Pulmonary vascular pathology forms an important challenge in daily clinical practice; pulmonary embolism (PE) is the third leading cause of cardiovascular mortality in North America and is responsible for 510% of all in-hospital deaths. Furthermore, the diagnosis of PE remains one of the most difficult problems confronting clinicians. Timely diagnostic testing must be performed to enable the initiation of antithrombotic therapy for patients proven to have this condition while avoiding the risks of anticoagulation for patients without PE. The widespread adoption of right heart catheterisation.