PubMed Health⌕ Search

Biomedical subjects

C W Tang

Publications and source records attributed to C W Tang.

7 recordsLinked to original sources
PubMed1995

Use of P wave configuration during atrial tachycardia to predict site of origin.

OBJECTIVES: This study sought to construct an algorithm to differentiate left atrial from right atrial tachycardia foci on the basis of surface electrocardiograms (ECGs). BACKGROUND: Atrial tachycardia is an uncommon form of supraventricular tachycardia, often resistant to drug therapy. METHODS: A total of 31 consecutive patients with atrial tachycardia due to either abnormal automaticity or triggered rhythm underwent detailed atrial endocardial mapping and successful radiofrequency catheter ablation of a single atrial focus. P wave configuration was analyzed from 12-lead ECGs during tachycardia during either spontaneous or pharmacologically induced atrioventricular block. P waves inscribed above the isoelectric line (TP interval) were classified as positive, below as negative, above and below (or conversely, below and above) as biphasic and flat P waves as isoelectric (0). In 17 patients the tachycardia was located in the right atrium: crista terminalis (n = 4); right atrial appendage (n = 4); lateral wall (n = 4); posteroinferior right atrium (n = 3); tricuspid annulus (n = 1); and near the coronary sinus (n = 1). In 14 patients, atrial tachycardia was located in the left atrium: at the entrance of the right (n = 6) or left (n = 4) superior pulmonary veins; left inferior pulmonary vein (n = 1); inferior left atrium (n = 1); base of left atrial appendage (n = 1); and high lateral left atrium (n = 1). RESULTS: There were no differences in P wave vectors between sites at the right atrial lateral wall versus the right atrial appendage or between sites at the entrance of right versus left superior pulmonary veins. However, analysis of P wave configuration showed that leads aVL and V1 were most helpful in distinguishing right atrial from left atrial foci. The sensitivity and specificity of using a positive or biphasic P wave in lead aVL to predict a right atrial focus was 88% and 79%, respectively. The sensitivity and specificity of a positive P wave in lead V1 in predicting a left atrial focus was 93% and 88%, respectively. CONCLUSIONS: 1) Analyses of surface P wave configuration proved to be reasonably good in differentiating right atrial from left atrial tachycardia foci. 2) Leads II, III and aVF were helpful in providing clues for differentiating superior from inferior foci.

Adolescent↗
PubMed1970

Elimination of sodium-24 and potassium-42 interferences in activation analysis of biological samples.

We have developed a simple novel column technique for the removal of sodium-24 and potassium-42 based on a heterogeneous isotopic exchange reaction between an organic eluting solution (acetone-hydrochloric acid) and fine crystals of sodium chloride or potassium chloride or their analogs. The technique is fast, efficient, and highly selective; it has been successfully applied to irradiated human tissues prior to gamma-ray spectrometry with lithium-drifted germanium detectors.

Activation Analysis↗
PubMedDate not supplied

Pediatric foot fractures: evaluation and treatment.

Foot fractures account for 5% to 8% of all pediatric fractures and for approximately 7% of all physeal fractures. A thorough understanding of the anatomy of the child's foot is of central importance when treating these injuries. Due to the difficulties that may be encountered in obtaining an accurate physical examination of a child with a foot injury and the complexities of radiographic evaluation of the immature foot, a high index of suspicion for the presence of a fracture facilitates early and accurate diagnosis. Although the treatment results in pediatric foot trauma are generally good, potential pitfalls in the treatment of Lisfranc fractures, talar neck and body fractures, and lawn mower injuries to the foot must be anticipated and avoided if possible.

Child↗