Heart Failure Flashcards
Define heart failure
state ‘in which the heart fails to maintain an adequate circulation for the needs of the body despite an adequate filling pressure’.
Describe the signs and symptoms of heart failure
dyspnoea and fatigue (limiting exercise tolerance)
due to tissue hypoperfusion
tissue fluid retention (pulmonary and/or peripheral oedema)
Explain the pathophysiology of heart failure
Remodelling (e.g. loss of myocytes, fibrosis) of cardiac muscle changes ventricular function/size.
Causes - CHD, hypertension, valvular disease e.g. aortic stenosis
In ejection failure - chamber size is enlarged (overstretched sarcomeres) because muscle walls are thinner and fibrosed.
Uncoordinated contraction.
All causes poor contraction so cannot empty well.
In filling failure- Ventricular chambers too stiff and thickened - space reduced so EDV reduced.
Be able to draw and explain the normal relationship between
CVP (or EDP) and cardiac output and how that relationship alters with increasing severity of heart failure
Y axes = CO
X axes = EDP
In normal heart - inc EDP means inc SV means inc CO
In heart failure - inc EDP - SV cannot inc due to IMPAIRED CONTRACTILITY - dec CO with inc EDP
Be able to define and calculate ejection fraction and explain the factors which lead to the development of heart failure with preserved ejection fraction and heart failure with reduced ejection fraction
Ejection fraction = fraction of the end diastolic volume which is pumped out with each heartbeat.
It is the stroke vol as percentage of EDV.
Should be 50-70%.
HFpEF - LV can’t fill properly, has become stiff so EDV dec and SV has also dec due to this. The EF is same though because it is proportional.
HFrEF / LV systolic dysfunction - heart failure with reduced ejection fraction = inability of the heart muscle to contract properly
Explain the factors which lead to the development of left
ventricular failure, biventricular failure and isolated right ventricular failure and describe the clinical characteristics of each type of heart failure
Left ventricular heart failure - fatigue
Breathlessness
Paroxysmal nocturnal dyspnoea
Orthopnoea
Basal pulmonary crackles
Cardiomegaly (displaced apex beat indicating enlarged LV)
RV heart failure
Fatigue
Breathlessness
Peripheral oedema
Raised JVP
Tender, enlarged liver (liver congestion)
Biventricular = both signs
Describe the involvement of the renin-angiotensin-aldosterone
system and the sympathetic nervous system in heart failure
A drop in BP:
Due to drop in CO
Baroreceptors detect this
Inc symp response- inc HR and inc peripheral resistance.
This means inc afterload.
fall in tissue perfusion:
stimulates renin release from the kidneys.
Renin is an enzyme which catalyses the conversion of angiotensinogen to angiotensin I.
Angiotensin I is converted to angiotensin II (vasoconstriction = inc afterload) by the action of ACE.
Promotes aldosterone release = inc BV (also ADH) = inc preload.
Heart works harder = further deterioration in CO
Explain the formation of the 2 types of oedema in heart failure
Peripheral oedema - right-sided heart failure - raises venous pressure and therefore capillary pressure - inc capillary hydrostatic pressure water moves out.
Sign - raised jugular VP. Touching oedema keeps indentation.
Pulmonary oedema - left sided heart failure - raises left atrial pressure - inc hydrostatic pressure of venules in the pulmonary system - inc volume of tissue fluid accumulates within pulmonary interstitium.
Signs -
Dyspnoea (breathlessness)
Basal pulmonary crackles (on auscultation)
Orthopnoea
Paroxysmal nocturnal dyspnoea
formation of normal tissue fluid
Inc hydrostatic pressure in arteriole end of capillary so fluid moves out. Exchanges oxygen for waste products eg CO2, urea etc. Now at venule end hydrostatic pressure is lower so fluid diffuses back. Excess tissue fluid is drained into lymphatics.
Identify targets for drug action to manipulate cardiac output
RAAS
Afterload
Preload
SNS
Describe the principles involved in the general management of
heart failure, and the categories of drugs used in its therapy.
echocardiogram
Can see if structural/functional issue with the heart causing failure - confirm diagnosis. Diff treatment options for HFrEF and HFpEF.
Identifies potential causes e.g. valvular problems.
ACE inhibitors
Diuretics
