heart failure Flashcards
what is heart failure
Heart provides continuous oxygen supply to the body parts
Heart failure is a clinical syndrome that affects the ability of the heart to provide sufficient blood to meet the body’s needs
Can be sub-divided into either acute or chronic heart failure based on causes
Mainly classified as systolic and diastolic heart failure
Can affect just one side (right side/left side heart failure)
\
Can cause series of deleterious effects in the body
Result in myocardial infarction (sudden stop of cardiac function)
Always heart failure is a secondary condition due to other diseases
explain the cardiac function
Heart meets the demand of the body’s oxygen needs
Heart chambers: right/left atria and right/left ventricles
Right atrium collects deoxygenated blood from the body parts via vena cava
Right atrium supplies the blood to the right ventricle and pumped to the lungs via pulmonary artery
Pulmonary vein collects oxygenated blood from the lungs to the left atrium
Oxygenated blood goes to the left ventricle and pumped to the body parts via aorta
Heart valves: tricuspid & pulmonary on the right; aortic & mitral on the left
what are the classifications of a heart failure
Systolic heart failure
Diastolic heart failure
what is systolic heart failure?
The heart fails to pump the blood out of the ventricles fully
Mainly due to the thin & weak cardiac muscles
Further classified as left and right-side systolic heart failure
Mainly caused by cardiac muscle death, thinner muscles & enlarged ventricles
Ejection fraction is reduced (<40%) although the filling is unaffected
what is diastolic heart failure
Diastolic heart failure
The heart doesn’t fill the blood efficiently
Due to larger cardiac muscles and thus reduced ventricle sizes
Further classified as left and right-side diastolic heart failure
Therefore reduced blood volume in ventricles
Ejection fraction may be same due to the reduced ejected volume & filled volume (i.e. preserved ejection fraction)
Hypertrophy (increased muscle growth) - reduces the ventricle sizes
Stiffening of muscles (muscles die due to lack of O2 and get hardened due to dead cells) – affect the contraction
Failure of one part of heart leads to the dysfunction of other parts of the heart
Usually the left side gets affected first and moves to the right
Heart failure leads to congestion in lungs or other body parts based on the side of HF
(Congestive heart failure)
what is cardiac output?
Total amount of blood pumped out/minute (normally 5L/min)
Cardiac output alters if either stroke volume or heart rate changes
Compensation occurs by increasing stroke volume (squeezing more) or beat faster
what is stroke volume
Stroke volume: amount of blood pumped out for every beat
what is ejection fraction
Ejection volume/fraction = % of blood ejected by each beat
Volume ejected/total volume filled X 100
Normally 55-70% (under 40% for HF)
what are the causes of systolic heart failure
Coronary heart disease (due to plaque deposition) – reduced blood supply to the cardiac myocytes
Cardiomyopathy (Heart muscle diseases due to several factors) – weakens the heart muscles
Valve diseases (including congenital)
Backward blood flow to the atria due to weak valves – increases heart beat to meet the demands
Stenosis – narrowing of aortic & pulmonary valves, stroke volume gets reduced, so heart beats faster
Cardiac arrhythmias (irregular heart beats) – either slow (bradycardia) or faster (tachycardia) or uncontrolled
Increased beating requires more O2 and heart fails to meet this
what are the causes of diastolic heart failure
Hypertension (chronic) - due to other metabolic diseases e.g. DM & obesity
Smaller blood vessels make the heart to work harder to pump the blood
Thus, increase the muscle growth – reduces the size of the ventricles
Aortic stenosis (narrowing of aortic valves) – restricts blood flow and makes harder to pump – increases muscle growth
Cardiac myopathy
Hypertrophy – increased muscle growth that needs more O2
Stiffening of muscles (muscles die due to lack of O2 and get hardened due to dead cells) – affect the contraction
Endocarditis – infection in endocardium
Other factors – such as age, other diseases, alcohol & medications
compensation and decompensation
Activation of sympathetic nervous system
Induces sympathetic nervous system to enhance the cardiac activity
Receptors-mediated effects – contraction & relaxation
Prolonged activation leads to receptor desensitisation
Increasing the preload
Release aldosterone which increase the filling volume and stroke volume
Increased muscle activity
Cardiac hypertrophy
Increase muscle growth to increase ejection volume
Decompensation
In all the cases, increased activity requires more O2, and if body can’t supply more blood, then it will lead to cell death
what are the symptoms of heart failure - backward + forward LEFT SIDE
Forward failure
Tiredness & fatigue - heart is not supplying enough blood/O2 to the body parts
Decreased urination – due to lack of blood supply & reduce fluid loss
Irregular heart beats – to supply more blood
Backward failure
Pulmonary oedema - fluid back up in lungs due (congestion) to reduced pumping
Difficulty breathing & coughing – due to congestion or fluid build up in lungs
Weight gain – due to fluid build up
what are the symptoms of heart failure - backward + forward RIGHT SIDE
Forward failure (can’t pump blood to the lungs)
Tiredness & fatigue – reduced supply to the lungs and thus lack of oxygenated blood
Irregular heart beats – to supply more blood
Backward failure (backup of blood in body)
Oedema - fluid back up in the body (congestion) extremities (e.g. legs) and jugular vein in the neck
Weight gain – due to fluid build up
Increased urination – due to more back up of blood
what are the methods of diagnosis for heart failure
X-ray (to monitor enlarged heart & lungs)
Echocardiogram (to monitor ejection fraction, valves & enlargement)
Blood tests (B-type natriuretic peptides (BNP) from cardiac myocytes)
Classification of severity of heart failure
Treadmill test or exercise activity
Class I: Asymptomatic Heart Failure
no symptoms and no impact on normal activities
Class II: Mild Heart Failure
mild symptoms (i.e. occasional oedema) and somewhat limited ability to exercise
Class III: Moderate to Severe Heart Failure
Comfortable only at rest, noticeable limitations in exercise capacity
Class IV: Severe Heart Failure
Symptoms experienced at rest, not able to exercise without discomfort
