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Accelerator control systems have evolved from centrally oriented systems with direct connection to the equipment, through ad-hoc networks to multi-computer systems interconnected by local-area networks (LANs). As accelerators become larger, and as technology advances, it becomes questionable whether continued use of LAN technologies at all levels of the control system is appropriate. This paper traces the data communication strategies adopted for accelerator control systems over the years, and suggests a new approach which makes use of the very high link bandwidths now available.

In pediatric patients cardiac pacing has been traditionally carried out by the epicardial approach in Taiwan. This study was to define the long-term results of transvenous endocardial pacemaker therapy in growing children. From 1994 to 1997, patients with sympatomatic bradycardia referred for permanent pacemaker were enrolled. Permanent pacemaker was implanted under propofol anesthesia and direct puncture of subclavian vein and creation of prepectoral pocket. A total of 10 patients ( 5 male, 5 female) aged from 5 to 17 years (13 +/- 4 yrs), constituted the study population. Follow-up period ranged from 14 to 48 months (29 +/- 14 months) . Underlying rhythm disturbances and pacemaker type implanted were: complete atrioventricular (AV) block 5 (VDD pacemaker in 3 and VVIR in 2), sick sinus syndrome 2 (DDDR pacemaker in both), sick sinus syndrome with abnormal AV conduction 1 (WIR), long QT syndrome 1 (VVIR) and hypertrophic cardiomyopathy 1 (DDDR). Pacemaker dysfunction occurred in only one patient in whom the endocardial lead was fixed by absorbable thread with an aim to have more flexibility of the lead. The endocardial lead was dislodged but properly reimplanted about 3 months after the initial implantation. All patients had satisfactory lead sensing and pacing threshold during the long-term follow-up. The pacing threshold was much better than that usually neededfor epicardial leads. With growing, none have the problems of lead length. Quality of life was reported to be improved in all. Tranvenous permanent pacemaker implantation is feasible in children aged 5 or older The long-term efficacy is satisfactory. Physiological pacing using a single lead (VDD) is recommended for younger patients with impaired AV conduction.

Cardiac catheterization can be superfluous and risky for sick babies, infants, and young children with total anomalous pulmonary venous connection (TAPVC). This study assessed the accuracy of echocardiography in the clinical assessment of pediatric patients with TAPVC before cardiac surgery.A total of 15 consecutive patients with TAPVC treated between July 1, 1993, and December 31, 1999, were included in this retrospective study. Patients with TAPVC with heterotaxy syndrome were excluded. We assessed this cardiac anomaly preoperatively using plain chest roentgenograms, echocardiography, and magnetic resonance imaging. A combination of suprasternal, parasternal, subcostal, and apical four-chamber views and their tilting scans were employed for diagnosis and to trace the course of the anomalous pulmonary venous connection.Interatrial right-to-left shunt via atrial septal defects were documented by two-dimensional echocardiography with color Doppler mapping in all 15 patients. Patent ductus arteriosus was found in six patients. Cardiomegaly with enlargement of the right atrium and the right ventricle could be seen on plain chest roentgenograms and by echocardiography in all but two patients with infracardiac TAPVC. In all patients, the left innominate vein, coronary sinus or right atrium, and portal vein were the draining sites of supracardiac, cardiac, and infracardiac TAPVC, respectively. A pattern of continuous flow without phasic variation, which is suggestive of stenosis of the pulmonary vein, was found in two patients with infracardiac TAPVC with obstruction. The surgical findings were reviewed and correlated well with those of the echocardiography.In infants and children with TAPVC, the drainage sites and flow profiles of the pulmonary veins can be exactly determined by Doppler echocardiography preoperatively, which makes cardiac catheterization and angiocardiography unnecessary.

