Beta Blockers in Heart Failure Flashcards
What 3 compensatory mechanisms are there in heart failure?
- Increased sympathetic activity
- Activation of renin-angiotensin-aldosterone system
- Myocardial hypertrophy
What is decompensated heart failure?
When adapted mechanisms fail to maintain cardiac output
What is the most common cause of heart failure?
Left ventricular systolic dysfunction (LVSD)
In a normal heart, what is the resting cardiac output?
5L/min (approx)
In a normal heart, what is the mean heart rate?
70bpm
In a normal heart, what is the stroke volume?
70ml
In a normal heart, what is the volume of filled ventricle?
130ml
In a normal heart, what is the residual volume?
60ml
In a normal heart, what is the fraction ejected of the ventricular contents?
50%
In LVSD, what is the ejection fraction?
<45%
In LVSD, at what ejection fraction do symptoms occur?
<35%
In LVSD, at what ejection fraction is there risk of thrombus formation?
<10%
In LVSD, when there is risk of thrombus formation, what drug is required?
Anti-coagulant
What changes happen to the heart in systolic dysfunction?
Heart increases in size, chambers dilate and become more rounded
What are the causes of systolic dysfunction?
Excessive elongation of the muscle fibres which causes weaker contractions
Altered shape of the ventricles reduces ability to eject blood
What are the causes of diastolic dysfunction?
Hypertrophy - wall thickening - decrease in ventricular volume
Decreases ability to relax and receive blood
What is systolic failure?
Ventricle unable to pump efficiently
What is diastolic failure?
Ventricle unable to fill adequately -> inadequate cardiac output
What is the result of increased and sustained sympathetic drive?
Left ventricular dysfunction and remodelling
Down regulation and desensitisation of cardiac beta receptors
What does down regulation and desensitisation of cardiac beta receptors lead to?
Impairment of myocardial reserve and exercise tolerance
What are the cellular abnormalities in the heart manifested by?
- Defects in calcium handling of the sarcoplasmic reticulum
- Defects in myocardial energetics
- Ongoing loss of cardiomyocytes through necrosis or apoptosis
Carvedilol
What receptor(s) is this selective for, and what dosage?
Beta-1 antagonist, Alpha-1 antagonist
Twice daily
Metoprolol
What receptor(s) is this selective for, and what dosage?
Beta-1 selective antagonist
Once daily
Bisoprolol
What receptor(s) is this selective for, and what dosage?
Beta-1 selective antagonist
Once daily
Nevibolol
What receptor(s) is this selective for, and which patients is this approved for?
Beta-1 selective antagonist
Patients over 70
