Cardiac Output
Measures the effectiveness of the heart’s pumping abilities.
CO is defined as the amount of blood that leaves the heart in one minute.
    CO = Stroke Volume (SV) X Heart Rate (HR)
Normal CO: Approximately 4-8 liters/minute
Cardiac Index: CO per square meter of BSA

Stroke Volume (SV)
The amount of blood that leaves the heart with each beat or ventricular contraction.
Not all blood ejected
Normal Adult 70 ml / beat
Ejection Fraction (EF)
The percentage of end-diastole blood actually ejected with each beat or ventricular contraction.
Normal adult 55-70% (healthy heart)

Three factors regulate stroke volume:
Preload - The degree of stretch of the ventricle at the end of diastole.
Contractility - Force of ventricular contraction (systole); inotropy.
Afterload - The amount of resistance the ventricular wall must overcome to eject blood during systole.

Serum Enzymes: Cardiac 
Creatine Phosphokinase  (Total CK / CPK)
 Non-Specific: enzyme elevated with damage to  heart or skeletal muscles and brain tissue.
  Elevates in 4 to 8 hours
  Peaks in 15 to 24 hours
  Returns to normal in 3 to 4 days
Creatine Phosphokinase Isoenzyme (CPK-MB)
 Specific: isoenzyme of CPK; elevated with cardiac muscle damage.
  Elevates in 4 to 8 hours
  Peaks in 15 to 24 hours
  Returns to normal in 3 to 4 days
Myoglobin
 Non-specific: a heme protein found in muscle tissue; elevated with damage to skeletal or cardiac muscle.
  Elevates in 2 to 3 hours
  Peaks 6-9 hours
  Returns to normal 12 hours
Lactic Acid Dehydrogenase (LDH)
 Non-specific: enzyme elevated with damage to many body tissues. (i.e. heart, liver, skeletal muscle, brain and RBC’s); Not frequently used today.

Share Medical Presentations