart disease characterized by malnutrition. The patient population consisted of 6 females, age range between 42 and 60, average 52.2 years old. The valve lesions were mitral stenosis in 2, combined aortic and mitral valve diseases in additional 4 patients, and moderate to severe tricuspid regurgitation was noted in 5 of these 6 patients. All 6 patients underwent a successful mitral (c/s aortic) valve replacement, and 5 of 6 tricuspid annuloplasty. The ideal body weight increased significantly from 77.9 +/- 3.4% preoperatively to 84.6 +/- 3.9% postoperatively (p < 0.01). Late postoperative cardiac catheterization revealed an improvement of mixed oxygen saturation (61.3 +/- 3.8%, preoperatively vs 67.3 +/- 5.6%, postoperatively; p < 0.01). The postoperative serum prealbumin, retinol binding protein and K value in intravenous glucose tolerance test increased significantly (p < 0.05) compared to those before operation. In conclusion, our data suggested that corrective surgery would have a good effect on nutritional improvement of the protein-calorie malnutrition caused by valvular heart diseases.

Adult↗
PubMed1993

[Excellent late results of total circulatory annuloplasty with absorbable suture for the repair of mitral regurgitation of atrioventricular septal defects in children].

We treated 15 children with atrioventricular septal defects (6 complete type and 9 incomplete type) using total circulatory annuloplasty for mitral regurgitation. In 14 patients, total circulatory annuloplasty was performed with absorbable suture and in one patient with polypropylene suture. Operative death was one patient associated with tetralogy of Fallot and another 14 patients survived. Preoperative mitral regurgitation was grade 1 in one patient, grade 2 in 6 patients and grade 3 in 7 patients. After operation mitral regurgitation reduced to grade 1 in 13 patients and grade 2 in one patient. In the late results, only one patient underwent reoperation for exacerbation of mitral regurgitation. The present data suggested that total circulatory annuloplasty with absorbable suture was very useful technique for the repair of mitral regurgitation of atrioventricular septal defects in children.

Child↗
PubMed1993

[Flow characteristics and responses to vasoactive drugs in canine gastroepiploic artery].

We studied flow characteristics and response to norepinephrine, Chlorpromazine and gastrin in 22 canine gastroepiploic artery (GEA) recirculation model. The GEA flow was obtained by a drip for a minute, opening the end of pedicle GEA. Furthermore, aortic flow and celiac arterial flow were measured by magnetic flow probe. The administration of chlorpromazine, vagostigumine, and gastrin induced a increase in both celiac arterial flow and pedicle GEA graft flow. Especially, the administration of gastrin induced significant increase in GEA flow and celiac arterial flow. Furthermore, adding norepinephrine step-wisely, the GEA flow increased remarkably, in spite of decrease of celiac arterial flow. This response was caused from difference in vascular resistance among celiac arterial branches. Therefore, the pedicle GEA graft has homogenous response as same as intact GEA that perfuses stomach, because its flow was affected by adrenergic and parasympathetic agent, alpha-blocker and gastric hormone.

Animals↗