Flashcards in CVS Session 11 Deck (94):
What is high output heart failure?
When the output remains the same but demand increases
Give examples of some causes of heart failure.
What is the primary cause of systolic heart failure?
What can cause high output heart failure?
What can cause dilated cardiomyopathy?
What kind of care is often needed with class IV heart failure?
Describe Class I heart failure.
What class of heart failure is a patient who describes having symptoms of breathlessness on ordinary physical activity but is asymptomatic at rest?
How do patients with Class III heart failure present?
Marked limitation of physical activity
Asymptomatic at rest
Which class of heart failure do patients who are unable to carry out physical activity w/out symptoms belong?
Which class of heart failure patients may be symptomatic at rest?
What does cardiac output depend on?
Aortic and peripheral impedance
What is left ventricular preload?
What is after load?
Pressure needed to overcome aortic and peripheral impedance
What is plotted on each axis to give a graph of Starling's law of the heart?
X = cardiac filling/end diastolic volume
Y = cardiac output
What does Starling's law of the heart state?
Force developed in a muscle fibre depends on the degree to which the fibre is stretched
What is the average cardiac output for an adult?
5 litres per minute
What is the average stroke volume for an adult?
75 ml per beat
What is the average LV end systolic volume?
What is the average LV end diastolic volume?
In what range does a healthy ejection fraction lie?
Who much does the average adult heart weigh?
Describe the fine line in treatment for gross heart failure.
Over treat with too many diuretics
Undertreat so fluid levels are too high --> congestive symptoms
What can decrease cardiac output it becomes ineffective in a normal heart?
What is systolic heart failure?
Inability to effectively pump blood out of the heart
How does the remodelling of the heart in acute infarction and diastolic/systolic heart failure differ?
Acute - one sided due to injury
Diastolic/systolic - same both sides
What happens to the left ventricular capacity in systolic dysfunction?
Increases due to thinning of myocardial wall
What causes mitral regurgitation in systolic dysfunction?
Valve leaflets are pulled apart due to cardiac dilation
What changes to the heart are seen in diastolic dysfunction?
What are the structural changes to the heart in heart failure?
Loss of muscle
Myocardial fibre orientation slips
What happens to the collagen levels in the ECM of cardiac myocytes in heart failure?
III > I
What is heart failure?
Clinical syndrome caused by an abnormality of the heart which means cardiac output does not meet the demand of metabolising tissues
What happens to myocytes in systolic dysfunction?
Changes the calcium availability
Changes to receptor regulation
What mediates the sympathetic nervous system?
What effects does activation of the sympathetic nervous system have?
Increase cardiac contractility
Arterial and venous vasoconstriction
What long-term damaging effects does activation of the sympathetic nervous system have?
Down regulation of beta-adrenoceptors
Myocyte apoptosis and necrosis via alpha-receptor stimulation
Reduce HR variability
Name an anti-diuretic hormone.
What does ADH act on?
V2 receptors in the collecting duct
What electrolyte state does ADH release cause?
How does ADH increase cardiac output?
Causes water retention
Decreases systemic resistance
Give the products of angiotensinogen.
Angiotensinogen --> angiotensin I --> angiotensin II
Which receptors does angiotensin II act on?
How does bradykinin work?
Acts on Bk2R
What can activation of the AT1R cause?
What are the effects of natriuretic hormones?
Increased sodium excretion
What does natriuretic hormone stimulate upon detection of atrial and ventricular stretch?
Constriction of afferent and dilatation of efferent arterioles in kidney
What effect does constriction of afferent arterioles and dilatation of efferent arterioles have on kidney function?
Decreases sodium retention
Where does brain natriuretic detect stretch?
Do atrial and brain natriuretic peptides have the same effects?
What can be measured in the blood in addition to carrying out an ECG to investigate heart failure?
Brain natriuretic hormone
What balances effects of RAAS on vascular tone and sodium/water balance?
Atrial and brain natriuretic hormones
Where is angiotensinogen released from?
