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Flashcards in Heart Failure Deck (21)
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1
Q

What is heart failure?

A

The inability of the heart to meet the demands of the body.

demands= deliver blood volume (oxygen/glucose) allowing the body to function as required.

“clinical syndrome of reduced cardiac output, tissue hypoperfusion, increased pulmonary pressures and tissue congestion”

2
Q

What are the five things that enable a heart to work effectively as a pump?

A
  • Output
  • Input
  • One-way valves
  • Functioning muscle
  • Chamber size

Conditions that affect/impair these potentially lead to impairment of cardiac function.

3
Q

What is aetiology?

A

The cause or set of causes that enable a disease/ condition to occur.

4
Q

What is the most common cause of heart failure?

A

Ischaemic heart disease:

  • myocardial dysfunction through fibrosis and remodelling of muscle.
5
Q

What are other causes of heart failure?

A
  • Hypertension
    • increased afterload on the ventricle & accelerates atherosclerosis
  • Aortic stenosis
    • increased afterload on the ventricle
  • Cardiomyopathies
    • hypertrophy
    • dilation
  • Arrhythmias
  • Other valvular or myocardial structural diseases
    • acquired or congenital
  • Pericardial disease
6
Q

What is a cardiomyopathy?

A

Diseases of the heart muscle

7
Q

What are the rare causes of heart failure?

A

When there is a grossly elevated demand on cardiac output:

  • sepsis
  • severe anaemia
  • thyrotoxicosis
8
Q

How do we measure the ability of the heart to meet the demands of the body?

A

CO = SV x HR

Stroke volume (SV) is the volume ejected by a single ventricle per beat

Heart rate (HR) is the beats of the heart per minute

Cardiac output (CO) is measured in volume per min and conferred the amount expelled per ventricle per minute

9
Q

What is the stroke volume?

A

The volume of blood ejected by a ventricle in a single beat.

Note: SV is only a fraction of the total volume within the ventricle at the end of diastole (EDV)

10
Q

What is the ejection fraction?

A

The amount of blood ejected from the ventricle during systole.

EF = SV / EDV (end diastole volume)

11
Q

What influences stroke volume?

A
  • Pre-load
    • volume in the ventricle at the end of diastole (EDV)
    • stretch of the ventricle just before the contraction
    • High pre-load increases stroke volume (Starling’s Law)
  • Myocardial contractility
  • After-load
    • total peripheral resistance
    • high after load reduces stroke volume
12
Q

What is the Frank-Starling’s Law?

A

More ventricular distension during diastole = greater volume ejected (SV) during systole

13
Q

What is inotropy?

A

The force of muscle contraction.

Note: inotropic drugs alter the contractility of the heart. Positive inotropes strength the force of the heartbeat and negative inotropes weaken the force of the heartbeat.

14
Q

How does the inotropic state of the heart alter Frank-Starling curves when sympathetic activity is increased?

A

Contractility of the heart increases with increased sympathetic activity. The curve shifts upwards and to the left. To summarise; greater cardiac output for a given l_eft ventricular end diastolic pressure._

Note for graph: x-axis can be LVEDP/pre-load/EDV or central venous pressure

15
Q

Why is cardiac output reduced in heart failure?

A

Stroke volume is reduced by:

  • Reduced preload/EDV
    • from the impaired filling of the ventricle during diastole
  • Reduced myocardial contractility
    • heart muscle no longer able to produce the same force of contraction for a given volume at the end of diastole (EDV)
  • Increased afterload
    • increased pressure against which the ventricle is contracting against
      • from aortic stenosis or chronic severe hypertension
16
Q

What is the difference between systolic and diastolic heart failure?

A

Diastolic HF is due to the reduced filling of the heart from:

  • stiff ventricular chambers/ chambers not relaxing enough
  • thickened ventricular walls
  • basic terms.. not enough space

Systolic HF is due to reduced contractility (force):

  • cannot empty the ventricles enough
  • muscle walls are thin and fibrosed, chambers enlarged causing overstretched sarcomeres
  • abnormal or uncoordinated myocardial contraction
17
Q

What is HFrEF?

A

Heart Failure with reduced Ejection Fraction

  • systolic dysfunction
  • most common heart failure
18
Q

What is HFpEF?

A

Heart Failure with preserved Ejection Fraction

  • diastolic dysfunction
  • nearly 50% of patients
19
Q

What are the parameters for a reduced, normal and typical ejection fraction?

A
  • Reduced: <40%
  • Normal 50<%
  • Typical 60<%

Ejection fraction is the amount of blood pumped out of the ventricle/total amount of blood in the ventricle.

Note: If it were a ‘filling problem’ then the ventricle ejects less volume due to less volume, to begin with so the ejection fraction preserved.

20
Q

What are the types of heart failure?

A
  • Systolic vs Diastolic
  • Left Ventricle vs Right Ventricle
    • most common is left ventricle but with subsequent involvement of the right ventricle
  • Can involve both ventricles - Biventricular

Note: Right ventricular heart failure can occur in isolation secondary to chronic lung diseases but the most common cause for RVHF is LVHF

21
Q

How does the Frank-Starling’s curve change in Heart Failure?

A

Increased LV filling in the fiale (slide 16)