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Biomedical subjects

Masaaki Kawada

Publications and source records attributed to Masaaki Kawada.

At least 19 recordsLinked to original sources
PubMed2006

Discrepancy between intraoperative transesophageal echocardiography and postoperative transthoracic echocardiography in assessing congenital valve surgery.

BACKGROUND: The purpose of this study was to investigate the discrepancy between intraoperative transesophageal and postoperative transthoracic echocardiography in assessing residual regurgitation in children undergoing valve repair. METHODS: Forty-two consecutive children (median age, 5.1 years) who underwent valve repair for valvar regurgitation from 2001 to 2004 were retrospectively analyzed. The patients were divided into two groups: atrioventricular valve group (n = 33) and aortic valve group (n = 9). Regurgitation grade, fractional shortening, and atrioventricular inflow velocity obtained by intraoperative transesophageal echocardiography were compared with those obtained by transthoracic echocardiography at discharge (median, 11 days) and at follow-up (median, 8 months). RESULTS: Intraoperative transesophageal echocardiography revealed specific residual lesions in 4 patients, leading to successful re-repair. Fractional shortening obtained by intraoperative transesophageal echocardiography was lower than that obtained by predischarge transthoracic echocardiography (p < 0.01). In the atrioventricular valve group, the regurgitation grade obtained by intraoperative transesophageal echocardiography was lower than that obtained by predischarge transthoracic echocardiography (0.7 +/- 0.8 versus 1.4 +/- 0.9; p < 0.01), and agreement between the two examinations was found in 12 patients (38%). Peak atrioventricular inflow velocity obtained by intraoperative transesophageal echocardiography was lower than that obtained by predischarge transthoracic echocardiography (p < 0.01). In the aortic valve group, there was no significant difference between the regurgitation grades in the two examinations (0.8 +/- 0.8 versus 1.1 +/- 0.9), and complete agreement in regurgitation grade was found in 5 (56%) of 9 patients. CONCLUSIONS: There were considerable discrepancies between the examinations in evaluation of residual atrioventricular valve regurgitation and potential atrioventricular valve stenosis: most of the residual regurgitations were underestimated by intraoperative transesophageal echocardiography. In contrast, reasonable agreement was found between the two examinations in evaluation of aortic valve regurgitation.

Adolescent↗
PubMed2006

Mitral-aortic intervalvular pseudoaneurysm with ventricular septal defect.

A 35-year-old woman was found on echocardiography to have a pseudoaneurysm of the mitral-aortic intervalvular fibrosa, residual ventricular septal defect, and aortic regurgitation. She had undergone surgical closure of a ventricular septal defect at age 7 and was found to have residual shunt several years later. She had been followed nonsurgically and had symptoms of cardiac failure during her 2 pregnancies. The pseudoaneurysm and the septal defect were successfully repaired.

Aneurysm, False↗
PubMed2006

Late outcome after repair of aortico-left ventricular tunnel: 10-year follow-up.

Despite successful surgical repair, patients with congenital aortico-left ventricular tunnel (ALVT) are at risk of developing aortic incompetence in the late postoperative period. Two cases of ALVT were followed for 10 years with special reference to aortic incompetence and geometry of the aortic root. The patients underwent repair of ALVT, one at 4 years of age and the other at 4 months of age. The first patient had a slit-like tunnel (type I) and the aortic orifice was closed with a pericardial patch. The second patient had a large tunnel with an extracardiac aneurysm (type II) and was closed with a pericardial patch at the aortic orifice and a Dacron patch at the left ventricular orifice, thereby completely obliterating the tunnel. The last echocardiographic evaluation showed no residual flow in the tunnel and no aortic incompetence in case 1, but there was mild aortic valvular regurgitation with deformity of the right sinus in case 2. Careful long-term follow-up is necessary because patients with ALVT have some inherent structural abnormalities from the left ventricular outflow tract to the aortic root.

Aortic Aneurysm↗
PubMed2006

Repair of a dysplastic tricuspid valve using artificial chordae: case report.

