ESSENTIALS OF DIAGNOSIS
Common but rarely symptomatic.
Ambulatory ECG monitoring to quantify daily burden of PVCs. Asymptomatic patients with greater than 10% PVC burden should have periodic echocardiogram to exclude development of LV dysfunction.
Ventricular premature beats, or PVCs, are isolated beats typically originating from the outflow tract or His-Purkinje regions of ventricular tissue. In most patients, the presence of PVCs is a benign finding; however, they rarely may trigger ventricular tachycardia or ventricular fibrillation, especially in patients with underlying heart disease (see eFigure 10–56).
The patient may or may not sense the irregular beat, usually as a skipped beat. Exercise generally abolishes premature beats in normal hearts, and the rhythm becomes regular. Ventricular premature beats are characterized by wide QRS complexes that differ in morphology from the patient’s normal beats. They are usually not preceded by a P wave, although retrograde ventriculoatrial conduction may occur. Unless the latter is present, there is a fully compensatory pause (ie, without change in the PP interval). Bigeminy and trigeminy are arrhythmias in which every second or third beat is premature; these patterns confirm a reentry mechanism for the ectopic beat (eFigure 10–87). Ambulatory ECG monitoring may reveal more frequent and complex ventricular premature beats than occur in a single routine ECG. An increased frequency of ventricular premature beats during exercise is associated with a higher risk of cardiovascular mortality and should be investigated further.
Sinus rhythm with ventricular bigeminy due to digitalis toxicity. Ventricular premature complexes follow each sinus-conducted QRS at a fixed coupling interval. ST-segment depression and T wave inversion in the sinus-conducted beats is seen in V6; however, since each sinus-conducted beat is a postextrasystolic one, correct interpretation of ST-T abnormalities is difficult. The sinus rate is not measurable when ventricular bigeminy is present since consecutive sinus complexes are not present. Although ventricular bigeminy in this patient was associated with a toxic serum level of digoxin, this arrhythmia is not specific for digitalis intoxication. If a ventricular arrhythmia is due to digitalis toxicity, it is expected to disappear as the serum level of digitalis is lowered. Note the presence of P waves deforming the ST segments of the premature ventricular depolarizations (arrows); since the intervals between them and the preceding sinus P waves is not half the measured sinus cycle length, they are probably retrogradely conducted. (Reproduced, with permission, from Goldschlager N, Goldman MJ. Principles of Clinical Electrocardiography, 13th ed. Originally published by Appleton & Lange. Copyright © 1989 by The McGraw-Hill Companies, Inc.)
If no associated cardiac disease is present and if the ectopic beats are asymptomatic, no therapy is indicated. Mild symptoms or anxiety from palpitations may be allayed with reassurance to the patient of the benign nature of ...