Normal EKG Q-T interval 0.35 sec P-R interval 0.16 sec R R P T Q Ventricular Atrial S repolarization depolarization Ventricular depolarizatio n Copyright © 2006 by Elsevier, Inc. P T Q S Standardized EKGs Figure 11-1; Guyton & Hall • Time and voltage calibrations are standardized as shown on figure 11-1. Copyright © 2006 by Elsevier, Inc. Heart Rate Calculation • R-R interval = 0.83 sec • Heart rate = (60 sec)/(0.83 sec) = 72 beats/min min beat Copyright © 2006 by Elsevier, Inc. Bipolar Limb Leads • Bipolar means that the EKG is recorded from two electrodes on the body. Figure 11-6; Guyton & Hall Copyright © 2006 by Elsevier, Inc. Bipolar Limb Leads (cont’d) 0.5 mV 1.2 mV 0.7 mV Figure 11-7; Guyton & Hall Copyright © 2006 by Elsevier, Inc. Other EKG Leads • Chest Leads (Precordial Leads) known as V1V6 are very sensitive to electrical potential changes underneath the electrode. Figure 11-9; Guyton & Hall Copyright © 2006 by Elsevier, Inc. Cardiac Cycle Figure 9-5; Guyton & Hall Copyright © 2006 by Elsevier, Inc. Phases of the Cardiac Cycle Copyright © 2006 by Elsevier, Inc. Pressure and Volume Relationships in the Cardiac Cycle Copyright © 2006 by Elsevier, Inc. A Simple Model of Stroke Volume Copyright © 2006 by Elsevier, Inc. Factors Affecting Cardiac Output Copyright © 2006 by Elsevier, Inc. Figure 20.20
