ANATOMY

Detailed explanation-1: -It is the sinoatrial (SA) node of the intrinsic conduction system that stimulates the atrioventricular (AV) node to conduct impulses to the atrioventricular bundle.

Detailed explanation-2: -Mobitz type 2 AV block can be associated with severe bradycardia and hemodynamic instability. It has a greater risk of progressing to third-degree (complete) heart block or asystole.

Detailed explanation-3: -The most common causes of first-degree heart block are AV nodal disease, enhanced vagal tone (for example in athletes), myocarditis, acute myocardial infarction (especially acute inferior MI), electrolyte disturbances and medication.

Detailed explanation-4: -These causes include idiopathic fibrosis and underlying chronic cardiac diseases such as structural heart disease, acute ischemic heart disease, medication toxicity, nodal ablation, electrolyte abnormalities, and post-operative heart block such as after surgical or transcatheter aortic valve replacement.