The aim of this study is to assess the ability of clonidine to reduce the mean pulmonary artery pressure in patients with pulmonary hypertension subjected to cardiac surgery.

Prospective, clinical-interventionist, randomized, and double-blind study. Patients with group 2 pulmonary hypertension will be included and subjected to cardiac surgery with extracorporeal circulation. Mean pulmonary artery pressure and the doses of dobutamine and sodium nitroprusside will be assessed four times: before (T0) administration of 2 μg/kg of intravenous clonidine or a placebo, 30 minutes after the onset of treatment (T1), immediately after extracorporeal circulation (T2), and 10 minutes after the injection of protamine (T3).

Inclusion Criteria:

• Signing an informed consent form,
• Aged 18 to 80 years
• Pulmonary hypertension due to left heart disease,
• Physical status 2 or 3 according to the classification system of the American Society of Anesthesiologists,
• Subjected to cardiac circulation with extracorporeal circulation