Biomedical subjects

J L Lin

Publications and source records attributed to J L Lin.

201 records · Page 12Linked to original sources

PubMedDate not supplied

Transvenous permanent pacemaker implantation in children and adolescent.

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.

Adolescent↗

PubMedDate not supplied

Nicotine analysis of commercial tobacco products.

The use of AOAC standard methods for the determination of nicotine in commercial tobacco products is shown to be inappropriate. The methods do not provide for suitable sample preparation of these products for the analysis and, in addition, they yield high results. Evidence is presented that the nicotine or total alkaloids measured includes artifact nicotine. The distillation method was developed at a time when the complex alkaloid chemistry of tobacco was unknown, and does not take into consideration the possible contribution of substances in tobacco capable of contributing falsely to the result. The Cundiff-Markunas method, developed more recently, also fails to account for this effect--probably because it was designed to produce results matching those of the distillation method. Replacement of the standard methods is proposed and some alternative procedures are suggested.

Chromatography, Gas↗

PubMedDate not supplied

Radiofrequency catheter ablation of supraventricular tachycardias in pediatric patients.

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)

Adolescent↗