Health Tips - Ventricular complex

Sunday, February 19, 2012

The letters P, Q.R.S and T were applied to the various waves many years ago by Einthoven. The P wave represents the passage of the activating impulse through the atria. The QRS complex represents the passage of the activating impulse through the ventricles, Q being applied to an initial negative deflection, R to the first positive deflection (whether preceded by a Q wave or not) and S to a negative deflection following an R wave. The PR interval is measured from the start of the P wave to the start of the ventricular complex (i.e. if a Q wave is present, it is strictly speaking the PQ interval). The T wave represents ventricular recovery. The S-T segment extends from the end of the QRS complex to the commencement of the T wave. The heavy vertical lines on the paper, on which the electro cardiogram is recorded, are one-fifth of a second apart and the fine vertical lines are 0.04 seconds apart. The approximate rate of the heart per minute can be calculated by dividing 1500 by the number of fine divisions between two successive corresponding points on the electrocardiogram, e.g. the peaks of the R waves.