Clinical correlates and prognostic significance of six-minute walk test in patients with primary pulmonary hypertension. Comparison with cardiopulmonary exercise testing

A new era in the management of pulmonary arterial hypertension related to scleroderma: endothelin receptor antagonism

Evidence suggests that endothelin may have a fundamental role in scleroderma pathogenesis, including pulmonary arterial hypertension (PAH)--a leading cause of death in patients with scleroderma. Development of a new class of drug, endothelin receptor antagonists, heralds an improved outlook for patients with scleroderma and related diseases. Heightened vigilance towards early detection of PAH in scleroderma and a multidisciplinary approach to diagnosis and treatment may improve clinical outcomes for these patients.

Screening, early detection, and diagnosis of pulmonary arterial hypertension: ACCP evidence-based clinical practice guidelines

Pulmonary arterial hypertension (PAH) occurs as an idiopathic process or as a component of a variety of disease processes, including chronic thromboembolic disease, connective tissue diseases, congenital heart disease, and exposure to exogenous factors including appetite suppressants or infectious agents such as HIV. This article reviews evidence for screening in susceptible patient groups and the approach to diagnosing PAH when it is suspected, and provides specific recommendations for applying this evidence to clinical practice.

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.

Interventional and surgical modalities of treatment for pulmonary arterial hypertension

Beyond medical therapy, different interventional and surgical approaches exist for treatment of pulmonary arterial hypertension (PAH). Atrial septostomy has been applied in patients with lack of response to medical therapy in the absence of other surgical treatment options. With growing experience, procedure-related death rates have been reduced to 5.4%, and the most suitable patient group has been identified among patients with a mean right atrial pressure between 10 and 20 mm Hg. Pulmonary endarterectomy is the accepted form of treatment for patients with chronic thromboembolic pulmonary hypertension. Establishing the diagnosis and the classification of the type of lesions by pulmonary angiography is crucial for optimal patient selection. Perioperative mortality rates have been reduced to <10% in experienced centers, and the hemodynamic improvement is dramatic and sustained. Lung and heart-lung transplantation remains the procedure of choice for patients unsuitable for other treatment modalities. Timing of the procedure is difficult because waiting times vary between centers and usually are in a high range. Early referral of patients unresponsive to other treatment forms is therefore of importance to avoid transplantation of patients with established significant comorbidity. The survival rate during the first five years after transplantation for PAH is intermediate among the lung diseases, lower than chronic obstructive pulmonary disease but higher than idiopathic pulmonary fibrosis.

The six-minute walk test in community dwelling elderly: influence of health status

Background

The 6 minutes walk test (6MWT) is a useful assessment instrument for the exercise capacity of elderly persons. The impact of the health status on the 6MWT-distance in elderly, however, remains unclear, reducing its value in clinical settings. The objective of this study was to investigate to what extent the 6MWT-distance in community dwelling elderly is determined by health conditions.

Methods

One hundred and fifty-six community dwelling elderly people (53 male, 103 female) were assessed for health status and performed the 6MWT. After clinical evaluation, electrocardiography and laboratory examination participants were categorized into a stratified six-level classification system according to their health status, going from A (completely healthy) to D (signs of active disease at the moment of examination).

Results

The mean 6MWT-distance was 603 m (SD = 178). The 6MWT-distance decreased significantly with increasing age (ANOVA p = 0.0001) and with worsening health status (ANCOVA, corrected for age p < 0.001).

A multiple linear regression model with health status, age and gender as independent variables explained 31% of the 6MWT-distance variability. Anthropometrical measures (stature, weight and BMI) did not significantly improve the prediction model. A significant relationship between 6MWT-distance and stature was only present in category A (completely healthy).

Conclusions

Significant differences in 6MWT-distance are observed according to health status in community-dwelling elderly persons. The proposed health categorizing system for elderly people is able to distinguish persons with lower physical exercise capacity and can be useful when advising physical trainers for seniors.

Prognosis of Pulmonary Arterial Hypertension*

Although idiopathic pulmonary arterial hypertension is perceived as a progressive disease with a uniformly poor outcome, the natural history of disease is heterogeneous, with some patients dying within months of diagnosis and others living for decades. The course of the disease has also been altered by advances in medical therapies. The outcome of patients with other types of pulmonary arterial hypertension (PAH) has been less well characterized. Assessment of prognosis of such patients is important, as it influences both medical therapy and referral for transplantation. This chapter will provide evidence based recommendations to assess the prognosis of patients with PAH.

Feasibility of Routine Pulmonary Arterial Impedance Measurements in Pulmonary Hypertension

OBJECTIVES

Right ventricular (RV) afterload is best described by a pulmonary arterial impedance (PVZ) spectrum, which integrates pulmonary vascular resistance (PVR), elastance, and wave reflection. We evaluated the feasibility of PVZ determinations in patients with pulmonary arterial hypertension (PAH) during routine right heart catheterization and Doppler echocardiography.

DESIGN

Prospective study.

SETTING

Academic hospital.

PATIENTS

Twenty-two patients with PAH.

INTERVENTIONS

Right heart catheterization with a fluid-filled Swan-Ganz catheter, Doppler echocardiography, and administration of inhaled nitric oxide (NO) [10 to 20 ppm; 17 patients], maximum tolerated dose of IV epoprostenol (average, 8.5 ng/kg/min; 5 patients), and IV dobutamine (8 micro g/kg/min; 8 patients).

