Biomedical subjects

H C Lue

Publications and source records attributed to H C Lue.

At least 127 records · Page 7Linked to original sources

PubMedDate not supplied

Inward rectifier and delayed outward potassium currents in isolated guinea-pig ventricular myocytes: maturation and its role in repolarization.

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, p > 0.05) 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, p < 0.01). 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.

Action Potentials↗

PubMedDate not supplied

Rupture of chordae tendineae in acute rheumatic carditis: report of one case.

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.

Acute Disease↗

PubMedDate not supplied

Sinus node dysfunction in children.

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.

Child↗

PubMedDate not supplied

Influence of maturation on diastolic events of left ventricle in children.

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.

Adolescent↗

PubMedDate not supplied

Atrial overdrive pacing for conversion of atrial flutter in children.

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.

Adolescent↗

PubMedDate not supplied

Rapid diagnosis of streptococcal pharyngitis with enzyme immunoassay.

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.

Adolescent↗

PubMedDate not supplied

An electrophysiologic study of a child with idiopathic sustained left ventricular tachycardia.

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.

Child↗

PubMedDate not supplied

Echocardiographic changes following balloon valvuloplasty in valvular pulmonic and aortic stenosis.

Nineteen patients with pulmonary valvular stenosis and two with aortic valvular stenosis, aged 20 days to 12 years, were studied before and after balloon dilatation valvuloplasty (BDV) by M-mode, 2-D, pulsed wave (PW) and continuous wave (CW) Doppler, and color flow mapping echocardiography. In those with pulmonary stenosis, a dome-shaped valve was found in 16(84%) of 19 cases before BDV, and the valve remained dome shaped only in 4(27%) of 15 after procedure (P less than 0.001). Restricted valve motion which was noted in 18(95%) of 19 before BDV, persisted only in 2(13%) of 15 after procedure (P less than 0.001). Thickening of the pulmonic valve and poststenotic dilatation of the main pulmonary artery stayed almost unchanged. The pressure gradient across the pulmonic valve measured by cardiac catheterization and CW Doppler agreed well (r = 0.862). Echocardiographic evidence of pulmonary regurgitation was detected in 1(25%) of 4 patients before, and 7(50%) of 14 after BDV. In two patients with aortic stenosis, the echocaardiograms showed the valve was thickened and dome-shaped. Following BDV, echocardiographic evidence of mild aortic regurgitation was observed only in one patient who had had such a regurgitationn before BDV. The diameter of the valve annulus measured on 2-D echo and angiocardiograms correlated well (r = 0.912), and it stayed unchanged following BDV. It is concluded that 2-D and Doppler echocardiographic examinations proved to be useful in the measurement of valve annulus, delineation of stenotic semilunar valves and monitoring of the efficacy of BDV.

Aortic Valve↗

PubMedDate not supplied

[Readmission to International Pediatric Association: a review and perspective].

The Pediatric Association of the Republic of China, which was founded in 1960 for the promotion of child health care, research and teaching as well as of friendship among pediatricians, entered the International Pediatric Association (IPA) in May, 1961. This Association actively participated in the 10th to 13th International Congresses of Pediatrics (ICP) held in Lisbon 1962, Tokyo 1965, Mexico City 1968 and Vienna 1971, respectively. It also sent a group of delegates to the Ist Asian Congress of Pediatrics, organized by the Association of Pediatric Societies in South East Asian Region (APSSEAR), held in Manila in 1974. Regretably, this Association was forced out of IPA in October 1973, and APSSEAR in 1974, simply because that the pediatric society of Mainland China had been admitted to the IPA. The members of the Association continued working hard and strived for the excellence in clinical pediatrics. Our members were encouraged to attend the international meetings regardless of membership problems. Some international meetings were organized and held in Taiwan attracting many experts and investigators from abroad. In July 1989, this Association was readmitted to the IPA under the name of "Chinese Taipei", likewise in Olympics, during the 19th ICP, held in Paris. Also granted was the right of voting. Re-admission to the APSSEAR was also approved. With gratitude and rejoice, we commemorate the return to International arena. It is hoped that more expert advices and friendship will come from IPA, WHO, UNICEF, and some member countries. They may help us update clinical practices, and engage in more important surveys and research programmes, such as the international surveys on pediatric education, expanded programmes for immunization, and global accident prevention programmes. They may also help us achieve our unfulfilled tasks, such as pediatric subspecialization, renovation of the births registration system, founding of children's medical centers and health insurance coverage among children. We are now in a better position to advocate the child health care in Taiwan, hoping that health for all including children will be achieved by the year 2000.

Forecasting↗

PubMedDate not supplied

Arrhythmogenic right ventricular dysplasia: report of one case.

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.

Adolescent↗

PubMedDate not supplied