Step eight
The eighth and final step in cardiac rhythm analysis is measurement of the Q-T interval. The Q-T interval represents ventricular activation to recovery and is measured from the beginning of the Q wave to recovery and is measured from the beginning of the Q wave to the end of the T wave. A normal Q-T interval should be equal to or less than one-half the distance of the R-to-R interval. A prolonged Q-T interval can be congenital or caused by electrolyte imbalances, hypothermia, myocardial ischemia, or administration of certain anti-arrhythmic or psychotropic agents. A prolonged QT interval places a patient at increased risk for life-threatening dysrhythmias.