chronic heart failure Flashcards
(41 cards)
1
Q
what is chronic heart failure? 2
A
- a state which develops when the heart fails to maintain an adequate cardiac output to meet the demands of the body
- results from any structural or functional abnormality that impairs the ability of the ventricle to eject blood (systolic HF) or fill with blood (diastolic HF)
2
Q
what is stroke volume affected by? 3
A
- contractility
- preload
- afterload
3
Q
what does an excessively high heart rate result in?
A
a decrease in the amount of time allowed for the ventricles to fill in diastole which causes SV and thus CO to fall
4
Q
what is preload?
A
the volume of blood or stretching of the cardio myocytes at the end of diastole prior to the next contraction
5
Q
what affects preload? 4
A
- by the venous blood pressure and the rate of venous return to the heart
- this, in turn, is affected by venous tone and volume of circulating blood
- preload increases with increasing blood volume and vasoconstriction
- decreases with blood volume loss and vasodilation
6
Q
what is the frank-sterling law? 4
A
- describes relationship between preload and cardiac output
- an increase in volume of blood filling, stretching the heart muscle fibres, causing greater contractile forces which in turn increases the stroke volume
- is true only up to a certain point, at some stages the fibres can become overstretched and the force contraction is reduced
- increase in preload, increases stretch, increases contraction and increases SV and CO
7
Q
what is afterload? 3
A
- the resistance/ end load against which the ventricle contracts to eject blood
- the pressure in the aorta/ PA that the ventricular muscles must overcome to eject blood
- the greater the pressure in the aorta/ PA, the greater the afterload on the ventricles
8
Q
what affects afterload? 3
A
- increases with hypotension and vasoconstriction
- decreases with vasodilation
- as the afterload increases, cardiac output decreases
9
Q
name 2 types of low output heart failure?
A
systolic
diastolic
10
Q
describe high output heart failure? 2
causes? 5
A
- occurs in context of other medical conditions which increase the demand on the cardiac output causing a clinical picture of HF
- the heart is functioning normally, but cannot keep up with the high demand for blood in one or more organs in the body
- thyrotoxicosis
- anaemia
- pregnancy
- acromegaly
- sepsis
11
Q
what is systolic heart failure? 4
A
- progressive deterioration of myocardial contractile function
- ischaemic injury
- volume overload
- pressure overload
12
Q
what is diastolic heart failure? 5
A
- inability of the heart chamber to relax, expand and fill sufficiently during diastole to accommodate an adequate blood volume
- significant left ventricular hypertrophy
- infiltrative disorders
- constrictive pericarditis
- restrictive cardiomyopathy
13
Q
name some causes of heart failure? 5
A
- coronary heart disease
- hypertensive heart disease
- valvular heart disease
- myocardial disease/ cardiomyopathies
- congenital heart disease
14
Q
what are cardiomyopathies?
name 3 different types?
A
- diffuse disease of the heart muscle leading to functional impairment
- dilated cardiomyopathy
- hypertrophic cardiomyopathy (hereditary)
- restrictive cardiomyopathy
15
Q
describe dilated cardiomyopathy? 4
A
- various causes 50% familial
- ETOH, pregnancy, systemic disease, muscular dystrophies
- drug toxicities
- myocarditis
16
Q
what is the main cause of restrictive cardiomyopathy?
A
amyloid
17
Q
describe the pathophysiology of heart failure? 3
A
- pump failure leads to the reduced SV and CO. compensatory mechanisms kick in to maintain arterial pressure and perfusion of vital organs
- the frank sterling mechanism
- myocardial structural change: augmented muscle mass (hypertrophy) with or without cardiac chamber
18
Q
describe the activation of the neurohormonal system? 3
A
- release of noradrenaline= increases the heart rate and myocardial contractility- causes vasoconstriction
- release of ANP/BNP
- activation of RAAS
19
Q
how can compensatory mechanisms worsen heart failure? 3
A
- vasoconstriction= increased resistance against which heart has to pump and may decrease CO
- Na and water retention= increased fluid volume which increases preload. if too much it will stretch, decreasing contractile strength and CO
- excessive tachycardia= decreased diastolic filling time leads to decreased ventricular filling and decreased SV and CO
20
Q
what are the clinical types of heart failure? 3
A
- left sided, right sided and biventricular failure
- acute and chronic failure
- compensated and decompensated heart failure
21
Q
describe left sided heart failure?
