HEART FAILURE Flashcards
what is heart failure?
the inability of the heart to deliver adequate blood to the body to meet end organ metabolic needs and oxygenation at rest or mild exertion
what is systolic heart failure?
when the heart cant contract enough and pump the blood hard enough during systole
has an ejection fraction of <40
what is diastolic heart failure?
when the heard cannot relax enough to adequately fill with blood during diastole
normal ejection fraction as both stroke volume and total volume are decreased
what is pre-load?
the pressure in the ventricle just before it begins contraction
what is after-load?
the systemic vascular resistance - the resistance the heart must overcome to open the aortic valave and push blood out of the heart
what is the Frank-Starling relationship?
the force developed in a muscle fivre depends on the extent to which the fibre is stretched (e.g. more blood fills ventricles = harder ventricles contract)
what is the cardiac output?
the volume of blood ejected from the heart in 1 minute
norm = 4-8L/min
what is the ejection fraction?
stroke volume/total volume
norm = 50-70%
what is it called when you get heart failure of both ventricles?
biventricular HF
what are some causes of systolic HF
ischaemic heart disease
long standing hypertension
dilated cardiomyopathy
how does long standing hyertension lead to systolic HF?
increased vascular peripheral resusrance leads to left sided hypertrophy which increases metabolic demands as well as compressing the coronary vessels and therefore reducing suppky
increased demand and reduced supply leads to failure
how does dilated cardiomyopathy lead to heart failure?
heart chambers dilate in an attempt to fill the ventricle with larger volumes of blood so it will contract more (Frank-Starling law)
overtime muscles thin and get weak
what are some causes of diastolic HF?
hypertension
aortic stenosis
hypertophic cardiomyopathy
restrictive cardiomyoapthy
why do hypertension, aortic stenosis and hypertrophic cardiomyopathy cause diastolic HF?
they lead to concentric hypertrophy (thickening of chamber walls) leaving less room for filling
how does restrictive cardiomyopathy lead to diastolic HF?
the muscles become stiff and less compliant so the ventricles cannot easily expand and fill with as much blood
outline how the kidneys play a role in HF?
when the blood doesnt pump out enough blood there is less blood flow to the kidneys, this activates RAAS causing Na+ and H2O reabsorbiton = fluid retention which can increase pre-load of the heart but in the long term this leads to a lot of fluid leaking from the vessels
what are the heart failure?
pulmonary oedema symptoms
anasarca
fatigue
what is anasarca?
fluid in the wrong place presenting as gradual weight gain, oedema, ascites and pleural effusions
what are some typical x-ray findings of pulmonary oedema?
upper lobe diversions
kerley B lines
cardiomegaly
interstital oedema/pleural effusions
what are the signs of pulmonary oedema?
breathlessness orthopnoea paroxysmal noctural dyspnoea using accessoru muscles sweating cold clammy cysnosed pink frothy sputum
why do we get pulsus alternas in severe left ventricular HF?
reduced ejection fracture leaving blood in the ventrcile (weak pulse) and then on the next beat it will be strong as ventricle is already half full (strong pulse)
what are some signs of right ventricular sided HF?
JVP distention
hepatospenomegaly
how do we diagnose HF?
BNP in blood >400pg/ml
echocardiography to estimate ejection fraction, ventricular wall and chamber size, asses heart valves and pulmonary arterial pressures
how do we classify heart failure?
using the New York Heart Association classification: class 1 - symptoms on extreme exertion class 2 = symptoms on moderate exertion class 3 = symptoms on mild exertion class 4 = symptoms at rest
whats the aim of treatment for heart failure?
reducing bp to reduce the workload of the heart
outline the treatment of HF?
reduce Na+ and fluid intake
beta blocker
ACEi
if class 2 add a diuretic
if class 3 add aldosterone antagonists or vasodilators
if class 4 ass an inotrope (e.g. digoxin) and get a heart transplant
