New therapies for primary pulmonary hypertension

Influence of age on L-type Ca2+ channels in the pulmonary artery and vein of spontaneously hypertensive rats

The influence of age on the density and localization of L-type Ca2+ channels was studied during development of hypertension in the pulmonary artery and vein of spontaneously hypertensive rats (SHR) and age-matched normotensive Wistar-Kyoto (WKY) rats by radioligand binding assay and light microscope autoradiography. SHR were examined at 6 weeks (juvenile, pre-hypertensive stage), 12 weeks (young, developing hypertension) and 24 weeks (mature, established hypertension). The dihydropyridine-type Ca2+ antagonist [3H]nicardipine was used as a radioligand. It was bound specifically to sections of rat pulmonary artery and vein. Dissociation constant (Kd) values were similar in WKY rats and SHR, whereas maximum density of binding sites (Bmax) values increased in SHR in comparison with WKY rats. This increase was noticeable from the pre-hypertensive phase. The pharmacological profile of [3H]nicardipine binding was similar in different age groups of either normotensive and hypertensive rats. Quantitative analysis of autoradiographs from SHR revealed a progressive increase of silver grains in smooth muscle of tunica media and to a lesser extent in the adventitia of pulmonary artery but not of pulmonary vein from pre-hypertensive stage to developing hypertension. No further changes were observed in established hypertension. The above data indicate that the density of L-type Ca2+ channels of pulmonary arteries is increased in SHR. This augmentation after the pre-hypertensive phase suggests the occurrence of dysregulation of Ca2+ handling in the pulmonary vasculature of developing SHR.

Epoprostenol in primary pulmonary hypertension

OBJECTIVE

To review briefly the epidemiology, pathophysiology, and current treatment of primary pulmonary hypertension (PPH) and review the available clinical data on epoprostenol in PPH.

DATA SOURCES

A MEDLINE search (January 1966-August 1998) was used to identify case reports and clinical studies pertaining to epoprostenol in PPH. Bibliographic lists were also used.

STUDY SELECTION

All English-language clinical studies of epoprostenol in PPH were included. Incomplete study descriptions (abstracts) were not included.

DATA EXTRACTION

Study design, population, methods, clinical outcomes, and adverse effects were evaluated.

DATA SYNTHESIS

PPH is a relatively rare disease that results in symptoms of congestive heart failure and has a five-year survival rate of 34%. Therapy has consisted of vasodilators, anticoagulation, oxygen, and ultimately lung transplantation. Epoprostenol, which has recently become available as an integral pharmacotherapeutic option, has been shown to improve hemodynamic parameters such as cardiac output, pulmonary artery pressure, and pulmonary vascular resistance. It has been shown to improve exercise parameters, New York Heart Association (NYHA) functional class, and survival. Epoprostenol is indicated for patients with severe disease (NYHA class III or IV) who do not respond to acute vasodilator challenge or chronic calcium-channel blocker therapy. Its chronic administration is challenging as it requires continuous infusion via central venous catheter and a special infusion pump. Administration is further complicated by the 48-hour expiration of reconstituted epoprostenol and the need to refrigerate the reconstituted drug.

CONCLUSIONS

Epoprostenol improves hemodynamics and clinical outcome in patients with severe PPH. Epoprostenol therapy requires intensive patient education and medical monitoring, but it can improve well-being and delay the need for lung transplantation.

a 49-year-old woman with dyspnoea, palpitations and syncope

Pulmonary hypertension is rarely described in association with Sjögren's syndrome. The authors report the case of a patient in which pulmonary hypertension was the inaugural clinical manifestation of primary Sjögren's syndrome. Clinical assessment, differential diagnosis, etiopathological implications, and therapeutic approach are discussed.

Pulmonary hypertension in chronic liver disease

Pulmonary hypertension develops in approximately 2% of patients with portal hypertension. Diagnosis is often difficult and requires a high degree of clinical suspicion. Treatment of patients with portal and pulmonary hypertension is limited, and mean survival following diagnosis is approximately 15 months. The effect of liver transplantation on the natural history of disease is discussed.

Appetite suppressants and primary pulmonary hypertension in the United Kingdom

OBJECTIVE

Amphetamine-like appetite suppressants, particularly fenfluramines, have been implicated in the aetiology of primary pulmonary hypertension. At one specialist centre in France 20% of patients with primary pulmonary hypertension had been exposed to fenfluramine. The prevalence of primary pulmonary hypertension associated with fenfluramines and other appetite suppressants in the United Kingdom is unknown. This study was performed to measure prior exposure to appetite suppressants in patients with primary pulmonary hypertension.

SETTING

Heart lung transplantation centres in England.

PATIENTS

United Kingdom residents with proven primary pulmonary hypertension referred for consideration of heart lung transplantation.

METHODS

Case surveillance study, obtaining data from the hospital and general practitioner's notes and directly from the patients or their relatives.

RESULTS

55 patients were identified. Drug histories were available from hospital records in all patients, from the general practitioner's notes in 51, and from the patients or relatives in 44. Of these, 3 female patients had been exposed to appetite suppressants (2 fenfluramine, 1 diethylpropion): 2 have since died. In each case exposure was brief and apparently predated the development of symptoms by several years.

CONCLUSIONS

Exposure of patients with severe primary pulmonary hypertension to fenfluramine and other appetite suppressants is uncommon in the United Kingdom unlike in France, where most of the cases associating primary pulmonary hypertension with fenfluramine use have originated. This may reflect more conservative prescribing of these agents in the United Kingdom.