Cardiovascular Medicine Book

Congestive Heart Failure

  • Brain Natriuretic Peptide

Coronary Artery Disease

Hyperlipidemia

http://www.fpnotebook.com/

Brain Natriuretic PeptideAka: B-Type Natriuretic Peptide, BNP

Advertisement

  1. Mechanism
    1. Heart secretes natriuretic peptides
      1. Maintains Blood Pressure and blood volume
      2. Prevents excessive salt and water retention
    2. Specific activity of natriuretic peptides
      1. Suppresses sympathetic nervous system
      2. Suppresses renin-Angiotensin-aldosterone system
      3. Stimulates diuresis
      4. Decreases peripheral vascular resistance
      5. Increases smooth muscle relaxation
    3. Pathway for heart BNP release
      1. Left ventricular wall stretched by volume overload
      2. Cardiac muscle cells secrete BNP precursor
      3. Precursor converted to proBNP
      4. ProBNP cleaved into 2 parts
        1. C-terminal BNP (biologically active)
        2. N-terminal BNP or NT-proBNP (biologically inactive)
  2. Indication
    1. Congestive Heart Failure Marker
    2. Dyspnea Evaluation
      1. Most useful for Negative Predictive Value
      2. Level <50 pg/ml suggests other Dyspnea cause
      3. Level >150 pg/ml suggests Congestive Heart Failure
  3. Intrepetation of BNP Levels
    1. No Congestive Heart Failure: BNP <50 pg/ml
      1. Median BNP: 9 pg/ml
    2. Congestive Heart Failure
      1. CHF Diagnosis: >150 pg/ml (standard cutoff)
      2. NYHA Class I CHF: Median BNP 83 pg/ml (49-137)
      3. NYHA Class II CHF: Median BNP 235 pg/ml (137-391)
      4. NYHA Class III CHF: Median BNP 459 pg/ml (200-871)
      5. NYHA Class IV CHF: Median BNP 1119 pg/ml (>728)
  4. Interpretation of NT-proBNP
    1. Cutoffs in studies: NT-proBNP>300 suggests CHF
  5. Causes of increased BNP level
    1. Congestive Heart Failure
      1. BNP released from left ventricle
      2. Response to volume overload
      3. Response to pressure overload
    2. Left Ventricular Hypertrophy
    3. Cardiac inflammation
      1. Myocarditis
      2. Cardiac allograft rejection
    4. Kawasaki disease
    5. Primary Pulmonary Hypertension
    6. Renal Failure
    7. Ascitic Cirrhosis
    8. Endocrine disease
      1. Primary Hyperaldosteronism
      2. Cushing Syndrome
    9. Advanced age
    10. Medications that raise BNP
      1. Digoxin
      2. Beta Blockers (some)
  6. Causes of artificially lowered BNP levels
    1. Diuretics (e.g. Spironolactone)
    2. ACE Inhibitors
    3. Angiotensin Receptor Blockers (ARBs)
  7. Efficacy
    1. Most effective for Negative Predictive Value
      1. See above under indications
      2. CHF very unlikely if BNP<50 pg/ml
    2. BNP cutoff for CHF diagnosis at 150 pg/ml
      1. Test Sensitivity: 82%
      2. Test Specificity: 83%
  8. References
    1. Cheng (2001) J Am Coll Cardiol 37:386
    2. Collins (2003) Ann Emerg Med 41:532
    3. Dao (2001) J Am Coll Cardiol 37:379
    4. Doust (2004) Arch Intern Med 164:1978
    5. Mueller (2004) N Engl J Med 350:647
    6. Wieczorek (2002) Am Heart J 144:834

Navigation Tree