Atrioventricular Block: The Daily PANCE Blueprint
A 72-year-old male presents with fatigue and lightheadedness. ECG shows complete dissociation between P waves and QRS complexes. What is the most likely diagnosis?
A. Atrial fibrillation
B. Third degree AV block
C. Sinus bradycardia
D. Second degree AV block Type II
E. Severe hyperkalemia
Answer and topic summary
The answer is B. Third degree AV block
A third-degree heart block (also known as complete heart block) is characterized by complete atrioventricular dissociation (i.e., P waves are not associated with QRS complexes). The impulses from the atria do not reach the ventricles; thus, the atria and ventricles are firing in dyschrony. Causes include medications (AV-nodal blocking agents), myocardial ischemia, infiltrative diseases, Lyme disease, hyperkalemia, hypothyroidism, or post-cardiac surgery. Most patients will present with fatigue or dyspnea (due to reduced cardiac output). In unstable patients, options include atropine, transcutaneous or transvenous pacing, and dopamine or epinephrine infusions. Asymptomatic, stable patients do not need immediate therapies. Definitive treatment is permanent pacemaker placement.
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Covered under ⇒ PANCE Blueprint Cardiology ⇒ ⇒