Reoperation is inevitable for some patients with pulmonary atresia who receive a heterograft or homograft in a primary Rastelli operation. Nonetheless, the need for reoperation in patients with classic Fallot's tetralogy who have undergone total correction with a transannular patch is unusual. We sought to change pulmonary atresia into Fallot's tetralogy and used a transannular patch instead of the conventional Rastelli operation.Valveless outflow direct reconstruction was performed on 10 consecutive patients with pulmonary atresia and ventricular septal defect between August 1997 and 1999. Patient ages ranged from 1.3 to 11.5 years. A Blalock-Taussig shunt was previously constructed in four of these patients and a central shunt was constructed in five. The major aortopulmonary collateral arteries were occluded in one patient by repeated coil embolization after the central shunt. The strategy was to connect the right ventriculotomy with the pulmonary arteries directly, even if there was a gap with a long atretic cord. In patients with a previous central shunt covered with a Gore-Tex membrane, the reactive visceral pericardium over the in situ tissue (the left atrium, right ventricle, or aorta) was used as the autologous posterior wall. Thus, only autologous, fresh pericardium without a valve was used to cover the anterior part of the right ventricular outflow tract, as in the repair of classic Fallot's tetralogy with a transannular patch.There was no mortality, and the postoperative central venous pressure was low in all patients. No gradient was noted across the right ventricular outflow tract. Follow-up echocardiography revealed a competent tricuspid valve with mild pulmonary regurgitation in all patients.The results of this study suggest that valveless outflow direct reconstruction provides adequate pulmonary circulation without hypertension in pulmonary atresia patients with a ventricular septal defect if the tricuspid valve is competent.

Conventional repair of congenitally corrected transposition of the great arteries (CCTGA) is directed at eliminating the associated defects and leaves the right ventricle in a systemic position. The long-term outcome of this procedure may involve deterioration of right ventricular function with tricuspid regurgitation and failure of the conduction system. We describe two consecutive patients with CCTGA, one of whom had apicocaval juxtaposition. The patients were aged 19 and 16 months, respectively, and both underwent a combination of atrial and arterial switch. These are the first two reported cases of successful completion of this type of operation in Taiwan. Our review of previously reported cases suggested that no significant difference exists in the outcome of patients with this condition who undergo either arterial switch or Rastelli-type repair plus atrial redirection. However, reported patients who underwent anatomic repair had lower early mortality, late mortality, and incidence of complete heart block than those who underwent conventional repair. The present two cases and our review of the literature suggest that, among patients with apicocaval juxtaposition, 1) Mustard operation is optimal for patients with small atrial volume; 2) one-and-one-half ventricular repair may be helpful to the outcome, especially when treatment is combined with Rastelli-type repair; and 3) excellent access to the ventricular septal defect through the tricuspid valve is afforded via a left atriotomy. From the present two cases and our review of the literature, we conclude that anatomic repair is superior to conventional repair of CCTGA in terms of protection against dysfunction and failure of the anatomic right ventricle, tricuspid valve, and conduction system. Long-term follow-up is mandatory.

To investigate the usefulness of electron beam computed tomography (EBCT) in the preoperative detection and perioperative management of insidious concomitant primary tracheobronchial anomalies in patients with tetralogy of Fallot (TF).From July 1995 to October 1999, 88 children (38 girls, 50 boys) with TF were enrolled in this study. EBCT examinations provided information needed to plan management. The final diagnoses of airway abnormalities were correlated with the findings of bronchoscopy in five patients and confirmed during surgery.Fourteen (16%) of the 88 patients had associated primary tracheobronchial anomalies. Nine patients had tracheal bronchi, which were combined with tracheobronchial stenosis in two patients and with tracheal stenosis in one patient. Two patients had tracheal diverticulum, which was combined with lower tracheal stenosis in one patient. Two patients had congenital tracheal stenosis. Tracheomalasia was found in one patient. Three patients with ventilation difficulties died postoperatively. Special attention was given to the care of the diseased airways perioperatively, and the remaining 11 patients had a smooth course of hospitalization and discharge.Our results show that EBCT provides good delineation of both cardiac and tracheobronchial anomalies and suggest that it should be used perioperatively to detect associated airway anomalies in TF, to facilitate the design of an appropriate ventilation care strategy.

To study the epidemiology of leprosy in children in Taiwan.Taiwan, with a population increase from 3.3 to 21.7 million, several tides of immigration and national leprosy control programs, from 1910 to 1997.To collect and analyze the documents of Taiwan leprosy surveys and charts of the National Leprosy Control Center.Cumulative and new number of all-age and pediatric-age patients, prevalence rates, new case detection rates, and results of skin bacterial smears.The prevalence rates of all-age leprosy ranged between 1.54 and 3.22 per 10,000 population. The proportion of children among all-age patients reached the highest of 4.93% in 1966, dropping to 0% in 1984 and thereafter, until 1988 and 1991 when two and one pediatric-age patients appeared, respectively, following the influx of immigrants from leprosy-endemic countries. The rise and fall of new patients younger than 15 years and 15 years or older were slightly correlated (r = 0.935, p0.001). Detection and confirmation of leprosy in children are usually belated. Physicians should still be acquainted with the clinical diagnosis of leprosy since sporadic cases of leprosy can reappear, particularly among children coming from endemic countries.

