Applied Cardiac Phsyiology Flashcards
What is preload ?
Volume in Ventricles in the end of diastole
Increased preload= increased stretch of myocardium
Too much stretch = unable to squeeze properly
What is the Frank Starlings Mechanism ?
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What will increase preload?
- Reduced HR - Allows more time for ventricles to fill
- Increased circulating volume - eg giving fluids
- Valve defects - eg aortic stenosis or aortic regurgitation
What will decrease preload?
- Decreased venous blood pressure - eg hemmorhage
- Atrial contraction failure
-Increased HR
-Increased intrathoracic pressures
-Valvular problems
-Ventricular failure
What do these terms mean in regards to myocardium contractility ?
- inotropic (increases contractility)
- chronotropic (increases heart rate)
- Dromotropic (increases rate of conduction through AV node)
- Lusitropic (increases relaxation of myocardium during diastole)
Contractilityis the intrinsic strength of the cardiac muscle independent of preload, but a change in preload will affect the force of contraction.
What is contractility?
What can affect it?
Intrinsic strength of the cardiac muscle independent of preload, but a change in preload will affect the force of contraction.
Oxygenation
Electrolytes abnormality
PH
Temperature
Hormones
Medications
NS
What is afterload ?
Determines of peripheral vascular reistance ?
Will GTN increase of decrease afterload?
Afterload will decrease
Will cold weather ( with poor protection) increase of decrease afterload ?
Afterload will increase
How do you work out cardiac output?
HR X SV
How do you work out stroke volume
Blood volume x vascular resistance
45 yo
Severe Chest pain since 2 h
Dx?
Preload? - Increase
Contractility? - Decrease
Afterload? Initially, this will change, however, there will be an increase in afterload.
Stroke Volume? - Decrease
What will happen with Heart Rate? increase
What will happen with CO? Decrease?
What will happen with BP? Decrease
What is BECKS triad ?
What is the Classic AAA triad ?
