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Heart blocks

An ECG & Rhythm Interpretation term on the RCES exam blueprint, defined for cath lab and EP clinicians.

First-degree AV block shows a prolonged but constant PR interval with every P wave conducted; second-degree Mobitz I (Wenckebach) shows progressively lengthening PR intervals until a beat is dropped; Mobitz II shows a sudden dropped QRS without preceding PR prolongation and carries higher risk of progression to complete block; third-degree (complete) heart block shows complete dissociation between P waves and QRS complexes, each marching to its own independent rate.

Domain: ECG & Rhythm Interpretation · Blueprint: RCES exam guide

Related RCES terms

WPW / pre-excitation Wide-complex tachycardia differentiation STEMI mimics Atrial fibrillation and flutter

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Written and reviewed by John-Philip (JP) Maarschalk, BSN, RN, CNML — a nurse manager who runs operations for the cardiac cath lab, electrophysiology, and interventional service lines at an academic health system in North Carolina. He hires and develops the staff who sit for these exams. More about JP and how this content is made →
Cardiac Codex is an independent study tool published by MdoubleA LLC, not affiliated with or endorsed by CCI or any certifying body. This glossary entry is exam-preparation information, not medical advice or a substitute for clinical judgment. Always verify current clinical practice against primary sources and institutional protocol.