Primary pulmonary hypertension

Brain Natriuretic Peptide and Exercise Capacity in Lung Fibrosis and Pulmonary Hypertension

Pulmonary hypertension (PH) can develop in lung fibrosis, and contributes to increased morbidity and mortality. Noninvasive parameters in the evaluation of PH in lung disease could aid in the management of these subjects. In this study, we aimed to characterize the role of brain natriuretic peptide (BNP) and the six-minute walk distance (6-MWD) in the assessment of pulmonary hypertension (PH) in subjects with lung fibrosis. Subjects with lung fibrosis and elevated BNP levels (n = 20) had significantly more severe PH during right heart catheterization than those with lung fibrosis, and normal BNP levels (mean pulmonary arterial pressure (40.85 +/- 3.2 mm Hg vs. 23.42+/-1.44 mm Hg, respectively) (n = 19) (p < 0.001). Significant correlations between lung volumes and BNP concentrations were not observed. A weak correlation existed between capillary pO(2) and 6-MWD (r = 0.42; p < 0.001). The presence of moderate-severe PH was associated with significant reduction of the 6-MWD. BNP concentrations predicted moderate-severe PH with 100% sensitivity and high specificity (89%). We conclude that BNP is an excellent marker for the presence of PH in patients with lung fibrosis. In addition, our data suggest that PH contributes significantly to exercise limitation in patients with severe lung fibrosis, raising the possibility that treatment of PH may be beneficial in these patients.

Inhaled iloprost: in primary pulmonary hypertension

Iloprost is a stable prostacyclin analogue with a pharmacokinetic profile allowing nebulised administration in patients with primary pulmonary hypertension (PPH). Inhaled iloprost is a potent acute pulmonary vasodilator with a duration of action of about 60 minutes. It may exert additional long-term benefit through antiproliferative and antithrombotic effects. Inhaled iloprost 2.5 or 5 microg six or nine times daily for 12 weeks (n = 101) significantly (p < 0.01) improved a combined clinical endpoint of a > or =10% increase in distance walked in 6 minutes and an improvement of > or =1 class in New York Heart Association functional class without clinical deterioration or death (16.8 versus 4.9% of placebo recipients, n = 102) in patients with severe PPH or selected forms of nonprimary pulmonary hypertension. Statistical analysis of the response for the PPH subgroup (20.8 versus 5.5% with placebo; n = 51 and 51) was not reported. Improvements from baseline in exercise capacity and haemodynamic/gas exchange variables have been reported in patients with PPH with continued use of inhaled iloprost. In addition, improvement in preinhalation vascular resistance occurred after 12 weeks of inhaled iloprost (p < 0.01 versus placebo) in a large randomised trial. Increased cough, headache, flushing and an influenza-like syndrome were the most common adverse events in the largest trial of patients receiving inhaled iloprost. Headache, flushing and jaw pain occurred significantly more frequently with inhaled iloprost than with placebo.

Molecular biology of primary pulmonary hypertension

Primary pulmonary hypertension (PPH) is a rare but often fatal condition characterized by pulmonary artery remodeling leading to chronic elevation of pulmonary artery pressure in the absence of causes. The pathophysiology of PPH is not completely understood, but a number of recent studies have elucidated many possible gentic, hormonal, and environmental factors. Current treatment options slow the progression of the disease but do not halt it. The study of molecular mechanisms that result from mutations in onmental and hormonal modifiers holds great promise for the development of novel therapies that may halt the progression of the disease.

Gender issues in pulmonary vascular disease

Gender differences in pulmonary vascular diseases, as exemplified by primary pulmonary hypertension and scleroderma-related pulmonary hypertension, are not well-explained; however, in general terms, they seem to be related to a combination of genetic predispositions and gender-specific environmental triggers. More information is needed in both areas with respect to mechanisms of disease. More information also is needed about possible gender differences in disease presentation,course, and response to treatments.

Use of assisted reproductive technologies and anesthesia in a patient with primary pulmonary hypertension

OBJECTIVE

To report the use of assisted reproductive technologies (ART) in a patient with primary pulmonary hypertension.

DESIGN

Case report.

SETTING

University medical center.

PATIENT(S)

A 28-year-old nulliparous woman with primary pulmonary hypertension (PPH) treated with continuous intravenous epoprostenol.

INTERVENTION(S)

Ovarian stimulation, egg retrieval, general anesthesia, and pregnancy by surrogate carrier.

MAIN OUTCOME MEASURE(S)

Successful ART cycle(s) in patient with PPH and successful gestational carrier pregnancy.

RESULT(S)

Successful pregnancy by surrogate gestational carrier.

CONCLUSION(S)

Assisted reproductive technologies and a surrogate gestational carrier were a successful reproductive option for a patient with primary pulmonary hypertension. Ovarian stimulation, oocyte retrieval, and general anesthesia are not without risk but were well tolerated in this case. Multidisciplinary involvement in the planning and administration of such procedures is necessary for optimal outcomes in these patients.

