The effect of aging on the specialized conducting system: A telemetry ECG study in rats over a 6 month period

Stefano Rossi, Ilaria Fortunati, Luca Carnevali, Silvana Baruffi, Francesca Mastorci, Mimosa Trombini, Andrea Sgoifo, Domenico Corradi, Sergio Callegari, Michele Miragoli, Emilio Macchi

Research output: Contribution to journalArticle

Abstract

Advanced age alone appears to be a risk factor for increased susceptibility to cardiac arrhythmias. We previously observed in the aged rat heart that sinus rhythm ventricular activation is delayed and characterized by abnormal epicardial patterns although conduction velocity is normal. While these findings relate to an advanced stage of aging, it is not yet known when and how ventricular electrical impairment originates and which is the underlying substrate. To address these points, we performed continuous telemetry ECG recordings in freely moving rats over a six-month period to monitor ECG waveform changes, heart rate variability and the incidence of cardiac arrhythmias. At the end of the study, we performed in-vivo multiple lead epicardial recordings and histopathology of cardiac tissue. We found that the duration of ECG waves and intervals gradually increased and heart rate variability gradually decreased with age. Moreover, the incidence of cardiac arrhythmias gradually increased, with atrial arrhythmias exceeding ventricular arrhythmias. Epicardial multiple lead recordings confirmed abnormalities in ventricular activation patterns, likely attributable to distal conducting system dysfunctions. Microscopic analysis of aged heart specimens revealed multifocal connective tissue deposition and perinuclear myocytolysis in the atria. Our results demonstrate that aging gradually modifies the terminal part of the specialized cardiac conducting system, creating a substrate for increased arrhythmogenesis. These findings may open new therapeutic options in the management of cardiac arrhythmias in the elderly population.

Original languageEnglish
Article numbere112697
JournalPLoS One
Volume9
Issue number11
DOIs
Publication statusPublished - Nov 14 2014

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ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Medicine(all)

Cite this

Rossi, S., Fortunati, I., Carnevali, L., Baruffi, S., Mastorci, F., Trombini, M., Sgoifo, A., Corradi, D., Callegari, S., Miragoli, M., & Macchi, E. (2014). The effect of aging on the specialized conducting system: A telemetry ECG study in rats over a 6 month period. PLoS One, 9(11), [e112697]. https://doi.org/10.1371/journal.pone.0112697