We report on a 2-month-old infant girl who had right pulmonary agenesis and an unusual course of the left pulmonary artery. Computed tomography and cardiac catheterization showed that the left pulmonary artery arose from the main pulmonary artery, crossing the midline, and reaching the left lung via an aberrant course between the esophagus and trachea. The coexistence of right pulmonary agenesis and left pulmonary sling is extremely rare. Unlike in other reports, our patient remained symptom-free and in good health, with normal growth and development until age 2 years, when she died from complications during an attack of bronchiolitis caused by respiratory syncytial virus.

The association of tricuspid atresia and persistent truncus arteriosus is a very rare congenital anomaly. We report a newborn with a prenatal diagnosis of tricuspid atresia, in whom associated type II persistent truncus arteriosus was found by postnatal echocardiography. The patient had mild cyanosis and developed heart failure soon after birth. Balloon septostomy was performed to enlarge the interatrial communication. However, her condition rapidly deteriorated and she died of sepsis and heart failure at the age of 14 days.

Hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are two different diseases and have distinct etiologies. HCM is rare in children and rarely progresses to DCM. We report a 5-year-old Taiwanese girl with a definite diagnosis of hypertrophic obstructive cardiomyopathy. The diagnosis was based on echocardiograms, cardiac catheterization, and endomyocardial biopsy. However, the clinical features progressed to a picture of nonobstructive HCM at age 9, and the patient developed dilated poorly contractile ventricles with intractable congestive heart failure at age 10. She died from ventricular tachycardia at age 13. This report emphasizes the importance of periodic reevaluation for children with HCM.

To describe four patients having total anomalous pulmonary venous connection with an intrapulmonary vertical vein, rendering difficulty in diagnosis and surgery.a tertiary referral center.By reviewing medical records, 4 of 25 patients with right atrial isomerism and total anomalous pulmonary venous connection were identified to have an intrapulmonary vertical vein. All four patients underwent echocardiography, catheterization, and angiography. One underwent MRI. Two underwent open-heart surgery and one received a modified Blalock-Taussig shunt.Right atrial isomerism was present in all four patients. On chest x-ray films, an abnormal shadow resembling scimitar syndrome was seen in two patients. Imaging the vertical vein was unsuccessful with an echocardiogram in all four patients. The intrapulmonary course of the vertical vein was depicted with a pulmonary venogram in two patients and with magnetic resonance in one patient. The intrapulmonary segment remained undetected until autopsy in one patient. All four patients died. At autopsy, the pulmonary venous confluence was hypoplastic in all four hearts. The vertical vein was buried in pulmonary parenchyma and drained to superior vena cava with significant obstruction.In the presence of right atrial isomerism and total anomalous pulmonary venous connection, there may be an intrapulmonary pulmonary venous connection that may be obstructed. Anastomosing the pulmonary venous confluence to the atrium may be difficult because of hypoplasia of the pulmonary venous confluence.

To assess the pattern of aortic sinus in varied aortopulmonary rotations and its clinical implications, three aortic sinuses at the diastolic phase in true lateral view are identified in 53 angiograms of complete transposition of the great arteries recorded between 1988 and 1993. The patients with the high takeoff of the coronary arteries found at surgery and in the literature were selected for additional investigation. Six regions were defined on the horizontal plane. From left anterior 89 degrees to 61 degrees, the non-facing sinus moved toward the anterior aspect (one patient). From left anterior 60 degrees to left anterior 1 degree, the left-hand sinus moved gradually from an anterior toward a posterior location (two patients). From directly anterior 0 degree to right anterior 59 degrees, the right-hand sinus moved from posterior toward an anterior position (30 patients). From right anterior 60 degrees to right posterior 105 degrees, the non-facing sinus moved posteriorly (20 patients). On approaching directly anterior 0 degree and toward right anterior 60 degrees, the left-hand sinus was the lowest in anterior transposition of the great arteries instead of the non-facing sinus, as in left anterior 90 degrees and in posterior transposition of the great arteries. High takeoff occurred commonly above the lowest left-hand sinus in anterior transposition of the great arteries (2 cases here and 5 in the literature, 100%). In conclusion, aortopulmonary rotations about the short and long axes were both evident on identification of the aortic sinus in various rotations. The aortic sinus did not rotate along the long-axis in anterior transposition of the great arteries, thus making the left-hand sinus, the lowest of this group, vulnerable to the high takeoff of the coronary arteries in anterior transposition of the great arteries.

