Clinical insights into the pathogenesis of primary pulmonary hypertension

Efficacy and safety of tadalafil in a pediatric population with pulmonary arterial hypertension: phase 3 randomized, double-blind placebo-controlled study

This study evaluated the efficacy and safety of tadalafil in pediatric patients with pulmonary arterial hypertension. This phase-3, international, randomized, multicenter (24 weeks double-blind placebo-controlled period; two-year, open-labeled extension period), add-on (patient's current endothelin receptor antagonist therapy) study included pediatric patients aged <18 years with pulmonary arterial hypertension. Patients received tadalafil 20 mg or 40 mg based on their weight (heavy-weight: ≥40 kg; middle-weight: ≥25 to <40 kg) or placebo orally once daily for 24 weeks. Primary endpoint was change from baseline in six-minute walk distance in patients aged ≥6 years at Week 24. Sample size was amended from 134 to ≥34 patients, due to serious recruitment challenges. Therefore, statistical significance testing was not performed between treatment groups. Results showed that patient demographics and baseline characteristics (N = 35; tadalafil = 17; placebo = 18) were comparable between treatment groups; median age was 14.2 years (6.2-17.9 years) and majority (71.4%, n = 25) of patients were in the heavy-weight cohort. Least square mean (standard error) changes from baseline in six-minute walk distance at Week 24 was numerically greater with tadalafil versus placebo (60.48 (20.41) vs 36.60 (20.78) meters; placebo-adjusted mean difference (standard deviation) 23.88 (29.11)). Safety of tadalafil treatment was as expected without any new safety concerns. During study Period 1, two patients (one in each group) discontinued due to investigator's reported clinical worsening, and no deaths were reported. In conclusion, the statistical significance testing was not performed between the treatment groups due to low sample size; however, the study results show positive trend in improvement in non-invasive measurements, commonly utilized by clinicians to evaluate the disease status for children with pulmonary arterial hypertension. Safety of tadalafil treatment was as expected without any new safety signals.

Can anticoagulants improve the survival rate for patients with idiopathic pulmonary arterial hypertension? A systematic review and meta-analysis

BACKGROUND

Anticoagulant therapy is believed to be an important component of treatment for idiopathic pulmonary arterial hypertension (IPAH). Recent data suggest that therapy that does not include anticoagulants results in no significant difference in patient survival. We sought to evaluate the effect of anticoagulants on survival in patients with IPAH.

METHODS

A systematic review and a random-effects meta-analysis to estimate hazard ratio (HR) and 95% confidence intervals (CI) were performed. PubMed/MEDLINE, Web of Knowledge and other databases were searched for eligible literature. Review articles and references were also screened.

RESULTS

8 studies with a total of 1812 patients with IPAH were included in this analysis. No randomized controlled trials (RCT) were identified. All the 8 studies had a mean complete follow-up ranging from 3 to 14 years. In this analysis, use of anticoagulants did not significantly decrease mortality risk (P = 0.07, HR = 0.77, 95% CI [0.58, 1.02]). Sensitivity analysis showed similar results (P = 0.12, HR = 0.80, 95% CI [0.60, 1.06]). Subgroup analysis showed that anticoagulants performed no significant advantages with the use of PAH-specific therapies (P = 0.82, HR = 0.95, 95% CI [0.63, 1.44]).

CONCLUSIONS

No randomized evidence to support the use of anticoagulants in IPAH. No significant benefit for patients' survival was found in our analysis. The potential biases of included observational studies made it hard to achieve a meaningful conclusion. The necessity of anticoagulants for IPAH patients remains to be evaluated.

Discovery of 2-(((1r,4r)-4-(((4-Chlorophenyl)(phenyl)carbamoyl)oxy)methyl)cyclohexyl)methoxy)acetate (Ralinepag): An Orally Active Prostacyclin Receptor Agonist for the Treatment of Pulmonary Arterial Hypertension

The design and synthesis of a new series of potent non-prostanoid IP receptor agonists that showed oral efficacy in the rat monocrotaline model of pulmonary arterial hypertension (PAH) are described. Detailed profiling of a number of analogues resulted in the identification of 5c (ralinepag) that has good selectivity in both binding and functional assays with respect to most members of the prostanoid receptor family and a more modest 30- to 50-fold selectivity over the EP3 receptor. In our hands, its potency and efficacy are comparable or superior to MRE269 (the active metabolite of the clinical compound NS-304) with respect to in vitro IP receptor dependent cAMP accumulation assays. 5c had an excellent PK profile across species. Enterohepatic recirculation most probably contributes to a concentration-time profile after oral administration in the cynomolgus monkey that showed a very low peak-to-trough ratio. Following the identification of an acceptable solid form, 5c was selected for further development for the treatment of PAH.

