1. EKG Ventricular Pressure Aortic Pressure Ventricular Volume P 120 0 Mm Hg 130 40 ml A The P wave denotes atrial depolarization.

2. EKG Ventricular Pressure Aortic Pressure Ventricular Volume P 120 0 Mm Hg 130 40 ml B PR interval of EKG Atria depolarized and contracting Contracting atria cause ventricular volume and pressure to increase – See units to the right

3. EKG Ventricular Pressure Aortic Pressure Ventricular Volume P 120 0 Mm Hg 130 40 ml Preload – Usually represented as the pressure immediately preceding ventricular contraction C

4. EKG Ventricular Pressure Aortic Pressure Ventricular Volume P 120 0 Mm Hg 130 40 ml QRS represents depolarization of the ventricles Following ventricular depolarization the ventricles begin to contract this causes the pressure in the ventricles to begin to rise and the AV valves close. However, since all the valves are now shut…… ventricular volume remains constant as no blood can leav (isovolumetric) D

5. EKG Ventricular Pressure Aortic Pressure Ventricular Volume P 120 0 Mm Hg 130 40 ml AV valves close QRS To review, the QRS wave denotes ventricular depolarization. This is followed by ventricular contraction causing pressure in the ventricles to begin to rise. This intraventricular pressure increase immediately closes the AV valves. E

6. EKG Ventricular Pressure Aortic Pressure Ventricular Volume P 120 0 Mm Hg 130 40 ml AV valves close QRS Semilunar valves open As pressure builds in the ventricles all the valves remain shut. Aortic and pulmonary artery pressures oppose opening of the respective valves. They remain closed until ventricular pressures very slightly exceed the arterial pressures in these vessels. When this pressure is achieved, the pulmonary and aortic valves open. F

7. EKG Ventricular Pressure Aortic Pressure Ventricular Volume P 120 0 Mm Hg 130 40 ml AV valves close QRS Semilunar valves open As long as ventricular pressure exceeds arterial pressure, blood is squeezed out of the ventricles and their volume decreases. G

8. EKG Ventricular Pressure Aortic Pressure Ventricular Volume P 120 0 Mm Hg 130 40 ml F, AV valves close QRS Preload Afterload Semilunar valves open Afterload is the intraventricular pressure required to cause blood to exit the ventricles. It varies throughout the ejection phase. H

9. EKG Ventricular Pressure Aortic Pressure Ventricular Volume P 120 0 Mm Hg 130 40 ml F, AV valves close QRS Afterload Semilunar valves open Note that aortic pressure is lower than ventricular pressure while blood is exiting the ventricle I

10. EKG Ventricular Pressure Aortic Pressure Ventricular Volume P 120 0 Mm Hg 130 40 ml F, AV valves close QRS Semilunar valves open Semilunar valves close After a period of time the ventricles cease to contract and begin relaxing. When this occurs, the pressure in the ventricles drops below arterial pressure and the aortic and pulmonary valves are pushed shut by backflow of blood into their chambers. J

11. EKG Ventricular Pressure Aortic Pressure Ventricular Volume P 120 0 Mm Hg 130 40 ml F, AV valves close QRS Semilunar valves close J, T T Relaxation begins after the T wave of the EKG. With the aortic valve shut, ventricular pressure drops but volume stays constant (isovolemic) because all the valves are closed. K

12. EKG Ventricular Pressure Aortic Pressure Ventricular Volume P 120 0 Mm Hg 130 40 ml F, AV valves close QRS Semilunar valves open Semilunar valves close J, T T When ventricular pressure is less than atrial pressure the AV valves open and blood enters the ventricles which increases their volume. L

13. EKG Ventricular Pressure Aortic Pressure Ventricular Volume P 120 0 Mm Hg 130 40 ml F, AV valves close AV valves open QRS Semilunar valves open Semilunar valves close J, T T Please take note on this panel when the valves open and close and what events are associated with their opening and closing. M

14. EKG Ventricular Pressure Aortic Pressure Ventricular Volume P 120 0 Mm Hg 130 40 ml F, AV valves close Systole AV valves open QRS Semilunar valves open Semilunar valves close J, Ventricular systole is that time when the ventricles are contracting and includes the isovolumetric contraction and ejection phases. N T T

15. EKG Ventricular Pressure Aortic Pressure Ventricular Volume P 120 0 Mm Hg 130 40 ml F, AV valves close Diastole AV valves open QRS Semilunar valves open Semilunar valves close J, Ventricular diastole is that time when the ventricles are relaxed. O T T

16. Left Ventricular Pressure Aortic Pressure 120 0 Mm Hg AV valves close Semilunar valves close Semilunar valves open AV valves open Left Ventricular and aortic pressure profiles.

17. Left Ventricular Pressure Aortic Pressure 120 0 Mm Hg AV valves close Semilunar valves close Semilunar valves open AV valves open Right Ventricular Pressure Pulmonary Artery Pressure Right ventricular and pulmonary artery pressure profiles.

18. 120 0 Mm Hg “v” wave (ventricular filling) “a” wave atrial contraction “c” wave (ventricular contraction) Jugular Venous Pressure