To investigate the effects of 3-week versus 4-week administration of benzathine penicillin G (BPG) on the incidence of Group A streptococcal infections and the recurrences of rheumatic fever (RF).We started, in 1979, randomly allocating all patients with RF to a 3-week or 4-week BPG prophylaxis program. They were examined at the RF clinic, every 3 to 6 months, and at any time they did not feel well. During 1979 to 1989, throat cultures and sera for antistreptolysin O and streptozyme titers were obtained at each clinic visit. Chest radiographs, electrocardiogram, color Doppler echocardiograms, and acute phase reactants were obtained.Two hundred forty-nine patients fulfilled the revised Jones criteria and were followed until December 1991: 124 in the 3-week and 125 in the 4-week program. Their age, sex, weight, percentage with history of RF, severity of cardiac involvement, follow-up duration, and compliance to program were comparable. Eight hundred eighty throat cultures were collected in the 3-week program and 770 were collected in the 4-week program. Six hundred sixteen and 627 sera were determined in each program for antistreptolysin O, and 582 and 592 sera for streptozyme titers.True streptococcal infections occurred in both programs: 39 infections in the 3-week program, and 59 infections in the 4-week program (7.5 vs 12.7 per 100 patient-years). Four infections with no antibody response occurred in the 3-week program, and three such infections in the 4-week program. Nine RF recurrences occurred in 8 patients in the 3-week program, and 16 recurrences in 16 patients in the 4-week program. Prophylaxis failure occurred in 2 of 124 patients in the 3-week program, and in 10 of 125 patients in the 4-week program (0.25 vs 1.29 per 100 patient-years). The overall recurrences/infections rate in each program was comparable, 13.6% vs 15.5%, but the recurrences/ infections rate due to prophylaxis failure was higher in the 4-week program than in the 3-week program, 3.0% versus 9.7%.This 12-year prospective and controlled study documented that streptococcal infections and RF recurrences occurred more often in the 4-week program than in the 3-week program. The risk of prophylaxis failure was fivefold greater in the 4-week program than in the 3-week program.

To define the nature and course of left ventricular (LV) thrombi in pediatric patients, the charts and echocardiographic records of 32 pediatric patients with dilated cardiomyopathy from 1986 to 1991 were retrospectively reviewed. Five patients who were identified according to echocardiographic evidence of LV thrombi fulfilled the criteria of dilated cardiomyopathy. Systemic embolization occurred in three patients with LV thrombi who invariably died despite anticoagulant treatment. Although it was not statistically significant, patients with LV thrombi tended to have a lower ejection fraction compared to patients without LV thrombi. The morphology of LV thrombi in patients with systemic embolization showed nonprotruding features. Thus, children with dilated cardiomyopathy are at risk of developing LV thrombi and systemic embolization. Although it was not possible to identify the risk factors, the risk of developing LV thrombi and systemic embolization may be higher in patients with lower ejection fraction of the left ventricle.

Ventriculo-coronary communication is frequently encountered in pulmonary atresia patients who have an intact ventricular septum. Preoperative documentation is important to decide the feasibility of right ventricular decompression procedure. Experience of Doppler echocardiographic visualization of this anomaly in a case of critical pulmonary stenosis with intact ventricular septum is reported. Doppler echocardiography is a promising method of detection and should be used in every patient with a high-pressured hypoplastic ventricle before intervention.

Supraventricular tachycardia (SVT) is the most common cardiac arrhythmia in children. Atrioventricular (AV) reciprocating tachycardia utilizing an accessory pathway and AV nodal reentrant tachycardia (AVNRT) constitute a majority of SVTs. Radiofrequency energy ablation has recently become the treatment of choice in adults. Initial experience in pediatric patients in this Institute is reported in this study. Six consecutive patients (aged 5-22 years, mean age 13 years; 3 boys, 3 girls) with narrow-QRS SVT were studied from July to October in 1993. They had experienced symptomatic SVT for a mean period of five years (ranged from 1 to 15 years). Anti-arrhythmic agents, including beta-antagonists and calcium channel blockers, were unable to satisfactorily suppress these SVTs. Four of the six patients were shown to have a left-sided concealed accessory connection as the retrograde limb of the reentrant circuit. After identification of the earliest retrograde activation site, a steerable 7F catheter with a 4-mm-long electrode at the distal tip was placed within the left ventricle and positioned against the atrio-ventricular annulus. Another two patients were proved to have AVNRT. The ablation catheter was placed at the posterior/inferior aspect of the tricuspid annulus and guided by putative slow potential. Radiofrequency current was delivered at a power from 15 to 25W for four to six times with a mean duration of 40 seconds in patients with AV reciprocating tachycardia, and a single time in those with AVNRT. All six SVTs were successfully ablated. No complication was noted in any patient. Follow-up for three to seven months has indicated no recurrence of SVT.(ABSTRACT TRUNCATED AT 250 WORDS)

