Heart Failure Flashcards
Define 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
What is the primary cause for heart failure
Ischaemic heart disease
Name some causes of heart failure
Hypertension, alcohol, pregnancy, valvular disease, collagen deposition, arrhythmia
What is class I heart failure
No symptomatic limitation of physical activity
What is class IV heart failure
Inability to carry out physical activity without symptoms, with symptoms coming at rest
What the ejection fracture
50% plus
In heart failure what 4 things can affect the cardiac output
- heart rate
- LV preload
- after load
- myocardial contractility
what is left ventricular systolic dysfunction
where theres increase LV capacity but reduced LV cardiac output
how des LVSD affect the mitral valves
it pulls the cusps apart due to the widening of the LV
what are the structural changes of the heart in LVSD
- loss of muscle
- abnormal contraction
- increase in collagen
why does LVSD result in thinning of the walls
there is fibrosis and necrosis as well as activity of proteinases
true or false - LVSD causes neuro-hormonal activation
true - it activates the sympathetic NS, RAAS, natuiretic hormones, endothelin, prostaglandins and TNF
how does activation of the sympathetic NS affect LVSD
- compensatory mechanisms to improve cardiac output including increasing contractility, vasoconstriction and tachycardia
what are the detrimental affect of the sympathetic NS being activated in LVSD
- beta adrengeric receptors become down regulated as they are being over used
- noradrenaline induces cardiac hypertrophy and necrosis and there is an up-regulation of the RAAS system
what does RAAS do in LVSD
causes fluid retention increasing the stress on the walls of the ventricles leading to decreased contractility and hypertrophy
outline RAAS
angiotensinogen from the liver is converted into angiotensin I by renin (from the kidney). this is then converted to angiotensin II by ACE enzymes. angiotensin I can act on type 1 and 2 receptors
what does angiotensin II cause when it binds to type 1 receptors
vasoconstriction and an increase in salt and water retention and causes aldosterone release
what does angiotensin II cause when it binds to type 2 receptors
increasing amounts of nitric oxide
what causes an increase in nitric oxide
bradykinin
why is nitric oxide advantageous in LVSD
it is a vasodilator
why is RAAS often activated in LVSD
there is reduced renal flow from the reduced cardiac output so the sympathetic nervous system induces the production of renin from the macula densa
what do natriuretics do
they inhibit renin and aldosterone, decrease sodium absorption in the kidneys and causes vasodilation
when are natriuretic hormones released
when the increasing volume to the heart causes it to stretch
what is anti-diuretic hormone
causes salt and water retention
