Session 9 Flashcards
What is heart failure?
A state in which the heart fails to maintain an adequate circulation for the needs of the body despite an adequate filling pressure
Failure of the pump action of the heart
What is the primary cause of systolic heart failure?
ISCHAEMIC HEART DISEASE
Apart from ischaemic heart disease, what are some other causes of heart failure?
Hypertension Dilated cardiomyopathy Valve disease Pericardial disease Arrhythmias - e.g. persistent tachycardia High-output heart failure
What happens in high-output heart failure?
Heart can’t keep up with the amount of cardiac output the body needs
How can arrhythmias (persistent tachycardia) cause heart failure?
Persistent tachycardia —> Changes in structure of the heart —> Failure of pump action —> Heart failure
How is heart failure progression classified by the NYHA functional classification?
Class I - Class IV
In which classes of the NYHA functional classification of heart failure is there no symptoms at rest?
Classes I-III (class IV may have symptoms at rest)
Heart failure is classified by the NYHA functional classification based on the occurrence/absence of symptoms due to different levels of…
Physical activity
What is the typical…
I) cardiac output II) stroke volume III) LV ESV IV) LV EDV V) Ejection fraction
5 litres/min
75 ml/beat
75 ml
150 ml
50% +
State 4 factors influencing cardiac output
Heart Rate
Venous Capacity (LV preload)
Aortic & Peripheral Impedance (afterload)
Myocardial Contractility
How can heart rate affect cardiac output?
Increasing heart rate, increases cardiac output up until a certain point
What functional and structural changes are seen in left ventricular systolic dysfunction?
Increased LV capacity —> Reduced LV cardiac output
Thinning of the myocardial wall (fibrosis/necrosis)
LV dilated
How can left ventricular systolic dysfunction affect the mitral valve?
LV dilation leads to cusps of valves being pulled apart and incompetence of the mitral valve
Describe the structural heart changes seen in heart failure (3)
Loss of muscle
Changes to the ECM (increased type III collagen)
Change of cell structure/function (e.g. Myocyte hypertrophy)
How can the structural heart changes seen in heart failure affect myocardial contraction?
Results in uncoordinated/abnormal myocardial contraction
Describe the ventricular remodelling that occurs in…
I) diastolic heart failure
II) systolic heart failure
Hypertrophied heart
Dilated heart
Describe the ventricular remodelling seen after acute infarction
Global remodelling and scarring to protect damaged areas
Describe the early role of the sympathetic nervous system (baroreceptor-mediated response) in heart failure
Works to improve cardiac output by increased contractility, HR (tachycardia) and arterial and venous vasoconstriction
What long term deleterious effects can activation of the sympathetic nervous system in heart failure have?
B-adrenoceptors become down-regulated/uncoupled
Noradrenaline induces cardiac hypertrophy, apoptosis and necrosis via a-adrenoreceptors
Noradrenaline induces up-regulation of the RAAS
State long term deleterious effects of activation of the sympathetic nervous system in heart failure, with regards to the increased noradrenaline levels
Induces cardiac hypertrophy, myocyte apoptosis, myocyte necrosis via a-adrenoreceptors
How can sympathetic nervous stimulation (in the long term) seen in heart failure affect the variability of the heart rate
Reduction in heart rate variability
Where is angiotensinogen produced?
Liver
Angiotensinogen is clever to _______________ by the action of __________
Angiotensin I
Renin
Angiotensin I is clever to __________________ by the action of ___________________
Angiotensin II
ACE - angiotensin converting enzyme
Angiotensin I and II can both be used to produce angiotensin III by the action of…
NEP
Angiotensin II carries out its effects via which receptors?
AT1 receptors (type 1) AT2 receptors (type 2)
Which receptors does angiotensin III act on?
Type 2 receptors
Which angiotensin II receptors lead to more beneficial effects for a patient?
Type 2 receptors
What effect can activation of the angiotensin II receptors have?
Vasodilator effect by increasing NO levels
Nitric oxide is a powerful _________________
Vasodilator
Name three deleterious effects of angiotensin II binding to type 1 receptors
Vasoconstriction —> Increased afterload —> Decreased CO —> Stroke/Hypertension
LV hypertrophy —> Fibrosis/Remodelling —> HF/MI
Aldosterone release —> Increased salt/water retention —> Renal failure
Angiotensin II results in the release of ____________ which results in increased salt/water retention
Aldosterone
Why is the RAAS commonly activated in heart failure?
Reduced renal blood flow (perfusion pressure) in the kidneys
Atrial natriuretic peptides respond to _________ due to increased ____________
Stretch
Volume
What effect do natriuretic hormones have? (4)
Constricts afferent arterioles
VASODILATOR of efferent arterioles
Decreases Na+ reabsorption in the collecting duct
Inhibits secretion of renin/aldosterone
Where is brain natriuretic peptide produced? Where is atrial natriuretic peptide produced?