MEASUREMENTS AND RESULTS

PVZ was calculated from the spectral analysis of synchronized pulmonary artery pressure (Ppa) and flow waves. The mean (+/- SE) Ppa was 63 +/- 3 mm Hg, and the mean PVR was 16 +/- 2 Wood units. The PVZ spectrum was markedly shifted to higher than normal pressures and frequencies, with a mean 0-Hz impedance (Z(0)) of 1,506 +/- 138 dyne. s. cm(-5), and a mean characteristic impedance (Zc) of 124 +/- 11 dyne. s. cm(-5), which are in keeping with data from previous studies. Inhaled NO levels decreased Ppa, PVR, Z(0), and Zc without a change in cardiac output. Epoprostenol administration did not affect Ppa, increased cardiac output, and decreased Z(0) and Zc. Dobutamine administration increased cardiac output and Ppa, and decreased PVR and Z(0), without changing Zc.

CONCLUSIONS

The determination of PVZ to quantify RV afterload is feasible during routine right heart catheterization and Doppler echocardiography. The measurement is sensitive to pharmacologic interventions.

End points and clinical trial designs in pulmonary arterial hypertension

To date, randomized controlled clinical trials performed in pulmonary arterial hypertension (PAH) have been relatively short-term studies involving mainly patients with advanced disease. The primary end points in these trials have addressed exercise capacity, usually by using the 6-min walk test. Although this approach is still warranted in future trials assessing new treatments, it is likely that the focus will shift toward trials of longer duration, involving patients with less advanced disease, and that different drugs and drug-combination regimens will be compared. In such trials, it is possible that a composite of markers indicating clinical deterioration (e.g., hospitalization for right heart failure, the requirement for the introduction of an alternative treatment, and predefined indicators of worsening exercise tolerance) may be more useful as primary end points. Quality of life will become a very important issue; however, appropriate quality-of-life questionnaires for PAH have yet to be developed. In addition, hemodynamics will likely remain valuable as secondary end points, but future clinical trials should include hemodynamics obtained both during exercise and at rest. Finally, cardiopulmonary exercise testing, echocardiographic studies, and biochemical parameters, such as brain natriuretic peptide or troponin T, may also prove useful as secondary end points in the future.

Clinical significance of brain natriuretic peptide in primary pulmonary hypertension

OBJECTIVES

The aim of this study was to investigate the potential role of brain natriuretic peptide (BNP) levels in the assessment of functional status and right heart performance in primary pulmonary hypertension (PPH).

BACKGROUND

Primary pulmonary hypertension is a progressive disease leading to right heart failure and death. Right heart catheterization and maximal or submaximal exercise tests are employed to assess the course of the disease and the effect of therapeutic interventions. Additional noninvasive and reproducible parameters would be helpful to assess the status of patients with PPH. The natriuretic peptide system is up-regulated in PPH patients. Brain natriuretic peptide (BNP) is produced from the cardiac ventricles and elevated in PPH. The aim of our study was to evaluate the clinical significance of BNP in PPH patients.

METHODS

Correlation analysis was performed for plasma BNP levels of 28 PPH patients and World Health Organization (WHO) functional class (WHO-class), distance walked in 6 min, peak oxygen uptake (peak Vo(2)), and oxygen pulse during spiroergometry and various hemodynamic parameters, including pulmonary vascular resistance (PVR), pulmonary artery pressure (PAP), right atrial pressure (RAP), and cardiac index.

RESULTS

The BNP levels were inversely correlated with the 6-min walk (r = -0.70; p < 0.001) and peak Vo(2) (r = -0.61; p < 0.01), and positive correlation was observed with WHO-class (r = 0.79; p < 0.001). Moreover, BNP levels were also correlated to PVR (r = 0.61; p < 0.01), PAP (r = 0.48; p < 0.05), and RAP (r = 0.78; p < 0.01), and were inversely related to cardiac index (r = -0.48; p < 0.05).

CONCLUSIONS

Our data suggest that plasma BNP levels are closely related to the functional impairment of PPH patients and parallel the extent of pulmonary hemodynamic changes and right heart failure. Serial measurements of plasma BNP concentrations may help improve the management of PPH patients.

The body-mass index, airflow obstruction, dyspnea, and exercise capacity index in chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterized by an incompletely reversible limitation in airflow. A physiological variable--the forced expiratory volume in one second (FEV1)--is often used to grade the severity of COPD. However, patients with COPD have systemic manifestations that are not reflected by the FEV1. We hypothesized that a multidimensional grading system that assessed the respiratory and systemic expressions of COPD would better categorize and predict outcome in these patients.

METHODS

We first evaluated 207 patients and found that four factors predicted the risk of death in this cohort: the body-mass index (B), the degree of airflow obstruction (O) and dyspnea (D), and exercise capacity (E), measured by the six-minute-walk test. We used these variables to construct the BODE index, a multidimensional 10-point scale in which higher scores indicate a higher risk of death. We then prospectively validated the index in a cohort of 625 patients, with death from any cause and from respiratory causes as the outcome variables.