Atrioventricular valve repair with artificial chordal replacement has been widely used for congenital and acquired mitral valve abnormalities, but not for tricuspid valve abnormalities. A case is presented of dysplastic tricuspid valve that was successfully repaired using artificial chordae. A 2-year-old female presented with poor weight gain. Echocardiography revealed severe tricuspid regurgitation due to dysplastic tricuspid valve, poor coaptation by prolapse of the anterior leaflet, and tethering of the septal leaflet by short chordae. The prolapsed anterior leaflet was repaired with three pairs of 6-0 expanded polytetrafluoroethylene sutures. The short chordae of the septal leaflet were detached, and the septal and posterior leaflets were sutured together. Trivial tricuspid regurgitation was noted postoperatively. There was no tricuspid regurgitation during the follow up period of three years. The present case provides further evidence that artificial chordal replacement is a useful technique even for small children with congenitally abnormal tricuspid valves.

Child, Preschool↗
PubMed2006

Protein-losing enteropathy seven years after total right ventricular exclusion procedure for arrhythmogenic right ventricular dysplasia.

A 27-year-old man who was diagnosed with arrhythmogenic right ventricular dysplasia (ARVD) underwent the total right ventricular (RV) exclusion procedure: the RV free wall was resected and an extracardiac total cavopulmonary connection (TCPC) was created using a 24-mm-diameter polytetrafluoroethylene (PTFE) graft. After an uneventful period of 7 years, he began to develop protein-losing enteropathy (PLE), which was resistant to medical therapy, moderate mitral regurgitation (MR) and right femoral arteriovenous fistula due to heart catheterization. Therefore, fenestration of TCPC, mitral annuloplasty and ligation of arteriovenous fistula were performed. After the operation, symptoms and levels of total protein and albumin were immediately improved and normalized.

Adult↗
PubMed2005

Mid-term results of open aortic valvotomy for infants with critical aortic stenosis: seven-year experience including delayed Ross strategy.

OBJECTIVES: The purpose of this study is to provide short- and mid-term results of open aortic valvotomy (OAV) for patients with critical aortic stenosis (AS). METHODS: Between December 1993 and June 1996, 6 patients with critical AS underwent an OAV in our unit. Their ages and body weights at operation ranged from 1 to 65 days (median age, 9 days) and from 2.4 to 5.7 kg (median weight, 3.3 kg), respectively. Peak pressure gradient and diameter of the aortic valve ranged from 25 to 111 mmHg (mean value, 79 mmHg) and from 4.6 to 7.5 mm (mean diameter, 6.1 mm), respectively. OAV comprised the valvular commissurotomy and excision of the myxomatous nodules with cardiopulmonary bypass. RESULTS: No early or late death occurred. Mean peak pressure gradient across the aortic valve was reduced to 33 mmHg (from 15 to 44 mmHg) with no aortic insufficiency in 2 patients and trivial insufficiency in 4. During the follow-up period of 6 to 9 years, 3 out of 6 patients required no reintervention. The other 3 patients required repeated valvotomy for recurrent stenosis within 0.2 to 1.3 years after the operation. Of these, 2 patients required the Ross procedure at 7 years of age or older, and another at 6 years of age awaits the Ross procedure. CONCLUSION: OAV for critical AS was effective without causing mortality or significant aortic insufficiency. Our current strategy comprising the initial OAV and "delayed Ross procedure" for recurrent stenosis with or without insufficiency is a promising therapeutic option for infants with critical AS.

Aortic Valve↗
PubMed2005

Coarctation of the thoraco-abdominal aorta associated with mucopolysaccharidosis VII in a child.

Herein we describe a case of atypical coarctation of the thoraco-abdominal aorta associated with mucopolysaccharidosis VII in a 4-year-old girl. Aortography showed diffuse narrowing of the descending aorta. An extra-anatomic bypass was constructed using an 8-mm Dacron graft (Meadox Medicals Inc, Oakland, NJ) between the proximal and distal portion of the descending aorta. Balloon angioplasty was necessary to treat stenoses in the infrarenal abdominal aorta. Two years postoperatively at age 6, aortography revealed no stenosis at the anastomotic sites or in the prosthesis, but the hypoplastic segment of the descending aorta between the anstomoses was completely occluded.

