Abstract
Scalar electrocardiography, despite its shortcomings, is still the best single clinical tool for the detection of enlargement of cardiac chambers, particularly the left ventricle. The electrocardiographic diagnosis of left ventricular enlargement is primarily based upon increase in the QRS voltage in conventional limb and precordial leads. | Admittedly, the usage of increase in voltage for diagnosis of left ventricular enlargement leads to both, false positive and false negative results. The source of error lies in the fact that several other factors besides increase in left ventricular mass can influence the QRS voltage. | It has been recognized that body build, the position of chest electrodes, the amount and type of the electrocardiographic paste, skin resistance, respiratory motion, age of the patient and many other factors can modify voltage. The effect of heart rate has been noted but not fully investigated particularly in regard to its influence upon the voltage criteria commonly used in the diagnosis of left ventricular enlargement.