Pathophysiology of cardiac disease (Yr 3) Flashcards
what is backwards heart failure also known as?
congestive heart failure
what is heart failure?
clinical syndrome caused by heart disease resulting in systolic/diastolic function severe enough to overwhelm the normal compensatory mechanisms resulting in poor cardiac output and reduced perfusions (forward) or oedema and effusions (congestive)
what are the possible results of heart failure?
poor cardiac output and reduced peripheral perfusion (forwards)
elevated filling pressures, oedema, effusions (backwards)
what are the major consequences of congestive heart failure?
oedema and effusions
peripheral vasoconstriction
tachycardia/arrhythmias
remodelling/fibrosis of myocardium
when there is a drop in cardiac output and blood pressure which is detected by the baroreceptors, what happens to sympathetic drive?
increased sympathetic drive causing vasoconstriction and increased heart rate and contractility
renin release
what receptors are stimulated to cause vasoconstriction?
alpha adrenoreceptors
what receptors are stimulated to cause increased heart rate?
beta receptors
when is the RAAS stimulated?
decreased glomerular perfusion, which is sensed by the juxtaglomerular apparatus
what happens with RAAS activation?
renin is release
angiotensinogen is converted to angiotensin 1 in the liver
ACE catalyses angiotensin 1 converting to angiotensin 2 in the lungs
angiotensin 2 triggers aldosterone release from adrenal cortex
aldosterone acts on distal convoluted tubules and collecting duct to cause sodium/water retention
what are the effects of angiotensin 2?
causes aldosterone release
causes vasoconstriction
increases sympathetic drive
causes vasopressin release
triggers endothelin
what effects does vasopressin have?
cause water retention
causes vasoconstriction
what substances causes remodelling and fibrosis in congestive heart failure?
angiotensin 2
aldosterone
endothelin
what are the endogenous counteractions of RAAS?
atrial natiuretic peptide
brain natiuretic peptide
what causes atrial natiuretic peptide release?
atrial stretch
what causes brain natiuretic peptide release?
increase ventricular pressure (released from ventricles)
what effects do atrial/brain natiuretic peptides have?
vasodilators
natiuretics/diuretics
why would natriuretic peptides be measured in congestive heart failure?
it is a test for wall stretch (diagnostic for congestive heart failure)
what natriuretic peptide is used to test for congestive heart failure?
NT-pro-BNP
what is the function of peripheral vasoconstriction of CHF?
arterioconstriction to maintain blood pressure
venoconstricition to increase preload
what are the mediators of vasoconstriction in CHF?
alpha 1 receptors (sympathetic nervous system)
angiotensin 2
reduced bradykinin levels (ACE breaks down bradykinin)
vasopressin
endothelin
how does angiotensin 2 help to control glomerular filtration?
constricts the efferent arteriole more than the afferent
what are the effects of ACE inhibitors?
reduce aldosterone release
reduce glomerular capillary pressure
prevent angiotensin 2 mediated remodelling/fibrosis
reduced vasopressin and endothelin release
what drug can be used as an aldosterone antagonist?
spironolactone
what is the main cause of tachycardia in CHF?
elevated catecholamine levels
increased sympathetic drive
reduced vagal tone
