Dysrhythmias & EKG Interpretation Q 13

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A nurse is watching the cardiac monitor and notices that the rhythm suddenly changes. There are no P waves, the QRS complexes are wide, and the ventricular rate is regular but over 100. The nurse determines that the client is experiencing:

  

     A. Premature ventricular contractions

     B. Ventricular tachycardia

     C. Ventricular fibrillation

     D. Sinus tachycardia

    

    

Correct Answer: B. Ventricular tachycardia

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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.

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Option A: During a premature ventricular contraction (PVC), the heartbeat is initiated by the Purkinje fibers rather than the SA node. Given that a PVC occurs before a regular heartbeat, there is a pause before the next regular heartbeat. In patients with PVCs, the ECG may reveal other findings that include: electrolyte abnormalities (peaked T waves, QT prolongation); left ventricular hypertrophy; with an old MI, one may see Q waves, loss of R waves, and/or a bundle branch block; and acute ischemia may present with ST-segment elevation/depression and/or T wave inversion.

Option C: 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 D: Sinus tachycardia is a regular cardiac rhythm in which the heart beats faster than normal and results in an increase in cardiac output. While it is common to have sinus tachycardia as a compensatory response to exercise or stress, it becomes concerning when it occurs at rest.

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