PAC stands for which cardiac event?

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Multiple Choice

PAC stands for which cardiac event?

The event described is an early beat originating in atrial tissue, so the term that best expands PAC is Premature Atrial Contraction. This conveys that the atria fire a premature impulse, causing a contraction before the next scheduled beat. On the ECG, you typically see a premature P wave with an abnormal shape, followed by a normal QRS complex, and often a short compensatory pause before the next beat. Why this is the best fit: the acronym PAC is commonly taught and used to refer to a premature contraction of the atria, not a conduction pathway or a ventricular event. The word “contraction” specifies the muscular action of the atria, whereas “conduction” would refer to the electrical pathway, and “complex” is a less standard way to describe the beat itself. Premature Atrial Complex can appear in some texts, but the standard and most precise expansion in exams is Premature Atrial Contraction. Distinguishing from a ventricular premature contraction (PVC): a PVC originates in the ventricles and typically widens the QRS complex and lacks a preceding P wave, whereas PACs involve atrial activity with an identifiable, though sometimes altered, P wave and usually normal QRS.

The event described is an early beat originating in atrial tissue, so the term that best expands PAC is Premature Atrial Contraction. This conveys that the atria fire a premature impulse, causing a contraction before the next scheduled beat. On the ECG, you typically see a premature P wave with an abnormal shape, followed by a normal QRS complex, and often a short compensatory pause before the next beat.

Why this is the best fit: the acronym PAC is commonly taught and used to refer to a premature contraction of the atria, not a conduction pathway or a ventricular event. The word “contraction” specifies the muscular action of the atria, whereas “conduction” would refer to the electrical pathway, and “complex” is a less standard way to describe the beat itself. Premature Atrial Complex can appear in some texts, but the standard and most precise expansion in exams is Premature Atrial Contraction.

Distinguishing from a ventricular premature contraction (PVC): a PVC originates in the ventricles and typically widens the QRS complex and lacks a preceding P wave, whereas PACs involve atrial activity with an identifiable, though sometimes altered, P wave and usually normal QRS.

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