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Year 3 Medicine > Heart failure > Flashcards

Heart failure Flashcards

1
Q

Definition of heart failure

A
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2
Q

Physiological control of cardiac output

A
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3
Q

Response to increased demand on the heart in physiological state vs heart failure

A
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4
Q

Significance of the circulatory system . being a closed loop

A

Because the circulatory system is a closed loop, heart failure on either side would eventually lead to biventricular failure

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5
Q

Overview of causes of heart failure

A
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6
Q

Common causes of heart failure

A
  • Ischaemic heart disease
  • hypertension
  • valvular disease- mitral and aortic
  • shock
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7
Q

Molecular changes that occur in heart failure

A
  1. induction of foetal genes: alpha myosin to beta myosin, which is less efficienct at contracting
  2. abnormal protein synthesis: ion channels, contractile proteins. abnormal excitation/contraction coupling.
  3. production of cytokines, growth factors and neurohormones: eg noradrenaline, angiotensin by myocytes or stromal cells. results in autocrine/paracrine loops causing local myocyte damage–once initiated they may result in ongoing myocardial damage
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8
Q

Myocardial Remodelling in heart failure

A

(debate as to whether it’s a cause or effect of heart failure)

Myocardial cells

  • hypertrophy: thickening by increasing the number of sarcomeres eg left ventricular wall
  • lengthening: sarcomeres overlap. associated with ventriuclar dilatation and more advanced disease

Changes in ECM

-fibrosis triggered by Ang2 and aldosterone. Alter the way forces are transmitted through the myocardium

Myocardial death

Apoptosis triggered by SNS, Ang2 and other local factors

Changes in heart shape

  • heart becomes more globular and spherical
  • this is a macroscopic change
  • poor mechanics- increases end-diastolic wall stress
  • pulls apart papillary muscles of mitral/tricuspid valves
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9
Q

Macroscopic appearance of heart in heart failure

A
  • ventricular dilatation
  • compensatory hypertrophy: weight and thickness

General rule of thumb:

a) Pressure overload–>hypertorphy
b) Volume overload–>hypertrophy AND dialtation
- might detect underlying cause: amyloid, HOCM, infarction etc

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10
Q

Microscopic appearance of heart in heart failure

A
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11
Q

What are the broad categories of intrinsic diseases of the heart?

A

Ones affecting the:

myocardium

endocardium

pericardium

valves

(but main cause of HF is obviously IHD)

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12
Q

3 patterns of myocardial disease (Cardiomyopathies)

A
  1. dilated cardiomyopathy
  2. hypertorphic cardiomyopathy
  3. restrictive cardiomyopathy
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13
Q

Most common cardiomyopathy

A

Dilated cardiomyopathy

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14
Q

What happens in Dilated cardiomyopathy?

A
  • increased mass- slight, due to hypertrophy
  • but most importantly- THINNED walls as CHAMBER DILATES
  • macro: globular heart
  • micro: (non-specific) hypertrophy and fibrosis
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15
Q

Patohgenesis of DCM

A
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16
Q

Inflammatory causes of dilated cardiomyopathy (i.e. myocarditis)

A

Infection: viral, bacterial (less common), protozoal (trypanosome)

Drug: hypersensitivity reaction to a drug

Systemic: SLE, amyloid

Idiopathic: giant cell myocarditis

17
Q

Familial hypertrophic cardiomyopathy

A

A cause of hypertrophic cardiomyopathy

18
Q

Microscopic changes in Familial HOCM

A

Myocyte disarray (not aligned) and fibrosis.

This leads to arrythmias.

19
Q

Pathogenesis of HOCM

A
20
Q

What is restrictive cardiomyopathy?

A

Heart muscle is unable to relax so ventricles can’t fill properly.

This could be because of abnormalities in the heart MUSCLE itself (myocardium) or because of abnormalities in the PERICARDIUM/ENDOCARDIUM.

Myocardial: amyloid

Pericardial fibrosis

Endocardial fibrosis

21
Q

2 broad categories of cardiac amyloid (a cause of restrictive cardiomyopathy)

A
  1. senile atrial amyloid
    - amyloid is derived from ANP
    - normal ageing change
  2. systemic
    - AL amyloid: produced in myeloma
    - AA amyloid: produced in autoimmune diseases like RA
    - can be hereditary

Essentially amyloid protein deposits in the myocardium and impairs normal function of muscle

22
Q

Causes of endomyocardial fibrosis

A
23
Q

How can disease of pericardium cause heart failure?

A

Constrictive pericarditis

Can happen following bacterial or viral pericarditis, for eg

24
Q

Which valve diseases can cause heart failure and how?

A

Mitral

Mitral regurgitation- leads to volume overload

Aortic

Aortic stenosis- leads to pressure overload

Aortic regurgitation- leads to volume overload

25
Q

Macro changes in valvular heart failure

A
26
Q

How does congenital heart disease cause heart failure?

A

Ventricular septal defect

Causes right ventricular hypertrophy as blood flows from left ventricle into the right ventricle upon systole.

Pressure in thin walled right ventricle rises, causing right heart failure

27
Q

Extrinsic causes of heart failure

A
  1. Pulmonary hypertension–>right heart failure
  2. Systemic hypertension–>right heart failure
28
Q

Causes of pulmonary hypertension

A

obstruction or destruction of pulmonary vessels

  • pulmonary fibrosis
  • pulmonary thromboembolic disease eg DVT

chronic hypoxia- this will cause pulmonary vessels to vasoconstrict (to shunt blood away from poorly ventilated areas)

  • COPD
  • lung fibrosis
  • cystic fibrosis
29
Q

Complications of heart failure

A

Local

  1. arrythmias, sudden cardiac death
  2. further ischaemic myocardial damage

Systemic

  1. Left sided HF
    a) Forward failure: hypoperfusion of Kidneys, GI tract and brain
    b) Backward failure: pulmonary congestion and oedema
  2. Right sided HF
    a) Forward failure: not that important
    b) Backward failure: systemic oedema and organ congestion (nutmeg liver- impaired liver function)
30
Q

Schematic of systemic hypoperfusion of kidneys

A
31
Q
A

Year 3 Medicine (9 decks)

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