Note that the first three account for almost 90% of ECG tracings with LAD. If the QRS is predominantly negative in lead I and positive in lead aVF, then the axis is rightward (right axis deviation).

In a “normal” electrocardiogram (ECG), the transition of the QRS axis in the precordial leads occurs between leads V 3 and V 4 (i.e., there is a dominant S in V 3 and a dominant R in V 4).

A 76-year-old woman presents with a persistently rapid heart rate that she attributes to her pacemaker. What does the ECG ...

Left axis deviation occurs when the QRS axis falls between -30 and -90. There are a variety of causes, including left anterior fascicular block and left ventricular hypertrophy. See the ECG basics ...

The goal of ECG interpretation in athletes is to classify the ECG as: (1) ‘normal’—no further evaluation needed or (2) ‘abnormal’—further evaluation needed. Normal ECGs include common, ...