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Biomedical subjects

Y Imai

Publications and source records attributed to Y Imai.

At least 991 records · Page 55Linked to original sources
PubMed1989

[An experimental study of the use of fresh aortic valve homograft for the usage of the vena caval valve. Part 1. The evaluation of hemodynamics and cineangiographic study].

The purpose of this study is to develop a vena caval valve using the fresh aortic valve homograft. A preliminary study was performed in six dogs by interposing a cryopreserved aortic valve homograft with sinus Valsalva into SVC. After making the tricuspid regurgitation, the aortic valve homograft was closed by the regurgitant flow in the systolic phase and opened by the venous return in the diastolic phase. The preliminary study showed that the cryopreserved aortic valve homograft with sinus Valsalva was useful as a vena caval valve immediately after the implantation. Fresh aortic valve homografts were implanted in 11 dogs in the same manner. Eighteen pressure studies and cine-angiographies were performed in six dogs on 8 to 165 days after the implantation. Pressure studies showed minimal/small pressure gradients across the implanted homografts. However, cineangiography revealed appearance of regurgitation through the implanted homograft three months later. Thromboembolism was not happened in all dogs at all. Therefore, we concluded that the fresh aortic homograft with sinus Valsalva might be clinically feasible for use as a vena caval valve.

Animals↗
PubMed1989

[New selection criterion for Fontan procedure: pulmonary artery clamping test and pulmonary vascular resistance in increased pulmonary blood flow].

A new selection criterion for Fontan procedure, pulmonary artery clamping test (PACT) was developed and employed in 13 candidates for Fontan procedure. PACT was aimed to evaluate the response of pulmonary vascular bed to increased pulmonary blood flow and calculate the pulmonary vascular resistance in the increased pulmonary blood flow as a selection criterion for Fontan procedure, preoperatively. After a median sternotomy incision, an electromagnetic flow meter was employed for measuring the pulmonary blood flow (Qp) on the pulmonary trunk. By clamping the left pulmonary artery and the right pulmonary artery, right pulmonary vascular resistance and the left pulmonary resistance in the pulmonary blood flow of Qp were calculated respectively. By means of electrical analogue, right and left lungs were simulated as resistors in parallel. And the equivalent pulmonary vascular resistance Rpc was calculated as the predicted pulmonary vascular resistance in the increased pulmonary blood flow of two times Qp. Fontan procedure was performed in 9 cases with a Rpc of less than 3 unit.m2 with a successful result and no death. Postoperative cardiac index ranged from 2.6 to 3.7 L/min.m2 with a mean of 2.8 L/min.m2. Postoperative pulmonary vascular resistance ranged from 1.6 to 3.2 unit.m2. Postoperative cardiac index was correlated with postoperative pulmonary vascular resistance. And postoperative pulmonary vascular resistance was well correlated with equivalent pulmonary vascular resistance but was not correlated with preoperative pulmonary vascular resistance measured by Fick's method at the preoperative catheterization. In Fontan procedure, the pulmonary blood flow frequently increases to a certain degree postoperatively. And pulmonary vascular resistance is not a static resistance, but a dynamic resistance. Hence, in discussing a pulmonary vascular resistance as a selection criterion for Fontan procedure, the pulmonary blood flow in which the pulmonary vascular resistance stand should be taken into account. Equivalent pulmonary vascular resistance Qpc is a theoretical selection criterion for Fontan procedure and well reflects the postoperative pulmonary vascular resistance. Fontan procedure can be successfully performed with a Rpc of less than 3 unit.m2.

Adolescent↗
PubMed1989

[Intracardiac repair in anatomically corrected malposition of the great arteries (SDL): report on 2 successful repair].

Two cases of anatomically corrected malposition of the great arteries (SDL) with aorto-mitral fibrous continuity and pulmonary-tricuspid discontinuity are presented. Case 1 was a 24-year-old male with an associated ventricular septal defect (VSD) and pulmonary stenosis. Case 2 was a 1-year-old boy also with VSD. Both cases successfully underwent total correction. The aorto-mitral fibrous continuity was verified in both cases through right ventriculotomy during the operation. The postoperative course was uneventful in both cases and they have remained asymptomatic 5 years after operation. We believe this report to be the first one of anatomically corrected malposition of the great arteries with aorto-mitral fibrous continuity.

