heart failure Flashcards
What is heart failure
A state where the heart fails to maintain an adequate CO to meet the demands of the body
What is the equation
CO=HR*SV
What is preload
The degree of stretching of the cardiomyocytes at the end of diastole prior to the next contraction and it is dictated by venous return.
What is afterload
the resistance against which the ventricles contract to eject blood
What factors affect preload
Venous tone, the volume of circulating blood and decreases with blood volume loss and vasodilation.
What is the frank starling law
An increase in the volume of blood filling the heart stretches the heart muscle fibres which causes greater contractile forces which, in turn, increases the stroke volume. This is true only up to a certain point.
What is low output HF
due to systolic or diastolic HF
What is high output HF
Occurs in the context of other medical conditions which increases the demands on the CO.
The heart itself is functioning normally but cannot keep up with the high demand for blood to one or more organs in the body, e.g. pregnancy, sepsis
What are the causes of systolic HF
Ischaemic injury
volume overload
pressure overload
What are the causes of diastolic HF
Sig left ventricular hypertrophy
infiltrative disorders
constrictive pericarditis
restrictive cardiomyopathy
What is systolic HF and diastolic HF
Progressive deterioration myocardial contractile function.
Diastolic HF is the inability of the heart chamber to relax, expand and fill sufficiently during diastole to accommodate an adequate blood volume.
What are the causes of HF
CHD, hypertensive HD, vascular HD, myocardial HD, congenital HD.
What is a cardiomyopathy
Diffusion disease of the heart muscle leading to functional impairment.
What are the 3 types of cardiomyopathy
Dilate cardiomyopathy
hypertrophic cardiomyopathy- affects young people and athletes (hereditary)
restrictive cardiomyopathy- almost impossible to treat
What are the types of HF
Left side, right side and biventricular failure
acute or chronic HF
compensated and decompensated HF
What are the causes of LSHF
cant get blood out of the LA so it backs up to the pulmonary circulation which leads to pulmonary oedema
causes: IHD, hypertension, VHD and myocardial disease.
What does LSHF lead to
increase in breathlessness, increase in orthopnoea (breathlessness lying flat) and dyspnoea (extreme attacks at night, bordering suffocation).
How does LVF affect the kidneys?
A decrease in renal perfusion activated the RAAS which in turn increases salt and water retention which increase blood volume which in turn increases BP.
Outline causes of RHF
a common cause is LHF, VHD and CHD
What are the systemic effects of RHF
congestive splenomegaly, ascites, peripheral oedema and congestive hepatomegaly
What are clinical presentations of HF
Dyspnoea, orthopnoea, oedema, hepatic congestion, ascites
due to a reduction in CO
Fatigue and weakness
What are clinical signs of cardiac failure
cool, pale, tachycardia, elevated JVP, displaced apex, peripheral oedema, ascites and hepatomegaly
What are clinical tests in HF
ECG, blood investigations, echocardiogram, coronary angiography
Current drug treatment for HF
ACEi, aldosterone antagonists and ARBs, beta-blockers, SA node blockade and diuretics
What is the effect of loop diuretics and give an example
Frusemide: inhibits sodium reabsorption in the PCT, decreased absorption of potassium in the DCT
What is an example of an ACE inhibitor and what do they do
Ramipril: decreases the RAAS which leads to vasodilation, decreased BP and less cardiac work.
What is an example of a beta-blocker and what do they do
bisoprolol: decrease HR and BP, blocks the action of adrenaline and noradrenaline.
Give an example of a SA node blockade and its effects
blocks a channel in the SA node and decreases HR, causes bradycardia and a visual aura.