- what are the causes? 4
A
- blood backs up progressively from the left atrium to the pulmonary circulation
- ischaemic heart disease
- hypertension
- valvular disease
- myocardial disease
22
Q
how does left ventricular failure affect the lungs? 3
A
- pressure on the pulmonary veins is transmitted retrogradely to the capillaries and the arteries
- this leads to pulmonary congestion and oedema
- heavy wet lungs
23
Q
what do heavy wet lungs lead to? 3
A
- breathlessness exaggeration of the normal breathlessness that follows exertion
- orthopnoea= breathlessness lying flat that is relived by sitting or standing
- paroxysmal nocturnal dyspnoea= an extension of orthopnoea with attacks of extreme dyspnoea bordering on suffocation usually at night
24
Q
describe how left ventricular failure can affect the kidney? 4
A
- decreased cardiac output
- reduction in renal perfusion
- activation of renin-angiotensin-aldosterone system
- retention of salt and water with consequent expansion of interstitial fluid and blood volumes
25
how can left ventricular failure affect the brain? 5
- hypoxic encephalopathy
- irritability
- loss of attention
- restlessness
- stupor or coma
26
describe right sided heart failure? 4
- usually as a consequence of left sided heart failure (congestive cardiac failure)
- cor-pulmonale: right sided heart failure due to significant pulmonary hypertension due to increased resistance within pulmonary circulation. usually as a result of respiratory disease
- valvular heart disease
- congenital heart disease
27
what are the systemic effects of heart failure? 5
- liver and portal system= congestive hepatomegaly, centrilobular necrosis when severe, cardiac cirrhosis
- spleen= congestive splenomegaly
- abdomen=ascites-accumulation of transudate in peritoneal cavity
- subcutaneous tissue= peripheral oedema of dependent portions of the body especially the ankle and pretibial
- pleural and pericardial space= effusions
28
describe biventricular failure? 3
- (congestive cardiac heart failure)
- either due to the same pathological process on each side of the heart
- or a consequence of left heart failure leading to volume overload of the pulmonary circulation and eventually the right ventricular causing right ventricular failure
29
what is the clinical presentation of heart failure? 8
- due to excess fluid accumulation:
- dyspnoea
- orthopnoea
- oedema
- hepatic congestion
- ascites
- due to reduction in cardiac output:
- fatigue
- weakness
30
how do we classify heart failure? 4
- class I: no limitation of physical activity
- class II: slight limitation of ordinary activity
- class III: marked limitation, even during less than ordinary activity
- class IV: severe limitation with symptoms at rest
31
what are the clinical symptoms of heart failure? 8
- cool, pale extremities
- tachycardia -elevated JVP
- third heart sound - gallop rhythm
- displaced apex-left ventricular enlargement
- crackles or decreased breath sounds at bases on chest auscultation
- peripheral oedema
- ascites
- hepatomegaly
32
what are the clinical tests we use to determine heart failure? 5
- CXR
- ECG
- blood investigations
- echocardiogram, cardiac MRI
- coronary angiography
33
name 2 loop diuretics?
what they do? 3
side effects?
- frusemide, bumetanide
- inhibit Na+ reabsorption from the proximal tube
- K+ loss from the distal tube
- can be given IV or orally
- electrolyte abnormalities and diminished renal perfusion
34
name 2 mineralocorticoid receptor antagonists?
what they do? 3
side effects? 2
-eplerenone, spironolactone
- acts on the distal tube
- promotes Na+ excretion and K+ reabsorption
- reduced hypertrophy and fibrosis
- gynaecomastia
- electrolytes and renal function abnormalities
35
name 5 ACE inhibitors?
what they do? 3
side effects? 3
-ramipril, perindopril, enalapril, captopril, lisinopril
- act on activated RAAS
- given orally in small doses with slow titration
- block the production of angiotensin causing vasodilation, BP lowering, reduce cardiac work
- cough
- hypotension
- renal impairment
36
name 3 beta blockers?
what they do? 4
side effects?2
-bisoprolol, carvedilol, metoprolol
- block the action of adrenaline and noradrenaline on adrenergic beta receptors
- small HR, reduce BP
- given orally in small doses with slow titration
- treat arrhythmias
- bronchospasm
- claudication
37
name a SA node blockade?
what they do? 3
side effects? 2
- ivabradine
- blocks the If channels within the SA node
- slow heart rate, no effect on BP
- given orally with dose titration
- visual aura
- bradycardia
38
name an ARNI
what they do? 4
side effects? 2
-sacubitril valsartan
- acts on activated renin-angiotensin system
- also blocks the breakdown of ANP/BNP
- blocks the production of angiotensin causing vasodilation, low BP and lower cardiac work
- promote natriuresis= sodium exertion, vasodilation, reduce hypertrophy and fibrosis
- hypotension
- renal impairment
39
what is digoxin? 4
- increases myocardial contractility
- slows conduction at the AV node- use in AF
- excreted by the kidney- toxicity important
- given in acute HF, especially in AF, in chronic HF in selected cases
40
name some other therapies for heart failure? 7
- Cardiac resynchronisation therapy (CRT)
- Implantable cardioverter defibrillator (ICD)
- Dialysis and ultrafiltration
- Ventricular assist device (LVAD/RVAD)
- Intra-aortic balloon pump
- Cardiac transplantation
- Stem cell therapy
41
what is CRT? 3
cardiac resynchronisation therapy
- biventricular pacing
- standard pacemaker equipped with 2 wires conducting pacing signals to specific regions of the heart
