Provides reference values for left ventricular parameters.

Important notes:

• The API matches the exact combination of parameter, gender, pm, and age to return appropriate reference values.
• The pm parameter specifies whether papillary muscles are included in "mass" or "volume" calculations.
• Age validation:
  • If pm=mass, request age must be between 18 and 83 (inclusive).
  • If pm=volume, request age must be between 16 and 83 (inclusive).
  • The age query parameter must be an integer. The sheet matching process prefers an exact numeric age row; if none exists it will fall back to a row with a blank age cell.