Electrocardiogram in heart failure

: Heart failure is basically a manifestation of mechanical disturbances of the heart, but not of electrical abnormalities and is not associated with specific ECG patterns. Several ECG findings are, however, experienced in cases with heart failure as a result of cardiac chamber enlargement and other related changes. Left atrial enlargement is known to cause characteristic P wave changes, which sometimes show parallel course with the clinical state. ECG criteria for atrial enlargement are critically reviewed. In cases with cardiac enlargement, which was improved in a relatively short period of time, R wave height often showed first increase and then decrease. Tissue edema was thought to be the major reason for the initial increase and the distance between the recording electrode and the heart for the later decrease, although other factors can contribute and modify the findings. Minor conduction disturbances due to myocardial stretch and other reasons may also contribute to changes of QRS complex. Analysis of RR intervals offers another possibility to characterise heart failure. A decrease in variability of the RR intervals and in high frequency components on frequency spectrum has been reported in cases with heart failure.