Main pulmonary artery dilatation in patients with anthracofibrosis

This study assessed main pulmonary artery diameter of patients with anthracofibrosis. Patients with anthracofibrosis and CT scans were evaluated after exclusion of patients with co-existing disease. We measured the diameter of the main pulmonary artery (PAD) and ascending aorta (AD) and calculated the pulmonary artery to aorta ratio (APR). The upper reference limit for comparison of PAD was 29 mm. Cut-off values for PAD and APR indicating pulmonary hypertension were 33 mm and 1. We correlated the CT parameters with echocardiographic results. Total 51 patients were included in the analysis. The mean PAD, AD, and APR were 33 mm, 38 mm, and 0.87 respectively. The PAD was larger than the upper reference limit, 29 mm (P<0.001). The PAD was >33 mm in 30 (65%) and the APR was >1 in 9 patients (18%). Of 21 patients with echocardiography, 11 (52%) were found to have pulmonary hypertension. There was no statistical difference in the diagnosis of pulmonary hypertension between echocardiography and CT (P=1.000). In conclusion, main pulmonary artery is dilated in patients with anthracofibrosis more than in the healthy population.

Gene transfer therapy by either type 1 or type 2 adeno-associated virus expressing human prostaglandin I2 synthase gene is effective for treatment of pulmonary arterial hypertension

Prostaglandin I(2) (PGI(2)) plays an important role in the clinical treatment of pulmonary arterial hypertension (PAH). However, the administration of PGI(2) involves continuous intravenous infusion using an indwelling catheter, which limits the patient's quality of life and increases the risk of infection. We therefore investigated whether human PGI(2) synthase (hPGIS) gene transfer using an adeno-associated virus (AAV) vector is still effective in a mouse model of PAH and tested for differences in the therapeutic efficacy of PAH among AAV serotypes. The PAH was induced by subjecting mice to hypoxia (10% O(2)). Type 1 AAV expressing hPGIS (AAV1-hPGIS) or type 2 AAV expressing hPGIS (AAV2-hPGIS) was injected into the thigh muscle of mice. Both vectors expressing hPGIS produced strong hPGIS protein expression in the mouse thigh skeletal muscles after 8 weeks of hypoxia. The administration of AAV1-hPGIS or AAV2-hPGIS also significantly inhibited the hypoxia-induced increase in right ventricular systolic pressure, the ratio of right ventricular weight to body weight (RV/BW), and the ratio of RV weight to left ventricular plus septal weight (RV/LV + S), and significantly attenuated the hypoxia-induced increase in medial wall thickness of peripheral pulmonary arteries. Furthermore, there were no significant differences in the degree of amelioration in RV systolic pressure, RV/BW, RV/LV + S, and percentage of wall thickness of peripheral pulmonary arteries between AAV1-hPGIS and AAV2-hPGIS administrations. In conclusion, we revealed that type 1 and type 2 AAV are equally effective for the treatment of PAH in a hypoxia-induced mouse model. Gene-transfer therapy using AAV expressing hPGIS is, therefore, a potential therapeutic breakthrough for PAH.

Plexiform lesions in the lungs of domestic fowl selected for susceptibility to pulmonary arterial hypertension: incidence and histology

Plexiform lesions develop in the pulmonary arteries of humans suffering from idiopathic pulmonary arterial hypertension (IPAH). Plexogenic arteriopathy rarely develops in existing animal models of IPAH. In this study, plexiform lesions developed in the lungs of rapidly growing meat-type chickens (broiler chickens) that had been genetically selected for susceptibility to IPAH. Plexiform lesions developed spontaneously in: 42% of females and 40% of males; 35% of right lungs, and 45% of left lungs; and, at 8, 12, 16, 20, 24, and 52 weeks of age the plexiform lesion incidences averaged 52%, 50%, 51%, 40%, 36%, and 22%, respectively. Plexiform lesions formed distal to branch points in muscular interparabronchial pulmonary arteries exhibiting intimal proliferation. Perivascular mononuclear cell infiltrates consistently surrounded the affected arteries. Proliferating intimal cells fully or partially occluded the arterial lumen adjacent to plexiform lesions. Broilers reared in clean stainless steel cages exhibited a 50% lesion incidence that did not differ from the 64% incidence in flock mates grown on dusty floor litter. Microparticles (30 μm diameter) were injected to determine if physical occlusion and focal inflammation within distal pulmonary arteries might initiate plexiform lesion development. Three months postinjection no plexiform lesions were observed in the vicinity of persisting microparticles. Broiler chickens selected for innate susceptibility to IPAH represent a new animal model for investigating the mechanisms responsible for spontaneous plexogenic arteriopathy.

