A nurse notes that a client with sinus rhythm has a premature ventricular contraction that falls on the T wave of the preceding beat. The client’s rhythm suddenly changes to one with no P waves or definable QRS complexes. Instead, there are coarse wavy lines of varying amplitude. The nurse assesses this rhythm to be:
A. Ventricular tachycardia
B. Ventricular fibrillation
C. Atrial fibrillation
D. Asystole
Correct Answer: B. Ventricular fibrillation
Ventricular fibrillation is characterized by irregular, chaotic undulations of varying amplitudes. Ventricular fibrillation has no measurable rate and no visible P waves or QRS complexes and results from electrical chaos in the ventricles. VF is a WCT caused by irregular electrical activity and characterized by a ventricular rate of usually greater than 300 with discrete QRS complexes on the electrocardiogram (ECG). QRS morphology in VF varies in shape, amplitude, and duration with a prominent irregular rhythm.
Option A: Ventricular tachycardia is characterized by the absence of P waves, wide QRS complexes (usually greater than 0.14 second), and a rate between 100 and 250 impulses per minute. The rhythm is usually regular. Ventricular tachycardia is characterized as a wide complex (QRS duration greater than 120 milliseconds) tachyarrhythmia at a heart rate greater than 100 beats per minute. It is classified by duration as non-sustained or sustained. Non-sustained ventricular tachycardia is defined as more than 3 beats of ventricular origin at a rate greater than 100 beats per minute that lasts less than 30 seconds in duration.
Option C: Atrial fibrillation is characterized by a loss of P waves; an undulating, wavy baseline; QRS duration that is often within normal limits; and an irregular ventricular rate, which can range from 60 to 100 beats per minute (when controlled with medications) to 100 to 160 beats per minute (when uncontrolled). Atrial fibrillation is the most common type of cardiac arrhythmia. It is the leading cardiac cause of stroke. Risk factors for atrial fibrillation include advanced age, high blood pressure, underlying heart and lung disease, congenital heart disease, and increased alcohol consumption.
Option D: Asystole, colloquially referred to as flatline, represents the cessation of electrical and mechanical activity of the heart. Asystole typically occurs as a deterioration of the initial non-perfusing ventricular rhythms: ventricular fibrillation (V-fib) or pulseless ventricular tachycardia (V-tach). Additionally, pulseless electrical activity (PEA) can cease and become asystole.
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