Adult↗
PubMed1989

[Pulmonary valve replacement using the right ventricle-pulmonary artery bypass without cardiopulmonary bypass].

We underwent pulmonary valve replacement using the right ventricule pulmonary artery bypass without cardiopulmonary bypass. This right heart bypass was consisted of the vascular graft and the polystyrene tube. The vascular graft was anastomosed to the main pulmonary artery and the polystyrene tube was inserted into the free wall of the right ventricle. These were connected with a cannulating magnetic flow probe. After the bypass was established, the pulmonary artery was clamped and divided. The pulmonary valves were excised and the pulmonary valve replacement was undergone with a pulmonary valve homograft. Hemodynamics during the pulmonary valve replacement was stable and the postoperative course was uneventful. One month later, the cardiac catheterization and cineangiography showed that the implanted homograft was effective sufficiently. We concluded that this right heart bypass was useful for the pulmonary valve replacement.

Anastomosis, Surgical↗
PubMed1989

[Direct aortic reimplantation for BWG syndrome including mitral valve repair].

Direct aortic reimplantation is the ideal treatment for the BWG syndrome, but is often impossible to obtain a sufficient length of the coronary artery without undue tension on the vessel. We experienced a 6-year-old boy whose left coronary artery was originated from pulmonary trunk widely distant from aorta. Direct reimplantation was successfully performed taking care of excising the ostium of the anomalous vessel as a largest flange and mobilizing the coronary artery from the adjacent tissue sufficiently. Mitral valve regurgitation is also a poor prognosis factor of BWG syndrome. We performed direct reimplantation and mitral valve repair (anterior commissuroplasty) simultaneously to a 3-year-old boy of BWG syndrome with severe mitral valve regurgitation. Postoperative data showed improvement of cardiac performance. Possibility of recovering the papillary muscle function by valve repair without replacement was suggested.

Aorta↗
PubMed1989

[A new valved conduit with commissures using a glutaraldehyde preserved equi pericardium].

We developed a new valved conduit with commissures using a glutaraldehyde preserved equine pericardium, and implanted this prosthesis between the right ventricle and the pulmonary artery in the dog to examined the movement of the valve. Our new prosthesis consists of a conduit and three leaflets. Each leaflet is sutured to the inner surface of the conduit to form a valve. The adjacent free edges of the leaflets are sutured together by placing a mattress stitch 2 mm from their attachment to the conduit so that the leaflets form commissures. These commissures are designed to facilitate prompt coaptation of the three leaflets in diastole. A radiopaque marker is anchored to the center of the free edge of each leaflet and to the outer surface of the conduit to investigate its movement. The movement of the radiopaque markers studied by cineangiography revealed good coaptation of three leaflets in diastole and their full opening in systole. These findings demonstrated that the valve in our prosthesis might function well to prevent regurgitation across it.

Animals↗
PubMed1989

[A case of mitral valve replacement with autologous pulmonic valve in congenital mitral stenosis].

A one-year-old infant with congenital mitral stenosis and pulmonary hypertension underwent by mitral valve replacement with his pulmonic valve autograft and pulmonary tract reconstruction with heterogeneous pericardial conduit. His postoperative hemodynamics data showed that left atrial pressure decreased and pulmonary hypertension continued. Echocardiography showed that the implanted autograft functioned properly. On the seventh postoperative day, he died of pulmonary hypertension. In case with congenital mitral stenosis with the small mitral annulus and the small left ventricular cavity, it is difficult to perform mitral valve replacement by commercially available mechanical or tissue valves. Because these valves are not suitable for the small mitral annulus. The mitral valve replacement with pulmonic valve autograft is recommended in such a case with the congenital mitral stenosis.

Female↗
PubMed1989

[The results of surgical treatment of total anomalous pulmonary venous return in neonates].

