In automatic tachycardia, phase 4 elevation indicates increased automaticity. which statement is true?

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Study for the EPU Electrophysiology Exam with comprehensive questions and explanations. Enhance your knowledge with flashcards and a variety of question formats to ensure you are prepared to excel!

Multiple Choice

In automatic tachycardia, phase 4 elevation indicates increased automaticity. which statement is true?

Explanation:
In automatic tachycardia, the key feature is increased automaticity of ectopic pacemaker tissue, which shows up as elevated phase 4 depolarization. This diastolic depolarization brings the membrane potential toward the threshold more quickly, so impulses fire spontaneously at a faster rate, independent of the SA node. Phase 0 is the rapid upstroke for conduction, and phases 2 and 3 are the plateau and repolarization phases; they drive contraction and electrical recovery, not the spontaneous firing that defines automaticity. Thus, phase 4 elevation directly reflects the mechanism behind automatic tachycardia.

In automatic tachycardia, the key feature is increased automaticity of ectopic pacemaker tissue, which shows up as elevated phase 4 depolarization. This diastolic depolarization brings the membrane potential toward the threshold more quickly, so impulses fire spontaneously at a faster rate, independent of the SA node. Phase 0 is the rapid upstroke for conduction, and phases 2 and 3 are the plateau and repolarization phases; they drive contraction and electrical recovery, not the spontaneous firing that defines automaticity. Thus, phase 4 elevation directly reflects the mechanism behind automatic tachycardia.

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