Haemodynamics in HF Flashcards
what is preload
the level of stretch that a cardiomyocyte is exposed to before ventricular ejection
LV EDV
what is after load
the pressure against which the heart is contracting which it ejects blood
increased after load in hypertension
describe the specific baroreceptor reflex
arterial stretch sensed
afferent loop ends in Nucleus tracts solitarius (NTS) and rostral; ventrolateral medulla
reduces sympathetic tone and augment vagal tone by reducing HR and SV
what is the mechanism of action at the juxtaglomerular apparatus
renal perfusion pressure sensed at glomerulus - sodium concentration sensed in fluid surround distal convoluted tubule
if ether of these are reduced renin is released
what happens during diastolic dysfunction vs systolic
known as HF with reserved ejection fraction (HFPEF)
sys - known as HF with reduced ejection fraction (HFREF)
what happens during HF
raised pressure in pulmonary circulation - interstitial space in lungs falls with fluid - pulmonary oedema/pleural effusion
sudden breathlessness and low sao2
lying flat worsens the symptoms
what happens when there is reduced ejection fraction
reduced CO, Reduced SBP
reduced arterial stretch
reduced renal perfusion
what is the cardiovascular maladaptive to reduced EF
increased preload lengthens sarcomeres
raise in EDV of LV and compensates for a while
what is the bowditch effect
as HR increases so does cardiac performance up until a point where HR increase too much as performance decreases
how does morphine help in HF
relax pulmonary vessels
reduce preload and take the strain off the LV
help with breathing and pain
how do diuretics help HF and what are some side effects
limit reabsorption of fluid, maximise LV contractility
renal dysfunction, reduces Na K Mg, can induce diabetes (thiazides)
how do beta blockers help in HF
involved in myocardial and renal responses to reduced CO
these are blocked and reduce HR allows more LV filling time
blunts RAAS over activation