From July 1992 to January 1993, a total of 5 cases of hypoplastic left heart syndrome were diagnosed by echocardiograms and confirmed by available angiographic, surgical or autopsy results. The flow dynamics disclosed by spectrum display in the aortic root and patent ductus arteriosus (PDA), in systole, were: (1) antegrade in the ascending aorta and descending aorta (below PDA), and retrograde in the transverse aorta, and (2) right-to-left shunt in the PDA. While in diastole, there were (1) antegrade in the transverse aorta, and retrograde in the ascending aorta and descending aorta (below PDA), and (2) left-to-right shunt in the PDA. No ventriculocoronary fistulas were identified. With both the characteristic flow pattern and the extremely narrow diameters of the ascending aorta in hypoplastic left heart syndrome, we can differentiate it from those heart diseases associated with secondary hypoplastic left heart due to total anomalous pulmonary venous connection or congenital pulmonary venous stenosis. Both help us understand better the hemodynamics and pathophysiology of hypoplastic left heart syndrome in these patients.

To compare the efficacy of injections of 1.2 million units of benzathine penicillin G given every 3 weeks versus every 4 weeks for secondary prevention of rheumatic fever, based on the long-term outcome of patients receiving such prophylaxis.A total of 249 consecutive patients with rheumatic fever, randomly assigned to either a 3-week or a 4-week regimen, were examined every 3 to 6 months, and followed for 794 and 775 patient-years, respectively.Compliance with each regimen was comparable: 83 (66.9%) of 124 patients in the 3-week group versus 92 (73.6%) of 125 patients in the 4-week group stayed in the program (p0.05). Streptococcal infections occurred less frequently in those receiving the 3-week regimen: 7.5 versus 12.6 per 100 patient-years (p0.01). Prophylaxis failed in 2 patients receiving the 3-week regimen and in 10 receiving the 4-week regimen (0.25 and 1.29 per 100 patient-years respectively; p = 0.015). Serum penicillin levels were adequate (or = 0.02 micrograms/ml) in 100 (56%) of 179 samples obtained 21 days after penicillin injection in the 3-week regimen, and in 51 (33%) of 155 samples obtained 28 days after injection in the 4-week regimen (p0.01). Of 71 patients with mitral regurgitation in the 3-week regimen, 47 (66%) no longer had the murmur; of 87 patients in the 4-week regimen, 40 (46%) no longer had the murmur (p0.05).This 12-year controlled study indicates that the outcome of patients with rheumatic fever is better with a 3-week than with a 4-week penicillin prophylaxis regimen. Greater emphasis and more widespread use of the 3-week regimen should be recommended.

Two cases of double-orifice mitral valve are reported. The first case was associated with coarctation of the aorta and a large perimembranous ventricular septal defect, and the second case had an associated large patent ductus arteriosus. A bridge-type defect created two equal-sized openings in the mitral valve in case 1. In case 2, a small accessary opening was located in the posteromedial leaflet of the mitral valve. Double-orifice mitral valve is a rare anomaly associated with coarctation of the aorta, ventricular septal defect, and patent ductus arteriosus. The morphology of a double-orifice mitral valve can be clearly delineated by 2-D echocardiography.

A male infant with stenosis of the left pulmonary veins and atrial septal defect is reported. He began to have repeated pulmonary infections, with poor response to medical treatment, when he was 6 months old. Localized stenosis of the left upper and lower pulmonary veins were diagnosed with cardiac catheterization at the age of 7 months. Transvenous balloon dilation was attempted, but failed. Surgical treatment with pericardial patch venoplasty of the left pulmonary veins and closure of the atrial septal defect successfully released the pulmonary venous obstruction. There has been a follow-up for more than one year, and no cardiopulmonary symptoms were reported.

