Scenario: The electrocardiographic (ECG) rhythm strip below (leads V1 and II) is from a 68-year-old woman with pneumonia who was admitted to the step-down unit from a long-term care facility. Vital signs upon arrival included blood pressure, 107/61 mm Hg; body temperature, 98.9 °F (37.2 °C); heart rate, 68/min; respiratory rate, 21/min; and oxygen saturation (SpO2), 96% on 4 L of oxygen. The attending physician ordered intravenous levofloxacin based on culture of a blood sample collected in the emergency department. Per unit policy, because intravenous levofloxacin is known to prolong the QT/QTc, the nurse must measure and document the QT/QTc before starting the medication in order to determine whether QT/QTc prolongation occurs after administration. How should the QT/QTc be measured in this patient?
Sinus rhythm, right bundle branch block (RBBB), possible prior anteroseptal myocardial infarction (MI), and old inferior wall MI.
When measuring the QT/QTc in...