Third Degree Atrioventricular Block
When the conduction starts within, or close to, the atrioventricular node, a narrow QRS complex escape rhythm is seen. If a wide complex escape rhythm is visible, then the conduction is of ventricular origin and thus may be considered as a ventricular escape. The closer the origin to the atrioventricular node, the faster the rate.
Third degree atrioventricular block is also referred to as complete heart block.
In the following example, whilst some P waves are obscured, the underlying atrial activity (shaded) at a rate of 59 bpm is still apparent. The ventricular rate (arrowed) is slower at 38 bpm.