Definitions Flashcards
Ejection Fraction
ratio of vol of blood ejected from ventricle per beat (SV) to vol of blood in ventricle at end of diastole, load-dependent parameter
Chronotrophy
Changes in HR
Lusitrophy
myocardial relaxation; energy-consuming process linked to reuptake of Ca
SNS stimulation: +lusitrophic effect
Ventricular relaxation impaired by hypoxia, acidosis, cardiac dz (LV hypertrophy, ischemia)
Bathmotrophy
changes to excitability of heart m
Dromotrophy
conduction velocity through AVN
Ventricular Systolic Function
principal determinant of SV
myocardial contractility, relaxation, preload, afterload
Ventricular Diastolic Function
coronary perfusion, myocardial relaxation
myocardial compliance, filling pressures, mechanical rhythm/function, SNS activity, venoconstriction, venous return
Stroke Volume
vol of blood ejected during one ventricular ctx
Consists of preload, after load, contractility
=EDV-ESV
Preload
venous return during diastole preloading ventricle before ctx/eject
Afterload
resistance against systolic ejection that ventricle must overcome IOT eject blood
Frank Starling
more heart muscle is stretched during filling, greater the force of ctx, greater quantity of blood pumped into the area
SAP
peak pressure maintained in artery or arteriole during one cardiac cycle
Determined by SV, velocity of LV ejec, arterial resistance, blood viscosity
DAP
lowest arterial pressure measure during cycle
Affected by blood viscosity, arterial compliance, cardiac cycle length
Isovolumetric contraction
rapid increase in ventricular pressure while both AV, semilunar valves closed so ventricular vol remains constant, right arm of PV loop
Isovolumetric relaxation
period btw closure of semilunar valves, opening of AV valves
o Beginning of ventricular diastole
o Rapid decrease in ventricular pressure, no change in ventricular vol
Isotonic Contraction
period where semilumar valves open, minimal changes in ventricular pressure but ventricular vol decreases
Frank Starling Curve
SV vs EDP: afterload dependent measure of inotropy
Increased inotrophy shifts curve up, L
Decreased shifts curve down, R
QT Interval
duration of ventricular AP, ventricular depolarization, repolarization
PR Interval
onset of P wave to start of QRS complex, reflects conduction through AV node
RR Interval
duration btw each cardiac cycle
PR/PQ Interval
time for atria to contract prior to ventricular filling, atrial kick
ST Segment
interval beginning immediately after S wave of QRS (J point) and preceding T wave
Unstressed Volume
certain vol required to fill vascular bed to point where presence exerts force on vessel walls
Stressed Volume
any vol above unstressed volume’s exertion of pressure, exerts increasing depress of pressure on venous vascular bed
Ohm’s Law
current inflow in electrical circuit = electromotive force/voltage or resistance to flow
o I (current) = E (voltage)/R
o Flow of fluids through non-distensible tube: flow = driving pressure/resistance to flow (Q=P/R)
Fahraeus-Linquist Effect
centralization of RBCs, decreased RBC #s at vessel wall (plasma skimming)
Small vessels