A 2-month-old infant, suffering from respiratory distress, was suspected to have scimitar syndrome from a chest roentgenogram and was diagnosed by cardiac catheterization. Ligation of the aberrant feeding arteries and right lung resection was performed at three and four months of age, respectively. However, the postoperative course was complicated with right pneumonectomy syndrome requiring continuous artificial ventilation. With supportive management, the patient improved gradually and was eventually weaned off the ventilator at three years of age.

A combination of absence of the pulmonary valve with ventricular septal defect, annular pulmonary stenosis and aneurysm of the pulmonary artery is called "absent pulmonary valve syndrome". Most patients with this condition suffered from severe respiratory symptoms in early infancy. Respiratory failure which is the leading cause of mortality in infants with this syndrome, results from pulmonary emphysema, pulmonary atelectasis or pulmonary infection as a consequence of compression of the bronchus by the pulmonary aneurysm. If these patients can be treated medically to survive beyond one year old, gradual decrease in severity of symptoms is expected. A definite correction in childhood is recommended. Otherwise, palliative operation in infancy has a high mortality rate. This paper reported two cases with severe symptoms in infancy; one patient expired at nine months of age, and the other lived beyond one year to receive surgical correction at the age of three. The etiology, clinical features and treatment of absent pulmonary valve syndrome are also discussed.

Forty-nine out of 66 patients with Turner's syndrome and different karyotypes underwent full cardiological evaluations (physical examination, electrocardiography, chest X-ray and echocardiography). Congenital cardiovascular anomalies were found in 11 patients (22.4%). Among the cardiac anomalies in patients with Turner's syndrome, aortic malformations (aortic coarctation [27%], aortic stenosis [18%] and bicuspid aortic valve [18%]) were the most frequent. We observed that the most severe malformations were found in those with karyotype 45,X or 45,X/46,XX. No anomalies were detected in patients with the X isochromosome or those mosaic with the Y component.

Using the whole-cell voltage clamp method, sodium (Na) channel properties and their responses to lidocaine were studied in ventricular myocytes isolated from neonatal (N,3 days), infant (I, 10-17 days) and mature (M,3 months) rabbits. Developmental changes in the Na channels were characterized by a progressive right-shift in the inactivation curves and a faster recovery from inactivation. Lidocaine (10 microM) effectively reduced the peak Na currents in M myocytes, but had little affect on the current-voltage curve in N myocytes. The steady-state h inactivation curve shifted toward the left (ie, more negative potentials) after lidocaine, and the extent of the left-shift increased with maturation. Similarly, the magnitude of prolongation in Na channel recovery from inactivation by lidocaine increased with age. However, lidocaine at a higher concentration (30 microM) in N myocytes effectively blocked the Na channels, and the degree of suppression was comparable to that in M myocytes with 10 microM lidocaine. These data suggest that the Na channels of N myocytes per se are less sensitive to lidocaine. The results of this study indicate that the extent of Na channel inactivation becomes smaller during postnatal maturation. However, the Na channel of immature myocytes is less sensitive to the widely used Na channel blocker, lidocaine, which preferentially binds to the inactive state of the Na channel.

Acute rheumatic carditis is a rare cause of ruptured chordae tendineae of the mitral valve. Such rupture could result in severe mitral regurgitation and in fatality. Surgical valvuloplasty or valve replacement is usually necessary. A 12-year old boy presented with acute rheumatic carditis, complicated with rupture of the chordae tendineae of the mitral valve leading to intractable congestive heart failure and cardiogenic shock. He was successfully treated by a simple repair of the chordae and by mitral valvuloplasty.

In accord with previous reports, we have found that action potentials triggered from isolated mature (1 month) guinea-pig ventricular myocytes showed a longer duration than those from the neonate (1 day). A whole-cell voltage-clamp technique has been used to identify the postnatal changes of inward rectifier (Ikl) and delayed outward potassium currents (Ik), which may be related to the action potential transition. Our results have shown that the degree of maturation of the neonatal guinea-pig is much advanced, as compared to neonatal rabbits and rats. Slope conductance (1230 +/- 110 pS/pF, n = 10, for neonatal, and 1450 +/- 450 pS/pF, n = 10, for mature guinea-pig, p0.05) and the inward rectification occurring over a potential range from -50 to -10 mV were relatively similar between the neonatal and mature guinea-pig myocytes. But, the slope conductance of Ik was significantly greater in neonatal (702 +/- 80 pS/pF, n = 10) guinea-pig myocytes than in the mature (194 +/- 23 pS/pF, n = 10, p0.01). Therefore, we suggest that (1) the maturation of Ik appears later than that of Ikl, (2) age-related decrease of the slope conductance of Ik could contribute to an age-related lengthening of the action potential duration.

