Note that not all patients with AV dissociation have complete heart block. For example, patients with ventricular tachycardia have AV dissociation, but not complete heart block; in this example, AV dissociation is due to the ventricular rate being faster than the intrinsic sinus rate. On electrocardiography (ECG), complete heart block is represented by QRS complexes being conducted at their own rate and totally independent of the P waves (see the image below).
Third-degree AV block (complete heart block) exists when there are more P waves than QRS complexes, and there is no relationship between them (ie, no conduction). The conduction block may be at the level of the AVN, the bundle of His, or the bundle-branch Purkinje system. In most cases (approximately 61%), the block occurs below the His bundle. Block within the AV node accounts for approximately one fifth of all cases, whereas block within the His bundle accounts for slightly fewer than one fifth of all cases. [3]
Waves Complete 2017.05.01 Patch
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