By the time, the results of surgical treatment for total anomalous pulmonary venous return have been unsatisfactory. From 1981, we changed a surgical procedure fro Gersony-Malm procedure to the posterior approach method, and a surgical technique from the deep hypothermia and the circulatory arrest to the moderate hypothermia and the pump perfusion. Consequently, the results of surgical treatment was improved. From 1981 to 1987, 18 neonates with total anomalous pulmonary venous return underwent corrective operations in our institute. This diagnosis was decided by echocardiography without cardiac catheterization, because the preoperative status of these neonates were poor. Under the cardiopulmonary bypass, we performed the posterior approach method for type I and III, the cut-back method and Van Praagh procedure for II and IV without aortic clamping. According to the posterior approach method, the atrial septal defect was closed through the left atrial incision and the left atrium was anastomosed to the common pulmonary trunk during ventricular fibrillation. The incision was limited within the common pulmonary trunk or the vertical vein and was not extended into the pulmonary veins. According to cut-back method and Van Praagh procedure, the coronary sinus was closed internally so as to avoid the postoperative conduction disturbance. There were four hospital deaths (22.2%). The causes of deaths were pulmonary hypertension in two, low cardiac output in one, and intracranial bleeding in one. From the results of our institution, we concluded that the primary factors determining the outcome were the condition of the patients prior to repair and the severity of pulmonary hypertension.

Cardiopulmonary Bypass↗
PubMed1989

[Jatene procedure for the intermediate type between original Taussig-Bing malformation and posterior transposition of the great arteries: a case report].

A successful Jatene procedure (Lecompte modification) in a 8-month old boy with the intermediate type between the original Taussig-Bing and the posterior transposition of the great arteries (p-TGA) is described. The aorta was located posterior to the right of the pulmonary artery (PA) which overrode the interventricular septum. There was no fibrous continuity between aortic and atrioventricular valves. In the original Taussig-Bing, intraventricular rerouting is applicable because of malaligned infundibular septum. However, in our case which was similar to p-TGA, the infundibular septum extending anteriorly as far down as the anterior papillary muscle, was almost aligned to the interventricular septum, so that intraventricular rerouting is not applicable but arterial switch operation is preferable. Hence, the primary interventricular foramen was enlarged by the wedge resection and the secondary interventricular foramen was closed using pericardial patch through PA. The continuity of PA was reestablished anterior to the new aorta. The left half of distal orifice of PA was suture-closed to shift the site of anastomosis rightwards to avoid kinking and compression on the coronary arteries. Postoperative catheterization demonstrated no pressure gradient between left ventricle and aorta.

Aorta↗
PubMed1989

[New technique for enlargement of the pulmonary outflow tract in corrected transposition of the great arteries [SLL]--a report of 2 cases].

New technique for enlargement of the pulmonary outflow tract was performed in two patients with corrected transposition of the great arteries [SLL] associated with atrial septal defect, ventricular septal defect, pulmonary stenosis and mitral regurgitation. The middle of the anterior leaflet of the mitral valve was incised to the valve annulus towards the mid-point of the mitral-pulmonary fibrous continuity. In this approach, anterior node and anterior atrioventricular conduction bundle were securely protected from the surgical incision. The pulmonary annulus was divided posterolaterally and the incision was further extended into the pulmonary trunk to the bifurcation. The pulmonary trunk was enlarged with a fusiform patch of the xenogenous pericardium bearing monocusp. In case 1, St. Jude Medical valve #31 was implanted in the mitral position. In case 2, mitral valvular annuloplasty with Carpentier ring #36 which was deformed to admit enlarged portion of the pulmonary trunk. The VSD was closed through the right atrium, placing the suture on the left side of the septum. However, complete A-V block ensured temporarily due to retraction at the operation in case 1. No conduction disturbance ensured in case 2. This technique can provide some advantage in avoidance of injuries to the anterior node and the anterior atrioventricular conduction bundle. Application of this technique to the corrected transposition of the great arteries without mitral regurgitation is to be further evaluated.

Adolescent↗
PubMed1989

Staged operation for pulmonary atresia and ventricular septal defect with major aortopulmonary collateral arteries. New technique for complete unifocalization.

