Premature Ventricular Contractions
I. Background
a. Characterized by premature and bizarrely shaped QRS complexes
b. Usually wider than 120msec, not preceded by a P wave, and
the T wave is usually large and opposite in direction to QRS deflection
c. Reflect activation of the ventricles from a site below the AV node arising from
reentry, triggered activity, and enhanced automaticity
I. Frequency
a. One of the most common arrythmias and can occur in patients with or without
heart disease
b. Data from large population-based studies indicate that the prevalence ranges
from less than 3% for young white women without heart disease to almost 30% for older
AA’s with HTN
c. Increased risk in male, African American, advanced age, HTN
II. Causes
a. Cardiac
-acute MI/ischemia, myocarditis, cardiomyopathy, MV prolapse,
myocardial contusion
b. Hypoxia and/or hypercapnia
c. Medications (pro-arrythmic such as digoxin or theophylline, alter electrolytes,
ephedrine-containing, cocaine, caffeine)
d. Illicit substances
e. Hyperthyroidism
f. Electrolyte disturbances: hypomagnesemia, hypokalemia, hypercalcemia
III. Morbidity/Mortality
a. Clinical significance of PVCs depends on the clinical context in which they
occur
b. PVCs in young healthy patients without underlying structural heart disease are
usually not associated with any increased rate of mortality
c. PVCs in older patients, especially with underlying heart disease, are
associated with an increased risk of adverse cardiac events, esp sustained
ventricular dysrhythmias and sudden death
d. In patients who have had an MI, risk of malignant ventricular arrythmias and
sudden death is related to complexity and frequency of PVCs with patients in
Lown Classes 3-5 at greatest risk
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Grade 0 = No premature beats
Grade 1 = Occasional (<30/h)
Grade 2 = Frequent (>30/h)
Grade 3 = Multiform
Grade 4 = Repetitive (A = Couplets, B = Salvos of = or > 3)
Grade 5 = R-on-T pattern
IV. What to do
a. Make sure hemodynamically stable, secure ABC’s esp if frequent runs
i. Sx’s of palpitations, syncope, hypotension, hypoxia
b. History of cardiac disease or structural heart disease
i. Possibility of cardiac event?
c. Current medications
d. Correct electrolytes
e. Consider 12-lead ECG
f. Decision to treat depends on clinical scenario
i. In absence of cardiac disease, isolated, asymptomatic ventricular
ectopy, regardless of configuration or frequency, requires no
treatment
g. Consider cardiology consult if concerned