Interaction Between Accessory Pathways Resulting in Inability to Induce Reciprocating Tachycardia

A 44-year old male with Wolff-Parkinson-White syndrome presented with atrial fibrillation. The patient was found at the electrophysioiogical study to have two accessory pathways, one concealed and the other conducting exclusively in the anterograde direction. After radiofrequency catheter ablation of the anterograde conducting pathway, orthodromic reciprocating tachycardia, which previously could not be induced despite an aggressive protocol, was easily induced. Ablation of the concealed pathway resulted in termination of the tachycardia and suppression of inducibility. We propose that interaction between the two accessory pathways resulted in an inability to induce reciprocating tachycardia.     

The Search for Perinatal Definitions and Standards

ABSTRACT. Progress made during the last 60 years in reaching international agreement on perinatal terminology is reviewed. Agreed terms currently in use in respect to birthweight, gestational age and the collection of perinatal mortality and morbidity statistics are stated and defined. Arguments are advanced in support of an internationally agreed methodology for the measurement and reporting of infant growth in the perinatal period.     

Ectopic Gallstone as a Cause of Gastric Outlet Obstruction

Callstone ileus is, of course, a well known cause of small bowel obstruction. A gallstone, however, is a very rare cause of gastric outlet obstruction. Three cases illustrating this phenomenon are exhibited. Radiographs were diagnostic in two of the studies. All three patients did well postoperatively.     

Fetal habituation in high-risk pregnancies

Summary. Habituation is a basic form of learning and probably requires an intact central nervous system. Habituation in the behavioural response to vibration in 40 normal human fetuses was compared with that in a group of high-risk pregnancies with an increased risk of fetal neurological damage. Highly significant differences in habituation patterns between the high-risk groups and normal control subjects were found. This test may offer a method of assessing the integrity of the fetal central nervous system.     

Staging of Idiopathic Myelofibrosis: Significance of Haemoglobin Value and Reticulocyte Count

ABSTRACT. A retrospective analysis of 18 patients with idiopathic myelofibrosis (IMF) suggested that IMF is adequately staged by combining haemoglobin value and reticulocyte count. Four stages were recognized. All deaths occurred in late stage. The stages appeared to reflect a sequential course of the disease. The present staging system adequately identified patients at high risk. However, the rate of disease progress varied greatly. It is therefore suggested that the rate of disease progress should also be considered when an individual patient is evaluated.     

A radioreceptor assay for benzodiazepines

A simple, rapid and sensitive radioreceptor assay for determining benzodiazepines in serum is based on the displacement by the drug of specific [³H]diazepam binding to a membrane fraction from rat brain. The limit of detection of the more active benzodiazepines is about 0.5 ng. Diazepam, nitrazepam, clobazam and HR 458t have been assayed in human serum after a single oral clinical dose. The results can be used for determining pharmacokinetic parameters. The technique measures not only the parent benzodiazepine but also clinically active metabolites.     

Induced Concealed Dissimilar Atrial Rhythms

Electrophysiologic studies, including intra-atrial recordings and atrial stimulation, were performed in two patients with suspected sick sinus syndrome. Premature atrial stimuli induced atrial flutter in both patients. The arrhythmia was concealed, i.e., it was recordable only by intracavitary electrogram and invisible on surface electrocardiogram. In one case, simultaneous atrial fibrillation could be recorded in a segment of the right atrium. In this patient, the rhythm on the surface electrocardiogram changed during the study to "upper nodal" rhythm, though the atrial electrogram showed continuation of A waves at the same rate as before during sinus rhythm. It seems that atrial changes, which are frequently encountered in sick sinus syndrome, are a predisposing factor for spontaneous or inducible concealed atrial arrhythmias.