Asystole Following Nitroglycerin: A Review of Two Cases

Case 2: Nitroglycerin for Unstable Anginal Chest Pain

A 69-year-old obese woman with a medical history significant for HTN, HLP, and GERD presented to the ED for evaluation of nausea and chest pressure. She described the chest pressure as feeling dull and heavy. She further noted that the discomfort had been occurring intermittently upon exertion, but that this recent episode started while at rest and persisted.

The patient’s vital signs at presentation were: BP, 183/80 mm Hg; HR, 94 beats/min; RR, 20 beats/min; and T, 98.0°F. Oxygen saturation was 92% on room air. On a review of systems, the patient denied any associated symptoms; she likewise denied a history of any recent surgeries, immobilization, active malignancy, or recent travel. Her social history was noncontributory and was negative for tobacco, alcohol, or recreational drug use.

On physical examination the patient was nontoxic and resting comfortably, without signs of acute distress or diaphoresis. The cardiac and pulmonary examinations were normal, and radial pulses were 2+ and symmetric. The patient had trace pedal edema bilaterally, but her calves were symmetric and nontender. The abdomen was benign and the neurological examination was nonfocal. An ECG (Figure 2) showed a normal sinus rhythm with no signs of ischemia (eg, no ST-segment changes or T-wave inversions were present).

Cases 1 and 2: Shared Clinical Course

In both of the two cases presented, ECGs were obtained for the patients upon arrival at the ED. Both patients were placed on telemetry with continuous monitoring, and intravenous (IV) access was obtained. Baseline laboratory evaluation for each of these patients included a complete blood count, basic metabolic panel, and cardiac enzyme measurement. A D-dimer test was also ordered for the patient in Case 1 based on his concerning history and low-pretest probability for a pulmonary embolism (ie, positive pulmonary embolism rule-out criteria). Portable chest X-ray imaging on each of the patients showed no acute pathology, and all of their laboratory results were within normal ranges. Both of the patients in Case 1 and 2 received a 324-mg chewable aspirin and an IV fluid bolus.

Case 1

During evaluation, the patient in Case 1 developed unprovoked chest pain, which he rated as a “7,” for which he was given 400 mcg NTG sublingually (SL). After administration of NTG, the patient reported that his pain reduced to a “4.” Repeat ECG and vital signs remained unchanged. Though Case 1 patient’s pain abated, since it persisted, he was given a second dose of SL NTG. Within 2 minutes of receiving the second dose of NTG, the patient became bradycardic (30 beats/min) with a stable BP and then became unresponsive, converting to asystolic rhythm. Cardiopulmonary resuscitation (CPR) was initiated, with a successful return of vital signs and baseline cognition following 20 seconds of compressions. Despite success following critical interventions, his HR persisted at 30 beats/min with a narrow regular complex, and normal BP. Because of the persistent bradycardia and preceding asystolic rhythm, he was given 0.5 mg of atropine IV, which increased his HR to 80 beats/min. Cardiology service was consulted, and the patient was admitted following an otherwise stable course. Since the cardiologist did not feel emergent cardiac catheterization was indicated, the patient was observed and subsequently discharged home following an uneventful hospitalization, including a normal stress test.