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Ventricular Premature Beats (VPB)
Ventricular premature beats (VPB) are single ventricular impulses caused by reentry within the ventricle or abnormal automaticity of ventricular cells. They are extremely common in healthy patients and in patients with a heart disorder. VPB may be asymptomatic or cause palpitations. Diagnosis is by ECG. Treatment is usually not required.
VPBs, also called premature ventricular contractions (PVC), may occur erratically or at predictable intervals (eg, every 3rd [trigeminy] or 2nd [bigeminy] beat). VPBs may increase with stimulants (eg, anxiety, stress, alcohol, caffeine, sympathomimetic drugs), hypoxia, or electrolyte abnormalities.
VPBs may be experienced as missed or skipped beats; the VPB itself is not sensed but rather the following augmented sinus beat. When VPBs are very frequent, particularly when they occur at every 2nd heart beat, mild hemodynamic symptoms are possible because the sinus rate has been effectively halved. Existing ejection murmurs may be accentuated because of increased cardiac filling and augmented contractility after the compensatory pause.
Diagnosis is by ECG showing a wide QRS complex without a preceding P wave, typically followed by a fully compensatory pause.
In patients with a structural heart disorder (eg, aortic stenosis, post MI), treatment is controversial even though frequent VPBs (> 10/h) correlate with increased mortality, because no studies have shown that pharmacologic suppression reduces mortality. In post-MI patients, mortality rate is higher with class I antiarrhythmics than with placebo. This finding probably reflects adverse effects of the antiarrhythmics. β-Blockers are beneficial in symptomatic heart failure and post MI. If VPBs increase during exercise in a patient with coronary artery disease, evaluation for percutaneous transluminal coronary angioplasty or coronary artery bypass graft surgery should be considered.
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