A new staged operation for total correction of pulmonary atresia and ventricular septal defect with major aortopulmonary collateral arteries has been developed. In first-stage repair (complete unifocalization), intrapulmonary arteries were unified at the hilum with equine pericardial conduits (intrapulmonary bridges). In case of absent or severely hypoplastic central pulmonary arteries, new central pulmonary arteries were created. Finally, the unifocalization was completed by modified Blalock-Taussig shunts with the ligation of collateral arteries. In second-stage repair, right ventricular-pulmonary arterial continuity was established with a trileaflet pericardial conduit and closure of the ventricular septal defect. From January 1982 through July 1988, 34 patients, whose ages ranged from 1 month to 24 years (mean 6.6 years), underwent first-stage repair with two resultant late deaths (mortality rate 5.9%). Second-stage repair has been completed in 16 patients. There were two early deaths (mortality rate 12%) from bacterial infection. Postoperative right ventricular/left ventricular systolic pressure ratios ranged from 0.36 to 1.0 (mean 0.72). In four patients in whom the ratio was 1.0, the ventricular septal defect had been closed with a perforated patch. By complete unifocalization with the intrapulmonary bridge technique and the creation of new central pulmonary arteries, the majority of patients with major aortopulmonary collateral arteries can have successful repair.

Aorta↗
PubMed1989

Exogenous glucocorticoid eliminates or reverses circadian blood pressure variations.

The effect of glucocorticoid on circadian variations of blood pressure was examined. In untreated patients with essential hypertension, a clear nocturnal fall in blood pressure and heart rate was observed and this was unaffected by combined treatment with antihypertensive drugs. The circadian blood pressure variation in patients with chronic glomerulonephritis (CGN) not receiving glucocorticoid treatment was essentially the same as that in patients with essential hypertension. In both groups there was a positive correlation between blood pressure and heart rate. On the other hand, in patients with CGN and systemic lupus erythematosus (SLE) who were treated with glucocorticoid, there was no nocturnal fall in blood pressure, and often a significant rise. In these patients the blood pressure was lowest in the afternoon and began to rise from then, and during the night, attaining a peak level in the morning. Despite this changed pattern of blood pressure variations, the heart rate in these patients was clearly reduced at night. In 10 patients with CGN and SLE, circadian rhythm of blood pressure and heart rate was examined before and during treatment with prednisolone (40.2 +/- 17.0 mg/day for 58.0 +/- 19.4 days, mean +/- s.d.). Prednisolone abolished the nocturnal fall of blood pressure, while the nocturnal fall of heart rate remained. There was no correlation between blood pressure and heart rate in patients with glucocorticoid treatment. These results suggest that the circadian blood pressure variation is influenced by the hypothalamo-pituitary-adrenal axis, probably through its action on the autonomic nervous system.

Adult↗
PubMed1989

[Modified Fontan procedure on 106 cases: indication and surgical results].

Since 1974, we have performed modified Fontan procedure on 106 patients, ranging in ages from 1 to 32 years, consisting of 44 cases of tricuspid atresia (TA), 21 with univentricular heart (UVH) of right ventricular type, 18 with UVH of left ventricular type, for which ventricular partition was unfeasible, and 23 with various complex anomalies. Hospital mortality rates for TA and other complex anomalies were 11.4 and 11.3%, respectively. Surgical results have markedly improved recently. Since 1986, 50 cases underwent Fontan procedure with 3 hospital deaths (6.0%). Late death occurred in 4 cases in a mean follow-up period of 49 months. Regarding the indication for operation, majority of patients had 2 to 3 parameters which were out of 10 criteria for Fontan procedure. Regurgitation of atrioventricular valve was repaired by annuloplasty in 19 patients underwent Fontan procedure and 17 survived. Abnormal systemic venous connection was seen in 11 cases and all survived. Association of total anomalous pulmonary venous connection is still a difficult problem and 2 of 5 cases died. Fontan procedure was performed in 8 patients following palliative right ventricular outflow reconstruction for poor development of pulmonary artery and 7 survived. Cumulative mortality rate for the entire series was relatively well at 15.1%.

Adolescent↗