Angioplasty, Balloon↗
PubMed2005

Dor procedure for left ventricular diverticulum with mitral regurgitation in an infant.

Congenital left ventricular diverticulum accompanied by MR is a rare abnormality. A 5-month-old female infant with this clinical combination underwent a procedure comprising exclusion of a large diverticulum by using an endoventricular circular patch (Dor procedure). This technique allowed us to avoid restriction of the left ventricular cavity and to improve the orientation of the papillary muscles, thus leading to successful mitral valve repair.

Cardiac Surgical Procedures↗
PubMed2005

Usefulness of helical computed tomography in diagnosing pulmonary vein stenosis in infants.

We investigated the usefulness of helical computed tomography(CT)in the morphological diagnosis of pulmonary vein stenosis, particularly that in infants and small children. In total, 20 helical CT examinations were performed in 10 post-operative cases of Total Anomalous Pulmonary Venous Drainage(TAPVD), 3 cases of single right ventricle, and 1 case of single left ventricle. In all cases, distinct morphological imaging was possible. Pulmonary vein stenosis could be categorized into three types: (1)stenosis from the anastomosis of the common pulmonary vein (CPV)-the left atrium (LA) to the peripheral pulmonary vein; (2) stenosis only at the anastomosis of CPV-LA; and (3) stenosis due to compression by nearby organs. Coronal views by multiplanar reconstruction (MPR) provided morphological information along the up-down direction of the body axis. Morphological diagnosis of pulmonary vein stenosis is important in deciding prognosis and therapeutic regimens, and helical CT was considered useful for such diagnosis in our 14 young patients.

Child, Preschool↗
PubMed2004

Outcome of right ventricle-to-pulmonary artery shunt in first-stage palliation of hypoplastic left heart syndrome: a multi-institutional study.

BACKGROUND: To evaluate the developing surgical technique of a modified Norwood procedure using a right ventricle-to-pulmonary artery shunt, we analyzed data obtained from 73 infants who underwent first-stage palliation for hypoplastic left heart syndrome between 1998 to 2002 at three centers in Japan. METHODS: Procedures performed included an aortopulmonary neoaortic reconstruction and a nonvalved polytetrafluoroethylene shunt between a small right ventriculotomy and a distal stump of the main pulmonary artery. The size of the shunt used was 4 mm in 6 patients, 5 mm in 41, and 6 mm in 26. Continuous cerebral perfusion was used in all patients and an additional descending aortic perfusion was used in 39. Postoperative management was basically the same as that for infants undergoing other types of operations. RESULTS: There were 61 hospital survivors (84%), including 5 of 6 patients weighing less than 2 kg, with 8 late deaths. Risk factors for hospital mortality include preoperative treatment without ventilatory support and surgeon's experience (first 10 cases). Three patients underwent a primary Fontan operation at 5, 9, and 10 months of age, with one late death. Forty-one patients underwent the bidirectional Glenn shunt after a mean interval of 6.9 months, and 19 of them completed the Fontan operation at median age of 2.1 years. Overall survivals were 65% at 1 year and 63% at 2 years. CONCLUSIONS: Improved survival for patients after first-stage palliation of hypoplastic left heart syndrome is reproducible for many centers by an application of the modified Norwood procedure with the right ventricle-to-pulmonary artery shunt.

Aorta↗
PubMed2004

How to predict forced vital capacity after living-donor lobar-lung transplantation.

