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Published on: July 29, 2011
Delayed ventricular depolarization--correlation with ventricular activation and relevance to ventricular fibrillation
Insights
Signal averaging detected late potentials in patients with ventricular tachycardia (VT) and after cardiac surgery, indicating abnormal heart depolarization. These findings suggest late potentials reflect a substrate for re-entrant VT but are not predictive of ventricular fibrillation (VF).
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Diagnostics
Background:
- Ischaemic heart disease can cause abnormalities in ventricular depolarization.
- Late potentials, detected via signal averaging, are investigated as indicators of cardiac electrical activity.
Purpose of the Study:
- To evaluate the prevalence and significance of late potentials in patients with ischaemic heart disease.
- To determine if late potentials correlate with specific arrhythmias like ventricular tachycardia (VT) and ventricular fibrillation (VF).
Main Methods:
- Signal averaging was employed to analyze terminal ventricular depolarization in various patient groups.
- Late potentials were assessed in patients with different manifestations of ischaemic heart disease, including those undergoing cardiac surgery, and those with acute myocardial infarction (AMI), VT, or VF.
Main Results:
- Late potentials were frequently observed in patients with VT and those who underwent cardiac surgery.
- A strong correlation was found between late potentials and delayed, fragmented epicardial activation in the surgical group, supporting their role in re-entrant VT.
- Signal averaging proved feasible in a Coronary Care Unit (CCU) setting.
- Late potentials were rarely detected in patients early in acute myocardial infarction (AMI) or those experiencing ventricular fibrillation (VF).
Conclusions:
- Late potentials are common in patients with VT and after cardiac surgery, reflecting a substrate for re-entrant VT.
- Signal averaging is a viable technique for detecting late potentials, even in challenging CCU environments.
- Late potentials are not a reliable predictive index for ventricular fibrillation (VF).
Abstract:
Signal averaging to detect abnormalities in the terminal phase of ventricular depolarization has been performed in several groups of patients with various manifestations of ischaemic heart disease. Late potentials were common in patients with VT and in a group of patients having cardiac surgery. Findings in the surgical group highlighted the close correlation of late potentials with delayed, fragmented epicardial activation supporting the hypothesis that late potentials reflect a myocardial substrate which would support re-entrant VT. The findings in the surgical group allowed a definition of late potentials which could be applied to other patients in the study, and also demonstrated a spectrum of late depolarization abnormalities. Signal averaging is technically feasible in the noisy CCU environment but late potentials were detected in few patients early in AMI. Late potentials were also rarely seen in patients with VF and therefore cannot be construed as a predictive index of this arrhythmia.
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