Biomedical subjects
Publications and source records attributed to H Miyamura.
We describe transapical aortic cannulation in pediatric patients. This technique may help to establish cardiopulmonary bypass in small children in whom aortic root cannulation is undesirable or not feasible.
We reported a 26-year-old man with mitral regurgitation and sick sinus syndrome. He underwent VVI pacemaker implantation, and admitted to our hospital due to congestive heart failure. Echocardiography and cineangiography revealed severe mitral regurgitation. Mitral valvuloplasty and modified Maze procedure were performed, and a DDD pacemaker was implanted after cardiopulmonary bypass. We recognized cross stimulation 7 months after operation. The reason of the cross stimulation was the position of the implanted atrial lead, which was the low right atrium. Thus, an atrial lead of DDD pacemaker should be carefully implanted in the patients underwent Maze procedure.
We have developed a blood cardioplegia delivery system for children. Essential points of a delivery system in pediatric cardiac surgery are (1) a small amount of priming volume of a delivery system, and (2) slow, steady infusion of a cardioplegic solution. We changed a heat exchanger to a smaller one for reduction of priming volume, and changed a roller pump tube to a smaller one for slow, steady infusion. Thus, priming volume of a delivery system has reduced from 180 to 100 ml, and we can infuse a cardioplegic solution at a steady rate less than 10 ml/min. Our clinical experience with this system suggests that this blood cardioplegia delivery system is useful for pediatric cardiac surgery.
We herein review our 17-year surgical experience for the treatment of ascending aortic aneurysm in patients with Marfan syndrome to clarify the risks of increased mortality and reoperation. The subjects consisted of 15 patients who had all undergone surgery for the aortic root and ascending aorta at Niigata University Hospital between July 1978 and January 1995. Aortic valve replacement and ascending aortic wrapping were performed in 5 patients, Bentall or Cabrol operation in 6, and combined aortic arch reconstruction and Cabrol operation in 2, as the initial surgery. Patients who had an aortic dissection (Stanford type A) at initial surgery were assigned to group I (n = 7), while those with an aortic root aneurysm were assigned to group II (n = 8). In group I, 3 patients required a second operation for the remaining aortic arch aneurysm, and 1 died due to a late rupture of the distal aneurysm. In group II, no patient needed a reoperation; however, 1 died due to an intracranial hemorrhage and another due to composite valve graft failure and distal dissection. The results thus indicate that aortic dissection seems to affect long-term outcome, and therefore the combined repair of the aortic root and transverse arch is recommended in Marfan patients with aortic dissection involving the transverse aortic arch.
The transannular patch (TAP) repair used in the correction of tetralogy of Fallot (TOF) inevitably causes pulmonary regurgitation. We report herein the results of a long-term follow-up study conducted on 50 patients who had undergone a TAP repair 20-29 years earlier to evaluate the influence of pulmonary regurgitation on their late outcome and quality of life. As a control, 26 patients with an intact pulmonary valve ring and right ventricular outflow patch (RVP) confined to the subvalvular region were also studied. The 25-year survival rates of the TAP and RVP groups were 88.5% and 95.7%, respectively, and the event-free rates at 25 years were 73.3% and 90.9%, respectively. Although the absolute values of these rates were higher in the RVP group, there were no statistically significant differences between the two groups. To assess quality of life, the occupational status, childbearing ability, and late symptoms were evaluated, and found to be comparable between the two groups. Moreover, a treadmill submaximal stress test did not show any differences in exercise capacity between the two groups. In conclusion, the presence of a TAP does not significantly alter the late results or quality of life of patients who have undergone repair of TOF.
Two patients with aortic root abscess were successfully treated with a fringed valve prosthesis, in which a fringe material was secured to the sewing cuff of a bileaflet prosthetic valve using a 4-0 running suture. This fringed valve technique provides dual security for annular attachment of the prosthesis without coronary reimplantation. Good late outcome suggests it would be a useful alternative for aortic root abscess.
This report describes cardiac morphologic alterations in a patient who died 14 months following cryoablation. Histologic examination of the long-term cryolesion revealed a homogeneous fibrous scar with surrounding sinusoid capillary proliferation. The border between the fibrosis and the normal myocardium was sharply defined. Cryothermia is an excellent technique for the surgical correction of arrhythmias because it provides sharply demarcated lesions which lack arrhythmogenic potential.
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.
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.
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.
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.
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.
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.
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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.
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.
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.