Lecture 16- Pathophysiology Of Heart Failure Flashcards
What is heart failure?
Inability of the heart to meet the demands of the body
Results in hypoperfusion, reduced cardiac output, increased pulmonary pressure and tissue congestion
What allows heart to work effectively as a pump?
One way valves
Chambers
Functioning muscle
What causes heart failure?
Most common cause is ischaemic heart disease and myocardial dysfunction through fibrosis
Other causes include aortic stenosis, hypertension, arrythmias, cardiomyopathies and pericardial diseases
Rarely can be causes by sepsis anaemia etc
How to calculate ejection fraction?
Stroke volume divided by end diastolic volume
How is cardiac output measured?
Volume delivered per minute
Co= Sv X HR
What influences stroke volume?
Pre load, afterload and myocardial contractility
Frank starling’s law?
More ventricular distension during diastole means greater ejection volume during systole up to a point
Reasons why SV reduced in heart failure?
Reduced pre load
Increased afterload
Reduced myocardial contractility
Failure results from a filling or contractility problem
Classifying heart failure with ejection fraction?
No change in EF means contractility problem
Preserved EF points to diastolic filling problem
What is normal EF?
Normally over 50% typically over 60%
Reduced under 40%
Most common cause of right sided heart failure?
Left sided heart failure
What happens with cardiac failure?
Get neuro-hormonal activation. Good normally bad in HF.
Baroreceptors in carotid sinus trigger sympathetic activity leading to increas3d heart rate and peripheral resistance
Juxtaglomerular apparatus in kidney activates RAAS pathway leading to increased fluid volume, vasoconstriction and enhances sympathetic activity leading
Causes heart to work harder and makes condition worse
Main heart failure symptoms?
Fatigue, breathlessness, leg swelling
Why does oedema occur with heart failure?
Backing up of blood increaeses hydrostatic pressure so more fluid leaves the vasculature
How to tell right from left sided heart failure?
Right side causes systemic backing of blood so leads to peripheral oedema, raised jugular pressure and enlarged liver while also giving breathlessness and fatigue
LH causes orthopnoea, paroxysmal nocturnal dyspnoea, basal pulmonary crackles and cardiomegaly due to fluid contesting the lungs. Breathlessness and fatigue also
