HRS Board Review 2025 New Courses (Reviewers Copy)-Workshop 1_Tomaselli_2025

Video Transcription

Video Summary

Figure 9.1 displays activation maps and action potentials at different pacing cycles in ventricular cardiomyocytes. The pacing cycle lengths are 1,500 ms, 1,000 ms, and 500 ms, affecting conduction velocity and the duration of action potentials at 80% recovery (APD80). The question seeks to identify the cause of rate-dependent effects on conduction velocity and APD80. The options include synthetic activation of repolarizing currents, cumulative inactivation of delayed rectifier potassium currents (I_KS), depletion of calcium from the sarcoplasmic reticulum, and cumulative inactivation of the sodium current. Analyzing the traces helps explain these effects.

Keywords

ventricular cardiomyocytes

pacing cycle lengths

conduction velocity

action potentials

rate-dependent effects