MioAtlas
G1: Left-sided valves

Mitral valve prolapse (Barlow disease)

Advanced, diffuse form of myxomatous degeneration of the mitral valve apparatus (Barlow disease).

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Definition

Advanced, diffuse form of myxomatous degeneration of the mitral valve apparatus (Barlow disease), characterized by massive accumulation of glycosaminoglycans in the spongiosa layer producing thickened (> 5 mm), redundant, multisegmental billowing leaflets, marked mitral annular dilation, and elongation or rupture of chordae tendineae, resulting in holosystolic prolapse into the left atrium with a mid-systolic click and dynamic late systolic murmur [V1] [V3] [G1-07] [G1-08].

Severity criteria

  • Anatomic diagnostic criteria for Barlow: Systolic displacement of one or both mitral leaflets > 2 mm above the plane of the mitral annulus in the parasternal long-axis view; with diffuse diastolic leaflet thickening > 5 mm, multisegment bileaflet involvement, and marked annular dilation [V1] [G1-08].
  • Grading of accompanying mitral regurgitation:
    • Mild (L): EROA < 0.20 cm²; RV < 30 mL/beat; prolapse/click with minimal late systolic regurgitation [V1] [V3].
    • Moderate (M): EROA 0.20–0.39 cm²; RV 30–59 mL/beat [V1] [V3].
    • Severe (G): EROA ≥ 0.40 cm²; RV ≥ 60 mL/beat; RF ≥ 50 %; flow reversal in pulmonary veins due to massive chordal elongation or secondary rupture [V1] [V3].

Findings by layer

Hemodynamics

  • Cardiac output and intracavitary pressures normal in mild forms; progressive increase in LV end-diastolic volume and pulmonary capillary wedge pressure in forms with severe regurgitation [V1] [V3].

Rhythm

  • Predominant rhythm: Normal sinus rhythm [V1].
  • Increased susceptibility to ventricular premature beats or ventricular arrhythmias related to papillary muscle traction (mitral annular disjunction) [G1-08] [V1].

ECG

  • Frequently normal; occasionally non-specific repolarization abnormalities (flattening or inversion of T waves in leads II, III, and aVF) due to mechanical traction on papillary muscles [E1] [G1-08].

Heart sounds and murmurs

  • Non-ejection mid-systolic click: High-frequency, clicking, crisp sound produced by sudden tensing and checking of prolapsing redundant leaflets and elongated chordae during ventricular systole [G1-07].
  • Late systolic murmur: High-frequency crescendo murmur starting after the click and extending up to the second heart sound (S2), auscultated at the apex [G1-07] [G1-14].
  • First heart sound (S1): Usually normal or accentuated [G1-10].
  • Second heart sound (S2): Normal or slightly accentuated [G1-11].

Arterial pulse

  • Normal in mild and moderate forms [B4].

Jugular venous pulse

  • Normal, unless severe longstanding mitral regurgitation supervenes [B3].

Maneuvers

  • Strain phase of Valsalva maneuver / Standing: By decreasing left ventricular end-diastolic volume (reduced preload), redundant leaflets prolapse earlier in systole: the mid-systolic click moves earlier toward the first heart sound (S1) and the murmur becomes longer and more intense [G1-07] [B1].
  • Squatting / Leg raise: By increasing venous return and ventricular volume (increased preload), a more filled LV delays leaflet eversion: the click moves later toward the second heart sound (S2) and the murmur becomes shorter and later [G1-07] [B1].
  • Isometric handgrip: Increases late systolic murmur intensity due to increased systemic afterload [B1].

Simulator severity grades

Simulator severity grades: Mild, Moderate, Severe
Baseline rhythm: Normal Sinus Rhythm

Also known as: Barlow disease · Myxomatous mitral valve disease · Mitral valve prolapse · Floppy mitral valve syndrome · MVP

Other pathologies in this group

Sources

  1. [B1] Bedside diagnosis of systolic murmurs . N Engl J Med (1988) . DOI: 10.1056/NEJM198806163182404 PubMed: 2897627
  2. [B3] The jugular venous pressure revisited . Cleve Clin J Med (2013) . DOI: 10.3949/ccjm.80a.13039 PubMed: 24085809
  3. [B4] The Carotid Pulse . Clinical Methods: The History, Physical, and Laboratory Examinations (1990) . PubMed: 21250154
  4. [E1] AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part V: electrocardiogram changes associated with cardiac chamber hypertrophy: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society: endorsed by the International Society for Computerized Electrocardiology . Circulation (2009) . DOI: 10.1161/CIRCULATIONAHA.108.191097 PubMed: 19228820
  5. [G1-07] Late systolic murmurs and non-ejection ("mid-late") systolic clicks. An analysis of 90 patients . Br Heart J (1968) . DOI: 10.1136/hrt.30.2.203 PubMed: 5642419
  6. [G1-08] Epidemiology and pathophysiology of mitral valve prolapse: new insights into disease progression, genetics, and molecular basis . Circulation (2014) . DOI: 10.1161/CIRCULATIONAHA.113.006702 PubMed: 24867995
  7. [G1-10] The First Heart Sound . Clinical Methods: The History, Physical, and Laboratory Examinations (1990) . PubMed: 21250175
  8. [G1-11] The Second Heart Sound . Clinical Methods: The History, Physical, and Laboratory Examinations (1990) . PubMed: 21250183
  9. [G1-14] Systolic Murmurs . Clinical Methods: The History, Physical, and Laboratory Examinations (1990) . PubMed: 21250186
  10. [V1] 2025 ESC/EACTS Guidelines for the management of valvular heart disease . Eur Heart J (2025) . DOI: 10.1093/eurheartj/ehaf194 PubMed: 40878295
  11. [V3] Recommendations for Noninvasive Evaluation of Native Valvular Regurgitation: A Report from the American Society of Echocardiography Developed in Collaboration with the Society for Cardiovascular Magnetic Resonance . J Am Soc Echocardiogr (2017) . DOI: 10.1016/j.echo.2017.01.007 PubMed: 28314623