The nurse is analyzing the ECG strip of a 40 year old female and notes that the patient has a sinus arrhythmia. The nurse:

A. The 64-year-old admitted for weakness who has a first-degree heart block with a heart rate of 58 beats/min: This patient is stable, with a mild conduction delay and a slightly low heart rate but no acute symptoms. A float RN from a medical-surgical unit would be able to safely monitor vital signs, assess for changes, and provide routine care.

B. The 92-year-old admitted with chest pain who has premature ventricular contractions and a heart rate of 58 beats/min: This patient is higher risk due to age, symptomatic PVCs, and potential acute coronary syndrome. Close monitoring and rapid response capability are required, making this patient less suitable for a float RN unfamiliar with cardiac-specific interventions.

C. The 71-year-old admitted for heart failure who is short of breath and has a heart rate of 120 to 130 beats/min: Tachycardia with acute dyspnea indicates unstable heart failure requiring frequent assessment, interventions for fluid management, and possible oxygen therapy, which are beyond the comfort level of a float RN from a general medical-surgical unit.

D. The 88-year-old admitted with an elevated troponin level who is hypotensive with a heart rate of 96 beats/min: Elevated troponin and hypotension suggest acute myocardial injury with potential cardiogenic shock. This patient is unstable and requires experienced cardiac nurses for continuous monitoring and rapid intervention, making it inappropriate for a float RN assignment.

A. Identifies ventricular muscle depolarization: The P wave does not represent ventricular activity; ventricular depolarization is reflected in the QRS complex. Confusing the P wave with ventricular depolarization could lead to misinterpretation of arrhythmias or conduction abnormalities.

B. Reflects atrial muscle depolarization: The P wave represents depolarization of the atria, showing the spread of the electrical impulse through the atrial myocardium. This is important for assessing atrial rhythm, identifying atrial enlargement, or detecting ectopic atrial activity.

C. Indicates electrical impulse beginning in the AV node: The P wave originates from the sinoatrial (SA) node, not the AV node. The AV node serves primarily as a conduction delay to allow atrial emptying, and impulses passing through it are reflected later in the QRS complex, not in the P wave.

D. Reflects electrical impulse beginning at the SA node: The P wave reflects the electrical activity initiated by the SA node, the heart’s natural pacemaker. Proper interpretation of the P wave allows the nurse to assess whether the heart rhythm is sinus in origin and whether atrial conduction is normal.