Pulmonary arterial hypertension characterized

Primary pulmonary hypertension is a disease of unclear etiology that is characterized by abnormally high mean pulmonary arterial pressures, in the absence of a demonstrable cause. A wide variety of pulmonary and cardiac diseases can lead to secondary pulmonary hypertension. 

Portopulmonary hypertension (PPH) is characterized by (1.) elevated pulmonary artery pressure (>25 mm Hg), (2.) increased pulmonary vascular resistance (>120 dyne/sec/cm ), and (3.) normal pulmonary capillary wedge pressure (<15 mm Hg). The presence of portal hypertension is considered to be a prerequisite for the development of PPH. 

Pulmonary hypertension is characterized by a chronically elevated pulmonary artery pressure. As described in previous sections of this chapter, under normal conditions, the pulmonary artery pressure has a systolic value of 18 to 25 mm Hg, a diastolic value of 6 to 10 mm Hg, and a mean value ranging from 12 to 16 mm Hg. Pulmonary hypertension exists when the pulmonary artery systolic and mean pressures exceed 30 and 20 mm Hg, respectively. In the disease state, the pressure in the pulmonary artery may fluctuate widely and is often so high that it equals the blood pressure in the systemic arterial bed. As would be expected, pulmonary vascular resistance is also extremely high in patients with pulmonary hypertension. In addition, patients with this disease exhibit an enlarged right ventricle and an enlargement of the main pulmonary artery and its branches. Systemic hemodynamic parameters, however, such as cardiac output, cardiac index, systemic artery pressure, and pulmonary artery wedge pressure are usually not elevated. 

The use of iloprost has been proposed in patients with systemic sclerosis, a disease that is often characterized by pulmonary hypertension and Raynaud s phenomenon. Three patients with systemic sclerosis who were treated with iloprost developed acute thrombotic events (3). In one case, intestinal infarction occurred 1 day after infusion of iloprost. In another patient the left kidney was not perfused 22 days after the last infusion of iloprost because of thrombosis of the left renal artery. The last patient, 9 months after the start of treatment with iloprost, and 5 days after the last infusion, had an anterolateral myocardial infarction. The authors commented that their observations did not allow them to conclude that there is a direct relation between infusion of iloprost and thrombotic events. However, they said that this possibility should be considered, and they suggested that risk factors for thromboembolism should be carefully evaluated in each patient with systemic sclerosis who is receiving iloprost. 

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