Cardiac Function Flashcards
Fluid returns to the heart
Preload
Resistance, how much the heart needs to work to get blood out (SVR)
Afterload
Contractility, force of each beat
Contractile proteins, ATP, calcium
Ionotropy
Heart rate
Chronotropy
How much gets out / total vol.
Ejection Fraction
Atrial depolarization, diastole
P-Wave
Ventricular depolarization, systole
QRS-Complex
Ventricular repolarization
T-Wave
The force or tension developed in a muscle fiber depends on the extent to which the fiber is stretched
More preload and recoil, length-tension relationship
Frank-Starling Law
Parasympathetics, baroreceptor stimulates vagus nerve, low HR, low BP
Vasovagal Syncope
Most representative ECG picture
Lead 2
Coronary arteries fill
Diastole
Distribution system with the capillary bed acting as a filter to provide nutrients/O2 while removing waste/CO2
Left heart and arteries
Collection system with the pulmonary capillary bed acting as a gas exchange circuit
Right heart and veins
Heart contracts against closed valves, no change in volume
Isovolumetric contractions
Heart relaxes, all valves are closed
Isovolumetric relaxation
Volume of blood ejected from the ventricle (EDV - ESV)
Stroke volume
Blood left in the ventricle after the filling phase
End-diastolic volume
Blood left in the ventricle after contraction phase
End-systolic volume
EDV - ESV / EDV
Ejection fraction
Atrial contraction
A waves
Contraction of ventricles causing AV valves to bulge into atria
C waves
Atrial filling (pressure created by blood returning from the systemic circulation)
V waves
Release of norepi/epi, parasympathetic baroreceptor response (CN IX/X)
Determines HR
Right atrium/ventricle, SA/AV nodes, Bundle of His, intraventricular septum
Right coronary supplies…
Left ventricle, right atrium, R/L bundle branches, intraventricular septum, anterior papillary muscles
Left anterior descending artery supplies…
Left atrium/ventricle, SA node
Left circumflex artery
Increased coronary flow
Increased ATP, potassium channels close, depolarization smooth muscle cells = vasoconstriction
Decreased coronary flow
Decreased ATP, potassium channels open, inhibit depolarization of smooth muscle cells = vasodilation
Norepi/epi, thyroid hormone, caffeine, digitalis
Positive inotropes
Calcium channel blockers, beta blockers
Negative inotropes
Regulation of inotropy (contractility)
Contractile proteins, ATP, calcium
Regulation of automaticity
Sympathetic: increased contraction/rate, norepi
*Parasympathetic: decreased contraction/rate, acetylcholine
Autonomic regulation of coronary arteries
Alpha-1: vasoconstriction
*Beta-2: vasodilation
Atrial depolarization
P wave (electrocardiography)
Ventricular repolarization
T wave (electrocardiography)
atrial depolarization to ventricular depolarization, positive change
PR interval (electrocardiography)
Massive ventricular repolarization, necessary for pumping blood out of the heart
R wave (electrocardiography)
ANP
Atrial stretching results in excretion of sodium and volume reduction
Communicates with kidneys
Opposite of RAAS
BNP
Ventricular distention results in excretion of sodium and volume reduction
Communicates with kidneys
Opposite of RAAS
Clinical test of cardiac function
ECG, MRI/CT, echocardiography, SPECT (nuclear medicine), angiography of coronaries (“cath”), labs/bloodwork
