[Diagnostic importance of QRS voltage]

Voltage criteria of QRS are considered one of the signs of left ventricular hypertrophy. An increase of the R wave above the left precordium after a load is considered a manifestation of left ventricular ischaemia and evidence of coronary heart disease, but also a criterium of left ventricular function the volume of which increases as a result of altered haemodynamics. The voltage criteria of left ventricular hypertrophy are, however, of low sensitivity and specificity, as indicated by anatomical and echocardiographic investigations. The tracing of the electric field on the heart surface is not only influenced by the heart as a generator of electric energy but also by some other factors which are briefly discussed. Views on the change of voltage of the R wave after a load differ as regards its diagnostic impact, sensitivity and specificity for the diagnosis of coronary disease and the possibility to evaluate left ventricular function. From a review of the literature ensues that increase of the R wave after a load is due to a sufficient slower conduction in the ischaemic tissue but not as a result of enlargement of left ventricular volume which occurs as a result of altered haemodynamics induced by ischaemia.