BACKGROUND: Living-donor lobar-lung transplantation (LDLLT) has evolved from a rarely performed experimental procedure to an accepted therapy for selected patients who are unlikely to survive the long wait for cadaveric lungs. However, a convincing study has not been performed that shows the effects of small grafts and of pre-operative variables in predicting functional outcome of recipients after LDLLT. METHODS: From October 1998 to March 2002, 2 male and 11 female patients underwent LDLLT. Mean age was 27.3 years (range, 8-53 years). Diagnoses included primary pulmonary hypertension (n = 5), idiopathic interstitial pneumonia (n = 2), bronchiolitis obliterans (n = 2), bronchiectasis (n = 2), lymphangioleiomyomatosis (n = 1), and cystic fibrosis (n = 1). Donors included 12 men and 14 women with a mean age of 40 years. Given that the right lower lobe consists of 5 segments, the left lower lobe of 4, and the whole lung of 19, we estimated the graft forced vital capacity (FVC) based on the donor's measured FVC and compared this with the recipient's FVC measured after LDLLT. RESULTS: Currently, all patients are alive, with a mean follow-up of 22.2 months (range, 10-51 months). The recipients' FVC measured at 6 months (1,813 +/- 86 ml) correlated well with the graft FVC (1,803 +/- 70 ml), estimated based on the donors' measured FVC (r = 0.802, p = 0.00098). CONCLUSIONS: Recipient FVC after LDLLT can be predicted by measuring donor FVC before surgery regardless of the diagnosis of the recipient.

Adolescent↗
PubMed2004

Improved survival after living-donor lobar lung transplantation.

OBJECTIVE: Survival after living-donor lobar lung transplantation has been reported to be similar to that after cadaveric lung transplantation. The purpose of this study was to summarize our 5-year experience of living-donor lobar lung transplantation for critically ill patients. METHODS: Between October 1998 and April 2004, we performed living-donor lobar lung transplantation in 30 critically ill patients with various lung diseases, including 5 (17%) patients on a ventilator. Mean age was 30.4 years (range, 8-55 years). Postoperative management included slow weaning from a ventilator, relatively low-dose immunosuppressants, and careful rejection monitoring on the basis of radiographic and clinical findings without transbronchial lung biopsy. RESULTS: The average duration of mechanical ventilation was 15.4 days, intensive care unit stay was 23.5 days, and hospital stay was 64.6 days. Clinically judged acute rejection occurred at an average rate of 1.5 episodes per patient, but infection occurred in only one patient during the first month. In spite of the complicated postoperative course, all patients were discharged without oxygen inhalation. Four patients had unilateral bronchiolitis obliterans syndrome, but the decrease in their forced expiratory volume in 1 second values stopped within 9 months. All 30 recipients are currently alive, with a follow-up period of 1 to 66 months. All donors have returned to their previous lifestyles. CONCLUSIONS: Living-donor lobar lung transplantation can be applied to both pediatric and adult patients with very limited life expectancies. It might provide better survival than conventional cadaveric lung transplantation.

Adolescent↗
PubMed2004

Atrial natriuretic peptide protects against ischemia-reperfusion injury in the isolated rat heart.

BACKGROUND: Atrial natriuretic peptide (ANP), a stimulator of particulate guanylate cyclase, has been found to protect against reoxygenation-induced hypercontracture in isolated cardiomyocytes by increasing cyclic guanosine monophosphate synthesis. The purpose of this study was to investigate the cardioprotective effects of ANP against ischemia-reperfusion injury in isolated rat hearts. METHODS: Twenty-four hearts were perfused with ANP at 0.01, 0.1, and 1 micromol/L or without ANP (n = 6 each) in normoxic conditions. Because 0.1 micromol/L ANP induced a threefold increase in cyclic guanosine monophosphate release into the coronary effluent without any effect on cardiac function, we used the 0.1 micromol/L ANP dose for ischemia-reperfusion studies. Eighteen hearts were subjected to 15 minutes of normothermic global ischemia followed by 15 minutes of reperfusion. The hearts were divided into three groups (n = 6 each). RESULTS: In group 1, ANP was added before ischemia. In group 2, ANP was added to the reperfusate. Hearts were untreated in the control group. In group 1, the postischemic recovery of cardiac output, coronary flow, and cyclic guanosine monophosphate release was similar to the control group. In group 2, the recovery of cardiac output was significantly better than the control group (82.1% +/- 9.8% vs 61.8% +/- 6.8%, respectively, p < 0.01) with a similar trend to recovery of coronary flow (90.7% +/- 8.5% vs 79.3% +/- 11.8%, respectively). The improved cardiac function was closely related to a significant increase in postischemic cyclic guanosine monophosphate release. CONCLUSIONS: Administration of ANP at the time of reperfusion protects the myocardium from ischemia-reperfusion injury. The concentrations of administration must not only increase the release of cyclic guanosine monophosphate release, but also lack negative inotropic effects.

