Changes in Local Atrial Electrograms and Surface ECG Induced by Acute Atrial Myocardial Infarction
Gerard Amorós-Figueras1, Elena Roselló-Diez2, Damian Sanchez-Quintana3
1Department of Cardiology, Hospital de la Santa Creu i Sant Pau, Institute of Biomedical Research IIB Sant Pau, CIBERCV, Universitat Autònoma de Barcelona, Barcelona, Spain.
Insights
Atrial coronary branch occlusion causes atrial infarction and changes in local electrical activity, but these are not clearly visible on standard ECG. This study details these electrophysiological changes in an animal model.
Area of Science:
- Cardiology
- Electrophysiology
- Pathology
Background:
- Atrial coronary branch occlusion is a difficult-to-diagnose condition linked to atrial fibrillation.
- Current ECG diagnostic accuracy is limited due to poorly understood ischemia-induced changes in atrial electrograms.
Purpose of the Study:
- To investigate the effects of acute atrial branch occlusion on myocardial structure, atrial electrograms, and surface ECG.
- To characterize the electrophysiological and structural changes in a relevant animal model.
Main Methods:
- Surgical occlusion of an atrial coronary branch in anesthetized pigs for 4 hours.
- Simultaneous recording of atrial electrograms and surface ECG.
- Anatomopathological analysis of cardiac tissue post-occlusion.
Main Results:
- Occlusion led to patchy atrial necrosis with distinct borders.
- Atrial electrograms showed R wave enlargement, delayed activation, ST elevation, and monophasic potentials.
- Surface ECG exhibited decreased P wave amplitude and duration in later stages of occlusion.
Conclusions:
- Selective atrial branch occlusion causes atrial infarction and specific electrophysiological changes.
- These changes, including R/S wave and ST segment alterations, are not discernible on standard ECG.
- Only indirect ECG changes in P wave are observed in advanced occlusion stages.
Background:
Atrial coronary branch occlusion is a hardly recognizable clinical entity that can promote atrial fibrillation. The low diagnostic accuracy of the ECG could deal with the characteristics of the ischemia-induced changes in local atrial electrograms, but these have not been described.
Objectives:
We analyzed the effects of selective acute atrial branch occlusion on local myocardial structure, atrial electrograms, and surface ECG in an experimental model close to human cardiac anatomy and electrophysiology.
Methods:
Six anesthetized open-chest anesthetized pigs underwent surgical occlusion of an atrial coronary branch arising from the right coronary artery during 4 h. Atrial electrograms and ECG were simultaneously recorded. One additional pig acted as sham control. In all cases, the hearts were processed for anatomopathological analysis.
Results:
Atrial branch occlusion induced patchy atrial necrosis with sharp border zone. During the first 30 min of occlusion, atrial electrograms showed progressive R wave enlargement (1.8 ± 0.6 mV vs. 2.5 ± 1.1 mV, p < 0.01), delayed local activation times (28.5 ± 8.9 ms vs. 36.1 ± 16.4 ms, p < 0.01), ST segment elevation (-0.3 ± 0.3 mV vs. 1.0 ± 1.0 mV, p < 0.01), and presence of monophasic potentials. Atrial ST segment elevation decreased after 2 h of occlusion. The electrical border zone was ∼1 mm and expanded over time. After 2 h of occlusion, the ECG showed a decrease in P wave amplitude (from 0.09 ± 0.04 mV to 0.05 ± 0.04 mV after 165 min occlusion, p < 0.05) and duration (64.4 ± 8.0 ms vs. 80.9 ± 12.6 ms, p < 0.01).
Conclusion:
Selective atrial branch occlusion induces patchy atrial infarction and characteristic changes in atrial activation, R/S wave, and ST segment that are not discernible at the ECG. Only indirect changes in P wave amplitude and duration were appreciated in advanced stages of acute coronary occlusion.
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