RESULTS

There were 25 deaths among the first 207 patients and 162 deaths (26 percent) in the validation cohort. Sixty-one percent of the deaths in the validation cohort were due to respiratory insufficiency, 14 percent to myocardial infarction, 12 percent to lung cancer, and 13 percent to other causes. Patients with higher BODE scores were at higher risk for death; the hazard ratio for death from any cause per one-point increase in the BODE score was 1.34 (95 percent confidence interval, 1.26 to 1.42; P<0.001), and the hazard ratio for death from respiratory causes was 1.62 (95 percent confidence interval, 1.48 to 1.77; P<0.001). The C statistic for the ability of the BODE index to predict the risk of death was larger than that for the FEV1 (0.74 vs. 0.65).

CONCLUSIONS

The BODE index, a simple multidimensional grading system, is better than the FEV1 at predicting the risk of death from any cause and from respiratory causes among patients with COPD.

Association of Impedance Cardiography Parameters With Changes in Functional and Quality-of-Life Measures in Patients With Chronic Heart Failure

Assessment and prognosis of chronic heart failure is often difficult due to a lack of objective and easily obtainable parameters that accurately reflect disease status. This study was conducted to determine whether impedance cardiography (ICG) parameters were associated with changes in functional and quality-of-life measures in chronic heart failure patients. Retrospective chart review identified 64 patients (73% male, aged 73+/-13 years) with paired ICG measurements followed for 180+113 days. Outcome measures were changes in New York Heart Association class, 6-minute walk distance, patient visual analog scale score, and Minnesota Living with Heart Failure Questionnaire score. Measures of ICG, heart rate and blood pressure, left ventricular ejection fraction, and B-type natriuretic peptide levels were assessed for their association with outcome measures. From baseline to final evaluation, there were significant changes (p<0.05) in New York Heart Association class (from 3.2+/-0.5 to 3.0+/-0.6), 6-minute walk distance (from 668+/-380 m to 874+/-390 m), patient visual analog scale score (from 49+/-10 to 64+/-20), Minnesota Living with Heart Failure Questionnaire score (from 54+/-22 to 39+/-22), and ICG parameters of stroke index (from 38+/-9 to 41+/-8), left ventricular ejection time (from 273+/-42 to 291+/-33), and systolic time ratio (from 0.56+/-0.2 to 0.52+/-0.2). Changes in multivariate ICG parameters were significantly correlated to changes in New York Heart Association class (R, 0.80), 6-minute walk distance (R, 0.94), patient visual analog scale score (R, 0.69), and Minnesota Living with Heart Failure Questionnaire score (R, 0.67). ICG provides objective data that reflects changes in chronic heart failure disease status and treatment effectiveness.

Sitaxsentan Therapy for Pulmonary Arterial Hypertension

Sitaxsentan may benefit patients with pulmonary arterial hypertension by blocking the vasoconstrictor effects of endothelin-A while maintaining the vasodilator/clearance functions of endothelin-B receptors. Patients with pulmonary arterial hypertension that was idiopathic, related to connective tissue disease or congenital heart disease, were randomized to receive placebo (n = 60), sitaxsentan 100 mg (n = 55), or sitaxsentan 300 mg (n = 63) orally once daily for 12 weeks. The primary endpoint was change in peak VO(2) at Week 12. Secondary endpoints included 6-minute walk, New York Heart Association class, VO(2) at anaerobic threshold, VE per carbon dioxide production at anaerobic threshold, hemodynamics, quality of life, and time to clinical worsening. Although the 300-mg group increased peak VO(2) compared with placebo (+3.1%, p < 0.01), none of the other endpoints derived from cardiopulmonary exercise testing were met. However, both the 100-mg dose and the 300-mg dose, compared with placebo, increased 6-minute walk distance (100 mg: +35 m, p < 0.01; 300 mg: +33 m, p < 0.01); functional class, cardiac index, and pulmonary vascular resistance also improved (p < 0.02 for each parameter at both doses). The incidence of elevated aminotransferase values (> three times normal) was 3% for the placebo group, 0% for the 100-mg group, and 10% for the 300-mg group.

Effects of adrenomedullin inhalation on hemodynamics and exercise capacity in patients with idiopathic pulmonary arterial hypertension

BACKGROUND

Adrenomedullin (AM) is a potent pulmonary vasodilator peptide. However, whether intratracheal delivery of aerosolized AM has beneficial effects in patients with idiopathic pulmonary arterial hypertension remains unknown. Accordingly, we investigated the effects of AM inhalation on pulmonary hemodynamics and exercise capacity in patients with idiopathic pulmonary arterial hypertension.

METHODS AND RESULTS

Acute hemodynamic responses to inhalation of aerosolized AM (10 microg/kg body wt) were examined in 11 patients with idiopathic pulmonary arterial hypertension during cardiac catheterization. Cardiopulmonary exercise testing was performed immediately after inhalation of aerosolized AM or placebo. The work rate was increased by 15 W/min until the symptom-limited maximum, with breath-by-breath gas analysis. Inhalation of AM produced a 13% decrease in mean pulmonary arterial pressure (54+/-3 to 47+/-3 mm Hg, P<0.05) and a 22% decrease in pulmonary vascular resistance (12.6+/-1.5 to 9.8+/-1.3 Wood units, P<0.05). However, neither systemic arterial pressure nor heart rate was altered. Inhalation of AM significantly increased peak oxygen consumption during exercise (peak o(2), 14.6+/-0.6 to 15.7+/-0.6 mL. kg(-1). min(-1), P<0.05) and the ratio of change in oxygen uptake to that in work rate (Deltao(2)/DeltaW ratio, 6.3+/-0.4 to 7.0+/-0.5 mL. min(-1). W(-1), P<0.05). These parameters remained unchanged during placebo inhalation.

