Diltiazem-induced Transient Complete Atrioventricular Block in an Elderly Patient with Acute on Chronic Renal Failure
Our patient was an 88 year old Caucasian male with a history of Parkinson’s disease, hypertension, prior stroke and Stage 3 chronic renal failure who was brought to the Emergency Department with progressive dyspnea on exertion and profound fatigue for 48 hours. He had no prior history of presyncope, syncope or advanced conduction abnormalities, except for a longstanding first-degree heart block. His medications included sustained-release diltiazem 180 mg daily, aspirin 81 mg daily, simvastatin 40 mg daily, carbidopa/levodopa 25/100 mg twice a day, metolazone 5 mg daily and torsemide 10 mg daily. Vital signs on presentation were: oral temperature 36. 2 C, pulse of 38 beats per minute, respiratory rate of 20 breaths per minute, blood pressure of 141/78 mmHg, and oxygen saturation (SpO2) of 80% on ambient air. The patient was in moderate respiratory distress and had signs of volume overload. Laboratory data was significant for a potassium of 5.8 mmol/L, ionized calcium of 4.1 mg/dL, bicarbonate of 21 mmol/L, BUN of 134 mg/dL and creatinine of 5.0 mg/dL (patient’s baseline was 3.5 mg/dL a month earlier). ECG on admission revealed the presence of sinus rhythm with complete heart block (Fig ); transthoracic echocardiogram showed normal left ventricular size and function, no wall motion abnormalities and dilated inferior vena cava. Aggressive diuresis was instituted, as well as non-invasive ventilatory support with BiPAP. Diltiazem was held, and he was given 1 g of intravenous calcium gluconate with little effect. Repeat ECG at 6 hours continued to demonstrate complete heart block, with occasional premature junctional complexes (Fig ). He received an additional 2 g of intravenous calcium 12 hours after presentation; within 10 minutes after completion of the infusion, normal sinus rhythm with 1 to 1 conduction was restored (Fig. ) and maintained thereafter.