Animals↗
PubMed2004

Right ventricle-pulmonary artery shunt in first-stage palliation of hypoplastic left heart syndrome.

This article reviews our experience using a prosthetic conduit between the right ventricle (RV) and the pulmonary artery (PA), in lieu of the more traditional aortopulmonary shunt, for infants undergoing surgical palliation of hypoplastic left heart syndrome. Thirty-three consecutive infants underwent Norwood procedure between February 1998 and November 2003, using an RV-PA conduit. There were 31 hospital survivors (94%) and 25 patients have undergone a stage II bidirectional Glenn anastomosis with an additional two deaths. Nine patients have undergone completion Fontan. This technique provides reproducible results, simplifies postoperative management, and improves outcome, especially for "low volume" programs.

Anastomosis, Surgical↗
PubMed2003

Production and release of infectious hepatitis C virus from human liver cell cultures in the three-dimensional radial-flow bioreactor.

Lack of efficient culture systems for hepatitis C virus (HCV) has been a major obstacle in HCV research. Human liver cells grown in a three-dimensional radial-flow bioreactor were successfully infected following inoculation with plasma from an HCV carrier. Subsequent detection of increased HCV RNA suggested viral replication. Furthermore, transfection of HCV RNA transcribed from full-length cDNA also resulted in the production and release of HCV virions into supernatant. Infectivity was shown by successful secondary passage to a new culture. Introduction of mutations in RNA helicase and polymerase regions of HCV cDNA abolished virus replication, indicating that reverse genetics of this system is possible. The ability to replicate and detect the extracellular release of HCV might provide clues with regard to the persistent nature of HCV infection. It will also accelerate research into the pathogenicity of HCV, as well as the development of prophylactic agents and new therapy.

Amino Acid Sequence↗
PubMed2003

Total right ventricular exclusion improves left ventricular function in patients with end-stage congestive right ventricular failure.

BACKGROUND: We developed a total right ventricular (RV) exclusion procedure for the treatment of isolated congestive RV failure. The objective of the present study was to elucidate the effects of a complete removal of RV volume overload (RVVO) on the surgically created single left ventricle (LV). METHODS AND RESULTS: Three adults (2 arrhythmogenic RV dysplasia, 1 Ebstein) and 5 children (all Ebstein) in NYHA class IV underwent the procedure. The RV free wall was resected from the heart, and the tricuspid orifice was closed. Pulmonary blood supply was obtained by a cavopulmonary connection in 6 patients and a systemic-pulmonary shunt in 2. The LV function was evaluated by 2-dimensional echocardiography 1 month after the surgery. All patients are alive. The paradoxical movement of the interventricular septum and geometry of the LV expressed by its eccentricity (2.1 to 1.2, P<0.01) were normalized after the operation in all 8 patients. LV end-diastolic volumes (59% to 109% of normal value, P<0.01), indexed maximal left atrial area (6.5 to 10.5 cm2/m2, P<0.01), LV ejection fraction (27% to 62%, P<0.01), and cardiac index (2.1 to 3.3 L/min/m2, P<0.05) all significantly increased. CONCLUSIONS: Removal of the RVVO by means of the total RV exclusion procedure provides effective volume loading, restores a cylindrical shape, and improves contractile function of the LV, thus leading to increased systemic output.

Adult↗