CONCLUSIONS

Inhalation of AM may have beneficial effects on pulmonary hemodynamics and exercise capacity in patients with idiopathic pulmonary arterial hypertension.

Treatment of pulmonary arterial hypertension: a preliminary decision analysis

STUDY OBJECTIVE

New therapies for pulmonary arterial hypertension (PAH) improve functional status, quality of life (QOL), and survival. Clinicians must chose between very different therapies without the availability of comparison studies. We constructed a "virtual" clinical trial to help inform these treatment choices.

DESIGN

We compare key outcomes related to survival, costs, and QOL using a Markov-type decision model to estimate the expected outcomes and costs for PAH patients treated for 1 year with bosentan and treprostinil compared to patients treated with epoprostenol, as well as patients treated with bosentan compared to those treated with treprostinil. The allowed transitions in the model were between World Health Organization functional class I to IV and death. Transition probabilities were based on observed transitions for bosentan. Treatment effect was estimated using 6-min walk data for treprostinil and epoprostenol. Utilities were calculated from estimated EuroQol health states. Cost was estimated from average wholesale price and Medicare reimbursement data. The effects of changing values of input variables on the key outcomes were calculated.

RESULTS

Treatment with bosentan compared to treatment with either epoprostenol or treprostinil was less costly and resulted in a greater gain in quality-adjusted life years (QALYs). Conversely, treprostinil was significantly more expensive than epoprostenol, without an appreciable gain in QALYs. These findings were not substantially affected by the reasonable adjustments of transition probabilities, utility values, or tachyphylaxis to epoprostenol.

CONCLUSION

Treatment with bosentan is more cost-effective than treatment with either treprostinil or epoprostenol. In addition, a net improvement in quality-adjusted survival may be expected.

Right ventricular adaptation to pulmonary hypertension: an interspecies comparison

Right ventricular (RV) adaptation is an important prognostic factor in acute and chronic pulmonary hypertension. Pulmonary vascular basal tone and hypoxic reactivity are known to vary widely between species. We investigated how RV adaptation to acute pulmonary hypertension is preserved in species with low, intermediate, and high pulmonary vascular resistance and reactivity. Acute pulmonary hypertension was induced by hypoxia, distal embolism, and proximal constriction in anesthetized dogs (n = 10), goats (n = 8), and pigs (n = 8). Pulmonary vessels were assessed by flow-pressure curves and by impedance to quantify distal resistance, proximal elastance, and wave reflections. RV function was assessed by pressure-volume curves to quantify afterload, contractility, and ventricular-arterial coupling efficiency. First, hypoxia was associated with a progressive increase of resistance, elastance, and wave reflection from dogs to goats and from goats to pigs. RV contractility increased proportionally to RV afterload, and optimal coupling was preserved in all species. Second, embolism increased resistance and wave reflection but not elastance. The increase in RV contractility matched the increase in RV afterload and optimal coupling was preserved. Finally, proximal pulmonary artery constriction increased resistance, increased and accelerated wave reflection, and markedly increased elastance. RV contractility increased markedly and coupling showed a nonsignificant trend to decrease. We conclude that optimal or near-optimal ventricular-arterial coupling is maintained in acute pulmonary hypertension, whether in absence or presence of chronic species-induced pulmonary hypertension.

Differential responses to measures of gait performance among healthy and neurologically impaired individuals11No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated

OBJECTIVES

To compare gait during a 5-minute walk among healthy individuals, persons with spinal cord injury (SCI), and stroke survivors and to investigate whether simultaneous measures of oxygen consumption enhance information about performance.

DESIGN

Descriptive study.

SETTING

Veterans Affairs medical center.

PARTICIPANTS

Thirty-nine healthy individuals, 10 persons with SCI, and 20 stroke survivors.

INTERVENTIONS

Participants were fitted with a portable gas analyzer and walked on a 5-m walkway for 5 minutes.

MAIN OUTCOME MEASURES

Measures of walk distance, gait speed, gait energy expenditure (GEE), and gait cost were obtained, along with measures of ventilation (.Ve), ventilation and carbon dioxide production slope (.Ve . .VCo2), oxygen pulse, and heart rate.

RESULTS

The SCI group (127.65+/-81.74m) walked less than the stroke survivors (148.80+/-64.3m) or the healthy group (268.90+/-35.01m) but had higher energy demands, as shown by GEE (SCI group, 13.28+/-3.23mL.kg(-1).min(-1); stroke group, 10.18+/-2.14mL.kg(-1).min(-1); healthy group, 9.61+/-1.90mL.kg(-1).min(-1)) and by gait cost (SCI group,.57+/-.40 mL.kg(-1).m(-1); stroke group,.40+/-.52mL.kg(-1).m(-1); healthy group,.18+/-.02mL.kg(-1).m(-1)). Compared with the healthy group, the stroke group had higher .Ve (stroke group, 22.34+/-5.20L/min vs healthy group, 16.11+/-3.22L/min) and .Ve . .VCo2 slope (24.22+/-8.80 vs 18.73+/-5.44, respectively).

