Neurohormonal Responses to Cardiac Dysfunction Flashcards
heart failure
clinical syndrome defined by the inability of the heart to supply adequate blood flow (cardiac output)
decreased ability to accept or pump blood
is heart failure progressive
yes - does not fail acutely
what does decreased ability to accept blood cause
congestion behind the failed side
L sided HF: congests pulmonary veins and lungs
R sided HF: congests systemic veins and liver/abdomen
what does decreased ability to pump blood cause
low cardiac output
what are 3 common causes of heart failure
- myxomatous mitral valve disease - dogs
- dilated cardiomyopathy (DCM) - dogs
- hypertrophic cardiomyopathy (HCM) - cats
myxomatous mitral valve disease
mitral regurgitation leading to progressive volume overload
is myxomatous mitral valve disease systolic or diastolic dysfunction
systolic
mitral valve leaks fluid from LV to LA during systole –> blood accumulates in LA –> increases EDV and EDP
dilated cardiomyopathy (DCM)
enlarged chamber + thin ventricular walls –> decreased contractility
is DCM systolic or diastolic dysfunction
systolic
unable to contract to eject blood due to eccentric hypertrophy –> increases ESV –> volume overload
hypertrophic cardiomyopathy (HCM)
enlarged/thickened ventricular walls –> decreased filling
is HCM a systolic or diastolic dysfunction
diastolic
thick walls have decreased compliance –> decreases EDV, increases EDP
compensatory mechanisms to CV dysfunction
- frank starling
- sympathetic NS activation
- vasoconstriction
- renal Na + H2O retention
- cardiac hypertrophy
frank starling mechanism
increase in venous return (preload) –> heart fills with more blood –> heart wants to return to same ESV –> must eject more blood –> increased stroke volume
what does the frank starling mechanism require in order to work
functional cardiomyocytes
if dysfunctional cardiomyocytes: preload increases but unable to eject enough blood –> inability to increase SV to compensate
how does disease affect the frank starling curve
FS curve: SV (y axis) vs EDP (x axis)
shifts the curve right and down –> shallow slope in increase of SV as EDP increases