Here’s the explanation from the question explaining the answer choice, since I’m not able to upload an image of the ECG to go with the rationale for this:
Systemic lupus erythematosus is an autoimmune disease with a wide array of presenting symptoms which
often include fever, rash, photosensitivity, renal disease, and nonerosive arthritis. When present in pregnant
patients, complications can occur for both the mother and fetus. These adverse effects can be caused by the
disease itself or by the medications used to treat it. More severe disease, especially lupus nephritis or
cardiovascular involvement, carries even higher risks. Complications include miscarriage, preeclampsia,
preterm delivery, intrauterine growth restriction, and neonatal lupus. Neonatal lupus is caused by the
placental transfer of maternal autoantibodies and can cause heart block in the newborn, as in this patient, as
well as cardiomyopathy, aortic dilation, an erythematous rash involving the scalp and periorbital area,
photosensitivity, and telangiectasias. Heart block occurs in varying degrees. This patient appears to
demonstrate second degree (Mobitz type II) in a 3:1 ratio of conducted to blocked beats. Complete heart
block, also called third-degree atrioventricular block, occurs when no sinus impulses are transmitted through
the AV conduction pathway resulting in complete dissociation between atrial and ventricular contraction.
Ventricular contraction occurs secondary to a junctional rhythm, which can cause bradycardia and decreased
cardiac output. Treatment of high grade second-degree, and third-degree block includes the urgent
placement of a pacemaker.