Idiopathic pulmonary arterial hypertension: an avian model for plexogenic arteriopathy and serotonergic vasoconstriction

Idiopathic pulmonary arterial hypertension (IPAH) is a disease of unknown cause that is characterized by elevated pulmonary arterial pressure and pulmonary vascular resistance attributable to vasoconstriction and vascular remodeling of small pulmonary arteries. Vascular remodeling includes hypertrophy and hyperplasia of smooth muscle (medial hypertrophy) accompanied in up to 80% of the cases by the formation of occlusive plexiform lesions (plexogenic arteriopathy). Patients tend to be unresponsive to vasodilator therapy and have a poor prognosis for survival when plexogenic arteriopathy progressively obstructs their pulmonary arteries. Research is needed to understand and treat plexogenic arteriopathy, but advances have been hindered by the absence of spontaneously developing lesions in existing laboratory animal models. Young domestic fowl bred for meat production (broiler chickens, broilers) spontaneously develop IPAH accompanied by semi-occlusive endothelial proliferation that progresses into fully developed plexiform lesions. Plexiform lesions develop in both female and male broilers, and lesion incidences (lung sections with lesions/lung sections examined) averaged approximately 40% in 8 to 52 week old birds. Plexiform lesions formed distal to branch points in muscular interparabronchial pulmonary arteries, and were associated with perivascular mononuclear cell infiltrates. Serotonin (5-hydroxytryptamine, 5-HT) is a potent vasoconstrictor and mitogen known to stimulate vascular endothelial and smooth muscle cell proliferation. Serotonin has been directly linked to the pathogenesis of IPAH in humans, including IPAH linked to serotonergic anorexigens that trigger the formation of plexiform lesions indistinguishable from those observed in primary IPAH triggered by other causes. Serotonin also plays a major role in the susceptibility of broilers to IPAH. This avian model of spontaneous IPAH constitutes a new animal model for biomedical research focused on the pathogenesis of IPAH and plexogenic arteriopathy.

Nitrates and nitrites in the treatment of ischemic cardiac disease

The organic nitrite, amyl of nitrite, was initially used as a therapeutic agent in the treatment of angina pectoris, but was replaced over a decade later by the organic nitrate, nitroglycerin (NTG), due to the ease of administration and longer duration of action. The administration of organic nitrate esters, such as NTG, continues to be used in the treatment of angina pectoris and heart failure since the birth of modern pharmacology. Their clinical effectiveness is due to vasodilator activity in large veins and arteries through an as yet unidentified method of delivering nitric oxide (NO), or a NO-like compound. The major drawback is the development of tolerance with NTG, and the duration and route of administration with amyl of nitrite. Although the nitrites are no longer used in the treatment of hypertension or ischemic heart disease, the nitrite anion has recently been discovered to possess novel pharmacologic actions, such as modulating hypoxic vasodilation, and providing cytoprotection in ischemia-reperfusion injury. Although the actions of these 2 similar chemical classes (nitrites and organic nitrates) have often been considered to be alike, we still do not understand their mechanism of action. Finally, the nitrite anion, either from sodium nitrite or an intermediate NTG form, may act as a storage form for NO and provide support for investigating the use of these agents in the treatment of ischemic cardiovascular states. We review what is presently known about the use of nitrates and nitrites including the historical, current, and potential uses of these agents, and their mechanisms of action.

Treatment of pediatric pulmonary hypertension

Pulmonary hypertension was once thought to be a rare condition and only managed in specialized centers. Now however, with the advent of echocardiography, it is found in many clinical scenarios, in the neonate with chronic lung disease, in the acute setting in the intensive care unit, in connective tissue disease and in cardiology pre- and postoperatively. We have a better understanding of the pathological process and have a range of medication which is starting to be able to palliate this previously fatal condition. This review describes the areas that are known in this condition and those that are less familiar. The basic physiology behind pulmonary hypertension and pulmonary vascular disease is explained. The histopathologic process and the various diagnostic tools are described and are followed by the current and future therapy at our disposal.

Exercise-induced pulmonary arterial hypertension

BACKGROUND

The clinical relevance of exercise-induced pulmonary arterial hypertension (PAH) is uncertain, and its existence has never been well studied by direct measurements of central hemodynamics. Using invasive cardiopulmonary exercise testing, we hypothesized that exercise-induced PAH represents a symptomatic stage of PAH, physiologically intermediate between resting pulmonary arterial hypertension and normal.

METHODS AND RESULTS

A total of 406 consecutive clinically indicated cardiopulmonary exercise tests with radial and pulmonary arterial catheters and radionuclide ventriculographic scanning were analyzed. The invasive hemodynamic phenotype of exercise-induced PAH (n=78) was compared with resting PAH (n=15) and normals (n=16). Log-log plots of mean pulmonary artery pressure versus oxygen uptake (V(.)o(2)) were obtained, and a "join-point" for a least residual sum of squares for 2 straight-line segments (slopes m1, m2) was determined; m2<m1="plateau," and m2>m1="takeoff" pattern. At maximum exercise, V(.)o(2) (55.8+/-20.3% versus 66.5+/-16.3% versus 91.7+/-13.7% predicted) was lowest in resting PAH, intermediate in exercise-induced PAH, and highest in normals, whereas mean pulmonary artery pressure (48.4+/-11.1 versus 36.6+/-5.7 versus 27.4+3.7 mm Hg) and pulmonary vascular resistance (294+/-158 versus 161+/-60 versus 62+/-20 dyne x s x cm(-5), respectively; P<0.05) followed an opposite pattern. An exercise-induced PAH plateau (n=32) was associated with lower o(2)max (60.6+/-15.1% versus 72.0+/-16.1% predicted) and maximum cardiac output (78.2+/-17.1% versus 87.8+/-18.3% predicted) and a higher resting pulmonary vascular resistance (247+/-101 versus 199+/-56 dyne x s x cm(-5); P<0.05) than takeoff (n=40). The plateau pattern was most common in resting PAH, and the takeoff pattern was present in nearly all normals.

