Ventricular Rhythms

Premature Ventricular Complexes (PVC's)

• PVC's arise from an irritable focus within either ventricle.
• PVC's are premature - they occur earlier than the next expected sinus beat.
• PVC's are caused by enhanced automaticity or reentry.

Characteristics of PVC's

• Rate is usually within normal range but depends on underlying rhythm.
• Rhythm is essentially regular with premature beats.
• P wave is usually absent, or with retrograde conuction to the atria. May appear after the QRS.
• PRI - none with the PVC (because the ectopic beat originates in the ventricles).
• QRS is greater than 0.12 seconds, wide, and bizarre, T wave frequently in opposite direction of the QRS complex. QRS is greater than 0.12 seconds because the PVC depolarizes the ventricles prematurely and in an abnormal manner.

NOTE: A PVC is a single beat, not an entire rhythm. Therefore it is important to identify the underlying rhythm and the ectopic heat (ie: ST @ 138 bpm with frequent PVC's).

Types of PVC's

• Pairs (couplets): 2 sequential PVC's
• Runs or bursts: 3 or more sequential PVC's (AKA Ventricular Tachycardia - VT)
• Bigeminy PVC's: Every other beat is a PVC.
• Trigeminy PVC's: Every thrid beat is a PVC.
• Quadrigeminy PVC's: Every fourth beat is a PVC.

Uniform and Multifocal PVC's

• Uniform PVC's: Look the same and originate from the same site.
• Multiformed: PVC's that appear different from one and other.

Common Causes of PVC's

• Hypoxia
• Stress, anxiety
• Exercise
• Digoxin toxicity
• CHF
• Acid-base imbalance
• Electrolyte imbalance
• Myocardial ischema
• Stimulants (ETOH, caffeine, tobacco)
• Meds

Clinical Significance

• PVC's can occur in healthy persons with apparently normal hearts, and for no apparent cause.
• PVC's may or may not produce palpable pulses. Patient's experiencing PVC's may be asymptomatic or c/o palpitations, a "racing heart," skipped beats, or chest/neck discomfort.
• If frequent s/s, decrease C.O. may be present.

Interventions

• Tx depends on cause, s/s, and on clinical situation. Most patients do not require tx with antidysrhythmic meds.
• Tx of PVC's seen in the setting of acute MI should be directed at ensuring adequate oxygenation , pain relief, rapid identification and correctino of hypoxia, heart failure, and electrolyte or acid-base abnormalities.

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Ventricular Escape Beats/Rhythm

Characteristics of Ventricular Escape (Idioventricular) Rhythm

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