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[Depressed electrical atrial activity in hypertrophic and dilated cardiomyopathies. An electrocardiographic,
P Ginefra1, E C Barbosa, F M Albanesi Filho
1Hospital Universitário Pedro Ernesto, UERJ, Rio de Janeiro.
Insights
In hypertrophic (HC) and dilated (DC) cardiomyopathies with ventricular disturbances, low-voltage and prolonged P waves indicate intraatrial block. These P wave changes are linked to structural alterations in the atrial myocardium.
Area of Science:
- Cardiology
- Electrophysiology
- Cardiac Imaging
Background:
- Hypertrophic cardiomyopathy (HC) and dilated cardiomyopathy (DC) are significant causes of heart failure.
- Patients with these cardiomyopathies often experience complex ventricular arrhythmias.
- The P wave on a standard electrocardiogram (ECG) can provide insights into atrial electrical activity.
Purpose of the Study:
- To evaluate the characteristics of the P wave on a 12-lead conventional electrocardiogram (ECG) in patients with hypertrophic (HC) and dilated (DC) cardiomyopathies.
- To investigate the relationship between P wave abnormalities and severe electric ventricular disturbances in these patient groups.
Main Methods:
- Studied 20 patients (11 HC, 9 DC) with cardiomyopathies.
- Analyzed P wave using standard ECG, amplified ECG (ECG2), and Frank-system vector-cardiogram (VCG).
- Correlated electrical data with echocardiographic measurements of atrial and ventricular dimensions and function.
Main Results:
- P wave morphology and delay changes were best visualized on amplified ECG (ECG2) and VCG.
- Mean P wave voltage on standard ECG was 0.1 mV.
- Mean P loop duration on VCG was 133.7 msec (HC) and 145.2 msec (DC), with significant terminal delays indicating slow atrial depolarization.
Conclusions:
- In HC and DC patients with severe ventricular changes, low-voltage and prolonged P waves are observed.
- These P wave abnormalities are attributed to intraatrial block.
- Intraatrial block likely results from structural changes within the atrial myocardium.
Purpose:
To evaluate the "normal" or low-voltage P wave of the 12-leads conventional electrocardiogram (ECG), in patients with serious electric ventricular disturbances in hypertrophic (HC) and dilated (DC) cardiomyopathies.
Methods:
Twenty cases of cardiomyopathies, 11 HC and 9 DC, ages ranging from 23 to 73 (x = 41) years have been studied. The analysis of the P wave was performed with ECG, amplified ECG at 1 mv = 20 mm and speed-paper at 50 mm/sec (ECG2), and the Frank-system vector-cardiogram (VCG). Voltage, delays and shapes of the P wave were evaluated by ECG2 and amplified VCG with gain at 1 mv = 160 mm. All electrical data were correlated with dimension of the left atrium (LA), dimension of left ventricular diastolic diameter (LVDD), dimension of left ventricular systolic diameter (LVSD), interventricular septal thickness (IST), posterior wall thickness ((PWT) and ejection fraction (EF) of the left ventricle of bidimensional echocardiogram (ECHO).
Results:
Changes in morphologies and delays on the the P wave were best observed only on ECG2 and VCG. The mean voltage of P wave on ECG was 0.1 mv and the mean duration of the P loop on VCG was 133.7 msec in HC and 145.2 msec in DC, with mean terminal delay of 49.2 msec and 46.8 msec, respectively, due to slow atrial depolarization.
Conclusion:
In HC and DC with severe electric ventricular changes, the low-voltage and increased duration of P wave, are attributed to intraatrial-block due to structural changes of the atrial myocardium.