CONCLUSIONS

Exercise-induced PAH is an early, mild, and clinically relevant phase of the PAH spectrum.

A Long-Acting Prostacyclin Agonist with Thromboxane Inhibitory Activity for Pulmonary Hypertension

RATIONALE

The balance between prostacyclin and thromboxane plays an important role in the regulation of pulmonary vascular tone. Recently, we developed ONO-1301, a novel, long-acting prostacyclin agonist with thromboxane synthase inhibitory activity.

OBJECTIVES

We investigated whether modulation of prostacyclin/thromboxane balance by ONO-1301 ameliorates monocrotaline-induced pulmonary hypertension in rats.

METHODS

After subcutaneous injection of monocrotaline or vehicle, rats were randomized to receive repeated subcutaneous administration of ONO-1301 or vehicle twice per day for 3 wk.

MEASUREMENTS AND MAIN RESULTS

There was significant development of pulmonary hypertension 3 wk after monocrotaline injection. Treatment with ONO-1301 significantly attenuated the increases in right ventricular systolic pressure and ratio of right ventricular weight to body weight in monocrotaline rats. Furthermore, ONO-1301 significantly attenuated the increase in medial wall thickness of peripheral pulmonary arteries in monocrotaline rats. The half-life of plasma ONO-1301 concentration after a single subcutaneous administration was approximately 5.6 h. A single administration of ONO-1301 increased plasma cyclic adenosine 3', 5'-monophosphate level, which lasted at least up to 8 h. Treatment with ONO-1301 significantly decreased plasma 11-dehydro-thromboxane B2, a metabolite of thromboxane, in monocrotaline rats. Finally, Kaplan-Meier survival curves demonstrated that repeated administration of ONO-1301 improved survival rate in monocrotaline rats compared with vehicle administration (80 vs. 30% in 6-wk survival).

CONCLUSIONS

Subcutaneous administration of a novel prostacyclin agonist (ONO-1301) markedly attenuated monocrotaline-induced pulmonary hypertension and improved survival in rats. The beneficial effects of ONO-1301 may occur through its long-lasting stimulation of cyclic adenosine 3', 5'-monophosphate and inhibition of thromboxane synthase.

Development of hepatopulmonary syndrome and portopulmonary hypertension in a paediatric liver transplant patient

BACKGROUND

Hepatopulmonary syndrome (HPS) and portopulmonary hypertension (PPH) are pulmonary vascular disorders which occur in patients with severe liver disease and/or portal hypertension. Although these syndromes are frequently diagnosed in patients undergoing assessment for liver transplantation, they seldom occur in the same patient.

METHOD

This report describes a female paediatric patient, born with extra-hepatic biliary atresia, who required liver transplantation, at the age of 15, for secondary biliary cirrhosis. She had severe HPS prior to her first liver transplant, which resolved rapidly following surgery, as well as indirect evidence for PPH. She required a second liver transplant 1 yr later for chronic rejection. Whilst evaluating the patient for a third liver transplant, 4 yr later, severe PPH was discovered. The patient died 3 months later from right heart failure.

CONCLUSION

HPS and PPH may coexist however they may show differing responses to liver transplantation with progression of PPH despite the resolution of HPS.

Pulmonary capillary haemangiomatosis in children and adolescents: report of a new case and a review of the literature

Pulmonary capillary haemangiomatosis (PCH) in childhood is a rarity, characterised by the uncontrolled proliferation of pulmonary microvessels which may invade pulmonary, bronchial and vascular structures, resulting in diffuse alveolar haemorrhage, manifesting clinically in haemoptysis, dyspnoea and symptoms of pulmonary hypertension (PH). A 14-year-old boy with some particular features (pericardial effusion and thrombocytopenia) is presented and 14 paediatric/adolescent cases from the literature are surveyed. The diagnostic problems and difficulties are discussed, including the importance of imaging (high-resolution CT) and histopathological studies, with the aim of providing a clear-cut distinction of PCH from other conditions such as primary PH (PPH). The literature data can be regarded as ambiguous: both similarities and relatively sharp distinctions between PCH and PPH are to be found. New developments in the field of genetics are also discussed. The early coexistence of PCH and other (vascular) disorders and associations, involving focal or diffuse, disseminated forms is summarised briefly. Conclusion. The diagnosis of this progressive disorder may lead to effective therapy. Treatment possibilities include the rapidly evolving field of anti-angiogenic therapy, but at present lung transplantation is universally accepted as the final definitive treatment for pulmonary capillary haemangiomatosis.

