PRIMARY PULMONARY HYPERTENSION Primary pulmonary hypertension (PPH) is a rare disease characterized by elevated pulmonary artery pressure with no apparent cause. PPH is also termed precapillary pulmonary hypertension or, more recently, idiopathic pulmonary arterial hypertension (IPAH). The diagnosis is usually made after excluding other known causes of pulmonary hypertension. Dresdale and colleagues first reported a hemodynamic account of IPAH in 1951. Pathophysiology The pathophysiology of IPAH is poorly understood. An insult (eg, hormonal, mechanical, other) to the endothelium may occur, possibly in the setting of increased susceptibility to pulmonary vascular injury (ie, multiple hit theory), resulting in a cascade of events characterized by vascular scarring, endothelial dysfunction, and intimal and medial (smooth muscle) proliferation. At least 15-20% of patients with IPAH have a familial form, which has only recently been characterized. Some cases may be related to sporadic genetic defects. The most common genetic defect in these cases is related to the BMPR-II gene. Early in the disease, as the pulmonary artery pressure increases because of increasing right ventricle work, thrombotic pulmonary arteriopathy occurs. Thrombotic pulmonary arteriopathy is characterized by in situ thrombosis of small muscular arteries of the pulmonary vasculature. In later stages, as the pulmonary pressure continues to rise, plexogenic pulmonary arteriopathy develops. This is characterized by a remodeling of the pulmonary vasculature with intimal fibrosis and replacement of normal endothelial structure.
Clinical Presentation Pulmonary hypertension often presents with nonspecific symptoms (Table 4). These symptoms are often difficult to dissociate from those caused by a known underlying pulmonary or cardiac disorder. The most common symptoms--exertional dyspnea, fatigue and syncope--reflect an inability to increase cardiac output during activity. Typical angina may occur despite normal coronary arteries. The mechanism is unclear, but anginal chest pain may be due to pulmonary artery stretching or right ventricular ischemia. Hemoptysis resulting from the rupture of distended pulmonary vessels is a rare but potentially devastating event. Raynaud's phenomenon occurs in approximately 2 percent of patients with primary pulmonary hypertension but is more common in patients with pulmonary hypertension related to connective tissue disease.4 More specific symptoms may reflect the underlying cause of pulmonary hypertension. Abnormalities detected on physical examination tend to be localized to the cardiovascular system. A careful examination often detects signs of pulmonary hypertension and right ventricular hypertrophy. The findings on lung examination are nonspecific but may point to the underlying cause of pulmonary hypertension. For instance, wheezing may lead to a diagnosis of COPD, and basilar crackles may indicate the presence of interstitial lung disease.
Signs and Symptoms of Pulmonary Hypertension Symptoms Dyspnea on Fatigue Syncope Anginal chest Hemoptysis Raynaud's phenomenon Signs exertion Jugular vein distention Prominent right ventricular impulse Accentuated pulmonic valve component pain (P2) Right-sided third heart sound (S3) Tricuspid insufficiency murmur Hepatomegaly Peripheral edema