Cardiac output is the amount of blood pumped by the heart per minute, normally around 5 liters. It is determined by stroke volume and heart rate. Stroke volume is the volume of blood pumped out of the ventricles with each beat, normally 70ml. Stroke volume depends on preload, contractility, and afterload. Preload refers to the degree of tension on ventricular muscle at the start of contraction. Contractility is the force of ventricular contraction. Afterload is the pressure the ventricles must pump against. Cardiac output can be measured using echocardiography, indicator dilution, thermodilution, ballistocardiography, or cardiac catheterization using Fick's principle.

1. Cardiac Output (COP)
By Dr.Mohammed AL-Mojtba A. Awad

2. Objectives :
• Definition
• Determinants
Stroke Volume
Heart Rate
• Measurement

3. Definition:
• Amount of blood that is pumped by ventricles
of the heart per minute .
• Normally it = 5000ml (5 Liters)

4. Determinants :
• COP = Stroke Volume x Heart Rate
• So it is Determined by
+ Stroke Volume
+ Heart Rate

5. Stroke Volume
• The volume of Blood pumped out of the
Ventricles by each Beat
• It is Normally 70 ml
• Because End Diastolic Volume (EDV) = 120 ml
& End Systolic Volume (ESV) = 50 ml >>>>
Stroke Volume = EDV - ESV

6. Ejection Fraction
• The Ratio of Stroke Volume to End-Diastolic
Volume
• Or the Percentage of blood in the End of
Diastole that is pumped into the Circulation in
each heart beat
• It is Normally 55 % - 65 %
• It is a very important Practical Marker for
Ventricular wall function .

7. Determinants of Stroke Volume
• Preload
• Contractility
• Afterload

8. Preload :
• The degree of tension or load on the
ventricular muscle when it begins to contract
• It is determined by volume of blood within the
ventricle at the end of Diastole >> it further
depends on Venous Return

9. Frank-Starling Law of the Heart
• Otto Frank & Ernest Starling figured out the
Relationship between Myocardial fibers
Length & the Force of Contraction
• It states that : within limits , the longer , or
more stretched, the heart fibers at the
beginning of contraction, the stronger is their
contraction .

10. Contractility :
• Is a measure of Forcefulness of Contraction at
any Given Preload
• It Represent the Inotropic State of the Heart
>> Affected by :
Sympathetic Stimulation
Drugs ( Digitalis)
Heart Failure

11. Afterload :
• The pressure or Resistance against which
ventricles must pump blood
• affected by
Systemic Blood Pressure
Outflow Obstruction
Increased Afterload = decreased Stroke Volume

12. Laplace Equation & Afterload
• It states that Myocardial Wall Tension Needs
to Increase in Order to Generate an Increased
Intraventricular Pressure to Overcome an
Increased Afterload .
• Wall Tension = intraluminal pressure x
intraluminal Radius / 2*Wall Thickness

13. Measurement of COP :
• ECO-CARDIOGRAPHY
• Indicator (Dye) Dilution
• Thermodilution Technique
• BallistoCardiographic Method
• Cardiac Catheterization >> Using Fick’s
Principle .

14. THANQ