Final answer:
Mobitz type 2 AV block (second-degree Type II) on an ECG is characterized by a pattern of periodically dropped QRS complexes without a preceding change in the PR interval. This block may necessitate close monitoring and potentially a pacemaker due to its risk of progression to third-degree block.
Step-by-step explanation:
The ECG pattern associated with Mobitz type 2, also known as a second-degree atrioventricular (AV) block Type II, is characterized by periodic dropped beats that are not preceded by a change in the conduction time (PR interval). Unlike Mobitz type 1 or Wenckebach periodism, which shows progressively lengthening PR intervals until a QRS complex is dropped, Mobitz type 2 maintains a constant PR interval before a non-conducted P wave, reflecting a block in one of the bundle branches. Commonly, this results in a pattern in which some P waves are not followed by a QRS complex, while others are conducted and look normal, indicating that not all impulses from the sinoatrial (SA) node are able to reach the ventricles.
Understanding ECG patterns, such as those caused by various degrees of AV block, is crucial for accurate diagnosis and treatment planning. The type of AV block can impact the patient's symptoms and the urgency and type of treatment needed. For example, Mobitz type 2 often requires close monitoring and potentially a pacemaker if the dropped beats are frequent, as it can be associated with a higher risk of progression to a third-degree block, which is a complete dissociation between the atrial and ventricular activity.