Lecture 5 Acute and Chronic Heart Failure (drugs) Flashcards
What is a key parameter when finding heart failure?
Stroke volume
Which parameters determine stroke volume?
End systolic volume and end diastolic volume
Describe stroke volume?
The volume of blood pumped out that exits the left ventricle
What is the difference between acute and chronic?
Acute - sudden onset
Chronic - develops over time (elderly)
What are the 3 different types of heart failure?
Left sided heart failure (hypertension)
Right sided heart failure (lung disease)
Biventricular heart failure
What is pulmonary congestion?
The left ventricle causes pressure which backs up into the lungs meaning fluid enters the lungs and flows into the right side of the heart (biventricular heart failure)
What are the 5 classes of heart failure?
Class 1 - no symptoms normal activity (echocardiogram required)
Class 2 - comfortable at rest, physical activity triggers symptoms
Class 3 - comfortable at rest, minor physical activity triggers symptoms
Class 4 - unable to carry out any physical activity without discomfort, symptoms when resting
What are clinical features of heart failure?
Reduced ejection fraction (lower SV)
Hypotension (tired and dizziness)
Reduced urine flow
Cold peripheries
Breathlessness
Oedema
Atrial fibrillation (pressure on atrium, electrical disturbances)
What are the different causes of systolic left sided heart failure?
Systolic
Impaired contractility (myocardial infarction - over stretched)
Pressure overload (uncontrollable hypertension)
What are the different causes of diastolic left sided heart failure?
Diastolic
LV diastolic dysfunction (from LV hypertrophy, myocardial ischaemia
Obstruction of left ventricular filling (cardiac tamponade, narrowed valve)
What is the pathophysiology of systolic left sided heart failure?
Increased blood volume left in left ventricle at end of contraction (end systolic volume increase)
Reduced systolic emptying leads to end diastolic volume increasing
Overall stroke volume decreases
What is the pathophysiology of diastolic left sided heart failure?
Reduced ventricular compliance - diastolic dysfunction
Pressure in ventricle increases during diastole (stiffness)
End diastolic volume decreases (reduced filling of ventricle)
How do compensatory mechanisms impact heart failure?
They can cause additional strain
What are Frank-Starling curves?
Measurement of stroke volume agains left ventricular end diastolic pressure (allows a measurement of normal vs heart failure and the normal physiological healthy heart)
How can stroke volume be increased pharmacologically?
Positive ionotrope (beta agonists) - increasing force of contraction
Block compensatory mechanism using ACE inhibitors
Reduce after load using antihypertensive drugs
Reduce preload using ventilators
Reduce contractility using beta antagonists causing less strain on the heart
What are the 2 parameters in Frank-Starling curves in the heart failure category?
Hypotension and pulmonary congestion