CONCLUSION

Use of metabolic assessment during the 5-minute walk was feasible and provided further information for evaluating gait performance with the subjects studied.

Detectable serum cardiac troponin T as a marker of poor prognosis among patients with chronic precapillary pulmonary hypertension

BACKGROUND

Right ventricular failure is a leading cause of death in patients with chronic pulmonary hypertension (PH). We checked whether detection of cardiac troponin T (cTnT), a specific marker of myocyte injury, could be useful in prognostic stratification of those patients.

METHODS AND RESULTS

Initial evaluation of 56 clinically stable patients (age 41+/-15 years) with pulmonary arterial (51 patients) or inoperable chronic thromboembolic (5 patients) PH (mean pulmonary arterial pressure 60+/-18 mm Hg) included cTnT test, allowing detection of its serum levels > or =0.01 ng/mL [cTnT(+)]. cTnT was detectable in 8 of 56 (14%) patients (mean+/-SD, 0.034+/-0.022; range, 0.010 to 0.077 ng/mL). Despite similar pulmonary hemodynamics, they had higher heart rate (92+/-15 versus 76+/-14 bpm, P=0.004), lower mixed venous oxygen saturation (50+/-10% versus 57+/-9%, P=0.04), and higher serum N-terminal pro-B-type natriuretic peptide (4528+/-3170 versus 2054+/-2168 pg/mL, P=0.03) and walked less during the 6-minute walk test (298+/-132 versus 396+/-101 m, P=0.02). Cumulative survival estimated by Kaplan-Meier curves was significantly worse at 24 months in cTnT(+) compared with cTnT(-) (29% versus 81%, respectively, log-rank test P=0.001). Multivariate analysis revealed cTnT status (hazard ratio, 4.89; 95% CI, 1.18 to 20.29; P=0.03), 6-minute walk test (hazard ratio, 0.93 for each 10 m; P=0.01), and pulmonary vascular resistance (hazard ratio, 1.13; P=0.01) as independent markers of mortality. All 3 cTnT(+) patients who survived the follow-up period converted to cTnT(-) during treatment.

CONCLUSIONS

Detectable cTnT is a so-far ignored independent marker of increased mortality risk in patients with chronic precapillary PH, supporting the role of progressive myocyte injury in the vicious circle leading to hemodynamic destabilization.

Recipient selection

Since international recommendations for lung transplant recipients were made in 1998, newer tools for predicting mortality in patients who have end-stage lung disease have been investigated. This article reviews studies for predicting mortality in obstructive, restrictive, pulmonary vascular, and suppurative/bronchiectatic lung disease. Newer considerations for alternative treatments, postoperative risks, and contraindications are also examined. The article aims to provide more accurate data for selecting patients who will benefit from lung transplantation.

Pulmonary arterial hypertension: a new era in management

Pulmonary arterial hypertension (PAH) is a heterogeneous condition with a wide range of causes. The diagnosis is often delayed or missed. PAH is covert in its early stages, when its detection and treatment should have the most impact. Access in Australia to effective PAH therapies has lagged behind that in other affluent countries. New agents for PAH, now becoming available, improve symptoms and reduce pulmonary resistance, with some demonstrating an ability to reverse remodelling of the right ventricle. Best management of PAH is comprehensive and multidisciplinary. Centres of excellence are needed in geographically strategic areas. Aggressive efforts must be made to diagnose PAH and to facilitate access to effective therapies.

Six-minute walk distance in chronic obstructive pulmonary disease: reproducibility and effect of walking course layout and length

The 6-minute walk test is used in clinical practice and clinical trials of lung diseases; however, it is not clear whether replicate tests need to be performed to assess performance. Furthermore, little is known about the impact of walking course layout on test performance. We conducted 6-minute walks on 761 patients with severe emphysema (mean +/- SD FEV1% predicted = 26.3 +/- 7.2) who were participants in the National Emphysema Treatment Trial. Four hundred seventy participants had repeated walks on a separate day. The second test was improved by an average of 7.0 +/- 15.2% (66.1 +/- 146 feet, p < 0.0001, by paired t test), with an intraclass correlation coefficient of 0.88 between days. The course layout had an effect on the distance walked. Participants tested on continuous (circular or oval) courses had a 92.2-foot longer walking distance than those tested on straight (out and back) courses. Course length had no significant effect on walking distance. The training effect found in these patients with severe emphysema is less than in previous reports of patients with chronic obstructive pulmonary disease. Furthermore, the layout of the track may influence the 6-minute walk performance.

Primary pulmonary hypertension

Primary pulmonary hypertension (PPH) is a rare disorder characterised by raised pulmonary-artery pressure in the absence of secondary causes. Precapillary pulmonary arteries are affected by medial hypertrophy, intimal fibrosis, microthrombosis, and plexiform lesions. Most individuals present with dyspnoea or evidence of right heart failure. Echocardiography is the best non-invasive test to screen for suspected pulmonary hypertension. The discovery of mutations in the coding region of the gene for bone morphogenetic protein receptor 2 in patients with familial and sporadic PPH may help not only to elucidate pathogenesis but also to direct future treatment options. The pathogenesis is not completely understood, but recent investigations have revealed many possible candidate modifier genes. Without treatment, the disorder progresses in most cases to right heart failure and death. With current therapies such as epoprostenol, progression of disease is slowed, but not halted. Many promising new therapeutic options, including prostacyclin analogues, endothelin-1-receptor antagonists, and phosphodiesterase inhibitors, improve clinical function and haemodynamic measures and may prolong survival.

