Which of the following are the most common characteristics of PAC?
I.PACs may originate from a single ectopic focus or from multiple ectopic foci in the atria.
II.Ventricular QRS complexes are normal.
III.Ventricular QRS complexes are abnormally wide.
IV.QRS complexes are irregularly spaced.

Question

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Premature atrial contractions (PACs) (Figure 19-20) occur when an ectopic focus fires; an ectopic focus fires before the sinoatrial (SA) node would normally fire, causing an early atrial contraction (identified as P' on the ECG, Figure 18-20). Ventricular QRS complexes are normal because all impulses are conducted normally into the ventricles. QRS complexes are, however, irregularly spaced because of the PAC. PACs may originate from a single ectopic focus or from multiple ectopic foci in the atria.

Which of the Following Are the Most Common Characteristics of PAC