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

Rossi S, Fortunati I, Carnevali L, Baruffi S, Mastorci F, Trombini M, Sgoifo A, Corradi D, Callegari S, Miragoli M, Macchi E - PLoS ONE (2014)

Bottom Line: 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.We found that the duration of ECG waves and intervals gradually increased and heart rate variability gradually decreased with age.Our results demonstrate that aging gradually modifies the terminal part of the specialized cardiac conducting system, creating a substrate for increased arrhythmogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Sciences, University of Parma, Parma, Italy; CERT, Center of Excellence for Toxicological Research, INAIL, ex ISPESL, University of Parma, Parma, Italy.

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.

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Arrhythmia type and location.Histograms relating to the type (A) and the location (B) of arrhythmic events of control and aged animals which occurred during telemetry ECG recording. Number of arrhythmic events was evaluated on the ECGs from the 1st to the 6th month after radiotelemetry transmitter implantation, as compared to controls (ctrl).
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pone-0112697-g004: Arrhythmia type and location.Histograms relating to the type (A) and the location (B) of arrhythmic events of control and aged animals which occurred during telemetry ECG recording. Number of arrhythmic events was evaluated on the ECGs from the 1st to the 6th month after radiotelemetry transmitter implantation, as compared to controls (ctrl).

Mentions: During the aging process the number and complexity of arrhythmic events increased, especially during the last three months of age. Fig. 4A shows, all the arrhythmic events that belong to abnormalities in impulse formation and abnormalities in impulse conduction at each month of telemetry recordings. The number of arrhythmic events increased with age, showing a peak in the 4th month for abnormalities in impulse formation and a peak in the 6th month for abnormalities in impulse conduction. On average, the total number of impulse formation arrhythmias largely exceeded the number of impulse conduction arrhythmias, during the six-month recording period.


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

Rossi S, Fortunati I, Carnevali L, Baruffi S, Mastorci F, Trombini M, Sgoifo A, Corradi D, Callegari S, Miragoli M, Macchi E - PLoS ONE (2014)

Arrhythmia type and location.Histograms relating to the type (A) and the location (B) of arrhythmic events of control and aged animals which occurred during telemetry ECG recording. Number of arrhythmic events was evaluated on the ECGs from the 1st to the 6th month after radiotelemetry transmitter implantation, as compared to controls (ctrl).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4232439&req=5

pone-0112697-g004: Arrhythmia type and location.Histograms relating to the type (A) and the location (B) of arrhythmic events of control and aged animals which occurred during telemetry ECG recording. Number of arrhythmic events was evaluated on the ECGs from the 1st to the 6th month after radiotelemetry transmitter implantation, as compared to controls (ctrl).
Mentions: During the aging process the number and complexity of arrhythmic events increased, especially during the last three months of age. Fig. 4A shows, all the arrhythmic events that belong to abnormalities in impulse formation and abnormalities in impulse conduction at each month of telemetry recordings. The number of arrhythmic events increased with age, showing a peak in the 4th month for abnormalities in impulse formation and a peak in the 6th month for abnormalities in impulse conduction. On average, the total number of impulse formation arrhythmias largely exceeded the number of impulse conduction arrhythmias, during the six-month recording period.

Bottom Line: 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.We found that the duration of ECG waves and intervals gradually increased and heart rate variability gradually decreased with age.Our results demonstrate that aging gradually modifies the terminal part of the specialized cardiac conducting system, creating a substrate for increased arrhythmogenesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Sciences, University of Parma, Parma, Italy; CERT, Center of Excellence for Toxicological Research, INAIL, ex ISPESL, University of Parma, Parma, Italy.

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.

Show MeSH
Related in: MedlinePlus