Events of the Cardiac Cycle

Why did the blood flow across the valve? Desire - it wanted to Ability - it could do it Movement = Desire X Ability Flow = Driving Pressure X Conductance Flow = Driving Pressure X 1 Resistance

A B Driving Pressure = ∆P driving = P A -P B

DiastoleSystole Measure: ECG Sound Pressure Aorta Left Atrium

Measuring Left Atrial Pressure

P A = QR + P B P A - P B = Q X R.

DiastoleSystole Measure: ECG Sound Pressure Aorta Left Atrium Left Ventricle Volume of Left Ventricle Valves Flow of Blood Cardiac Muscle Tension

Diastasis Passive Ventricular Filling

Time (s) Left Ventricle Volume (ml) Pressure Sounds ECG mmHgkPa P wave Aorta Left Ventricle Left Atrium

Atrial Depolarization at the end of diastasis

Atrial Systole contraction of atrial muscle

Time (s) Left Ventricle Volume (ml) Pressure Sounds EKG mmHgkPa Phase Aorta Left Atrium Left Ventricle QRS 4 a wave Atrial Systole End-diastolic LV Pressure

Isovolumic Ventricular Contraction contraction of ventricular muscle - all valves closed

Time (s) Left Ventricle Volume (ml) Pressure Sounds EKG mmHgkPa Phase Aorta 1 Isovolumic Contraction Slope = LV dp/dt End-diastolic LV Volume mitral closes Left Ventricle Left Atrium

Rapid Ejection Ventricular Contraction: Semi-lunar valves open

Time (s) Left Ventricle Volume (ml) Pressure Sounds EKG mmHgkPa Phase Left atrium Diastolic arterial pressure C wave 4 8 Rapid Ejection Left Ventricle Aortic valve opens

Reduced Ejection Ventricular still contracting but arterial pressure is now falling

Time (s) Left Ventricle Volume (ml) Pressure Sounds EKG mmHgkPa Phase 4 8 End systolic LV pressure Reduced Ejection Aortic Valve Closes 2 T wave Systolic arterial pressure Arterial pulse pressure

Isovolumic Relaxation Ventricular Muscle relaxing: All valves closed

Time (s) Left Ventricle Volume (ml) Pressure Sounds EKG mmHgkPa Phase 4 8 Aortic Valve Closes Isovolumic Relaxation End-systolic volume Stroke volume Mitral Valve Opens Ejection Fraction = Stroke Volume End-diastolic volume Incisura

Rapid Ventricular Filling Ventricular Filling as Muscle Relaxes

Time (s) Left Ventricle Volume (ml) Pressure Sounds EKG mmHgkPa 4 8 Rapid filling (Early diastole) Mitral Valve Opens v wave 3

Diastasis Passive Ventricular Filling

Time (s) Left Ventricle Volume (ml) Pressure Sounds EKG mmHgkPa 4 8 Diastasis

Time (s) Left Ventricle Volume (ml) Pressure Sounds EKG mmHg kPa 4 8 a v c P QRS T EDV ESV SAP DAP EDLVP ESLVP MO MC AO AC

Aorta Left Ventricle Right Ventricle Pulmonary Artery LA RA Splitting of 2nd Heart Sound

A. Mitral regurgitation mmHg kPa Left Ventricle Volume (ml) Pressure Sounds EKG

Aortic Insufficiency B mmHg kPa Left Ventricle Volume (ml) Pressure Sounds EKG

Mitral Stenosis C mmHg kPa Left Ventricle Volume (ml) Pressure Sounds EKG

Aortic Stenosis D. kPa mmHg Left Ventricle Volume (ml) Pressure Sounds EKG

Isovolumic contraction Rapid Filling Isovolumic relaxation Rapid Ejection Reduced Ejection Aortic valve closes Aortic valve opens Mitral valve closes Mitral valve opens Diastasis & Atrial Systole

Stroke Volume End Diastolic Volume & Pressure Diastolic arterial blood pressure End Systolic Volume & Pressure Systolic arterial blood pressure

Stroke Work Stroke Volume Mean Ventricular Ejection Pressure Stroke Work X Heart Rate = Minute Work External Work of the Heart

Internal Work of the Heart Non-contractile metabolic needs Contractile energy not transferred to the blood Internal Work Depends on Pressure Generated Ventricular Radius