Systolic Function Flashcards
Ischemia
Lack of oxygenated blood supply to coronary arteries
Myocardial Infarction (MI)
Heart attack. Involves the development of ischemia and necrosis of myocardial tissue due to a sudden decrease or blockage in coronary perfusion (flow of blood through coronary arteries)
*Leading cause of death in US
Cardiac Ourput
Amount of blood pumped in one minute
Normal: 4-8 liters/minute
Cardiac Reserve
The heart’s ability to adjust quickly to immediate demands
Afterload
Amount of PRESSURE the ventricle must generate to force open the semilunar valves and overcome arterial pressure
Afterload= pressure
Preload
The amount of STRETCH in the heart before it can start to contract. Associated with volume
Preload= volume
Inotropic
Change in contractility strength
Frank Starling’s law of the heart
Heart muscle increases it’s strength of contractility in response to the stretching of the myocardial fibers. Greater stretch = stronger contraction
Stroke Volume
Volume of blood pushed into aorta with each beat (ventricular contraction)
SV=EDV-ESV
End-diastolic Volume (EDV)
Volume of blood in ventricle at the end of diastole
End-systolic volume (ESV)
Volume of blood in ventricle at the end of systole
Ejection Fraction
Percent of end diastolic volume pushed into aorta with each beat
Normal=
What two factors determine Cardiac Output? What is the formula for determining cardiac output?
Stroke Volume and heart rate
CO=SV x HR
How do you determine stroke Volume?
It is the volume of blood ejected in a stroke.
SV=EDV-ESV
What three elements effect stroke Volume?
Preload
Contractility
Afterload
Ejection Fraction
% of EDV pushed into the aorta with each beat
Normal Range: 55%-65%
Fractional Shortening
% cardiac muscle fibers shorten with
contraction
Hypokinesia
Akinesis/Akinesia
Dyskinesia/Dyskinesis
Asynchrony
Aneurysm
Best Measurement of Systolic Function
Ejection Fraction
Methods for Measuring EF
1) Modified Simpson’s in A4C and A2C views. Measures ventricular volume in diastole and systole to get difference and determine EF
2) 2D in PLAX View: Measures diameter of ventricle and endocardial wall thickness in diastole and systole
3) M-Mode in PLAX View: Places single beam through ventricle and traces diameter changes over time.
What are the factors of contractility?
Inotropic- strength of contractility
Chronotropic- heart rate
Dromotropic- Affects the speed of the electrical system
