Chapter 2 - Heart Failure Flashcards
What is chronic heart failure?
Heart failure occurs when the heart in unable to sufficiently pump blood around the body to meet the body’s needs.
What are the symptoms of heart failure?
- SOB
- Swelling (commonly feet, ankles, stomach, lower back)
- Fatigue
What measurement is commonly used to describe heart
Ejection fraction
EF = stroke volume* / end diastolic volume
*stroke volume = end diastolic volume - end systolic volume
What is the ejection fraction?
EF - is the % of blood volume leaving the heart with each beat, and is a measure of left ventricular pumping function.
The smaller the ejection fraction…..
…. the more severe the heart failure.
What is the normal EF %?
60%
People with an EF
<40%
What are the ‘typical’ signs and symptoms of someone with heart failure?
SOB, nocturnal paroxysmal dyspnoea (severe SOB and coughing waking someone up at night), orthopnoea (SOB when lying down), ankle swelling,
What are the common risk factors for developing HF?
Myocardial infarction, HTN, diabetes, thyroid disease, left ventricular hypertrophy (muscle wall of heart’s left ventricle becomes thickened).
How may thyroid disease contribute to the development of HF?
Thyroid hormones have an impact on cardiac myocytes: http://circ.ahajournals.org/content/116/15/1725
What is cardiac output?
The amount of blood pumped by the heart in one minute.
What happens to cardiac output in a patient with HF?
Cardiac output decreases, consequently leads to a fall in blood pressure.
How does the heart attempt to maintain normal cardiac output in HF?
By increasing the heart rate (beats per minute). This may allow less time for filling.
Decreased BP due to decreased cardiac output activates which two systems in the body?
RAAS system and sympathetic nervous system - in order to raise blood pressure. (Increasing myocardial contractility, tachycardia and vasoconstriction).
Although this mechanism is trying to increase cardiac output, chronic activation may exhaust the failing heart further.
How does the RAAS system work to raise BP?
Renin secreted by kidneys works to convert angiotensinogen (produced in the liver) to angiotensin 1. ACE then works to convert ang 1 to ang 2.
Ang 2 causes vasoconstriction (increase BP) and causes aldosterone to be released (increased water retention).
Which drug/ classes of drugs may precipitate HF?
B-blockers rate-limiting CCBs (diltiazem and verapamil) Corticosteroids Antiarrythmics (class 1) NSAIDs Lithium
The severity of heart failure is classified by the New York Heart Association (NYHA) as what?
Class I: No limitations. Ordinary physical activity does not cause fatigue, breathlessness or palpitation (asymptomatic LVD included in this category).
Class II: Slight limitation of physical activity. Comfortable at rest. Ordinary physical activity results in fatigue, palpitation, breathlessness or angina (symptomatically ‘mild’ heart failure)
Class III: Marked limitation of physical activity. Although comfortable at rest, less than ordinary physical activity will lead to symptoms (symptomatically ‘moderate’ heart failure).
Class IV: Inability to carry out any physical activity without discomfort. Symptoms of congestive cardiac failure are present even at rest. With any physical activity, increased discomfort is experienced (symptomatically ‘severe’ heart failure).
What is B-type natriuretic peptide (BNP) and what is its significance in HF?
BNP is secreted from by the ventricles of the heart in response to excess stretching of myocytes. Plasma concentrations of BNP are elevated in HF.
What is the first line treatment for HF?
ACE Inhibitor - shown to prolong life and delay progression of the disease. Beneficial use for patients with both symptomatic and asymptomatic HF.
When should B-blockers be considered in treatment of HF in addition to an ACE Inhibitor?
When patient has symptomatic heart failure and has a LVEF of <40%.
Which B-blockers have been studied and therefore licensed to be used for the treatment of HF?
Birsoprolol
Carvedilol
Nebivolol
If patients are still symptomatic after initial treatment with an ACEI and B-blocker, what is the next step in pharmacological treatment?
Adding in an aldosterone antagonist –> Spironolactone or eplerenone. These have been shown to reduce symptoms and hospitilisation in HF, whilst increasing patient survival.
What is the role of diuretics in HF?
Symptom control of oedema and dyspnoea (shortness of breath)
If treatment with an ACEI, B-blocker and aldosterone antagonist is still failing in the treatment of HF, what is the next step in therapy?
Consider adding angiotensin receptor neprilysin inhibitor (ARNI) –> sacubitril/valsartan.
Inhibits neprilysin which is an enzyme that breaks down natriuretic peptides which regulate fluid homeostasis, therefore protecting the cardiovascular system from fluid overload.
IMPORTANT: if treatment with an ARNI is being started ACEI or ARB must be stopped.
