Florida State Paramedic Practice Exam

Under what condition should procainamide be discontinued in a patient?

1. The patient develops bradycardia

2. QRS widens by 50%

3. Patient’s heart rate exceeds 100 bpm

4. Blood pressure drops greater than 15 mm Hg

The correct answer is: QRS widens by 50%

Procainamide is an antiarrhythmic medication that can be effective in treating certain types of tachyarrhythmias. However, one of the critical considerations while administering procainamide is monitoring the QRS duration on an ECG. If the QRS complex widens by 50% or more from the baseline during treatment, it indicates a significant effect of the medication on cardiac conduction. This level of QRS widening suggests that the patient's heart is experiencing an intensified response to the drug, which can lead to an increased risk of serious side effects, including potential progression to more severe arrhythmias. Therefore, discontinuing procainamide under these circumstances helps prevent further complications and ensures patient safety. Monitoring QRS duration is a standard practice when administering this medication, and it reflects the drug's impact on cardiac electrophysiology.