Seven out of 829 pediatric cardiac patients (0.84%) were found to have sinus node dysfunction (SND) over the past seven years. Of the seven patients, three had structurally normal hearts. One of these three patients had long QT syndrome. In four patients, structural heart disease was noted. In three of these four patients the sinus node dysfunction was attributed to cardiac surgery. The age of onset of SND ranged from four months to eight years. Presenting symptoms and signs included syncope, near-syncope, seizure and congestive heart failure. Two patients were asymptomatic. Five patients had episodic sinus pause. Sinus or junctional bradycardia was noted in four patients. Three had tachy-bradycardia. High grade atrioventricular block was noted in one patient. Treadmill exercise test revealed a nonsustained ventricular tachycardia in two patients. All seven patients were found to have prolonged maximal corrected sinus node recovery time. Prolonged intra-atrial conduction time was found in three, prolonged AV nodal conduction time in one, and prolonged His-Purkinje conduction time in one patient during the electrophysiologic study. All seven patients showed abnormal results in intrinsic heart rate study. Anti-arrhythmic drugs were prescribed. During the follow-up study, no patient died, but two patients received a pacemaker implantation. Because of the extent of their conduction system diseases, it is recommended that patients with SND should be thoroughly investigated.

Balloon pulmonary valvuloplasty (BPV) is a well accepted treatment for moderate and severe pulmonary stenosis. However, the efficacy of BPV in treating mild pulmonary stenosis is still unanswered. Therefore, the efficacy of BPV in treating patients with mild pulmonary stenosis was compared to that in treating patients with moderate or severe pulmonary stenosis. A total of 46 patients with pulmonary stenosis were arbitrarily divided into 3 groups; Group I consisted of 9 patients with a pressure gradient less than 40 mm Hg, Group II consisted of 5 patients with a pressure gradient ranged from 40 to 50 mm Hg, and Group III consisted of 32 patients with a gradient greater than 50 mm Hg. Following BPV, the gradient reduced significantly in all 3 groups (p less than 0.05 in each group). The efficacy of BPV in the 3 groups was evaluated and compared by two parameters; one is the percentage of gradient reduction, the other is the right ventricular pressure ratio (RV post-bpv/RV pre-bpv). The percentage of gradient reduction in Group I, II, and III were 28 +/- 20, 55 +/- 17 and 70 +/- 9% respectively. The right ventricular pressure remained 84 +/- 11, 59 +/- 16, and 46 +/- 12% of pre-valvuloplasty level in Group I, II and III respectively. If the efficacy of BPV was compared among the 3 groups. Groups III had the best efficacy and Group I had the worst.(ABSTRACT TRUNCATED AT 250 WORDS)

To delineate the influence of maturation process on diastolic events of cardiac cycle, we had performed M-mode and Doppler echocardiography in 120 normal subjects aged from 1 hour to 16 years. The isovolumic relaxation period (IVRP, msec), defined as the time interval between the aortic valve closure to the mitral valve opening, was not statistically different in various age groups. Different equations based on individual ranges of cycle length (CL) were disclosed for each of three different age groups, demonstrating a positive linear correlation between IVRP and CL. On the contrary, an equation showing a linear correlation between diastolic total period (DTP, msec) and CL could be applied to all age groups: DTP = 0.58 x CL-75.2 (r = 0.89, p less than 0.001). Similarly applicable to all age groups, the duration of early diastolic filling (D-F, msec) changed with DTP in all age groups by an equation: D-F = 0.57 x DTP + 0.11 (r = 0.93, p less than 0.001). Ratios between the maximal velocity of early (E) and atrial (A) diastolic filling increased gradually with age. This was largely due to an increase in E with maturation, suggesting a depressed early diastolic filling in the young hearts. We conclude that the patterns of diastolic relaxation and filling are heterogeneously affected by the degree of maturation and represent the net results of complex interactions between changing inactivation properties and loading status at various stages.

