A nurse in an urgent care center is assessing a client who reports a sudden onset of irregular palpitations, fatigue, and dizziness. The nurse finds a rapid and irregular heart rate with a significant pulse deficit. Which of the following dysrhythmias should the nurse expect to find on the ECG?

Atrial fibrillation is characterized by rapid, disorganized electrical impulses causing ineffective atrial contractions. This dysrhythmia originates from ectopic foci near the pulmonary veins, leading to blood stasis and thromboembolic risks. Diagnosis requires identifying a lack of p-waves and an irregularly irregular ventricular response. Rationale: A. Sinus bradycardia is defined by a regular rhythm with a rate below 60 bpm. It does not present with a pulse deficit or the chaotic, irregular rate described in the assessment. This rhythm typically originates from the sinoatrial node and maintains organized mechanical contraction. B. Sinus tachycardia involves a regular discharge from the SA node exceeding 100 bpm. While it causes palpitations and dizziness, the rhythm remains consistently regular without a discrepancy between apical and radial pulses. It is usually a physiological response to stress, pain, or fever. C. Supraventricular tachycardia presents as a rapid, regular rhythm originating above the ventricle bundle. It lacks the irregularity and pulse deficit characteristic of atrial fibrillation. Patients often experience a sudden onset and offset of symptoms, but the cadence is perfectly rhythmic. D. Atrial fibrillation causes a significant pulse deficit because many ineffective contractions fail to perfuse to the peripheral arteries. The hallmark finding is an irregularly irregular rhythm where the heart rate is high but the stroke volume varies. This directly explains the patient's palpitations and dizziness.