Search PubMed⌕ Search

Biomedical subjects

T Izukawa

Publications and source records attributed to T Izukawa.

At least 37 records · Page 2Linked to original sources
PubMed1980

Noninvasive assessment of left ventricular function related to serum digoxin levels in neonates.

Eighteen neonates in heart failure were investigated to assess whether high or low serum digoxin levels had differing effects on left ventricular function as determined by systolic time intervals obtained by echocardiography. Nine patients had digoxin levels of 1.99 +/- 0.35 ng/ml (group 1). Nine others had levels of 3.62 +/- 0.95 ng/ml (group 2). Systolic time intervals were obtained by echocardiography before and at 5 days after digoxin and correlated with serum levels. The heart rate, preejection period (PEP), left ventricular ejection time (LVET), electromechanical systole (QS2) and the PEP/LVET ratio were measured. LVET and electromechanical systole were indexed. These measurements were analyzed and the two groups were compared using Student's t test. The clinical improvement in both groups was similar and no difference in ECG changes were noted. Therapy with digoxin produced changes in heart rate and systolic time intervals in both groups. Both showed significant shortening of electromechanical systole index; group 1 significantly shortened the LVET index and PEP/LVET ratio, whereas group 2 significantly shortened the PEP. Statistical analysis comparing the two groups showed no difference between them. Digoxin produces measurable changes in the indices of left ventricular function. The magnitude of these changes suggests no therapeutic advantage to the higher levels.

Digoxin↗
PubMed1979

Repair of interrupted aortic arch and aortopulmonary window in an infant.

The diagnosis and repair in infancy of interrupted aortic arch and aortopulmonary window is described. Using deep hypothermia and circulatory arrest, aortic continuity was established with a prosthetic graft, which was anastomosed to the aortic orifice of the aortopulmonary window. The pulmonary artery side of the aortopulmonary window was closed directly. Postoperative cardiac catheterization demonstrated a good reconstruction. Previous experience with this rare variety of interrupted aortic arch complex is reviewed.

Aorta, Thoracic↗
PubMed1979

Structural heart disease in the newborn. Changing profile: comparison of 1975 with 1965.

The earlier detection and investigation of babies with congenital structural heart disease has resulted in earlier treatment and better management of these patients. In 1965, at the Hospital for Sick Children, Toronto, 121 cases were assessed and treated; by 1975 this figure had risen to 226 cases. Few changes were noted in the incidence of the 10 most common malformations, except for the obvious increase in the incidence of patient ductus arteriosus due to survival of increasingly premature infants. The sick cardiac neonate was referred earlier in 1975, studied with newer non-invasive investigations, and, according to the severity of symptoms and signs, was sent sooner to cardiac catheterisation. 80% of babies presenting with cyanosis survived the first month and 60% of babies with congestive heart failure survived. With better surgery and perioperative care, the survival rate in the first month after surgery rose from 37% in 1965 to 70% in 1975.

Cardiac Catheterization↗
PubMed1979

Conduction disturbances after surgical correction of ventricular septal defect by the atrial approach.

Conduction disturbances have been documented after correction of ventricular septal defects by the ventricular route. Recently, repair of the ventricular septal defect has been through the right atrium to overcome damage to the conduction system and a right ventriculotomy. Thirty-nine children with ventricular septal defects under the age of 5 years were operated upon by the atrial route (group 1). The incidence of conduction disturbances in this group was compared with that occurring in 19 children of comparable age with a ventricular septal defect repaired via a right ventriculotomy (group 2). Complete right bundle-branch block developed in 13 of 39 children (33.3%) in group 1, compared with 15 of 19 children (78.9%) in group 2. This was a statistically significant reduction in complete right bundle-branch block in group 1. The incidence of left axis deviation occurring with complete right bundle-branch block was similarly statistically reduced. Transient complete heart block and arrhythmias were not statistically different in the two groups. The atrial approach to the repair of the ventricular septal defect significantly reduced the incidence of complete right bundle-branch block alone and occurring with left axis deviation.

Aortic Coarctation↗
PubMed1978

Assessment of the cardiovascular system in conjoined thoracopagus twins.