Junctional ectopic tachycardia (JET) in infancy is one of the serious arrhythmias which can be fatal. Typical features of JET include rapid and irregular heart beats with atrioventricular dissociation. Two cases of JET are reported: Case 1 was a 35-week-gestational age newborn who was found to have hydropsy and fetal tachycardia at the 21st week of gestational age. Antiarrhythmic agents including digoxin, propranolol and verapamil were administered to his mother to treat the fetal arrhythmia without success. JET was recognized at birth which was spontaneously converted into a sinus rhythm at 1 month of age. The maternal history revealed that two previous pregnancies ended in hydrops fetalis, and one of these was documented to have fetal tachycardia. Case 2 was a 6-month-old male infant with JET and congestive heart failure. After failure of various antiarrhythmic agents, amiodarone finally slowed down his heart rate and controlled his congestive heart failure.

Atrial flutter (AF) is a potentially dangerous arrhythmia in children, which is difficult to be converted into sinus rhythm by drug therapy alone. In four young patients (3 had history of cardiac surgery, 1 had Ebstein's anomaly), the AF which had failed to medical therapy was converted into sinus rhythm by an intracardiac atrial pacing: In two patients the AF was terminated by atrial pacing alone, and in the other two the AF was converted into sinus rhythm by atrial pacing after procainamide infusion. In all patients an entrainment of AF was observed during the atrial pacing, which favored a reentrant mechanism for the AF in these patients. Evidences of sinus node dysfunction were observed in all three postoperative patients. We conclude that atrial pacing with or without procainamide infusion is an effective method for the conversion of atrial flutter. In addition, for patients with AF and concomitant sinus node dysfunction, this method can ensure the patients' safetiness.

The SSC control system must support a large number of “slow” or industrial type control points. A front-end system is described which could serve as both a data concentrator and a distributed process controller for these points. Unlike many distributed control systems, this front end is designed to provide strong support for centralized controls. The live parameter data base in the central system can be updated at a rate which is fast compared to that usually needed for process control loops. Portions of this data base can be optionally replicated in regional computers to provide both local control stations and distributed control loops. In addition to the global and regional levels the system also allows the distribution of loops to the local I/O crate level. A possible implementation of this system is under development which is based on industrial standard STD-Bus for accelerator hardware interfacing, time domain multiplexing (TDM) for communications transport, and a form of reflective memory for the back-end interface to the 1 rest of the control system.

The demands placed on the Superconducting Super Collider (SSC) control system due to large distances, high bandwidth and fast response time required for operation will require a fresh approach to the data communications architecture of the accelerator. The prototype design effort aims at providing deterministic communication across the accelerator complex with a response time of

A child with congestive heart failure was found to have a paroxysmal ventricular tachycardia (VT) without structural heart disease. This wide QRS tachycardia had an atrioventricular dissociation and a QRS pattern of right bundle branch block and left axis deviation. The tachycardia did not respond to lidocaine or procainamide but instantly responded to verapamil therapy. This VT could be initiated or terminated by either atrial or ventricular pacing during electrophysiologic study. The endocardial biopsy showed that there was myocardial hypertrophy with mild degree of interstitial fibrosis. This entity of ventricular tachycardia often occurs in young people with no overt heart disease but with subclinical endomyocardial changes.

From June 1988 to May 1989, 444 throat swab specimens were tested with an enzyme immunoassay kit for rapid diagnosis of group A streptococcal pharyngitis. The results were compared with those of throat culture method. The rapid test was positive in 37 of 42 culture-positive specimens and negative in 379 of 402 culture-negative specimens, thus yielding a total agreement of 93.7%, sensitivity 88.1%, specificity 94.7%, positive predictive value 61.7%, negative predictive value 98.7%. According to this practical application, we suggest that enzyme immunoassay test can be applied in outpatient clinics by busy pediatricians for rapid diagnosis of group A streptococcal pharyngitis.

Two methods arc presented in the frequency domain for obtaining reduced models of multivariable systems with various numbers of inputs and outputs. The method of matrix continued fraction and the mixed method are extended to obtain the reduced models. When the ratio of the rank and the dimension of a transfer-function matrix is not an integer or the ratio is an integer but there exist numerically ill-conditioned elements in the matrix, a technique is proposed to deal with these cases.

The performance of most algorithms in communications and signal processing is dependent upon the input signal-to-noise ratio (SNR). It is therefore useful to estimate input signal and noise variances. In this study, a method is developed for estimating these variances, given the input and output energies for a zero-phase band-pass filter and knowledge of the shapes, but not the amplitudes, of the signal and noise power spectral densities (PSD's). Expressions for the means and variances of the variance estimates are developed.

Arrhythmogenic right ventricular dysplasia is a rare disease that sometimes leads to sudden death in young people. In this report, we describe our experience with diagnosis and treatment of a case of arrhythmogenic right ventricular dysplasia.