19. Pathophysiology of Heart Failure Flashcards
Define Heart Failure
Syndrome that arises when the heart is unable to maintain an appropriate blood pressure without support
Definition of heart failure in Man
A clinical syndrome caused by an abnormality of the heart and recognised by a characteristic pattern of haemodynamic, renal, neural and hormonal responses
When heart failure occurs what other organ failure also occurs?
Kidney failure because they won’t be perfused enough
How much cardiac output do kidneys receive?
Kidneys receive 35-40% of cardiac output
List the causes of heart failure
Arrhythmias Valve Disease Pericardial Disease Congenital Heart Disease Myocardial Disease
What are Arrhythmias?
Irregular heart beat - mainly tachycardias
What are valve diseases?
mitral or aortic regurgitation or valve stenoses
What are pericardial diseases?
If the pericardium becomes inflamed and fibrotic then the heart can’t relax and pump as well
What is congenital heart disease?
If there are holes or misconnections then there is an increased risk of heart failure
What is the commonest cause of myocardial disease?
coronary heart disease
Types of cardiomyopathy?
- Dilated Cardiomyopathy (DCM) - specific or idiopathic
- Hypertrophic Cardiomyopathy (HCM or HOCM or ASH)
- Restrictive Cardiomyopathy
- Arrhythmic Right Ventricular Cardiomyopathy (ARVC)
List some examples of myocardial disease?
Cardiomyopathy
HOCM = Hypertrophic obstructive cardiomyopathy
ASH = Asymmetrical Septal Hypertrophy
Hypertension
What drugs can cause heart failure?
Overdosing on beta blockers - it can decrease heart rate so much you get heart failure
Anti-arrhythmics - cause dysfunction of the heart
Calcium antagonists
What is myocardial remodelling
When there is part of a heart that is thin and fibrotic so that when the heart contracts the fibrous tissue just expands - infarct expansion. In order to maintain normal pump activity the heart remodels itself.
How does part of the heart tissue become thing and fibrotic?
When an infarction has happened in that area
Define cardiomyopathy
Heart disease in the absence of a known cause
What is the most common cause of young athletes dropping dead?
Hypertrophic cardiomyopathy
Define dilated cardiomyopathy
The heart’s ability to pump blood is decreased because the left ventricle, is enlarged and weakened.
List an infectious cause of dilated cardiomyopathy?
Viruses such as HIV
What are the toxins and poisonous causes of dilated cardiomyopathy?
Ethanol and cocaine
What drugs can cause dilated cardiomyopathy?
Chemotherapeutic agents and antiviral agents
Define restrictive cardiomyopathy
The heart is restricted so can’t dilate normally. The ejection fraction is preserved by there is diastolic dysfunction so it’s slow in relaxing
What is restrictive cardiomyopathy associated with?
Fibrosis, hypertrophy and scleroderma
What is a common symptom of restrictive cardiomyopathy?
The patients will often be short of breath
What infiltrative disorders are associated with restrictive cardiomyopathy?
Amyloidosis and sarcoidosis
Define infiltrative disorders
Where there is infiltration of amyloid proteins and granulocytes into the heart muscle which impairs heart function
What are the hormonal mediators in heart failure
Constrictors, dilators and growth factor
During heart failure what hormone is increased?
Because the body things it is bleeding to death there is an increase in adrenaline, nor adrenaline and the sympathetic drive is switched on
During heart failure what organ tries to increase blood pressure?
The kidney as it tries to retain salt and water so the RAS system is switched.
What vasoconstrictors are produced in response to heart failure?
Endothelin-1, vassopressin and neuropeptide Y in the endothelial cells
What peptide is checked when diagnosing heart failure?
Atrial natriuretic peptide (ANP)
High = impaired heart
Troponin I and T levels are also increase in heart failure
What are the inflammatory markers and cytokines in heart failure specific to the heart?
Troponin T and Troponin I
What are the inflammatory markers and cytokines in heart failure specific to the vessel wall?
ICAM-1
VCAM-1
E-selectin
P-selectin
With heart failure what is the 5 year mortality rate?
50%
What is the median survival time following diagnosis of heart failure?
Men = 1.7 years Women = 3.2 years
What is most common symptom of heart failure
Fatigue - tiredness
What is orthopnoea?
Breathlessness when lying down. Where is a slight decrease in pressure in the atria when patients are propped up making it easier for the heart to function
What is PND?
Paroxysmal Nocturnal Dysopnoea - they start sleeping propped up and then slip down, they wake up gasping for air so they have to get up and go to the window for air - this is a sign of severe heart failure
How does heart failure affect heart rate and pulses?
Patients may have an increased heart rate to maintain cardiac output and have weak pulses
How does heart failure affect venous pressure?
Patients have increased venous pressure due to the elevated pressures in the right side of the heart
How does salt and water retention caused by heart failure affect the body?
Peripheral oedema
How does heart failure affect the liver and abdomen?
Hepatomegaly and ascites
What can be seen on heart failure chest X-ray?
Increase in the cardio-thoracic ratio.
What should the cardio-thoracic ratio be on a normal chest X-ray?
In normal people the width of the heart should not be more than 50% of the width of the thorax
What is the reason for using the New York Heart association classification of functional capcity?
So you can tell whether a patient has improved after treatment
List the classes and describe them?
1 = virtually no symptoms - the heart is dysfunctioning but most things are fine 2 = slight limitation of physical activity 3 = marked limitation of physical activity 4 = the patient can’t get out of a chair or is in bed
Describe the progression of heart failure?
There is a plateau and then it suddenly drops off. The last downwards section can happen in a matter of weeks or months
What are the syndromes of heart failure?
Acute Heart Failure - Associated with pulmonary oedema
Circulatory Shock - Associated with cardiogenic shock (poor peripheral perfusion, oliguria, hypotension)
Chronic Heart Failure - Untreated, congestive, undulatinf, treated, compensated
How will the patient look if there is a blockage of the coronary artery and the heart muscle dies?
They will look very sick, tachycardic, sweating, sitting upright in bed, very breathless, coughing up frothy sputum
How do you treat pulmonary oedema?
Give diuretics to get rid of the fluid in the lungs
What are the key investigations during heart failure?
ECG
Coronary Angiography - can show where there is a stricture
2D echocardiogram - you can see have the heart is actually pumping
MRI scanning
What is the management algorithm for heart failure?
- Establish that patient has heart failure
- Determine aetiology of heart failure
- Identify concomitant disease relevant to heart failure
- Assess severity of symptoms
- Predict prognosis
- Anticipate complications
- Choose appropriate treatment
- Monitor progress and tailor treatment
List the common drugs used for heart failure
Diuretics
Ace Inhibitors
Beta Blockers
Aldosterone Antagonists (Spironolactone)
Digoxin (for atrial fibrillation)
Devices (cardiac resynchronisatioin, implanted cardioverter defibrillator)
