What is Left Ventricular (LV) function?

Left Ventricular (LV) Function

Left ventricular function refers to the heart's ability to contract and relax properly, typically measured through parameters such as ejection fraction (LVEF), wall motion, wall thickening, and volumes, which are critical for assessing cardiac performance and predicting clinical outcomes.

Definition and Assessment Parameters

• Left ventricular (LV) function is a comprehensive assessment of the heart's pumping ability that includes both systolic (contractile) and diastolic (relaxation) components 1
• LV function assessment requires measurement of multiple parameters:
  • LVEF (Left Ventricular Ejection Fraction): Numerical values must be included in reports with appropriate reference values 1
  • LV volumes: Quantitative measurements with reference values 1
  • Wall motion (WM): Visual evaluation categorized as normal, hypokinesia (mild, moderate, severe), akinesia, or dyskinesia 1
  • Wall thickening (WT): Visual evaluation categorized as normal, decreased (mild, moderate, severe), or absent 1

Systolic Function Assessment

• LVEF is the primary measure of LV systolic function, representing the percentage of blood ejected from the LV during systole 1
• Normal LVEF values vary by imaging modality, but generally range from 55-70% 1
• LVEF is a powerful predictor of:
  • Overall mortality 1
  • Cardiovascular mortality 1
  • Heart failure risk 1
• Advanced measures of systolic function include:
  • Global longitudinal strain (GLS): More sensitive than LVEF for detecting early myocardial dysfunction 2
  • Midwall fractional shortening: Better reflects true myocardial contractility in hypertrophied ventricles 1

Diastolic Function Assessment

• Diastolic function evaluates the heart's ability to relax and fill properly 1
• Key parameters include:
  • Mitral inflow patterns (E/A ratio, deceleration time)
  • Tissue Doppler velocities (e', a')
  • E/e' ratio (correlates with LV filling pressures)
  • Left atrial volume index 1
• Diastolic dysfunction progresses through grades I-III, reflecting increasing LV filling pressures 1

Clinical Significance and Prognostic Value

• LV function assessment is essential for:

  • Diagnosis and management of heart failure 1
  • Risk stratification in coronary artery disease 1
  • Evaluation of valvular heart disease 1
  • Monitoring cardiotoxicity from chemotherapy 2
  • Assessment of cardiomyopathies 3

• LV reverse remodeling (LVRR), defined as an absolute increase in LVEF ≥10% with final LVEF ≥35%, indicates favorable prognosis in non-ischemic cardiomyopathy 3

• The LV global function index (LVGFI), which integrates LV structure with function, is a powerful predictor of heart failure and cardiovascular events 4

Interrelationship with Right Ventricular Function

• Left and right ventricular functions are intimately linked through:

  • Shared muscle fibers in the interventricular septum
  • Systolic ventricular interaction (LV contraction augments RV contraction)
  • Diastolic ventricular interaction (RV filling can affect LV filling through septal displacement) 5

• LV dysfunction can lead to pulmonary hypertension, increasing RV afterload and potentially causing right heart failure 5

Common Pitfalls in LV Function Assessment

• LVEF has limitations:

  • It measures chamber function rather than myocardial function
  • It is load-dependent and may be preserved despite myocardial dysfunction
  • It has limited sensitivity for detecting early disease 2

• Technical challenges in echocardiographic assessment:

  • Endocardial border definition may be suboptimal
  • Geometric assumptions may not apply to abnormally shaped ventricles
  • Visual estimation alone is suboptimal, particularly for intermediate degrees of dysfunction 1

• Age-related changes must be considered when evaluating diastolic function, as normal aging causes slowing of LV relaxation 1