Biomedical subjects
Publications and source records attributed to A M Levy.
Samples of aqueous humour were removed from 26 eyes at the start of cataract extraction. Two drops of timolol 0.5% had been instilled into the conjunctival sac 12-71 minutes before operation. Analysis by gas chromatography showed a mean timolol concentration of 55.46 ng/mg, with a range of 8 to 100 ng/mg.
In four cases of chaotic atrial rhythm in infancy, three infants died, two unexpectedly. Chaotic atrial rhythm may be associated with a relatively high mortality in the first year of life.
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After noting bradycardia-induced supraventricular tachycardia (SVT) in two successive children with SVT, we analyzed Holter monitor recordings done on 66 children with suspected or proved SVT. Ten children had apparent reentry SVT. The most common mode of initiation (eight of 10 patients) was not premature atrial beats, but sudden sinus pause with a junctional escape beat (JEB), usually fused with the delayed sinus P wave, initiating the tachycardia. Electrophysiologic studies in five children who had this mode of initiation showed evidence of reentry in four, possibly by dual atrioventricular nodal (AVN) pathways. Since sudden sinus pause and JEB are relatively uncommon in adults, the disappearance of this phenomenon with age may be the most significant reason why children often have less tachyarrhythmia as they get older. Both propranolol and digoxin significantly increased the numbers of episodes of SVT in the three patients tested with serial Holter monitoring.
A kindred with a high incidence of hypertrophic cardiomyopathy (HC) was studied to identify the presence of clinical hyperthyroidism. Two and possibly three members with HC had associated hyperthyroidism. In the propositus, clinical, ECG, and vectorcardiographic evidence for HC resolved after treatment of the hyperthyroidism. We hypothesize that the disproportionately high correlation of hyperthyroidism and HC and the resolution found in the propositus after treatment may indicate that antithyroid therapy should be considered in this form of cardiomyopathy.
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Twenty patients with congenital complete heart block (CHB) were monitored with ECG tape recordings while awake and asleep. Episodes of marked ventricular slowing during sleep (R-R greater than 3000 msec., i.e. less than 20 beats/min) were noted in 35% (7/20). Most of these sudden R-R prolongations were 2:1 or 3:1 exit block of the junctional focus. Atrial and ventricular rate changes were mostly concordant in 2/3 but the remainder demonstrated fixed ventricular rates while atrial rates varied normally, suggesting a "sick" or "lazy" junctional focus. Other arrhythmias were found in 60% (12/20), including several types of rhythms in three patients. One child with previously unsuspected superimposed multiple arrhythmias later had a syncopal episode despite proven supra-Hisian block. The multiple patterns of atrial and ventricular rate changes found indicate complex feedback mechanisms, suggesting that congenital CHB is not a single entity. Since a significant number of patients demonstrated one or another of these unexpected and potentially hazardous findings, we recommend that congenital block patients be carefully studied, including Holter monitoring done on a regular basis.
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