The thoracoomphalopagus conjoined twins comprise 75% of all conjoined twins. In the assessment of the organ systems of the twins, the cardiovascular system is important since union of this system in the twins has occurred in 75% of the cases. Of the five cases reported here, two had separate hearts and vessels with a common pericardium only. Two twins were joined at the right atrial level. The fifth pair were connected at both atrial and ventricular levels. It has been suggested that the presence of two separate QRS complexes in the ECG indicates complete separation of the two hearts. Case 4 shows that even in the presence of atrial union, the existence of an atrioventricular block in one twin may produce a very slow heart rate, while the other twin may have a normal rate that will not influence the ventricular rate of the other. In our experience, angiocardiography has been the most useful diagnostic procedure.

Angiocardiography↗
PubMed1978

Permanent cardiac pacing in infants and children.

This clinical review details our 15 year experience with permanent cardiac pacemakers in 81 infants and children. Pacing was found inappropriate in one infant. The other 80 patients were paced because of congenital heart block [24], post-operative block [50], or sick sinus syndrome [6]. Maintenance of long-term pacing requires all too frequent re-operation for battery depletion [37%], lead related problems [32%] or wound dehiscence [31%]. Problems related to pacemaker size and the presence of a high myocardial threshold are particularly important in the pediatric patient. In spite of these problems, children requiring cardiac pacemakers can be extremely well, their prognosis depending almost entirely on the presence of underlying heart disease.

Adolescent↗
PubMed1978

Nonstructural heart disease in the newborn. Observations during one year in a perinatal service.

One-third of 327 newborn infants referred to the perinatal service of the Hospital for Sick Children during 1975 with suspected cardiopulmonary disorders proved to have nonstructural heart disease. Most of these were term infants with transient tachypnoea or cyanosis who recovered. A history of fetal distress or difficult delivery was commonly associated. The haemodynamic disorder for most was a delay in the normal progress of the transitional circulation. Evidence of myocardial ischaemia was present in 40%, and about half of these developed congestive heart failure. Aids to diagnosis of the ischaemic complication included echocardiography and myocardial perfusion scanning. For a small proportion specific metabolic disturbances, myocarditis, or dysrhythmia seemed the primary cause but even for these there were reasonable grounds to suspect a prenatal origin. Current general supportive measures were of value in treatment.

Arrhythmias, Cardiac↗
PubMed1977

Evaluation of children with ventricular arrhythmias.

Ventricular arrhythmias are rare in childhood but may be associated with syncope and sudden death. This report describes 8 children with ventricular arrhythmias, 6 of whom suffered syncopal episodes. Ventricular tachycardia was documented in 5. One boy died suddenly. Complete cardiac investigation was carried out with exercise testing, Holter monitoring, echocardiography, cardiac catheterization, angiography, and electrophysiological studies. The spectrum of abnormalities related to the arrhythmias included prolapsing mitral valve, prolonged QT syndrome, sick sinus syndrome, congenital heart disease, cardiomyopathy, and idiopathic ventricular tachycardia. Exercise testing and Holter monitoring were particularly useful in documenting the arrhythmias and monitoring response to therapy.

Adolescent↗
PubMed1977

Atrial fibrillation in children.

Atrial fibrillation is rare in children. Previous reports associated it with severe rheumatic heart disease and a poor prognosis. This review is of the unique experience of 35 cases of atrial fibrillation in children in the past 22 years; 23 patients were boys. The age of onset ranged from 1 day to 19 years (average, 8 years). Associated cardiac conditions were severe rheumatic mitral regurgitation (3 cases), cardiomyopathy (5), atrial tumors (2), infective endocarditis (1), paroxysmal atrial tachycardia of infants (4), idiopathic paroxysmal atrial fibrillation (1), Marfan's syndrome with mitral regurgitation (1), endocardial fibroelastosis (1), and structural congenital heart malformations (17). Surgical correction of congenital heart lesions was directly related to the development of atrial fibrillation in 14. Varying arrhythmias of the sick-sinus syndrome were observed in five children. The atrial fibrillation was paroxysmal or transient in 21 patients and persistent in 14. Treatment depended on the underlying condition. Digoxin was used in all cases and cardioversion attempted in ten; no patient was given anticoagulants. Three children had cerebral emboli, with residual defects. Eighteen patients are known to be alive, 13 are dead, and 4 are lost to follow-up. Atrial fibrillation in childhood is an indication for complete investigation of the patient and for the institution of treatment appropriate to the underlying disease.

