Pathophysiology of Heart Failure Flashcards Preview

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Flashcards in Pathophysiology of Heart Failure Deck (22):
1

Prevalence, Incidence and Mortality of Heart Failure in the US

  • prev=~5,000,000
  • incidence=550,000
  • mortality=250,000

2

Approximate cost of heart failure in US

$37.5 billion

3

Reasons for increasing incidence and prevalence 

  • Aging population
  • Increased survival of initial cardiac disease
  • Therapies generally stabilize HF, but do not often cure it.

4

Heart failure syndrome (forward failure) definition

Heart failure is the inability of the hear to pump blood forward at a sufficient rate to meet the metabolic demands of the body. 

5

Heart failure syndrome (backward failure) definition

the ability to pump blood at a a sufficient rate to meet metabolic demands only if the cardiac filling pressures are abnormally high

6

Major characteristics of heart failure

  • Poor forward blood flow
    • Low flow →↓CO
  • Backward buildup of pressure
    • Congestion→↑filling pressure
    • Typically a response to low flow.
  • Decrease in cardiac output and an increase in filling pressure are fundamental to the pathophysiology of heart disease

 

7

Characteristics of systolic dysfunction that leads to heart failure

  • Systolic dysfunction: a problem with squeeze→↓contraction→↓inotropy.
  • Hallmark: decreased ejection fraction and ventricular enlargement
    • Decreased ejection fraction
      • Heart failure with reduced ejection fraction=HFrEF
      • Left ventricular systolic dysfunction=LVSD
    • Ventricular enlargement
      • Dilated cardiomyopathy= DCM

 

 

8

Primary causes of systolic dysfunction leading to heart failure (3)

  • Direct destruction of heart muscle cells
  • Overstressed heart muscle
  • Volume overloaded heart muscle

9

Causes of direct destruction of heart muscle cells

  • myocardial infarction
  • viral myocarditis
  • peripartum cardiomyopathy
  • idiopathic dilated cardiomyopathy
  • alcohol.

10

Casues of overstressed heart muscle

  • tachycardia-mediated HF
  • meth abuse
  • catecholamine mediated.

11

Causes of volume overloaded heart muscle

  • mitral regurgitation
  • high cardiac output

12

Characteristics of diastolic dysfunction leading to heart failure

  • problem with filling→↓lusitropy/decrease in relaxation.
  • Hallmark: normal ejection fraction and ventricular wall thickening.
    • Normal ejection fraction:
      • HF with preserved ejection fraction=HFpEF
      • Preserved systolic function=PSF
    • Ventricular wall thickening:
      • Left ventricular hypertrophy=LVH
      • Hypertrophic cardiomyopathy=HCM

 

 

13

Primary causes of diastolic dysfunction leading to heart failure (3)

  • High afterload/pressure afterload
  • Myocardial thickening/fibrosis
  • External compression

14

Causes of high afterload/pressure afterload

  • hypertension
  • aortic stenosis
  • dialysis (inadequate volume removal)

15

Causes of myocardial thickening/fibrosis

  • HCM
  • primary restrictive cardiomyopathy

16

Causes of external compression

  • pericardial fibrosis/constrictive pericarditis,
  • pericardial effusion

17

Main types of compensatory responses to heart failure (3)

  • heart failure --> decreased CO --> mechanisms that aim to increase CO/compensate for other effects
  • neurohormonal activation
  • frank-starling increases in preload
  • ventricular remodeling: hypertrophy and dilation

18

Characteristics of neurohormonal compensatory response to heart failure

  • ↓filling/↓SV→↓CO

  • Juxtaglomerular apparatus in kidney senses lower flow→renin-angiotensin-aldosterone (RAAS) activation

    • vasoconstriction --> ↑TPR --> helps maintain BP and perfusion of vital organs

    • ​aldosterone --> ↑Sodium retention

  • Carotid sinus/aortic baroreceptors sense lower pressure→autonomic nervous system (sympathetic)/adrenergic activation
    • ↑HR
    • vasoconstriction
  • ↑sodium retention + vasoconstriction + ↑HR →↑volume→↑LV filling

     

19

Characteristics of Frank-Starling compesatory response to heart failure

  • decreased output/ejection fraction → higher ESV in LV + filling during diastole → ↑LV filling

  • ↑LV filling→ increased preload → ↑SV

  • stroke volume is preserved by increasing the end diastolic filling/pressure.

20

Types of ventricular remodeling (compensatory response to heart failure) and long-term consequences

  • Long term increases in cardiac workload and increased metabolic demands promote adverse myocardial remodelling.
    • Ventricular hypertrophy
    • Ventricular dilation
    • Myocardial damage/apoptosis
    • Myocardial fibrosis
  • Overtime remodelling causes:
    • Decreased contractile force
    • Decreased dynamic function
    • Increased diastolic stiffness

 

 

 

21

Major characteristics of right-sided heart failure

  • Under normal circumstances, the pulmonary vasculature is a low pressure system
  • Stresses to the RV can cause it to fail to adequately pump blood through the lungs:
    • ↓ Circulating blood flow (forward RV HF)
    • ↑ Venous pressures (backward RV HF)

 

22

Major causes of right-sided heart failure (4)

  • Left heart failure
    • Backward HF from LV dysfunction stresses the right side by increasing pulmonary venous pressures.
  • Lung disease/pulmonary HTN/RV pressure overload
    • “cor pulmonale”→primary lung disease causes HF
    • COPD, primary pulmonary hypertension, sleep apnea
  • RV volume overload
    • Shunt
    • tricuspid regurgitation
  • Damage to the RV myocardium
    • Isolated RV infarct (rare)
    • myocarditis