A combination of the Q wave, R wave and S wave, the “QRS complex” represents ventricular depolarization. This term can be confusing, as not all ECG leads contain all three of these waves ...

Because the normal ventricular conduction system (His-Purkinje) is used, the QRS complex is frequently narrow. A junctional rhythm is normally slow — less than 60 beats per minute. When faster ...

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

During atrial overdrive pacing at a cycle length of 420 ms, the following EKG was recorded (Fig. 1). What is the mechanism for the progressive widening of QRS complexes and for the normal narrow ...

1a). The electrical events during the action potential, including initial firing (depolarization, corresponding to the QRS complex in the ECG) and subsequent return to the resting state ...

The regular arrhythmia occurring at the beginning of the electrocardiogram was identified as ventricular bigeminy. Single ventricular premature complexes (VPCs), as well as pairs and triplets of ...