Heart Failure Flashcards
What is heart failure?
The state in which the heart fails to maintain an adequate circulation for the needs of the body despite an adequate pressure.
Give some causes of heart failure
Ischaemic heart disease
Hypertension
Dilated cardiomyopathy
High output heart failure - AV fistula or Paget’s disease (extra blood vessels)
Arrhythmia
Restrictive cardiomyopathy e.g. amyloidosis
Valvular/congenital heart disease
What are the stages of heart failure?
I - no symptomatic limitations
II - slight limitations to physical activity, no symptoms at rest
III - limitations with less than normal activity. No symptoms at rest.
IV - can’t carry out physical activity without symptoms. May also have symptoms.
What is normal cardiac output?
5L/min
What is normal stroke volume?
75ml
What is the normal ejection fraction?
Above or equal to 50%
What affects cardiac output?
Venous capacity
Heart rate
Aortic and peripheral impedance
Myocardial contractility
What are the causes of systolic dysfunction?
Increased left ventricular dysfunction
Decreased left ventricular cardiac output
Thinning of the myocardial wall (fibrosis and necrosis, activity of matrix proteinases)
Mitral valve incompetence
Neural-hormonal inactivity
Cardiac arrhythmia
What structural changes can be seen in the heart in heart failure?
Reduced muscle
Uncoordinated or abnormal myocardial contraction
Changes to the ECM (increased collagen/slippage of fibre orientation )
Change in cellular structure and function (myocytolysis/vacuolation)
Myocyte hypertrophy
SR dysfunction
Change to calcium availability
Receptor regulation
Describe how the sympathetic nervous system is activated in heart failure
Baroreceptor mediation.
Instant response
What is the positive short term effect of sympathetic nervous system activation in heart failure
Increases cardiac output by improving contractility, arterial/venous contraction and causing tachycardia.
What are the long term negative effects of sympathetic nervous system activation in heart failure?
Beta-adrenergic receptors downregulated or uncoupled
Noradrenaline increases cardiac hypertrophy and triggers myocyte apoptosis/necrosis via alpha-receptors
Induce upregulation of RAAS
Describe briefly the renin-angiotensin-aldosterone system.
Angiotensinogen to angiotensin I by renin
Angiotensin I to angiotensin II by ACE
AT1R is detrimental
AT2R causes water retention and aldosterone secretion, increases NO production.
What effects does AT1R activation have on the vasculature?
Atherosclerosis
Vasoconstriction
Vascular hypertrophy
Endothelial dysfunction
What effects does AT1R activation have on the heart?
Left ventricular hypertrophy
Fibrosis
Remodelling
Apoptosis
What effects does AT1R activation have on the kidney?
Decreased GFR
Increased proteinuria
Increased aldosterone release
Glomerular sclerosis
What clinical problems can be caused by AT1R activation in the long term?
Stroke Hypertension Heart failure Myocardial infarction Renal failure
What are the effects of angiotensin II activation?
Vasoconstriction Increased left ventricular hypertrophy and myocyte dysfunction Increase aldosterone release More sodium and water retention Stimulate thirst by central activation
What is the function of natriuretic hormones activated in heart failure?
Decreases sodium reabsorption
Inhibits secretion of renin and angiotensin
Balance the effects of RAAS on vascular tone and sodium/water balance
What causes the release of natriuretic hormones in heart failure?
Stretch of the arteries/veins/vasculature in the brain
How can anti-diuretic hormone cause hyponatraemia?
Water is reabsorbed in excess of sodium.
Can also be due to excessive water consumption
What is the function of endothelin?
Systemic and renal vasoconstriction via autocrine action, activating RAAS.
What stimulates the release of prostaglandin E2/I2 in heart failure?
NA
RAAS
What is the function of prostaglandin E2/I2 in heart failure?
Vasodilate afferent renal arterioles
What drugs can block the action of prostaglandin E2/I2?
NSAIDs e.g. aspirin
What effect can alpha-TNF have in heart failure?
Decreases myocardial function
May stimulate NO synthase
Role in cachexia
How does changes to vascular tone exacerbate the clinical features of heart failure?
Decreased skeletal muscle tone
Decreased skeletal muscle mass including the limbs and respiratory muscles (can cause death)
Abnormal structure and function
Fatigue and exercise intolerance
How can heart failure precipitate renal failure?
GFR initially maintained by haemodynamic changes in the glomerulus
Increased sodium/water retention. Neurohormonal action.
Decreased GFR in severe heart failure which causes increased serum urea and creatinine
Can be exacerbated by treatment which inhibits angiotensin II
Who is left ventricular diastolic dysfunction most commonly seen in?
Elderly
Females
History of hypertension, diabetes and/or obesity
What are the problems in the heart when there is left ventricular diastolic dysfunction?
Low left ventricular compliance Impaired relaxation Impaired left ventricular filling Decreased CO Triggers neurohormonal activation
What are the different types of heart failure?
Right sided heart failure Left sided heart failure Biventricular (congestive) heart failure Systolic heart failure Diastolic heart failure
How can diastolic heart failure be caused by systolic heart failure?
Hypertrophy with disorganisation
or
MI which causes fibrous tissue formation
What are the potential causes of right heart failure?
Chronic lung disease (most common) Pulmonary embolism Pulmonary hypertension Pulmonary/tricuspid valvular disease ASD/VSD Isolated right ventricular hypertrophy
What are some symptoms of right heart failure?
Fatigue Dyspnea Anorexia Nausea (may be due to ascites Increased JVP Hepatic enlargement Ascites Pitting oedema Pleural effusion
How can right heart failure precipitate a DVT?
Systemic congestion which increases stasis in the veins and therefore increases the risk of a DVT
What are the principals of treating heart failure?
Correct the underlying cause
Pharmacological treatments
Non-pharmacological treatments
Treat complications, associated conditions and cardiovascular risk factors.
What lifestyle modifications could you suggest to someone with heart failure?
Reduce salt intake
Decrease alcohol intake
Increase aerobic exercise
Decrease blood pressure
What are the pharmacological treatments for heart failure
Diuretics ACEi/ARB Nitrates Beta blockers Spironolactone/amiloride Antiarrhythmics Inotropes (only in an acute setting)
Suggest a form of cardiac surgery which can be used to treat heart failure
Total heart transplantation
Mechanical assist devices
Underlying cause - valve surgery/revascularisation
Implantable pacemakers/defibrillator