Overexpression of human KCNA5 increases IK V and enhances apoptosis

Apoptotic cell shrinkage, an early hallmark of apoptosis, is regulated by K+ efflux and K+ channel activity. Inhibited apoptosis and downregulated K+ channels in pulmonary artery smooth muscle cells (PASMC) have been implicated in development of pulmonary vascular medial hypertrophy and pulmonary hypertension. The objective of this study was to test the hypothesis that overexpression of KCNA5, which encodes a delayed-rectifier voltage-gated K+ (Kv) channel, increases K+ currents and enhances apoptosis. Transient transfection of KCNA5 caused 25- to 34-fold increase in KCNA5 channel protein level and 24- to 29-fold increase in Kv channel current (I(K(V))) at +60 mV in COS-7 and rat PASMC, respectively. In KCNA5-transfected COS-7 cells, staurosporine (ST)-mediated increases in caspase-3 activity and the percentage of cells undergoing apoptosis were both enhanced, whereas basal apoptosis (without ST stimulation) was unchanged compared with cells transfected with an empty vector. In rat PASMC, however, transfection of KCNA5 alone caused marked increase in basal apoptosis, in addition to enhancing ST-mediated apoptosis. Furthermore, ST-induced apoptotic cell shrinkage was significantly accelerated in COS-7 cells and rat PASMC transfected with KCNA5, and blockade of KCNA5 channels with 4-aminopyridine (4-AP) reduced K+ currents through KCNA5 channels and inhibited ST-induced apoptosis in KCNA5-transfected COS-7 cells. Overexpression of the human KCNA5 gene increases K+ currents (i.e., K+ efflux or loss), accelerates apoptotic volume decrease (AVD), increases caspase-3 activity, and induces apoptosis. Induction of apoptosis in PASMC by KCNA5 gene transfer may serve as an important strategy for preventing the progression of pulmonary vascular wall thickening and for treating patients with idiopathic pulmonary arterial hypertension (IPAH).

Pulmonary Hypertension in Transgenic Mice Expressing a Dominant-Negative BMPRII Gene in Smooth Muscle

Bone morphogenetic peptides (BMPs), a family of cytokines critical to normal development, were recently implicated in the pathogenesis of familial pulmonary arterial hypertension. The type-II receptor (BMPRII) is required for recognition of all BMPs, and targeted deletion of BMPRII in mice results in fetal lethality before gastrulation. To overcome this limitation and study the role of BMP signaling in postnatal vascular disease, we constructed a smooth muscle–specific transgenic mouse expressing a dominant-negative BMPRII under control of the tetracycline gene switch (SM22-tet-BMPRII delx4+ mice). When the mutation was activated after birth, mice developed increased pulmonary artery pressure, RV/LV+S ratio, and pulmonary arterial muscularization with no increase in systemic arterial pressure. Studies with SM22-tet-BMPRII delx4+ mice support the hypothesis that loss of BMPRII signaling in smooth muscle is sufficient to produce the pulmonary hypertensive phenotype.

Long-Term Treatment With a Rho-Kinase Inhibitor Improves Monocrotaline-Induced Fatal Pulmonary Hypertension in Rats

Primary pulmonary hypertension is a fatal disease characterized by endothelial dysfunction, hypercontraction and proliferation of vascular smooth muscle cells (VSMCs), and migration of inflammatory cells, for which no satisfactory treatment has yet been developed. We have recently demonstrated that intracellular signaling pathway mediated by Rho-kinase, an effector of the small GTPase Rho, is involved in the pathogenesis of arteriosclerosis. In the present study, we examined whether the Rho-kinase–mediated pathway is also involved in the pathogenesis of fatal pulmonary hypertension in rats. Animals received a subcutaneous injection of monocrotaline, which resulted in the development of severe pulmonary hypertension, right ventricular hypertrophy, and pulmonary vascular lesions in 3 weeks associated with subsequent high mortality rate. The long-term blockade of Rho-kinase with fasudil, which is metabolized to a specific Rho-kinase inhibitor hydroxyfasudil after oral administration, markedly improved survival when started concomitantly with monocrotaline and even when started after development of pulmonary hypertension. The fasudil treatment improved pulmonary hypertension, right ventricular hypertrophy, and pulmonary vascular lesions with suppression of VSMC proliferation and macrophage infiltration, enhanced VSMC apoptosis, and amelioration of endothelial dysfunction and VSMC hypercontraction. These results indicate that Rho-kinase–mediated pathway is substantially involved in the pathogenesis of pulmonary hypertension, suggesting that the molecule could be a novel therapeutic target for the fatal disorder.

Critical care in cardiovascular medicine

The field of cardiac intensive care is rapidly evolving with nearly simultaneous advances in surgical techniques and adjunctive therapies, respiratory care, intensive care technology and monitoring, pharmacologic research and development, and computing and electronics. The focus of care has now shifted toward reducing morbidity and improving "quality of life" while the survival of infants and children with congenital heart defects, including those with univentricular hearts has dramatically improved during the last three decades. Despite these advances, there remains a predictable fall in cardiac output after cardiopulmonary bypass. This article focuses on early identification and aggressive treatment of the low cardiac output syndrome peculiar to these patients. The authors also briefly review the recent advances in the treatment of pulmonary hypertension, mechanical support, and neurologic surveillance after cardiac surgery.