Pathology of pulmonary hypertension

This article briefly discusses the traditional concepts of severe pulmonary hypertension and then details how the concept of severe pulmonary hypertension has moved from a vasoconstrictive to an angioproliferative disorder.

Pathologic assessment of vasculopathies in pulmonary hypertension

Pulmonary arterial hypertension (PAH) includes various forms of pulmonary hypertension of different etiology but similar clinical presentation and functional derangement. Histopathological vascular changes in all forms of PAH are qualitatively similar but with quantitative differences in the distribution and prevalence of pathological changes in various portions of the pulmonary vascular bed. The documentation of these topographic variations in the response of the pulmonary vasculature to injury may be important to understand the pathogenesis of the various subsets of PAH. To standardize the precise histopathological documentation of the pulmonary vasculopathy in PAH we propose a histopathological classification that includes both the predominant segment of the pulmonary vasculature affected and the possible coexistence of pathological changes in other vascular segments.

Effects of the dual endothelin receptor antagonist bosentan in patients with pulmonary arterial hypertension: a 1-year follow-up study

STUDY OBJECTIVES

We report on the long-term safety and efficacy of bosentan treatment in patients with pulmonary arterial hypertension (PAH).

BACKGROUND

In a preceding study, bosentan was well tolerated and significantly improved the exercise capacity and hemodynamics of patients with PAH after 12 weeks of treatment.

DESIGN

The present study was an open-label extension to the preceding double-blind, placebo-controlled study of 32 patients with PAH (primary or associated with scleroderma) who received bosentan or placebo at 125 mg bid for 3 to 7 months.

PATIENTS

Twenty-nine of the original 32 patients received bosentan for an additional year (62.5 mg bid for 4 weeks and then 125 mg bid).

INTERVENTIONS

Study end points included long-term safety, 6-min walk distance at week 4, modified New York Heart Association (NYHA) functional class of PAH at month 12, and the occurrence of withdrawal due to clinical worsening. Additional exploratory analyses included a walk test at month 6 for 19 patients and hemodynamic assessment at month 12 for 11 patients.

RESULTS

At month 6, assessed patients continuing bosentan treatment maintained the improvement in walk distance observed at the end of the previous study (mean +/- SEM, 60 +/- 11 m), and patients starting bosentan treatment improved their walk distance by 45 +/- 13 m. Long-term treatment with bosentan for > 1 year was associated with an improvement in hemodynamic parameters and modified NYHA functional class. Overall, bosentan treatment was well tolerated. No patient underwent transplantation or died.

CONCLUSIONS

Long-term treatment with bosentan is safe and has sustained benefits on exercise capacity and hemodynamics in patients with PAH.

Pulmonary thromboendarterectomy in the UK

This paper describes the disease of chronic thromboembolic pulmonary hypertension. This is a disease with an extremely poor prognosis, and the surgical procedure of pulmonary thromboendarterectomy represents the only possibility of a cure for patients with this condition. Further the paper describes the role and responsibilities of critical care nurses, specialist nurses in palliative care and pulmonary hypertension when caring for these patients before and after surgery.

VEGF-C mediates cyclic pressure-induced endothelial cell proliferation

Mechanical forces modulate endothelial cell functions through several mechanisms including regulation of gene transcription. In the present study, gene transcription by human umbilical vein endothelial cells (HUVEC) either maintained under control pressure (that is, standard cell culture conditions equivalent to 0.15 mmHg sustained hydrostatic pressure) or exposed to 60/20 mmHg sinusoidal pressures at 1 Hz were compared using Affymetrix GeneChip microarrays to identify cellular/molecular mechanisms associated with endothelial cell responses to cyclic pressure. Cyclic pressure selectively affected transcription of 14 genes that included a set of mechanosensitive proteins involved in hemostasis (tissue plasminogen activator), cell adhesion (integrin-alpha2), and cell signaling (Rho B, cytosolic phospholipase A2), as well as a unique subset of cyclic pressure-sensitive genes such as vascular endothelial growth factor (VEGF)-C and transforming growth factor (TGF)-beta2. The present study also provided first evidence that VEGF-C, the most highly induced gene under 60/20 mmHg, mediated HUVEC proliferation in response to this cyclic pressure. Cyclic pressure is, therefore, a mechanical force that modulates endothelial cell functions (such as proliferation) by activating a specific transcriptional program.

Significance of a plasma D-dimer test in patients with primary pulmonary hypertension

BACKGROUND

D-dimer, a degradation product of fibrin, has been increasingly used as a marker or prognostic factor in various thrombotic diseases.

OBJECTIVE

To assess the significance of a d-dimer test in patients with primary pulmonary hypertension (PPH).

PATIENTS AND METHODS

Fourteen patients with PPH (12 women and 2 men) aged 25 to 68 years (mean +/- SD age, 50 +/- 14 years) entered the study. Plasma d-dimer was determined by Miniquant assay (Biopool International; Venture, CA) 3 +/- 5 months after the disease onset, and patients were followed up for 1 year. We compared the d-dimer levels to the demographic, clinical, and hemodynamic data of the patients.

