Abstract
Three mutually exclusive entities can underlie a postpulmonary embolism syndrome (PPES):
not obstructed postpulmonary embolism syndrome (post-PE dyspnea), chronic thromboembolic
pulmonary disease (CTEPD), and chronic thromboembolic pulmonary hypertension (CTEPH).
Cardiorespiratory impairment in CTEPH and CTEPD underlies respiratory and hemodynamic
mechanisms, either at rest or at exercise. Gas exchange is affected by the space effect,
the increased blood velocity, and, possibly, intracardiac right to left shunts. As
for hemodynamic effects, after a period of compensation, the right ventricle dilates
and fails, which results in retrograde and anterograde right heart failure. Little
is known on the pathophysiology of post-PE dyspnea, which has been reported in highly
comorbid with lung and heart diseases, so that a “two-hit” hypothesis can be put forward:
it might be caused by the acute myocardial damage caused by pulmonary embolism in
the context of preexisting cardiac and/or respiratory diseases. More than one-third
of PE survivors develops PPES, with only a small fraction (3–4%) represented by CTEPH.
A value of ≈3% is a plausible estimate for the incidence of CTEPD. Growing evidence
supports the role of CTEPD as a hemodynamic phenotype intermediate between post-PE
dyspnea and CTEPH, but it still remains to be ascertained whether it constantly underlies
exercise-induced pulmonary hypertension and if it is a precursor of CTEPH. Further
research is needed to improve the understanding and the management of CTEPD and post-PE
dyspnea.
Keywords
venous thromboembolism - chronic thromboembolic pulmonary disease - chronic thromboembolic
pulmonary hypertension - exercise-induced pulmonary hypertension
