What is a sinus tachycardia w/ artifact and what is sinus tachycardia with pvc?

See below: Sinus tachy with artifact is a normal but fast rhythm; >100,with externally caused variations in the appearance of the tracing caused by body movement, poor electrode contact or external electrical interference. Sin. tachycardia with PVC is normal but fast rhythm,>100, & a premature ventricular contraction, PVC,;, which is an abnormal early heart beat originating in one of the ventricles.