RESULTS

D-dimer levels were positively correlated with New York Heart Association classification (r = 0.59, p = 0.01) and pulmonary artery pressure (r = 0.43, p = 0.03) and were negatively correlated with oxygen saturation (r = - 0.45, p = 0.03) and 6-min walk distance (r = - 0.49, p = 0.04). One-year survival was also negatively correlated with d-dimer (point-biserial r = - 0.71, p = 0.004), with a higher d-dimer value associated with poorer survival. No significant correlations were found between d-dimer values and sex, age, diffusing capacity of the lung for carbon monoxide, or cardiac index.

CONCLUSION

D-dimer levels may have a role in the evaluation of patients with PPH. This simple, noninvasive test may be helpful for identifying patients who are at a higher risk for severe disease.

Current and emerging therapy for primary pulmonary hypertension

OBJECTIVE

To review the epidemiology, pathophysiology, clinical symptoms, and diagnostic workup of primary pulmonary hypertension (PPH) and to discuss the available data on the current and emerging therapies being used to treat this disorder.

DATA SOURCES

Primary and review articles were identified with a MEDLINE search (1966-December 2001) and through secondary sources.

STUDY SELECTION AND DATA EXTRACTION

All articles identified from the data sources were evaluated and all information deemed relevant was included in this review.

DATA SYNTHESIS

In the absence of a definable cause, PPH is a disorder classified by a progressive increase in pulmonary vascular resistance and mean pulmonary artery pressure. A relatively rare condition, PPH has an annual incidence of 1-2 cases per million people, slightly higher in women than men. The prognosis is poor, with a mean survival time of 2.8 years after diagnosis if untreated. Vasoconstriction, vascular remodeling, and thrombosis are hallmarks of the disease process. Anticoagulation and vasodilators are the most commonly employed treatment options, showing benefits in clinical outcomes, hemodynamic parameters, and mortality. Several new vasodilators are being evaluated for the treatment of PPH. Bosentan was recently approved as the first oral agent for the treatment of PPH. Iloprost, treprostinil, and beraprost are investigational agents in Phase III studies.

CONCLUSIONS

Until additional studies and experience with these agents become available, calcium-channel blockers (CCBs) remain the first option for therapy. For patients not responding to CCBs, therapeutic options will now include epoprostenol and bosentan. Since there are no comparison trials between these 2 agents, therapeutic decisions should be based on patient-specific concerns. Clinical data and experience support the use of epoprostenol; however, in patients at risk or considered unsuitable candidates, bosentan may become a preferred option. Additional studies are warranted to address the potential therapeutic benefits of combination therapy and long-term benefits of agents to treat PPH.

Pulmonary hypertension in type 1 Gaucher's disease: genetic and epigenetic determinants of phenotype and response to therapy

Type 1 Gaucher's disease (GD) is recognized for striking but unexplained phenotypic diversity. Rarely, severe pulmonary hypertension (PH) may occur in GD but its clinical spectrum, determinants or its response to enzyme replacement therapy (ERT)+/-vasodilators is not known. One hundred and thirty-four consecutive patients with Type 1 GD were screened to estimate right ventricular systolic pressure (RVSP) by Doppler echocardiography. Ninety-four patients were on ERT and 40 were untreated. Eight additional GD patients were studied that represented consecutive tertiary referrals with severe PH. Angiotensin converting enzyme (ACE) gene polymorphisms and acid beta-glucosidase gene (GBA) mutations were determined by DNA analysis. Mild, asymptomatic PH (RVSP>35<50 mmHg) was prevalent in Type 1 GD: 30% in untreated patients and 7.4% among patients receiving ERT (P<0.001). Splenectomy was strongly associated with severe, life-threatening PH: all patients with severe PH (RVSP 50-130 mmHg) were asplenic compared to only 31% of patients with RVSP<50 mmHg (Odds ratio [OR] 28.8, 95% CI 1.6-531.6, P<0.001). Other characteristics of patients presenting with severe PH were poor compliance to ERT (4/9 patients) or no ERT (5/9 patients), a family history of a sib with GD and PH (2/2 patients), an excess of ACE I allele (OR 2.3, 95% CI 1.1-4.9, P=0.034) and an excess of non-N370S GBA mutation (OR 6.0, 95% CI 1.1-33, P=0.003). Severe PH was ameliorated by ERT+/-vasodilators during 4.6+/-4.0 yr (range 1-12 yr) follow-up; three patients were initially considered for lung transplantation but improved such that they are no longer active transplant candidates. Our study reveals a remarkable predisposition for PH in type 1 GD. Progression to severe, life-threatening PH occurs in the presence of additional genetic factors (non-N370S GBA mutation, positive family history, and ACE I gene polymorphism) and epigenetic modifiers (i.e., asplenia and female sex). Splenectomy should be avoided and in high-risk patients, ERT+/-vasodilators/coumadin should be initiated.

