Heart Failure Pathophysiology and Diagnosis

  • In an average healthy person, normal LV ejection fraction (LVEF):  >50%
  • Roughly 50% of those with heart failure have reduced left ventricular (LV) function (HFrEF)
    • Heart cannot squeeze/contract properly, and then progressively dilates.
  • The other 50% have preserved (normal contraction) LV function (HFpEF)
    • Cannot relax properly, leading to high diastolic (filling) pressures.
  • New heart failure – work patient up for ischemic disease (CAD) and ACS
    • Coronary Artery Disease causes 67% of heart failure!  #1 cause of heart failure
  • Symptomatic hypotension and kidney failure can be due to cardiac output failure.  Organs simply do not have sufficient blood to perfuse and stay alive.
  • Etiology of HFrEF
    • Hypertension
    • CAD
    • Myocarditis
    • Drugs – cyclophosphamide, doxorubicin, trastuzumab
    • Toxins – EtOH, cocaine, cobalt/lead, amphetamines
    • Systemic disease – hypo- or hyperthyroidism, HIV, SLE, Neuromuscular disease (Duchenne & Becker muscular dystrophy), scleroderma
    • Idiopathic (unknown cause)
  • Etiology of HFpEF
    • Hypertension
    • CAD
    • Infiltrative – amyloidosis & hemochromatosis (check ferritin)
  • Clinical signs and symptoms
    • Shortness of breath either with exertion or at rest
    • Orthopnea (shortness of breath lying flat on one’s back)
    • Paroxysmal nocturnal dyspnea (sudden bouts of shortness of breath and cough during the night/sleep hours)
    • Peripheral edema (swelling of feet/legs)
    • Decompensated signs/symptoms
      • More pillows at nighttime
      • Can’t walk up as many stairs before getting short of breath
      • Increased belly size, anorexia, nausea (gut edema)
  • Patients must weigh themselves daily, call the office if interval change.
  • History and physical
  • Paroxysmal nocturnal dyspnea leads to >2x increase in likelihood of HF
  • S3 confers 11x greater chance of HF.
  • If no dyspnea on exertion or crackles on lung exam, HF less likely.
  • BNP level – use when cause not clear.  If elevated, dyspnea is due to heart failure!  If not, consider other lungs as cause.
    • BNP level increases with age and bad kidneys
    • BNP level decreases with high BMI.
  • 12-lead EKG
    • Rule out MI, tachycardia, LV hypertrophy
  • CXR
  • Labs – BMP, CBC, UA, LFTs, lipid panel, TSH
Workup to Find A Cause
  • Must think of Ischemia first –
    • Serial EKGs and troponin levels to evaluate for NSTEMI/STEMI.
    • Routine investigation via stress or cath no longer part of routine workup for new HF patients.
    • However, if chest pain/pressure and/or risk factors are present –> proceed to cardiac cath.
  • Echocardiogram is most important test in HF.
    • “Wall motion abnormalities” is a clue to CAD or MI.
    • Assesses valvular anatomy and function
    • Left ventricular end-diastolic dimension:  can aid in telling how chronic the condition is and prognosis.
      • If DILATED w/acute symptoms –> chronic disease process.
      • If small LV –> better shot at recovery.
  • Cardiac magnetic resonance (CMR)
    • Looks for wall motion abnormalities, perfusion, and VIABILITY of tissue.
    • If thinking fibrosis, infiltration (amyloid/sarcoid), or iron deposition.

ACP MKSAP 17:  Cardiovascular Medicine, pp. 32-34
Image obtained via Google web search.

Share your thoughts