(a)
(b)
(c)
Figure 1: Serial ECGs: initial ECG performed at age 33 (a) with sinus rhythm and prolonged PR interval. Surveillance ECG performed one year later at age 34 (b) with slowing of the sinus rate and prolonged PR interval. First ECG during pregnancy performed at age 35 (c) showed new sinus bradycardia with competing junctional rhythm, occasional PVCs (RBS axis), and lower voltage QRS and poor R wave progression. Paper speed and amplification: 25 mm/s and 1 mV/10 mm.