The endothelin antagonist BQ123 reduces pulmonary vascular resistance after surgical intervention for congenital heart disease

OBJECTIVE

Postoperative pulmonary hypertension in children after surgical intervention for congenital heart disease has been attributed to failure of the pulmonary endothelium to provide adequate vasodilation. Although we have shown that the impaired vasodilatory component attributable to the l-arginine-nitric oxide pathway is almost completely reversible, a nonrestorable component persists, implying an additional vasoconstrictive mechanism in postoperative pulmonary endothelial dysfunction. In this study of children after surgical intervention for congenital heart disease, we measured endothelin-1 levels and used BQ123, a selective endothelin-A receptor antagonist, together with inhaled nitric oxide to discriminate dysfunctional pulmonary endothelial vasodilation from endothelin-mediated pulmonary vasoconstriction.

METHODS

All children were examined early after surgical intervention in the intensive care unit. Pulmonary vascular resistance (with respiratory mass spectrometry), as well as arterial and venous endothelin-1 levels (measured by means of a quantitative enzyme-linked immunosorbent assay), were determined in 7 children (age range, 3.3-13.7 months; median age, 6.3 months) with intracardiac shunting defects at baseline and during ventilation with a fraction of inspired oxygen of 0.65, with additional BQ123 (0.1 mg/kg infused over 20 minutes), and with inhaled nitric oxide (20 ppm).

RESULTS

Pulmonary vascular resistance decreased from 7.7 +/- 3.4 at baseline to 6.1 +/- 2.8 Woods units. m(-2) (P =.022) at a fraction of inspired oxygen of 0.65 and to 4.7 +/- 2.7 Woods units. m(-2) (P =.013) during BQ123 infusion. Inhaled nitric oxide had no further effect on pulmonary vascular resistance. Left atrial endothelin-1 levels (1.35-5.12 pg/mL; mean, 2.4 pg/mL) correlated significantly with the decrease in pulmonary vascular resistance in response to BQ123 infusion (r(2) = 0.89, P =.003).

CONCLUSION

Postoperative elevation of pulmonary vascular resistance in children after surgical intervention for congenital heart disease is responsive to endothelin-A blockade with BQ123. Increased levels of endothelin-1 predict the response to this therapy, which might become an important addition to the clinical armamentarium in postoperative pulmonary hypertensive disease.

Long-term intravenous epoprostenol infusion in primary pulmonary hypertension: prognostic factors and survival

OBJECTIVES

We sought to determine the factors associated with long-term survival in patients with primary pulmonary hypertension (PPH) treated with continuous epoprostenol infusion.

BACKGROUND

Epoprostenol improves survival in patients with PPH in New York Heart Association (NYHA) functional class III or IV. However, some patients do not benefit from epoprostenol and must be considered for lung transplantation. The best timing for listing these patients on a lung transplantation program is currently unknown.

METHODS

Between December 1992 and January 2001, 178 patients with PPH in NYHA functional class III or IV were treated with epoprostenol. The 6-min walk test (WT) and right-sided heart catheterization were performed at baseline, after three months on epoprostenol and thereafter once a year.

RESULTS

Overall survival rates at one, two, three, and five years were 85%, 70%, 63%, and 55%, respectively. On univariate analysis, the baseline variables associated with a poor outcome were a history of right-sided heart failure, NYHA functional class IV, 6-min WT <or=250 m (median value), right atrial pressure >or=12 mm Hg, and mean pulmonary artery pressure <65 mm Hg. On multivariate analysis, including both baseline variables and those measured after three months on epoprostenol, a history of right-sided heart failure, persistence of NYHA functional class III or IV at three months, and the absence of a fall in total pulmonary resistance of >30%, relative to baseline, were associated with poor survival.

CONCLUSIONS

Survival of patients with PPH treated with epoprostenol depends on the severity at baseline, as well as the three-month response to therapy. These findings suggest that lung transplantation should be considered in a subset of patients who remain in NYHA functional class III or IV or in those who cannot achieve a significant hemodynamic improvement after three months of epoprostenol therapy, or both.

Arterial oxygenation associated with portopulmonary hypertension

STUDY OBJECTIVES

To characterize arterial oxygenation in patients referred to Mayo Clinic for liver transplantation with a diagnosis of portopulmonary hypertension (portoPH).

DESIGN

Prospective study.

SETTING

Liver transplantation program and pulmonary hypertension clinic in a tertiary referral center.

PARTICIPANTS

Twenty consecutive patients with abnormal pulmonary hemodynamics documented by right-heart catheterization (mean pulmonary artery pressure [MPAP] > or = 25 mm Hg, pulmonary vascular resistance [PVR] > or = 120 dyne.s.cm(-5), and pulmonary capillary wedge pressure [PCWP] < or = 15 mm Hg). Liver transplant candidates with normal pulmonary hemodynamics via screening Doppler echocardiography (n = 40) served as control subjects. A subgroup of patients underwent postural and inspired 100% oxygen blood gas analysis, contrast echocardiography, and technetium-labeled macroaggregated albumin ((99m)TcMAA) lung/brain scanning to identify and quantitate the degree of intracardiac or intrapulmonary shunting.

