Infants' reliance on a social criterion for establishing word-object relations.

The language children hear presents them with a multitude of co-occurrences between words and things in the world, and they must repeatedly determine which among these manifold co-occurrences is relevant. Social factors--such as cues regarding the speaker's referential intent--might serve as one guide to whether word-object covariation should be registered. In 2 studies, infants (15-20 months and 18-20 months in Studies 1 and 2, respectively) heard novel labels at a time when they were investigating a single novel object; in one case the label was uttered by a speaker seated within the infant's view and displaying concurrent attention to the novel toy (coupled condition), whereas in the other case the label emanated from a speaker seated out of the infant's view (decoupled condition). In both studies, subsequent comprehension questions indicated that infants of 18-20 months registered a stable link between label and object in the coupled conditions, but not in the decoupled condition, despite the fact that covariation between label and object was equivalent in the 2 conditions. Thus, by 18-20 months children are inclined to establish a mapping between word and object only when a speaker displays signs of referring to that object.

Transesophageal echocardiography to improve positioning of radiofrequency ablation catheters in left-sided Wolff-Parkinson-White syndrome.

Two patients with the Wolff-Parkinson-White syndrome who underwent successful radiofrequency catheter ablation of their left-sided bypass tracts are described. Transesophageal echocardiography, a relatively new echocardiographic technique, was utilized in both patients and provided excellent visualization of intracardiac anatomy as well as the catheter tip. Transesophageal echocardiography was also synergistic with fluoroscopy and the intracardiac electrogram in providing more precise catheter placement. In addition, the use of transesophageal echocardiography may reduce fluoroscopic exposure and shorten the procedure time.

Circadian occurrence of symptomatic paroxysmal supraventricular tachycardia in untreated patients.

Fifty-two patients with paroxysmal supraventricular tachycardia were studied to determine whether there was a circadian pattern to the occurrence of this arrhythmia. Antiarrhythmic therapy was discontinued, and patients were followed until they had one recurrence of tachycardia documented by telephone transmission of the electrocardiogram. By least-squares analysis, the times of day that the 52 attacks (one from each patient) occurred were fit to a sinusoidal density function with a period of 24 hr. The highest relative incidence of tachycardia was at 4 P.M.; tachycardia was five times more likely to occur at 4 P.M. than at 4 A.M., the time of the lowest relative incidence. A second attack of tachycardia was recorded from 35 of the 52 patients. The times of the two attacks in individual patients were found to be independent; thus the times of day at which the second attacks occurred were used as a test set for the distribution estimated from the first. The empirical distribution for the times from the 35 second attacks was compared with the distribution function estimated from the 52 first attacks, and there was no significant departure; this finding confirmed the circadian pattern. Since the relative incidence of attacks of paroxysmal supraventricular tachycardia is higher in the afternoon, it may be helpful to target antiarrhythmic therapy to that time of day.

Influence of underlying coronary artery disease on the natural history and prognosis of exercise-induced left bundle branch block.

The long-term prognosis of exercise-induced left bundle branch block (BBB) in patients with and without underlying coronary artery disease (CAD) was examined by following 15 patients (7 with normal coronary arteries and 8 with CAD) for an average of 6.6 years (range 2.2 to 11.2). Over the follow-up interval, permanent left BBB developed in 8 of the 15 patients. Seven of these 8 had underlying CAD, compared to 0 of 6 patients with normal coronary arteries and normal left ventricular function (p less than 0.002). In 1 patient with normal coronary arteries and a left ventricular ejection fraction of 0.34, permanent left BBB developed. During follow-up, 4 patients died; 3 had significant CAD and 1 had depressed left ventricular function. In no patient did high-grade atrioventricular block develop and no patient required pacing. Thus, development of permanent left BBB in patients with exercise-induced left BBB is related to presence or absence of underlying CAD or myocardial disease. When left BBB is found in the absence of underlying heart disease, there does not tend to be progression of the conduction disturbance and the prognosis is excellent.

Atrial lead perforation: a case report.

We report a patient in whom a chronic atrial lead perforated the right atrium and the right lung. This resulted in an hemopneumothorax and pneumomediastinum which was clearly documented by a chest computerized tomographic scan. The finding of pneumomediastinum should suggest atrial lead perforation. The utility of the chest computerized tomographic scan in diagnosing lead perforation is well illustrated by this case.

Venous systolic thrill and murmur in the neck: a consequence of severe tricuspid insufficiency.

A palpable venous systolic thrill and murmur at the base of the neck are described as new physical findings in five patients with severe tricuspid regurgitation. In two of these patients, the tricuspid valve had been resected as treatment for infective endocarditis related to intravenous drug abuse. The third patient had severe chronic pulmonary disease with right heart failure. The fourth patient had a complex congenital defect in which the mitral valve served as the venous atrioventricular valve and was severely incompetent. The fifth patient suffered from long-standing rheumatic mitral and tricuspid disease with pulmonary hypertension 10 years after placement of a mitral prosthesis. From these observations, it is apparent that pulsatile retrograde flow in the cervical veins resulting from severe right-sided atrioventricular valve incompetence can produce a palpable systolic thrill and murmur at the base of the neck.