Ventricular myocytes (in the brain also)
Atrial myocytes
Natriuretic peptides work to lower the blood pressure and work carried out by the heart by reducing…
The volume of blood
What can be used as a sensitive marker for heart failure?
Natriuretic hormones
Name two things that can result in hyponatraemia (water in excess of Na+ retention) in normal conditions
Increased water intake (thirst)
Action of ADH on V2 receptors in collecting duct
ADH acts on which receptors in which part of the kidney?
V2 receptors
Collecting duct
Normally hyponatraemia _________ ADH release but ADH is ______________ in heart failure
Inhibits
Increased
How can the increased ADH seen in heart failure affect water retention and cardiac output?
Increased water retention
Increased systemic resistance —> Reduced cardiac output
Endothelial is secreted by…
Vascular endothelial cells
What effects does endothelin released from vascular endothelial cells have?
By which mechanism does endothelin communicate with vascular endothelial cells?
VASOCONSTRICTOR effect
Autocrine activity
Activating the RAAS
Describe the changes in levels of endothelin you may see in a patient with heart failure
Increased endothelin in HF
What effect can prostaglandins E2 and I2 have? What are they stimulated by?
VASODILATORS on afferent renal arterioles
Noradrenaline/RAAS
Nitric oxide is a potent ________________ produced by ________________ cells by the action of…
Vasodilator
Endothelial
Nitric oxide synthase
How can NO synthase be affected in heart failure? What effect does this have?
Reduced activity in heart failure
Loss of vasodilation
What does bradykinin promote? (2)
Natriuresis
Vasodilation
Bradykinin stimulates the production of…
Prostaglandins
Describe the levels of tumour necrosis factor seen in heart failure. What effect can these have on the heart?
Increased in HF
Represses myocardial function
What symptom is a tell-tale sign of heart failure?
Oedema
What is oedema?
Excessive volume of fluid within the tissues in the interstitium an intracellularly
Net filtration pressure = …
Hydrostatic pressure - osmotic pressure
How does heart failure affect net filtration pressure and cause oedema?
Increased capillary hydrostatic pressure —> Increased net filtration pressure
More fluid into the interstitium
How is skeletal muscle blood flow affected in heart failure? What consequence can this have on skeletal muscle mass? What symptoms can this result in?
Reduced
Reduction in skeletal muscle mass
Fatigue
Exercise intolerance
Diastolic HF is a less common form of heart failure. What is another name for it? In which patients is it more common?
Heart Failure with Preserved Ejection Fraction
Elderly + Women
In diastolic heart failure there is ___________ LV function with ______________ remodelling
Normal
Concentric
What happens in heart failure with preserved ejection fraction?
Reduced LV compliance and impaired myocardial relaxation. Impaired diastolic LV filling. LV filling becomes dependent on high LA pressure. RV dysfunction can result from high LA/PA pressure.
What can result from the high LA/PA pressures seen in diastolic heart failure?
RV dysfunction
In diastolic heart failure, LV filling becomes dependent on…
High LA pressure
Describe what happens to cardiomyocytes in diastolic heart failure. What causes a reduced LV compliance in diastolic HF?
Thicker and shorter cardiomyocytes - impaired relaxation
Increased deposition of collagen
In diastolic HF there is impaired…
Diastolic LV filling
State 4 common symptoms of left sided heart failure
Fatigue Exertional dyspnoea Orthopnea Paroxysmal nocturnal dyspnoea Tachycardia Cyanosis
What is dyspnoea?
What is orthopnea?
What is paroxysmal nocturnal dyspnoea?
Shortness of breath
Shortness of breath when lying flat
Attacks of shortness of breath at night
What is the name given to failure of both sides of the heart (ventricles)?
Biventricular (congestive) cardiac failure
Describe the term given to heart failure due to…
I) ‘pump failure’
II) ‘failure of LV relaxation)
Left ventricular systolic dysfunction
Heart failure with preserved ejection fraction
Right sided heart failure is often secondary to…
Can also result from…
Left sided heart failure
Chronic lung disease, PE, pulmonary hypertension
Right sided heart failure results in fluid accumulation in areas drained by systemic veins. State some symptoms of RSHF.
Fatigue Dyspnoea Nausea Anorexia Weight Gain DEPENDENT PITTING OEDEMA Enlarged liver/spleen Visible jugular vein
What is heart failure?
Where the heart fails to maintain an adequate circulation for the needs of the body despite an adequate filling pressure
What is chronic heart failure?
Clinical syndrome caused by abnormality of the heart and recognised by a characteristic pattern of renal, neural and hormonal responses
Heart failure incidence is ______________ while prevalence is ____________
Decreasing
Increasing
Give an example of a mineralocorticoid receptor antagonist. How do they work?
Spironolactone
Acts as a competitive inhibitor for aldosterone receptors