Where is the sympathetic nervous system stimulated?
What are the mechanisms of neuro-hormonal activation in heart failure?
Sympathetic nervous system
Prostaglandin E2 and I2
What method of hormonal secretion does endothelin use?
What can be measured in the blood that correlates with the severity of heart failure?
Brain natriuretic peptide
Where is endothelin released from?
Vascular endothelial cells
How does endothelin act as a renal vasoconstrictor?
What is stimulated by NA and RAAS to cause vasodilation on afferent renal arterioles?
Prostaglandin E1 and I2
Which enzyme may be blunted in heart failure which would result in a loss of vasodilation balance?
Nitric oxide synthase
What molecule promotes natriuresis and vasodilation and stimulates prostaglandin production?
What are the roles of alpha-TNF in heart failure?
Depress myocardial function
May stimulate NO synthase
May have role in cachexia
What might cause patients with chronic heart failure to lose weight?
Too breathless to eat
Alpha-TNF causing cachexia
What causes skeletal muscle changes in the later stages of heart failure?
Neuro-hormonal increase in peripheral arterial resistance
What causes the fatigue and exercise intolerance in the later stages of heart failure?
Decreased bloodflow to all skeletal muscles incl. limbs and respiratory
Are there abnormalities in structure, function or both of skeletal muscle in the later stages of heart failure?
Why does decreased cardiac output have renal effects?
Kidneys have a large requirement for blood
How is glomerular filtration rate maintained in early heart failure?
Haemodynamic changes at the glomerulus
How does a fall in GFR appear in the blood?
High serum urea and creatinine
What can exacerbate high serum levels of urea and creatinine?
Angiotensin II inhibitor
What is often confused with heart failure on diagnosis?
Anaemia - contributes to symptoms
What can cause anaemia in heart failure?
Chronic inflammatory disease (not in mild)
Expanded plasma volume
Chronic renal failure
What is a rare action of ACEI in some individuals on their bone marrow?
It is suppressed
What is diastolic dysfunction?
Failure of cardiac relaxation
Who is typically affected by diastolic dysfunction?
Elderly female w/ +ve Hx of hypertension/diabetes/obesity
How can left ventricle function be described in diastolic dysfunction?
What kind of left ventricular hypertrophy is seen in diastolic dysfunction?
How does diastolic dysfunction compare to systolic dysfunction clinically?
Diagnosis less clear cut
Hospitalisation and mortality similar
Describe the pathogenesis of diastolic dysfunction.
Impaired myocardial relaxation
Decreased LV compliance
Impaired diastolic LV filling
Unable to compensate by increasing LV end diastolic pressure
Decreased cardiac output --> neuro-hormonal activation
What is congestive heart failure?
When both sides of the heart are affected
What is the most common cause of right-sided heart failure?
Left heart failure
If right sided heart failure occurs in isolation, what is the likely cause?
Lung condition e.g. COPD, valvular disease, ASD, VSD
What are the S/S for right sided heart failure?
Tender, smooth hepatic enlargement
What type of heart rhythm is heard in a patient with left sided heart failure?
What are the S/S of mild left sided heart failure?
Paroxysmal nocturnal dyspnoea
What S/S are seen when LHF progresses from a mild state?
3rd +/- more rare 4th heart sound
Mitral regurgitation murmur
Basal pulmonary crackles
What is the first stage in heart failure management?
Correct underlying cause
What lifestyle modifications can be made to manage heart failure?
Decrease salt, alcohol and BP
More aerobic exercise
What classes of drugs can be used to improve the symptoms of heart failure?
What treatment can be used to inhibit rennin systems in order to delay the progression of heart failure if ACEI are not tolerated?
How does a biventricular pacemaker work?
Increase biventricular heart contraction coordination to increase cardiac output (heart still failing but CO sufficient)
How do implantable defibrillators work?
Pace quickly or deliver shock to heart to restore normal rhythm
Why can ACEI cause a dry cough?
Increase bradykinin levels in the lungs