This rhythm strip shows sinus tachycardia with premature ventricular complexes. The underlying sinus tachycardia is reflected by normal P waves preceding each sinus QRS at a rate greater than 100 per minute. Here the rate is approximately 120 beats per minute. The earlier premature ventricular complexes are wide and different from the sinus QRS and are not preceded by a premature P wave. Some are occurring in pairs, or couplets. The significance of isolated and paired ventricular complexes is determined by the clinical setting in which they occur.