Lecture 8: Cardiac Dysfunction and pharmacological treatment Flashcards
What is observed in MI on ECG?
Elevated ST segment
Necrosis current
How many hospital admissions are their for heart failure?
12000 per year.
Whats the mortality rate of heart failure post diagnosis?
20% dead at 6 months and 30% by 12.
5 years @ 50%
When does HF occur in moaris?
15-20 years earlier
What is the main cause of heart failure?
Coronary Artery Disease
Is heart failure restricted to the heart?
No it has multiorgan effects
Describe the NYRA classification of HF
Class 1 = No symptoms Class 2= Slight limitation of physical activity with fatigue, palpations, angina, dysnopea, comfortable at rest Class 3= marked limitation of physical activity, + class 2 Class 4= Unable to be physically active without discomfort, symptoms of cardiac insufficiency may be present at rest.
Whats the ACC classification?
Stage A: Patient at high risk for HF, no structural changes of heart
Stage B: Heart structure changes with no symptoms
Stage C: Heart structure changes with past/present HF symptoms
Stage D: End stage disease patient who requires specialist treatment.
Do different stages change treatment?
Each stage has a different drug treatment strategy.
What is heart failure characterised by?
- Progressive cardiac dysfunction
- Breathlessness
- Tiredness
- Neurohormonal activation
- Oedema (lungs, legs)
- Sudden death (myocytes stretch, alters electrical pathway, arrhythmia)
- Enlarged heart
How does the body respond to a decreased CO in HF?
- Increased TPR (to maintain BP), increased sympathetic tone (baroreflex)
- RAA activation to raise blood volume, BP, venous return, filling pressures
Describe the changes in VR/CO RAP curve in HF;
Following HF i.e caused by MI. CO/ VR drops. Both curves shift down and to the right as since the heart cannot pump (systolic HF) the RAP increases (causes dilation).
Baroreflex is initiated. Curves both shift up.
RAA is activated and this eventually results in a compensated heart failure (as CO never returns to normal) (curves shift up to just below normal)
A decompensated heart failure could occur where despite baroreflex and RAA CO never returns.
Why does RAP increase in heart failure?
It is an attempt to utilise the frank starling mechanism to increase CO. The heart does not respond well and dilates.
A viscous loop develops.
Describe the problems with heart failure
- Low CO
- Inadequate tissue perfusion
- Volume overload
Cardiac remodelling;
- Enlarged ventricles
- Spherical shape
- Reduced efficiency (EF)
What can be observed at a macroscopic level in heart failure?
- Loss of muscle mass
- Altered chamber size and shape
- In-coordinated contraction and abnormal contraction timing
