{'fraction_non_alphanumeric': 0.02640144665461121, 'fraction_numerical': 0.003978300180831827, 'mean_word_length': 5.6650602409638555, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Primary pulmonary hypertension: new reasons for optimism?

Primary pulmonary hypertension is a rare but devastating disease, with an incidence of I to 2 per million per year. Although the natural history is very variable, with some patients remaining well 10 or more years after diagnosis, prognosis is generally poor, with median survival of 30 months from diagnosis. Most commonly, it involves disease of the small pulmonary arteries, with muscular hypertrophy and intimal hyperplasia. Pulmonary veno-occlusive disease and pulmonary haemangiomatosis are rarer pathological forms. Treatment has remained generally unsatisfactory, but newly available therapies provide some cause for optimism that the condition of some patients can be stabilised. The cause of primary pulmonary hypertension is unknown. However, about 6% of cases appear to be familial, and reported risk factors include HIV infection, cirrhosis of the liver with portal hypertension, and use of cocaine, oral contraceptives and, more recently, dexfenfluramine, an appetite suppressant. A European case-control study found that people who had taken dexfenfluramine for more than three months had an estimated 23-fold higher incidence of primary pulmonary hypertension than those who had never taken the drug. I Typically, primary pulmonary hypertension occurs in young adults, in their twenties or thirties, and affects predominantly women (female-to-male ratio, 1.8:1). Symptoms are often vague, which may delay diagnosis, often for more than two years after onset." The commonest reported symptom is shortness of breath on exertion, but syncope, angina (right ventricular), and ankle and abdominal swelling occur in more advanced disease. To add to the difficulty of an early diagnosis, results of initial investigations, such as chest x-ray, electrocardiogram and simple spirometry, may be normal. A slightly reduced carbon monoxide diffusing capacity may be the first clue to diagnosis. Transthoracic echocardiogram usually confirms the presence of right ventricular dilatation. If tricuspid regurgitation is present, measurement of regurgitant jet velocity allows a Doppler estimate of pulmonary artery pressure. However, the gold standard for confirmation of pulmonary hypertension remains right heart catheterisation. The addition of a challenge with a "selective" pulmonary vasodilator (prostacyclin, nitric oxide or adenosine) can provide key information on prognosis and likely response to oral vasodilators. Differential diagnoses include pulmonary hypertension secondary to congenital heart disease, left heart disease or chronic lung disease, thromboembolic pulmonary hypertension (which is important to exclude as corrective surgery may be possible, although not yet performed in Aus-