Heeghtened or Heightened: How To spell?

The word Heeghtened is misspelled against Heightened, which is past tense of "Heighten"

Word contains consecutive vowels 'EI' in between alphabets h & ghtened is misspelled as 'EE'
Wrong Spelling:  h-ee-ghtened 
Correct Spelling:  h-ei-ghtened 
Explore spell check of Heightened to spell without errors.