Signs of complete heart block

The atrial rate is approximately 100 bpm. The ventricular rate is approximately 40 bpm. The two rates are independent; there is no evidence that any of the atrial impulses are conducted to the ventricles. [Source]

Two ECG strips obtained in the same patient simultaneously (each represents a different vector of the heart’s electrical conduction), demonstrating complete AV block (also called 3rd degree heart block). The solid arrows point to P waves, representing atrial electrical conduction originating from the sinus node. The dashed arrows denote electrical conduction in the ventricles (QRS complexes). Note that the P waves are not related to the QRS complexes, demonstrating that the atria are electrically disconnected from the ventricles. The QRS complexes represent an escape rhythm arising from the ventricle. [Source]

Complete heart block produces a slow regular pulse (25–50/min) that doesn’t vary with exercise. Usually, there is a compensatory increase in stroke volume with a large-volume pulse and systolic flow murmurs. Cannon ‘a’ waves are irregularly seen, and the intensity of the first and second heart sound varies due to the loss of atrioventricular synchrony.