Mobitz I (Second-Degree Atrioventricular Block)

Occurs after inferior MI or occasionally in trained athletes or in normal, sleeping people.

Incidence varies based on etiology.

Without associated heart disease and without symptoms, should not present undue risk during anesthesia (e.g., in trained athletes).

If occurs secondary to inferior MI, periop risk depends on extent of ischemic area.

Advancing to a higher-degree block if ischemic zone extends to anterior wall.

Papillary muscle dysfunction may occur.

Found usually in presence of CAD.

Block generally occurs in AV node, resulting in normal QRS complexes.

ECG reveals progressive lengthening PR intervals at decreasing increments and progressively shortening RR intervals leading to regular atrial rhythm and irregular ventricular rhythm.

Bradycardia usually responds to atropine.