CVD - Cardiac failure Flashcards
Define cardiac failure
- common cause
- 3 types
- Cardiac Output less than Body Needs
- Usually due to reduced Cardiac Output
- Rarely due to increased Body Needs
–“high output heart failure” - Usually due to reduced systolic function
–Low ejection fraction - May be due to stiff diastolic function
–Normal ejection fraction
How (4) is the cardiac output determined?
- Input (preload)
- rate (heart rate)
- strength (contractility)
- resistance (afterload)
(4) causes of oedema
•Increased venous pressure
–Heart failure
•Decreased osmotic pressure
–Plasma protein loss: renal or liver failure
•Blocked lymphatics
–Cancer
•Increased capillary permeability
–Infection.
NOTE: to do with venous pressure not arterial
Discuss the compensation of cardiac failure & its consequence
Maintain the same CO by increasing ventricular end diastolic pressure. But this compensation leads to pulmonary & systemic congestion due to fluid retention. (oedema in legs & lungs)
In severe heart failure, CO is low PLUS lungs are congested
Explain the pathogenesis of fluid retention in cardiac failure
Low CO -> low renal blood flow -> activation of RAAS -> fluid, Na+ retention, K+ loss & vasoconstriction -> increase BP & CO
Explain the association between sympathetic nervous system & cardiac failure
- initial consequence
- longterm consequence
Cardiac failure -> sympathetic nervous system stimulated -> increased noradrealine -> increased INITIAL contractility.
BUT longterm deleterious effect:
- vasoconstriction
- ventricular arrhythmias
- direct toxic effect
(7) causes of cardiac failure
- Ischaemic heart disease: myocardial infarct
- Valvular heart disease
- Hypertensive heart disease
- Congenital heart disease
- Cardiomyopathy
- Cor pulmonale (right heart)
- Pericardial disease
(2) possible causes of cardiomyopathy
- alcohol
- cytotoxic drugs
What should you ask in Hx to see if the patient has cardiac failure?
–Previous myocardial infarct(s)
–PHx Rheumatic Fever -> Valve Defect
–Known murmur -> Valve Defect
–PHx Hypertension – Degree of control
–PHx Congenital Heart Defect
–Possible causes of cardiomyopathy: alcohol, Cytotoxic Drugs
–PHx Lung Disease: Asthma, COPD, Cystic Fibrosis, Pulmonary Fibrosis
What does increased JVP usually correlate with?
Increased pulmonary venous pressure
I.e. left & right heart failure
NOTE: but it can be elevated with NORMAL pulmonary venous pressure due to pure RIGHT heart failure
(3) causes of right heart failure
•Pulmonary Hypertension
–Cor Pulmonale: Heart Failure due to Lung Disease. Eg COPD, Cystic Fibrosis, Pulmonary Fibrosis
–Pulmonary Embolism
•Right sided structural disease
–Pulmonary or Tricuspid Valves
–R Ventricular Cardiomyopathy
•Pericardial disease
What % of ejection fraction is mild, moderate & severe?
•40-50% Mild
•30-40% Moderate
•
What are the (4) principles of treatment of heart failure?
•Reduce the venous pressure
–Relieves congestion & oedema
–But without reducing Cardiac Output too much (too low CO & reduced BP may be dangerous)
•Block the Renin-Angiotensin-Aldosterone system
–Produces long-term fluid loss and vasodilatation
•Block the Sympathetic Nervous System (β)
–Block the direct cardiac toxic effect of β stimulation
•Treat the underlying & precipitating cause
Common (5) agents for Rx of cardiac failure
- Diuretics – eg frusmide
- Aldosterone Antagonists eg spironolactone
- Angiotensin Converting Enzyme (ACE) inhibitors eg ramipril
- Angiotensin Receptor Antagonists eg irbesartan
- Beta Blockers eg carvedilol
(3) surgical/mechanical Rx of cardiac failure
•Biventricular Pacing – Cardiac Resynchronisation
–Improves cardiac function
•Implantable Cardioverter Defibrillator
–Because ventricular arrhythmias and sudden death are common in heart failure
•Cardiac Assist Devices & Transplantation
–For a small group who do not respond to other treatment
