0071643192.pdf

PREMATUREATRIALCONTRACTION(PAC)

ECG FINDINGS

■ Premature beat with preceding P wave
■ Narrow or wide QRS complex depending on timing
■ P wave different from normal sinus P wave
■ Noncompensatory pause (sinus node is depolarized →next normal beat is
earlier than expected)

PREMATUREVENTRICULARCONTRACTION(PVC)

ECG FINDINGS(SEEFIGURE1.7)

■ Premature wide QRS without preceding P wave
■ Appropriate discordance present
■ Interpolated between normal beats or
■ Fully compensatory pause (one missed sinus beat, but sinus node notreset)

A 52-year-old male is brought to the ED by EMS complaining of palpita-

tions with shortness of breath and chest pain. At presentation he is

diaphoretic and pale. He speaks three words at a time and is clutching his

chest. After being transferred to a gurney he is placed on a cardiac monitor that

demonstrates a wide complex rhythm at 175 bpm. His BP is 110/80 and his RR is

30. How should you proceed?
    This patient has a wide complex tachycardia and is symptomatic with chest
    pain and shortness of breath. Because you are not given any further information
    to differentiate this rhythm from SVT with aberrancy you should treat it as VT.
    Start with immediate synchronized cardioversion at 100J.

DYSRHYTHMIAS

Dysrhythmias can be grouped based on whether the resulting rate is too slow
or too fast.

Rates that are too slow (bradydysrhythmias) can result from the following:

■ Depression of sinus node activity
■ Conduction blocks (see above)

Rates that are too fast (tachydysrhythmias) may result from three mechanisms:

■ Increased automaticity of a sinus or ectopic focus
■ Reentry via AV node or accessory pathway
■ Triggered rhythm (eg, R on T)

RESUSCITATION

FIGURE 1.7. Premature ventricular contraction.

Three mechanisms of

tachydysrhythmias:

Increased automaticity

Reentry

Triggered rhythm