Pulmonary hypertension: new perspectives

The World Health Organization symposium offers a new treatment-oriented classification of pulmonary hypertension based on an improved understanding of its pathophysiology. Regardless of the etiology, severe or unrelieved pulmonary hypertension leads to right heart failure. Symptoms and signs of pulmonary hypertension are often subtle and nonspecific. As a result, a significant delay between the onset of symptoms and the diagnosis of pulmonary hypertension is common. Echocardiography with Doppler flow is the most useful study to evaluate patients suspected of having pulmonary hypertension. The suspected diagnosis of pulmonary hypertension should then be confirmed by right heart catheterization. If present, further evaluation may include oxygen assessment, pulmonary function testing, high resolution computed tomography of the chest, and ventilation-perfusion lung scanning. Treatment of pulmonary hypertension requires uncommon expertise. General measures include correction of the underlying cause, reversal of hypoxemia and judicious use of diuretics. Advances in vasodilator therapy have increased treatment options beyond calcium channel blockers and intravenous epoprostenol. Lung transplantation remains an option for select patients with pulmonary hypertension not responding to medical management.

Effects of the oral endothelin-receptor antagonist bosentan on echocardiographic and doppler measures in patients with pulmonary arterial hypertension

OBJECTIVES

The purpose of this study was to investigate the effects of bosentan (125 or 250 mg twice daily) on echocardiographic and Doppler variables in 85 patients with World Health Organization class III or IV pulmonary arterial hypertension (PAH).

BACKGROUND

Bosentan, an orally active dual endothelin-receptor antagonist, improves symptoms, exercise capacity, and hemodynamics in patients with PAH.

METHODS

Patients had primary pulmonary hypertension (84%) or PAH associated with connective tissue disease. Of these, 29 patients received placebo and 56 received bosentan (1:2 randomization). Six-minute walk tests and echocardiograms were performed at baseline and after 16 weeks of treatment.

RESULTS

Baseline characteristics were similar in the placebo and bosentan groups, and echocardiographic and Doppler findings were consistent with marked abnormalities of right ventricular (RV) and left ventricular (LV) structure and function that were due to PAH. The treatment effect on 6-min walking distance was 37 m in favor of bosentan (p = 0.036). Treatment effects of bosentan compared with placebo on other parameters were as follows: Doppler-derived cardiac index = +0.4 l/min/m(2) (p = 0.007), LV early diastolic filling velocity = +10.5 cm/s (p = 0.003), LV end-diastolic area = +4.2 cm(2) (p = 0.003), LV systolic eccentricity index = -0.12 (p = 0.047), RV end-systolic area = -2.3 cm(2) (p = 0.057), RV:LV diastolic areas ratio = -0.64 (p = 0.007), Doppler RV index = -0.06 (p = 0.03), and percentage of patients with an improvement in pericardial effusion score = 17% (p = 0.05).

CONCLUSIONS

Bosentan improves RV systolic function and LV early diastolic filling and leads to a decrease in RV dilation and an increase in LV size in patients with PAH.

Portopulmonary hypertension: a tale of two circulations

Pulmonary involvement is common in patients with portal hypertension and can manifest in diverse manners. Changes in pulmonary arterial resistance, manifesting either as the hepatopulmonary syndrome or portopulmonary hypertension (PPHTN), have been increasingly recognized in these patients in recent years. This review summarizes the clinicopathologic features, diagnostic criteria, as well as the latest concepts in the pathogenesis and management of PPHTN, which is defined as an elevated pulmonary artery pressure in the setting of an increased pulmonary vascular resistance and a normal wedge pressure in a patient with portal hypertension.

Hyperuricemia as a prognostic factor in pulmonary arterial hypertension

Pulmonary arterial hypertension is a malignant disease with a median survival of 3 years. Uric acid levels are elevated in severe heart failure and in states of hypoxemia. Early data suggest a correlation between hyperuricemia and severe pulmonary arterial hypertension. We studied 29 patients with pulmonary arterial hypertension diagnosed and treated between 1998 and 2001. Clinical characteristics (6 min walk test and New York Heart Association class) and hemodynamic parameters (pulmonary artery pressure, pulmonary vascular resistance and cardiac output) were evaluated and correlated to uric acid level in a retrospective study. Uric acid levels correlated positively with New York Heart Association class (r=0.66, P<0.001) and negatively with 6 min walk test (r=-0.35, P=0.03). Uric acid levels were higher in patients who died than in patients who survived at the end ofthe follow-up period (8.8 vs. 5.7 mg/dl, P=0.001). This study shows that uric acid levels are elevated in severe pulmonary arterial hypertension and can be used as a prognostic marker of disease severity.

