Cardiovascular Systems 13 - Heart Failure Flashcards
Define cardiac output
The volume of blood leaving either side of the heart per minute (usually in the context of the left ventricle).
Define ejection fraction
Stroke volume / end diastolic volume
List the ranges for ejection fraction
> 55% normal
45-54% mildly reduced
30-44% moderately reduced
<30% severely reduced
How can ejection fraction be measured?
Transthoracic echocardiogram
Define heart failure.
- Inability of the heart to supply blood to the tissues sufficient to meet their metabolic needs
- Inadequacy of tissue perfusion
- Conjestion in the lungs and legs
List the types of heart failure
- Left or right
- Chronic or acute
- Heart failure with reduced ejection fraction or with preserved ejection fraction
Compare left and right sided heart failure
- Left sided is dysfunction in the left ventricle, right sided in the right side
- Both ejection or filling issue
- In left sided, blood backs up into the lungs causing congestion
- Right is due to increased afterload in the pulmonary circulation (pulmonary hypertension)
- Right side follows left side
List some of the symptoms of left sided heart failure
- Respiratory symptoms (breathlessness, coughing, wheezing)
- Dizziness
- Cyanosis
Compare acute and chronic heart failure
- Chronic heart failure has a slow onset
- Acute heart failure has a rapid onset
Describe what happens in heart failure with reduced ejection fraction
- Abnormal systolic function
- Ventricles have impaired contraction, so though heart rate increases there is decreased cardiac output
- Weakness is caused by damage/destruction of the ventricular myocytes
- Weaker ejection leads to higher diastolic pressures
Describe what happens in heart failure with preserved ejection fraction
- Abnormal diastolic function
- Normal ventricular contraction
- Increased stiffness of the ventricle, impaired relaxation or impaired filling
- EDV is reduced, the reduced stroke volume is masked when looking at ejection fraction.
Briefly describe some epidemiological factors of heart failure
- Highest incidence age 60-64
- Risk increases with age then decreases
- Most common cause is coronary artery disease
List the causes of heart failure
- Valve disease
- Ischaemic heart disease
- Myocardial infarction
- Hypertension
- Dilated cardiomyopathy
- Hypertrophic cardiomyopathy
Describe how valve disease causes heart failure.
Hardening of valve(s) reduces the ventricular filling or ejection
Describe how ischaemic heart disease causes heart failure
- Caused by narrowing of coronary arteries
- Ischaemia of the heart muscle
Describe how myocardial infarction causes heart failure
Occlusion leads to death of heart muscle
Describe how hypertension leads to heart failure
Hypertension increases the afterload, so the ventricle must work harder
Describe how dilated cardiomyopathy leads to heart failure
Dilated left ventricular volume reduces ability to generate pressure, so the ejection reduces
Describe how hypertrophic cardiomyopathy leads to heart failure
Increased left ventricular volume reduces internal ventricular volume and impedes filling
List the clinical features of heart failure
- Breathlessness and fluid accumulation (orthopnoea, fatigue, paroxysmal nocturnal dysnoea)
- Anorexia/weight loss
- Pitting oedema
- Tachycardia
- Increased jugluar vein pressure
- Ascites
List the investigations of heart failure
- x-ray
- Echocardiogram
- Ambulatory ECG
- Exercise test
- Angiogram
- BNP
What are ascites?
An accumulation of fluid in the peritoneal cavity
When is raised jugular venous pressure seen?
When in the right side of the heart, pressure increases causes pressures backing p into systemic veins
When is B-type natriuretic peptide seen, and what is its function?
- Natriuresis is sodim excretion
- Released from ventricular myocytes in response to stretch
- Causes vasodilation, reduced aldosterone secretion, reduced sodium reabsorption, and inhibited renin secretion
- Results in reduced extracellular filling and reduced pressure
