10: Pathophysiology of Heart Failure

Question 1

What is the effect of the valsalva maneuver?

Answer 1

• ↑intrathoracic pressure –> ↓venous return –> ↓preload
• ↓intensity of most heart murmurs
• ↑intensity of MVP, HTCM murmurs

Question 2

What is capacitance?

Answer 2

Volume at a specified pressure; the slope at that point is stiffness = 1/compliance

Question 3

What is arterial elastance?

Answer 3

• Ea = ESP/SV
• Ea = HR*TPR

Question 4

What is the basic pathophysiology of heart failure?

Answer 4

• Myocardial insult/stimuli/damage causes pump dysfunction.
• Pump dysfunction activates neurohormones:
  
  • Catecholamines
  • Angiotensin II
  • Cytokines
• Heart remodels by hypertrophy, fibrosis and apoptosis
• Process cycles

Question 5

Describe the neurohormonal activation in heart failure.

Answer 5

• Initial fall in LV performance –> ↑wall stress
• Activates RAS and SNS
• Remodeling and progressive worsening of LV function leads to arrhythmias, pump failure, death
• Fibrosis, apoptosis, hypertrophy, cellular/molecular alterations, myotoxicity
• Peripheral vasoconstriction, sodium retention and hemodynamic alterations lead to heart failure Sx:
  
  • Fatigue
  • Activity altered
  • Chest congestion
  • Edema
  • SOB

Question 6

Describe the adrenergic pathway in heart failure progression.

Answer 6

• ↑CNS sympathetic outflow
  
  • ↑Cardiac sympathetic activity
    
    • Beta-1
    • Beta-2
    • Alpha-1
      
      • Myocyte hypertrophy
      • Myocyte injury
      • ↑arrhythmias
  • ↑vascular sympathetic activity
    
    • Alpha-1
      
      • Vasoconstriction
  • ↑renal sympathetic activity
    
    • Beta-1
      
      • Activation of RAS
        
        • Vasoconstriction
    • Alpha-1
      
      • Sodium retention

Question 7

Describe the neurohormonal balance in heart failure.

Answer 7

Vasoconstrictive hormones (endothelin, aldosterone, angiotensin II, epinephrine) outweigh naturitic peptides (ANP, BNP).

Question 8

Describe the pathophysiology of myocardial remodeling.

Answer 8

• Insult/remodeling stimuli
• ↑wall stress, cytokines, neurohormones, oxidative stress
  
  • Myocyte hypertrophy
  • Altered interstitial matrix
    
    • Ventricular enlargement
  • Fetal gene expression
    
    • Diastolic dysfunction
  • Altered calcium handling proteins
  • Myocyte death
    
    • Systolic dysfunction

Question 9

What are the four basic mechanisms of heart failure?

Answer 9

1. ↑blood volume (XS preload)
2. ↑resistance to flow (XS afterload)
3. ↓contractility
4. ↓filling

Question 10

What are the etiologies of increased blood volume? What do they result in?

Answer 10

Mitral or aortic regurgitation, volume overload (IV fluid), L to R shunts, chronic kidney disease

Reduced CO to peripheries results in sodium retention, vasoconstriction –> increased preload –> ventricular remodeling (eccentric).

Question 11

What are the etiologies of increased afterload? What do they result in?

Answer 11

Caused by aortic stenosis, aortic coarctation, HTN.

Reduced CO from diastolic dysfunction results in sodium retention, vascoconstriction and concentric remodeling.

Question 12

What are the etiologies of decreased contractility? What do they result in?

Answer 12

Caused by ischemic cardiomyopathy (infarcion or ischemia), myocarditis, or toxins (anthracycline, alcohol, cocaine).

Reduced CO results in sodium retention and vasoconstriction, resulting in eccentric ventricular remodeling.

Question 13

What are the etiologies of decreased filling? What do they result in?

Answer 13

Caused by mitral stenosis, constriction, restrictive cardiomyopathy, cardiac tamponade, HTCM, ICM

Concentric ventricular remodeling causes a decrease in filling pressure, reduced capacitance.

Question 14

Systolic vs. diastolic heart failure

Answer 14

• Systolic
  
  • Impaired contraction
  • Eccentric remodeling
  • All ages
  • 2/2 CAD, MI
  • Decreased EF
  • Third heart sound
• Diastolic
  
  • Impaired filling
  • Concentric remodeling
  • >60y/o, women
  • 2/2 HTN
  • Unchanged EF
  • Fourth heart sound

Question 15

What is evidence for low perfusion?

Answer 15

• Narrow PP
• Pulsus alterations
• Cool forearms/legs
• Sleepy/obtunded
• ACEI-related
  
  • Symptomatic HoTN
• Declining serium sodium level
• Worsening renal function

Question 16

What is evidence for congestion (elevated filling pressure)?

Answer 16

• Orthopnea
• High JVP
• Increasing S3
• Loud P2
• Edema
• Ascites
• Abdominojugular reflux
• Valsalva square wave

Question 17

Distinguish between dilated, **hypertrophic **and restrictive heart failure.

Answer 17

• Dilated
  
  • Dilated left/both ventricles w/ impaired contraction (ischemic, idiopathic, familial, viral, alcoholic, toxic, valvular)
• Hypertrophic
  
  • L/R ventricular hypertrophy (familial w/ AD inheritance)
• Restrictive
  
  • Restricted filling, reduced diastolic filling of one/both ventricles, normal/near-normal systolic function (idiopathic, amyloidosis, endomyocardial fibrosis)

Question 18

Describe the NYHA Classification of heart failure.

Answer 18

• Class I: asymptomatic
• Class II: Sx w/ moderate activity
• Class III: Sx w/ minimal activity
• Class IV: Sx at rest

Question 19

Describe the **ACC/AHA Staging System **of heart failure.

Answer 19

• Stage A: High risk for developing HF (HTN, CAD, DM, FHx, obesity)
• Stage B: Asymptomatic LV dysfunction
• Stage C: Past/current Sx of HF
  
  • Once at C, cannot go back to B/A
• Stage D: End-stage HF

Question 20

What are the ACA treatment guidelines for Stage A HF?

Answer 20

• OPT
  
  • Aspirin
  • ACEI
  • Statins
  • B-Blockers

Question 21

What are the ACA guidelines for **Stage B **HF?

Answer 21

• OPT
• ICD if LV dysfunction present

Question 22

What are the AHA guidelines for Stage C HF?

Answer 22

• OPT
• ICD if LV dysfunction present
• Cardiac resynchronization therapy (CRT) if QRS wide, LVEF=35%

Question 23

What are the AHA guidelines for **Stage D **HF?