Development and validation of a one-mile treadmill walk test to predict peak oxygen uptake in healthy adults ages 40 to 79 years

The purpose of this investigation was to determine whether the Rockport one-mile walk test equation to predict maximal oxygen uptake was valid for application to treadmill walking. When the Rockport model was found to be inappropriate, a new regression model was developed for predicting peak oxygen uptake (VO2peak) from a one-mile treadmill walk. 304 healthy volunteers ages 40 to 79 years (mean age = 57.6 years, 154 men and 150 women) completed a VO2peak test and a one-mile treadmill walk. Stepwise regression was used to build a model for the relationship between VO2peak and a variety of predictor variables in a sub-sample development group (n = 154). This new model was then applied to a sub-sample validation group (n = 150). The new equation produced a correlation of 0.87, SEE = 4.7 ml x kg (-1) x min (-1) with a mean residual of 0.96 ml x kg (-1) x min (-1). The equation for predicting VO2peak developed in this investigation provides a means of assessing VO2peak that is easy to administer, allows for careful supervision of subjects, and can be completed at a low financial and temporal cost.

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.

Receiver operating characteristic curves to assess predictors of radiation-induced symptomatic lung injury

PURPOSE

To assess the utility of dosimetric/functional metrics as predictors of symptomatic radiation pneumonitis using receiver operating characteristic curves.

METHODS

Between 1991 and 1999, 277 patients were enrolled on a prospective clinical study to relate radiation therapy (RT) induced changes in lung function with dosimetric and functional metrics. Pre-RT whole and regional functional assessments included pulmonary function tests and single photon emission computed tomography lung perfusion scans. Patients had three-dimensional planning scans and dose calculations (reflecting tissue density heterogeneity) to provide a dose-volume histogram of the lung and associated dosimetric parameters (MLD = mean lung dose, V30 = % of lung receiving >or=30 Gy). Fusion of single photon emission computed tomography and computed tomography scans provides perfusion-weighted dose-function histograms and associated dosimetric parameters (mean perfusion-weighted lung dose). The incidence of clinically relevant radiation pneumonitis requiring steroids was related to the dosimetric and functional metrics. The predictive abilities of models (sensitivity and specificity) were calculated and compared based on the area beneath receiver operating characteristic (ROC) curves (Wilcoxon rank-sum and chi-square).

RESULTS

Twenty-seven of 162 evaluable patients with >or=6 months' follow-up developed pneumonitis requiring steroids. Single metrics were typically not good predictors for pneumonitis ( area under ROC curve = 0.5-0.68). The two-dimensional models (e.g., MLD and pre-RT diffusion capacity for carbon monoxide) generally provided greater ROC areas (0.61-0.72). Overall, the models that considered a measure of pre-RT lung function (i.e., pulmonary function tests), the MLD, and mean perfusion-weighted lung dose were best correlated with outcome (ROC area: 0.7) (p < 0.05 compared to unidimensional models). However, because the area under the ROC curve for these models was <<1, they too seemed not to be ideal.

CONCLUSION

Predicting symptomatic radiation pneumonitis remains difficult. Multiparameter models that consider pre-RT pulmonary function and the three-dimensional dose distribution seem to be best able to predict outcome. Additional studies are needed to better understand the dosimetric/functional determinants of radiation pneumonitis.

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.

Assessment of survival in patients with primary pulmonary hypertension: importance of cardiopulmonary exercise testing

BACKGROUND

Primary pulmonary hypertension (PPH) is a life-threatening disease. Prognostic assessment is an important factor in determining medical treatment and lung transplantation. Whether cardiopulmonary exercise testing data predict survival has not been reported previously.

METHODS AND RESULTS

We studied 86 patients with PPH (58 female, age 46+/-2 years, median NYHA class III) between 1996 and 2001 who were followed up in a tertiary referral center. Right heart catheterization was performed and serum uric acid levels were measured in all patients. Seventy patients were able to undergo exercise testing. At the start of the study, the average pulmonary artery pressure was 60+/-2 mm Hg, average pulmonary vascular resistance was 1664+/-81 dyne x s x cm(-5), average serum uric acid level was 7.5+/-0.35 mg/dL, and average peak oxygen uptake during exercise (peak VO(2) was 11.2+/-0.5 mL x kg(-1) x min(-1). During follow-up (mean: 567+/-48 days), 28 patients died and 16 underwent lung transplantation (1-year cumulative event-free survival: 68%; 95% CI 58 to 78). The strongest predictors of impaired survival were low peak VO(2) (P<0.0001) and low systolic blood pressure at peak exercise (peak SBP; P<0.0001). In a multivariable analysis, serum uric acid levels (all P<0.005) and diastolic blood pressure at peak exercise independently predicted survival (P<0.05). Patients with peak VO(2) < or =10.4 mL x kg(-1) x min(-1) and peak SBP < or =120 mm Hg (ie, 2 risk factors) had poor survival rates at 12 months (23%), whereas patients with 1 or none of these risk factors had better survival rates (79% and 97%, respectively).

CONCLUSIONS

Peak VO(2) and peak SBP are independent and strong predictors of survival in PPH patients. Hemodynamic parameters, although also accurate predictors, provide no independent prognostic information.

Hemodynamic effects of aerosolized iloprost in pulmonary hypertension at rest and during exercise

STUDY OBJECTIVES

Aerosolized iloprost, a stable prostacyclin analog, improves functional capacity even in patients with pulmonary hypertension who did not show a vigorous hemodynamic response after iloprost inhalation at rest. We therefore speculated that aerosolized iloprost elicits more beneficial effects on pulmonary hemodynamics during exercise than at rest.

DESIGN AND SETTING

A prospective, open, uncontrolled study at a university hospital.

PATIENTS

Sixteen patients with primary or secondary pulmonary hypertension.