Adolescent↗
PubMed1976

Congenital paroxysmal atrial tachycardia.

Ten infants who had paroxysmal atrial tachycardia in utero or at birth are reported. Because of apparent fetal distress, caesarean section was performed in 4 cases and labour was induced in 1. Birthweight was generally large for gestational age. Severe ascites and hydrops at birth were manifestations of cardiac failure. Atrial flutter was recorded in 4 infants and supraventricular tachycardia in 5. The WoLff-Parkinson-White syndrome became evident later in 2. Digoxin was given to all 10 infants, and cardioversion was required and was effective in 4. Known recurrences in childhood have occurred in only 1 patient. Congenital atrial tachyarrhythmias may be commoner than generally believed, and fetal electrocardiography may help to avoid unnecessary termination of pregnancy. Blood sugar determinations are important, since neonatal hypoglycaemia was found. Cardioversion should be performed promptly in severely ill infants or if there is no response to digoxin. Care is required to avoid digoxin toxicity.

Birth Weight↗
PubMed1976

Surgical treatment of pulmonary atresia with intact ventricular septum.

Fifty-nine children with pulmonary atresia and intact ventricular septum underwent various forms of surgical treatment at the Hospital for Sick Children, Toronto, during 1950 to mid 1975. Twenty-three patients had pulmonary valvotomy, 15 direct, 2 indirect, and 6 both direct valvotomy and infundibulectomy. All died, 19 early and 4 late. Of 13 patients who received a systemic-pulmonary artery shunt, 4 combined with surgical atrial septectomy, there are only 2 long-term survivors both of whom were children who had had a Waterston anastomosis. Recently we have been treating infants with small right ventricles with balloon atrial septostomy at cardiac catherterization followed by a Potts anastomosis and pulmonary valvotomy. If the Potts anastomosis appears satisfactory the persistent ductus arteriosus is ligated. This scheme was used in 23 infants, with 4 early deaths and 2 late deaths. Of 17 survivors, further shunts were required in 4 children. One child has had a formal repair, with insertion of valves in both tricuspid and pulmonary areas. We believe that this operative combination of Potts anastomosis and pulmonary valvotomy offers the infant with pulmonary atresia and a small right ventricle a relatively low initial mortality and the possibility of right ventricular enlargement and subsequent repair.

Ductus Arteriosus, Patent↗
PubMed1976

Echocardiographic assessment of bicuspid aortic valves. Angiographic and pathological correlates.

Aortic root echocardiograms were recorded from 89 patients whose aortic valves had also been adequately defined by selective angiography or viewed surgically or at autopsy. The eccentricity index (E.I.) of the aortic leaflets was measured at the onset of diastole and an E.I. of 1.3 or greater was taken as abnormal. Of 31 patients with isolated nonobstruced or mildly obstructed bicuspid aortic valves (7 viewed previously at valvotomy and 24 diagnosed radiologically) 23 (74%) had an abnormal E.I. Varying eccentricity occurred in some of these patients. Central leaflet echoes (E.I. of 1.0 to 1.25) were present in the other eight patients. All 14 patients with nonobstructed tricuspid aortic valves had central echoes. Additional multilayered diastolic echoes were found in patients with bicuspid aortic valves as well as in two patients with abnormal tricuspid aortic valves. The valves of 13 patients with aortic stenosis or incompetence were viewed surgically and the E.I. was abnormal in all patients with a bicuspid aortic valve in this group. Aortic leaflet echo findings were not diagnostically helpful in ten patients with tetralogy of Fallot, one of whom had a normal E.I. with a surgically confirmed bicuspid aortic valve. Of 21 patients with VSD only one had a bicuspid aortic valve but six had an abnormal E.I. This false positive sign was related to a high membranous VSD, sometimes with aortic valve prolapse. It is concluded that an E.I. of greater than or equal to 1.3 in the absence of an associated VSD is diagnostic of a bicuspid aortic valve and can be expected to be found in approximately three-quarters of subjects with this abnormality.

Adolescent↗