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The conduction system in Pompe's disease
Insights
Infants with glycogen storage disease show microscopic changes in the heart conduction system. These changes, including enlarged cells and altered topography, may explain rapid electrical conduction and short P-R intervals on ECG.
Area of Science:
- Cardiology
- Pediatric Pathology
- Electrophysiology
Background:
- Glycogen storage diseases (GSDs) can affect multiple organs, including the heart.
- Cardiac conduction abnormalities have been anecdotally reported in GSDs.
- Microscopic details of the cardiac conduction system in GSDs are not well-characterized.
Purpose of the Study:
- To investigate the microscopic anatomy of the cardiac conduction system in infants with GSD.
- To correlate electrophysiologic findings with structural changes in the conduction system.
- To explore potential mechanisms for observed electrophysiologic abnormalities in GSD.
Main Methods:
- Microscopic examination of the cardiac conduction system in four infants with GSD.
- Detailed electrophysiologic studies in one infant, including P-A, A-H, and H-V interval measurements.
- Histopathological analysis focusing on cell size, glycogen content, and topographical arrangement of conduction tissues.
Main Results:
- Electrophysiologic studies revealed normal P-A and A-H intervals, with a slightly prolonged H-V interval.
- Microscopic findings included enlarged cardiac cells, likely due to increased glycogen.
- The topography of the atrioventricular conduction system was altered, with bulging of the ventricular septum summit, possibly due to cellular enlargement.
Conclusions:
- The observed rapid conduction in GSD may not be localized to the H-V interval's anatomic correlate.
- Enlarged cardiac cells and altered conduction system topography in GSD are significant findings.
- These structural changes may contribute to the short P-R interval seen on ECG in GSD patients.
Abstract:
We report our findings in the microscopic examination of the conduction system in four infants with glycogen storage disease, one of whom had adequate electrophysiologic studies. The electrophysiologic studies in the latter case showed P-A and A-H intervals at the lower limits of normal, but the H-V interval was just above the normal mean. This suggests that the rapid conduction was not localized in the anatomic counterpart of the H-V interval. The short P-R interval in the ECG may be related to the enlargement of cells, which may in turn be related to increased glycogen content. The relationship of glycogen per se to the speed of conduction is unknown. We found that the summit of the ventricular septum bulged, probably because of the generally increased cell size, and that the topography of the atrioventricular conducting system was different from normal. This is possibly related both to an increase in the cell sizes of the specialized conducting tissue itself and to deforming effects of this bulging summit of the ventricular septum. New microscopic details of the components of the conducting system are described in these cases.