Usually portal vein clots causes portal hypertension and GI bleeding from tortuous vessels usually in the lower esophagus or stomach. Diagnosis is based on ultrasonography. "Treatment involves control of variceal bleeding (usually with endoscopic banding, IV octreotide, or both), prevention of recurrence using β–blockers and sometimes surgical shunts and thrombolysis (blood clots) for acute thrombosis."
Usually pulmonary hypertention has an underlying cause of blood clots in the lungs or pulmonary artery.
Hope this provides some insight into the medical problem. Thanks for the question and if you have any further questions or comments you are welcome to respond. Take care,
Ken