cardiovascular disorders
Ventricular Premature Beats (VPB)
Introduction
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 both healthy patients and patients with a heart disorder. VPB may be asymptomatic or cause palpitations. Diagnosis is by electrocardiography. Treatment is usually not required. (See also Overview of Arrhythmias .) Ventricular premature beats (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. 