The University of California, San Diego (UCSD) classification; a proposed new surgical classification of chronic thromboembolic pulmonary hypertension

Surgical levelLocation of thromboembolic disease
0No evidence of thromboembolic disease
IStarts in the main pulmonary arteries (patients with complete occlusion of one lung are classified as level IC)
IIStarts at the level of the lobar or intermediate pulmonary arteries
IIIStarts at the level of segmental arteries only
IVStarts at the subsegmental branches only
  • Preliminary results (M. Madani, Division of Cardiovascular and Thoracic Surgery, University of California, San Diego, La Jolla, CA, USA; unpublished data).