Lecture 12: Chronic heart failure Flashcards
What is the definition of heart failure?
A state that develops when the heart fails to maintain an adequate cardiac output to meet the demands of the body
What is systolic HF?
Structural or functional abnormality that impairs the ability of the ventricle to eject blood
What is diastolic HF?
Structural or functional abnormality that impairs the ability of the ventricle to fill with blood
What is the equation for CO?
CO = HR x SV
What is preload?
Volume of blood or stretching of cardiomyocytes at the end of diastole prior to the next contraction
What is after load?
Resistance/end load against which the ventricle contracts to eject blood
What happens to CO as after load increases?
Decreases
What is high output HF?
Occurs in the context of other medical conditions which increase demands on cardiac output, causing a clinical picture of HF
What may cause high output HF?
Thyrotoxicosis, profound anaemia, pregnancy, pagets disease, acromegaly, sepsis
What may cause systolic HF?
Ischaemic injury
Volume overload
Pressure overload
What may cause diastolic HF?
Significant left ventricular hypertrophy (LVH) e.g HCM
Infiltrative disorders
Constrictive pericarditis
Restrictive cardiomyopathy
What is the definition of cardiomyopathy?
Diffuse disease of the heart muscle leading to functional impairment
What are the three types of cardiomyopathy?
Dilated (various causes)
Hypertrophic (hereditary)
Restrictive (amyloid - rare)
What are the effects of active BNP?
Diuresis
RAAS inhibition
SNS inhibition
Vasodilation
(half life 20 minutes)
What is the inactive form of BNP?
NT-proBNP
half life 2 hours
What are the HF compensatory mechanisms?
Vasoconstriction
Na and water retention
Tachycardia
What is left sided HF?
Blood backs up progressively from the left atrium to the pulmonary circulation
What may causes left sided HF?
Ischaemic heart disease
Hypertension
Valvular heart disease
Myocardial disease
What are the symptoms of left sided HF?
Pulmonary congestion and oedema (breathlessness, orthopnoea, paroxysmal nocturnal dyspnoea)
Reduced renal perfusion (retention of salt and water - increased blood volume)
Hypoxic encephalopathy (irritability, loss of attention, restlessness, stupor and coma)
What is congestive HF?
Right sided HF as a result of left sided HF
What is cor-pulmonale?
Right sided HF due to significant pulmonary hypertension due to increased resistance within the pulmonary circulation - usually as a result of respiratory disease e.g. COPD or pulmonary emboli
What are the systemic effects of right heart failure?
Congestive hepatomegaly
Centrilobular necrosis
Cardiac cirrhosis
Congestive splenomegaly
Ascites
Peripheral or sacral oedema
Effusions
What are the classes of HF?
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
What are the clinical signs of cardiac failure?
Cool, pale, cyanotic extremities
Tachycardia
Elevated JVP
Third heart sound (S3) – gallop rhythm
Displaced apex (LV enlargement)
Crackles or decreased breath sounds at bases on chest auscultation
Peripheral oedema
Ascites
Hepatomegaly
What are the clinical test in HF?
CXR
ECG
Blood investigations
Echocardiogram /
Cardiac MRI or CT / CT-PET
CTCA / Coronary angiography
What values of NT-proBNP are used?
> 2000ng/L - refer urgently within 2 weeks
400-2000 - refer urgently within 6 weeks
<400 - HF not confirmed
What would you prescribe for HF with reduced ejection fraction?
ACE inhibitor and beta blocker
consider ARB if intolerant of ACEI
What would you prescribe for HF with preserved ejection fraction?
Manage comorbidities e.g. hypertension, AF, IHD
Name a loop diuretic.
Frusemide or bumetanide
Inhibit Na+ re-absorption from the proximal tubule
and K+ loss from distal tubule (can be given iv or orally)
Name a mineralocorticoid antagonist.
Eplerenone or spironolactone
Acts on distal tubule, promotes Na+ excretion and K+ re-absorption
Reduces hypertrophy and fibrosis
Name an ACE inhibitor.
Ramipril
What kind of drug is bisprolol?
Beta blocker
What kind of drug is ivabradine?
Blocks the If channel in the SA node
Slows HR, no effect on BP
Given orally with dose titration
(SE: visual aura, bradycardia)
How does digoxin work?
Increases myocardial contractility
Slows conduction at the AV node (use in AF)
(Excreted by kidney - toxicity important)
How do ARNIs work?
Blocks breakdown of ANP/BNP
Blocks RAAS
Promotes naturesis
(SE: hypotension, renal impairment)
Name an ARNI.
Sacubitril or valsartan
