What do echocardiogram measurements indicate?

Understanding Echocardiogram Measurements

Echocardiogram measurements provide critical information about cardiac structure, function, and hemodynamics that directly impact patient morbidity, mortality, and quality of life by enabling accurate diagnosis of cardiovascular conditions, guiding treatment decisions, and monitoring disease progression.

Key Cardiac Structural Measurements

• Left Ventricular Dimensions:

  • End-diastolic dimension (EDD) and end-systolic dimension (ESD) - used to assess ventricular size and remodeling
  • LV mass calculation indexed to body surface area (BSA) - critical for diagnosing LV hypertrophy
  • Sphericity index (ratio of LV short-to-long-axis dimension) - values >0.76 indicate pathological remodeling 1

• Chamber Volumes:

  • Left and right ventricular volumes (end-diastolic and end-systolic)
  • Left and right atrial volumes - enlarged atria may indicate diastolic dysfunction or valvular disease

• Wall Thickness:

  • Interventricular septum and posterior wall measurements - identify hypertrophy patterns
  • Regional wall thickness variations - help diagnose specific cardiomyopathies

Systolic Function Parameters

• Left Ventricular Ejection Fraction (LVEF):

  • Normal: >50-55%
  • Mildly reduced: 45-50%
  • Moderately reduced: 30-45%
  • Severely reduced: <30%
  • Critical for prognosis and treatment decisions in heart failure 2

• Global Longitudinal Strain (GLS):

  • Detects subclinical dysfunction before LVEF reduction
  • Normal values typically better than -18% (more negative is better) 1

• Regional Wall Motion:

  • Segmental wall motion abnormalities - crucial for detecting ischemic heart disease
  • Distribution patterns help identify specific cardiomyopathies 2, 1

Diastolic Function Parameters

• Mitral Inflow Velocities:

  • E/A ratio (early to late diastolic transmitral flow velocity)
    • Normal: 0.8-2.0
    • Impaired relaxation: <0.8
    • Pseudonormal: 0.8-2.0 (requires additional parameters to differentiate from normal)
    • Restrictive: >2.0 with shortened deceleration time 3

• Tissue Doppler Imaging:

  • E/e' ratio (mitral inflow E velocity to early diastolic mitral annular velocity)
    • <8: normal filling pressures
    • 8-15: indeterminate (requires additional parameters)

    • 15: elevated LV filling pressures 3

• Pulmonary Vein Flow:

  • Systolic (S) and diastolic (D) velocities
  • Atrial reversal (Ar) velocity and duration
  • Helps confirm diastolic dysfunction patterns 4

Valvular Assessment

• Valve Areas and Gradients:

  • Aortic valve area and mean/peak gradients - assess aortic stenosis severity
  • Mitral valve area and mean gradient - assess mitral stenosis severity

• Regurgitation Quantification:

  • Vena contracta width
  • Regurgitant volume and fraction
  • Effective regurgitant orifice area (EROA)
  • Critical for timing interventions in valvular disease 2

Pressure Measurements

• Pulmonary Artery Pressure:

  • Estimated from tricuspid regurgitation velocity using modified Bernoulli equation
  • Normal: <25 mmHg systolic
  • Pulmonary hypertension: >35 mmHg systolic 5

• Left Atrial Pressure Estimation:

  • E/e' ratio >15 suggests elevated left atrial pressure
  • Pulmonary vein flow patterns provide additional information 4

Disease-Specific Patterns

• Dilated Cardiomyopathy:

  • Ventricular dilation with normal wall thickness
  • Reduced systolic function (LVEF typically <40%)
  • Global hypokinesis 6

• Hypertrophic Cardiomyopathy:

  • Increased wall thickness (typically ≥15 mm)
  • Often asymmetric septal hypertrophy
  • Dynamic outflow tract obstruction may be present 1, 7

• Restrictive Cardiomyopathy:

  • Normal ventricular size and systolic function
  • Atrial enlargement
  • Restrictive filling pattern on Doppler 2, 6

• Cardiac Tamponade:

  • Pericardial effusion
  • Right atrial collapse (sensitive sign)
  • Diastolic right ventricular collapse (more specific sign)
  • Distended inferior vena cava without respiratory collapse 2

• Constrictive Pericarditis:

  • Pericardial thickening
  • Inferior vena caval enlargement
  • Exaggerated respiratory variation in flow velocities across atrioventricular valves 2

Technical Limitations and Interpretation Challenges

• M-mode measurements are prone to errors in patients with:

  • Inadequate acoustic access
  • Abnormally shaped ventricles
  • Segmental wall motion abnormalities 2

• Right ventricular quantification is challenging due to:

  • Complex shape
  • Heavy trabeculation
  • Difficulty obtaining standardized imaging planes 2

• Diastolic function indices are load-dependent and require careful interpretation 2

• All measurements should be indexed to body size (typically BSA) to avoid misdiagnosis, especially in patients with extreme body sizes 1

Clinical Applications

• Heart Failure Assessment:

  • Distinguishes heart failure with reduced ejection fraction (HFrEF) from heart failure with preserved ejection fraction (HFpEF)
  • Identifies underlying etiology (ischemic vs. non-ischemic)
  • Guides therapy selection and monitors response 4, 6

• Valvular Disease Management:

  • Determines timing of intervention based on valve severity and ventricular response
  • Monitors disease progression over time 2

• Ischemic Heart Disease:

  • Identifies regional wall motion abnormalities
  • Assesses viability and ischemia during stress testing
  • Evaluates complications of myocardial infarction 2

• Pulmonary Hypertension:

  • Estimates pulmonary artery pressure
  • Assesses right ventricular function and adaptation 5

Echocardiography remains the cornerstone of non-invasive cardiac imaging, providing comprehensive assessment of cardiac structure and function that directly impacts clinical decision-making and patient outcomes.