Diastolic Mitral Regurgitation in Complete Heart Block

A 71-year-old woman presented with generalized weakness and lightheadedness that she had experienced during the prior 24 hours. She reported no chest pain, dyspnea, recent tick bites, rashes, or febrile illnesses. Her blood pressure was 132/47 mmHg, and her pulse rate was 38 beats/min. The remainder of her physical examination revealed nothing of note. Results of routine laboratory tests were normal. Her 12-lead electrocardiogram showed sinus rhythm with 3rd-degree atrioventricular (AV) block, also known as complete heart block (Fig. 1). The patient was admitted to the intensive care unit. Serologic results were negative for Lyme disease. A transthoracic echocardiogram showed moderate diastolic mitral regurgitation (MR) and trace systolic MR in color-flow (Fig. 2A) and continuous-wave spectral Doppler modes (Fig. 2B). The patient underwent implantation of a dual-chamber pacemaker, after which an electrocardiogram showed an atrial-sensed, ventricularpaced rhythm (Fig. 3). A repeat transthoracic echocardiogram showed resolution of her diastolic MR (Fig. 4A) and no significant MR during systole (Fig. 4B). The patient's symptoms resolved, and she was discharged from the hospital.