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[Atrioventricular conduction in the Lown-Ganong-Levine syndrome]
Insights
Large granular lymphocyte (LGL) syndrome patients often show a shortened A-H interval. Rapid atrial pacing revealed varied conduction patterns, suggesting a James bundle bypass in only a few LGL syndrome cases.
Area of Science:
- Electrophysiology
- Cardiology
Context:
- Large granular lymphocyte (LGL) syndrome is a rare lymphoproliferative disorder.
- Cardiac involvement, particularly conduction abnormalities, can occur in LGL syndrome.
- His bundle electrography and atrial pacing are standard electrophysiological tests.
Purpose:
- To investigate atrial-ventricular (A-V) conduction properties in patients with LGL syndrome.
- To characterize the response of A-V conduction to rapid atrial pacing in LGL syndrome.
- To explore the potential role of a James bundle (an accessory pathway) in the shortened A-H interval observed in LGL syndrome.
Summary:
- Eighteen patients with LGL syndrome underwent His bundle electrography and atrial pacing.
- A significantly shortened A-H interval (58 msec) was observed in all patients, with normal H-V intervals.
- Four distinct patterns of A-V conduction response to rapid atrial pacing were identified, including sudden prolongation, continuous prolongation, and marked delay with block.
- Verapamil showed minimal effect on the A-H interval.
- The findings suggest that a James bundle bypassing the A-V node is responsible for the shortened A-H interval in only a small subset of LGL syndrome patients.
Impact:
- Provides insights into the electrophysiological characteristics of cardiac conduction in LGL syndrome.
- Helps differentiate potential causes of shortened A-V conduction in LGL syndrome.
- Contributes to understanding the spectrum of cardiac manifestations in LGL syndrome.
Abstract:
In 18 patients with LGL-syndrome His bundle electrography and atrial pacing were performed. In all cases the atrial conduction time was normal, the H-V interval within the lower limit (36 msec). The A-H interval was significantly shortened (58 msec). During rapid atrial pacing four different patterns of reaction could be distinguished: 1) A-H interval unchanged (1 case). 2) Sudden prolongation of the A-H interval at a critical rate (4 cases). 3) Continuous prolongation of the A-H time according to the driving frequency (9 cases). 4) Marked delay and block (4 cases). Verapamil had only little or no effect on the A-H interval in these patients. The results indicate, that only in a few cases with LGL-syndrome the shortened A-H time is due to a James bundle bypassing completely the A-V node.