A Pregnant Patient with Elevated Heart Rate

A 22-year-old pregnant female in her 35th week of gestation presented with 1-week history of shortness of breath, dizziness, and palpitations. She had a history of chronic urinary tract infection (UTI) on prophylactic antibiotics but no other medical issues. Symptoms were worse when ambulating, not fully alleviated when lying down, and had no improvement on the left lateral decubitus position. Vital signs on arrival included blood pressure 106/59 mm Hg, heart rate 130 beats per minute, respiratory rate 17 breaths per minute with no oxygen requirements. Her physical examination was unremarkable aside from tachycardia. Orthostatic vital signs were negative. Electrocardiogram on presentation revealed sinus tachycardia, and heart rate trends during hospitalization are shown in the Figure. Computed tomography of the chest revealed no pulmonary embolism. Transthoracic echocardiogram revealed normal left ventricular systolic function with no valvular or structural abnormalities. Workup for tachycardia was negative for any provocable cause including electrolyte abnormalities, thyroid irregularities, infection, and drug use. Oral intake was encouraged along with intravenous hydration with no decline in heart rate. Given persistent symptoms, metoprolol tartrate was initiated. The patient presented to the hospital 24 hours later due to recurrent symptoms. She was noted to exhibit postural tachycardia features with increased heart rate while going from supine to a standing position with associated dizziness that was not associated with hypotension. Continuous hydration was administered along with initiation of salt tablets. A few weeks later, the patient underwent delivery with no complications.