MEASUREMENTS AND RESULTS

portoPH was moderate to severe (MPAP > 35 mm Hg) in 18 of 20 patients (90%). Arterial-alveolar oxygen pressure gradient (P[A-a]O(2)) was abnormal (> or = 20 mm Hg) in 16 of 20 patients (80%). PaO(2) was abnormal (< or = 70 mm Hg) in 3 of 20 patients (15%). Pa0(2) was significantly less and P(A-a)O(2) was significantly greater compared to control subjects (p < 0.001). All patients had normal (99m)TcMAA brain uptake (< 6%) and negative transthoracic contrast echocardiographic findings. No significant correlations were found between oxygenation and hemodynamic variables (MPAP, PVR, PVR index, and transpulmonary gradient).

CONCLUSIONS

Arterial oxygenation associated with portoPH was frequently abnormal and significantly worse when compared to patients with normal pulmonary hemodynamics by Doppler echocardiography. Hypoxemia, as measured by PaO(2) and P(A-a)O(2), was usually mild even in the setting of moderate-to-severe portoPH.

von Recklinghausen Disease Complicated by Pulmonary Hypertension

Two patients with von Recklinghausen disease (neurofibromatosis type 1) were admitted to the hospital because of progressive heart failure. Both patients had prominent pulmonary hypertension revealed on cardiac catheterization. A lung perfusion scan did not show any gross defect. There were no underlying causes of pulmonary hypertension in either patient, such as chronic lung disease, congenital or acquired heart disease, deep vein thrombosis, or systemic hypercoagulable states. There may be an unrecognized association between von Recklinghausen disease and pulmonary hypertension.

Familial primary pulmonary hypertension and associated ocular findings

BACKGROUND

Familial primary pulmonary hypertension (PPH) is a rare, fatal, autosomal dominant disease that results in right heart failure from idiopathic obliteration of the pulmonary arteries. Patients develop stagnation of venous blood flow and elevated venous pressure.

METHODS

The authors retrospectively reviewed the clinical records of three patients diagnosed with PPH that was confirmed on the basis of physical examination, chest X-ray, electrocardiogram, and echocardiogram. Cardiac catheterization excluded cardiac shunt and other secondary causes of pulmonary hypertension.

RESULTS

Two patients presented with a clinical picture resembling venous stasis retinopathy, and one with bilateral choroidal detachments. Two patients had delayed choroidal filling on fluorescein angiography, which was confirmed in one patient with indocyanine green videoangiography.

CONCLUSIONS

Elevated venous pressure found in PPH is responsible for the delayed choroidal perfusion and the reduced venous blood outflow. This explains the clinical findings of venous stasis retinopathy and choroidal detachments seen in these patients.

Fine mapping of PPH1, a gene for familial primary pulmonary hypertension, to a 3-cM region on chromosome 2q33

Familial primary pulmonary hypertension (PPH) is a rare autosomal dominant disease characterized by distinctive changes in pulmonary arterioles that lead to increased pulmonary artery pressures, right ventricular failure, and death. Our previous studies had mapped the disease locus, PPH1, to a 27-cM region on chromosome 2q31-q33, with a maximum multipoint logarithm of the odds favoring genetic linkage score of 3.87 with markers D2S350 and D2S364. To narrow the minimal genetic region for PPH, we physically mapped 33 highly polymorphic microsatellite markers and used them to genotype 44 affected individuals and 133 unaffected individuals from 17 families with PPH. We observed recombination events that substantially reduced the interval for PPH1 to the approximately 3-cM region that separates D2S311 and D2S1384. This entire region lies within chromosome 2q33. A maximum two-point lod score of 7.23 at a recombination fraction of zero was obtained for marker D2S307. A maximum multipoint lod score of 7.41 was observed close to marker D2S1367. The current minimal genetic region contains multiple candidate genes for PPH, including a locus thought to play a role in lung cancer.

Pulmonary hypertension, anorexigens and 5-HT: pharmacological synergism in action?

In pulmonary hypertension (PHT), pulmonary vascular resistance is elevated as a result of increased pulmonary vascular tone and pulmonary vascular remodelling. Certain diet pills, such as the fenfluramines, have been associated with the development of PHT. This class of drugs act as indirect 5-HT receptor agonists and can inhibit 5-HT reuptake and cause the release of 5-HT from platelets. Many pulmonary vasoconstrictors, including 5-HT, activate both Gi- and Gq-linked receptors. Increasing evidence suggests that Gq activation might amplify Gi-linked intracellular pathways to 'uncover' or potentiate vasoconstrictor responses - a phenomenon known as pharmacological synergism, which occurs in the pulmonary circulation. In this review the evidence that 5-HT plays a role in PHT and that pharmacological synergism might contribute to its pathology is discussed.