**4.1.1 Pre-capillary**

#### **Pulmonary embolism**

Acute pulmonary embolism during cardiac surgery can lead to PH and, in some cases, evolve into CTEPH. Pulmonary thromboembolectomy, when surgically indicated, can help control PH and is currently the only curative treatment in patients with CTEPH (Jamieson & Nomura, 2000; Jamieson et al., 2003) (Fig. **6**). In case of CTEPH, evaluation of the feasibility of surgery mainly depends on the location of the obstruction (central vs. more distal pulmonary arteries) (Dartevelle et al., 2004). Patients who are not candidates for surgery may also benefit from PH-specific medical therapy, however, the use of these medications in CTEPH requires further evaluation in randomized controlled trials (Jais et al., 2008; Rubin et al., 2006; Suntharalingam et al., 2008).

The rationale for systemic anticoagulant therapy for chronic lung embolism in patients with PH may be justified by well-recognized risk factors for venous thromboembolism, such as heart failure, a sedentary lifestyle, and a thrombophilic predisposition (Bjornsson & Edwards, 1985). However, no data actually support anticoagulant therapy specifically in patients with PH. Warfarin has been evaluated in only two nonrandomized studies, one retrospective and the other prospective, involving a small number of patients (Fuster et al., 1984; Rich et al., 1992).
