SPR L12 Pathophysiology of Heart Failure Flashcards Preview

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Flashcards in SPR L12 Pathophysiology of Heart Failure Deck (23):
1

Pathophysiology of Heart Failure

Outcomes

  • Nature and causes of heart failure
  • Pathophysiological processes
  • Types of heart failure
  • Symptoms and signs
  • Investigation
  • Principles of Management

2

Heart Failure

  1. Give a definition 
  2. Outline the main causes
  3. How can it be classified?

  1. Impaired cardiac pump function (Acute or chronic)
  2. •Ischaemic heart disease

    •Dilated cardiomyopathy

    •Hypertension

    •Valve disease

  3. •Right or left heart failure

    •Systolic or diastolic dysfunction

    •Backward or forward failure

    •Low v high output failure

    •Functional limitation experienced by patient

     

3

Pathophysiology of HF

What are the main consequences of HF?

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  • Increased venous pressure
  • Ventricular dilatation
  • Reduced ejection fraction  (EF  = SV/EDV (%)

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4

Define Moderate heart failure

  • Normal or reduced SV
  • Normal or increased HR
  • Normal CO at rest (CO = SV x HR)
  • Reduced exercise tolerance

5

What is seen in Severe heart failure?

  • Reduced SV
  • Reduced CO at rest

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6

What are the main factors which contribute to the pathophysiology of HF?

  1. Salt and water retention
  2. Sympathetic Activation
  3. Pathological vasocontriction (increased afterload)
    1. Endothelial Dysfunction
  4. Myocardial Remodelling
  5. Increased ADH
  6. Increased natriuretic peptides

7

Factors which contribute to the pathophysiology of heart failure?

Salt and Water Retention

Discuss this factor

  • Reduced renal BF
    • Decreased GFR
    • Renin Release (JGA) (ACE)
    • AngII
      • vasoconstriction, increased PR
      • Aldosterone secretion
        • Increased renal Na+/H2O Absorption
        • Increased venous pressure

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8

Factors which contribute to the pathophysiology of heart failure

Sympathetic Activation

Discuss this factor

Reduced CO

Increased SYMP Activity 

Increased HR, Increased Vasoconstriction

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9

Factors which contribute to the pathophysiology of heart failure

Pathological vasoconstriction (increased afterload): Endothelial Dysfunction

Discuss this factor

  • reduced NO production
  • increased endothelin production

promotes peripheral vasoconstriction

Further decreases CO

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10

Discuss how the factors contributing to PathoP of HF interact

Which is the initiating event?

Myocyte damage => reduced CO

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11

Factors which contribute to the pathophysiology of heart failure

Myocardial Remodelling

Discuss this factor

  • Ventricular hypertrophy
  • Ventricular dilatation

  => reduced contractile efficiency

  • Myocyte hypertrophy
  • Myocyte death (apoptosis)
  • Interstitial fibrosis
  • Abnormal myosin expression
  • Abnormal Ca-signalling

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12

Law of Laplace

 

Give a worked example

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13

Factors which contribute to the pathophysiology of heart failure

Increased ADH

Discuss this factor

  • severe chronic heart failure
  • H2O retention, vasoconstriction, hyponatraemia
  • poor prognosis

14

Factors which contribute to the pathophysiology of heart failure

Increased natriuretic peptides

  1. When are these released?
  2. Give examples
  3. What happens as a result of NP release?

  1. Under stretch
  2. atrial natriuretic peptide (ANP; atria), brain natriuretic peptide (BNP; ventricles) and C-type peptide (endothelium)

  3. diuresis, natriuresis, vasodilatation - potentially beneficial

15

Types of Heart Failure

Give features of the following types of heart failure

  1. Left ventricular failure (systolic dysfunction)
  2. Right ventricular failure (systolic dysfunction)
  3. High output failure
  4. Diastolic heart failure

  1. ischaemic heart disease, hypertension, valve defects

  2. 2˚ to left ventricular failure, right ventricular ischaemia, valve defects, pulmonary hypertension (1˚ or 2˚), cor pulmonale (COPD)

  3. thyrotoxicosis, anaemia

  4. ejection fraction > 45%, increased ventricular stiffness/reduced compliance, impaired diastolic filling, reduced CO, hypertension, cardiomyopathies

16

Remodelling in different types of heart failure

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17

Signs and Symptoms of HF

What is the main sign?

What are the S+Ss associated with the following...

  1. Left ventricular failure  
  2. Right ventricular failure                              

Increased venous pressure

  1. increased pulmonary venous pressure, pulmonary oedema and decreased lung compliance

    dyspnoea (exertional/at rest)

    orthopnoea/paroxysmal nocturnal dyspnoea

    bilateral basal crackles

    hypoxaemia/central cyanosis

  2. Increased systemic venous pressure

    elevated JVP

    ankle oedema

    ascites

    tender hepatomegaly

18

What are the S+Ss associated with...

  1. Decreased cardiac output
  2. Ventricular Dilation/ Hypertrophy
  3. Sympathetic Compensation

 

  1. fatigue, hypotension, reduced peripheral perfusion (advanced stage), peripheral cyanosis (in absence of central cyanosis)

  2. displaced apex beat

  3. tachycardia

19

Heart Failure: Which investigations are important to consider?

  • blood: Hb, cardiac enzymes (acute failure), BNP levels
  • chest X-ray: cardiomegaly, evidence of pulmonary   oedema
  • electrocardiogram: ischaemia, arrhythmia, hypertension (LAD)
  • echocardiogram and other imaging techniques: cardiac size, ventricular systolic and diastolic function, ejection fraction, etc.
  • cardiac catheterisation:
    • right heart (via vein): pressure in right atrium and ventricle, pulmonary artery and left atrium (pulmonary ‘wedge’ pressure or pulmonary artery occlusion pressure)
    • left heart (via artery): left ventricular end diastolic pressure
  • blood gases
  • exercise testing: VO2 max (normal blood gases)

20

Heart Failure: Principles of Management

What are the main principles of management?

  • Reduce venous congestion (preload)
  • Reduce vasoconstriction (afterload)
  • Cardiac acting drugs
  • Cardiac transplant

21

Heart Failure: Principles of Management

Outline how the following forms of management can be beneficial

  1. Reduce venous congestion (preload)
  2. Reduce vasoconstriction (afterload)
  3. Cardiac acting drugs
  4. Cardiac transplant
  5.  

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1. reduced backwards failure but (some) increase in forwards failure.

  • Diuretics
  • ACE-Is and A2 Receptor Blockers (reduced aldosterone production;also reduces vasoconstriction)
  • Aldosterone Antagonists

2. vasodilators, eg hydralazine, nitrates

3. b-blockers (reduce sympathetic drive to heart), digoxin and other inotropes

4. in young patients with very poor prognosis

heart is denervated

  • high resting HR (parasympathetic output normally                dominates at rest)
  • very little increase in HR on exercise
  • increase in CO on exercise is driven by increase in   stroke volume

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22

Heart Failure: Principles of Management

Give an overview on how different ways of managing HF can act 

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23

Monitoring of HF Patients

Give examples of the following methods of monitoring...

  1. Clinical Evaluation

  2. Fluid Status 

  3. Cardiac Rhythm

  4. Functional Capacity

  1. Signs and symptoms
  2. clinical assessment of oedema, bodyweight,      U&Es
  3. ECG, 24 hr tape
  4. VO2 max, exercise tolerance test,             echocardiography

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