This ECG demonstrates sinus rhythm with premature atrial contractions (PACs), a normal axis, a right bundle branch block, a prolonged QTc interval, and T-wave abnormalities suggestive of lateral ischemia.
Sinus rhythm is indicated by a P wave for every QRS complex and a QRS complex for every P wave with a consistent PR interval.
PACs are seen on the seventh, 10th, and 12th beats on the rhythm strip. Notice that the R-R interval is shortened, the R wave of the PACs is identical to that of sinus rhythm, and there is a compensatory pause following the PAC before the sinus rhythm ensues. The R-wave axis of 26° is within the normal range (–30° to 90°).
A right bundle branch block is identified by a QRS duration > 120 ms (156 ms), an RSR’ “rabbit ear” pattern in the anterior precordial leads (particularly lead V1), and slurred S waves in leads I and aVL. Although opinions vary, a QTc interval > 460 ms in women (> 440 ms in men) is typically considered prolonged. This patient fits that criteria (529 ms). Finally, the ST depressions in leads V4 to V6 suggest lateral ischemia.
A comparison of this ECG to one obtained a year ago showed no difference, with the exception of new-onset PACs. The patient was cleared for surgical repair of her forearm fracture.