Proarrhythmic effects of antiarrhythmic drugs during programmed ventricular stimulation in patients without ventricular tachycardia.

The proarrhythmic effects of class IA antiarrhythmic drugs were prospectively evaluated during programmed ventricular stimulation in 24 consecutive patients with frequent ventricular premature beats whose baseline study, performed while no antiarrhythmic drugs were being taken, showed no inducible sustained ventricular arrhythmias. No patient had nonsustained (greater than 5 beats) or sustained ventricular tachycardia by history or baseline 24 hour ambulatory electrocardiographic monitoring. Sequential stimulation studies using up to three extra-stimuli were performed after administration of procainamide, quinidine and disopyramide on different days. Proarrhythmic response was defined as induction of one or more of the following: sustained monomorphic ventricular tachycardia; sustained polymorphic ventricular tachycardia; ventricular fibrillation; reproducibly inducible nonsustained monomorphic ventricular tachycardia. During 55 antiarrhythmic drug trials (24 of procainamide, 21 of quinidine, 10 of disopyramide) in the 24 patients, 6 patients had a proarrhythmic response: sustained monomorphic ventricular tachycardia in 3, ventricular fibrillation in 2, nonsustained monomorphic ventricular tachycardia in 1. Thus, 11% of drug trials resulted in a proarrhythmic response and 25% of patients had a proarrhythmic response to one of the drugs tested. A proarrhythmic response to one drug did not predict a similar response to another drug of the same class. The 6 patients with a proarrhythmic response did not differ significantly from the other 18 patients with regard to underlying heart disease, electrocardiographic or baseline 24 hour ambulatory electrocardiographic characteristics; however, they did have a higher incidence of digoxin usage (p less than 0.02), a shorter baseline right ventricular effective refractory period (p less than 0.01) and a smaller increment in effective refractory period during antiarrhythmic drug testing (p = 0.06).(ABSTRACT TRUNCATED AT 250 WORDS)

Intervertebral disc impingement syndrome in a child. Report of a case and suggested pathology.

Nerve root impingement syndrome is rare in children and adolescents. The symptomatology of the pediatric group sometimes differs from that of the adult. An accurate diagnosis is often delayed because of concerns for neoplasm, infection, and spondylolisthesis. A case report of an 11-year-old boy with symptoms and myelographic findings consistent with a herniated disc is presented. A review of the literature disclosed only four cases of herniated disc in children under the age of 12 years. Our case represents one of the youngest patients with documented intervertebral disc impingement syndrome. Rather than a herniation due to degenerative changes in the annulus, a slipping of the entire disc, and vertebral end-plate (a "slipped vertebral apophysis") may precipitate a central disc impingement in children and adolescents. This has been reported in cases of trauma previously. However, the authors think that this slipped vertebral apophysis may, in fact, represent a large number of the so-called herniated discs in adolescents. It is also suggested that this may be an identifiable syndrome with a susceptible age range, activity level and body habitus.

Congenital dislocation of the knees associated with a partial chromosome I deletion.

Congenital dislocation of the knee is a rare disorder that has been reported previously in association with neuromuscular disorders and ligamentous laxity syndromes and is related to mechanical factors. Concurrent chromosomal abnormalities have not been reported previously with congenitally dislocated knees. The authors present a case of congenitally dislocated knees in a patient with an extremely rare and only recently described partial deletion of chromosome I. There have been three previously reported cases of this particular chromosomal deletion, none of which included dislocated joints.