INTERVENTIONS

Right-heart catheterization at rest and during exercise before and after the inhalation iloprost, 14 to 28 microg.

RESULTS

Before iloprost treatment, exercise increased mean (+/- SD) pulmonary artery pressure (PAPm) from 45 +/- 8 to 70 +/- 13 mm Hg, cardiac output from 3.7 +/- 1.0 to 5.8 +/- 2.4 L/min, and pulmonary vascular resistance (PVR) from 904 +/- 322 to 1,013 +/- 432 dyne.s.cm(-5) (each p < 0.05). After recovery, iloprost reduced PAPm from 44 +/- 8 to 41 +/- 6 mm Hg, increased cardiac output from 3.7 +/- 1.0 to 4.9 +/- 1.4 L/min, and lowered PVR from 902 +/- 350 to 636 +/- 248 dyne x s x cm(-5) (each p < 0.05). During exercise after iloprost, PAPm increased to 57 +/- 8 mm Hg, cardiac output to 7.0 +/- 3.0 L/min, and PVR to 673 +/- 279 dyne x s x cm(-5) (each p < 0.05 vs first exercise test). Systemic BP was not altered significantly by iloprost treatment during exercise.

CONCLUSIONS

Aerosolized iloprost treatment exerts more favorable effects on pulmonary hemodynamics during exercise than at rest. These findings explain the functional improvement observed in patients with pulmonary hypertension who show only a moderate pulmonary vasodilatory response during iloprost inhalation at rest. Whether these beneficial effects have prognostic significance needs to be elucidated by further study.

Effects of beraprost sodium, an oral prostacyclin analogue, in patients with pulmonary arterial hypertension: a randomized, double-blind, placebo-controlled trial

OBJECTIVES

The purpose of this study was to assess the efficacy and safety of beraprost sodium, an orally active prostacyclin analogue, in New York Heart Association (NYHA) functional class II and III patients with pulmonary arterial hypertension (PAH).

BACKGROUND

Pulmonary arterial hypertension is a life-threatening disease for which continuous intravenous infusion of prostacyclin has been proven effective. However, this treatment is associated with serious complications arising from the complex delivery system.

METHODS

In this double-blind, placebo-controlled study, 130 patients with PAH were randomized to the maximal tolerated dose of beraprost (median dose 80 microg four times a day) or to placebo for 12 weeks. The primary end point was the change in exercise capacity assessed by the 6-min walk test. Secondary end points included changes in Borg dyspnea index, cardiopulmonary hemodynamics and NYHA functional class.

RESULTS

Patients treated with beraprost improved exercise capacity and symptoms. The difference between treatment groups in the mean change of 6-min walking distance at week 12 was 25.1 m (95% confidence interval [CI]: 1.8 to 48.3, p = 0.036). The difference in the mean change of Borg dyspnea index was -0.94 (95% CI: -1.63 to -0.24, p = 0.009). In the sub-group of patients with primary pulmonary hypertension, the difference in the mean change of 6-min walking distance was 46.1 m (95% CI: 3.0 to 89.3, p = 0.035). Cardiopulmonary hemodynamics and NYHA functional class had no statistically significant changes. Drug-related adverse events were common in the titration phase and decreased in the maintenance period.

CONCLUSIONS

Beraprost improves exercise capacity and symptoms in NYHA functional class II and III patients with PAH and, in particular, in those with primary pulmonary hypertension.

Oral beraprost sodium improves exercise capacity and ventilatory efficiency in patients with primary or thromboembolic pulmonary hypertension

OBJECTIVE

To investigate the effect of beraprost sodium, an orally active prostacyclin analogue, on exercise capacity and ventilatory efficiency in patients with primary pulmonary hypertension and chronic thromboembolic pulmonary hypertension.

PATIENTS AND DESIGN

Symptom limited cardiopulmonary exercise testing was performed before and 3 (1) months (mean (SEM)) after beraprost treatment in 30 patients with precapillary pulmonary hypertension (14 with primary pulmonary hypertension and 16 with chronic thromboembolic pulmonary hypertension).

RESULTS

Long term treatment with beraprost resulted in significant increases (mean (SEM)) in peak workload (87 (4) W to 97 (5) W, p < 0.001) and peak oxygen consumption (peak VO2, 14.9 (0.7) ml/kg/min to 16.8 (0.7) ml/kg/min, p < 0.001). Beraprost decreased the ventilatory response to carbon dioxide production during exercise (VE-VCO2 slope, 42 (2) to 37 (1), p < 0.001). No significant difference in the responses of these variables to beraprost treatment was observed between patients with primary pulmonary hypertension and chronic thromboembolic pulmonary hypertension.

CONCLUSIONS

Oral administration of beraprost sodium may improve exercise capacity and ventilatory efficiency in patients with both primary and chronic thromboembolic pulmonary hypertension.

Power of outcome measurements to detect clinically significant changes in pulmonary rehabilitation of patients with COPD

STUDY OBJECTIVES

Several validated instruments are used to measure outcomes, such as exercise performance, dyspnea, and health-related quality of life after pulmonary rehabilitation (PR) in patients with COPD. However, no study has simultaneously compared the responsiveness of the most frequently used outcome measurements after PR. We designed this study to investigate the capacity of several of the most frequently used outcome measurements to detect changes after PR in a population of patients with severe COPD who qualified for lung volume reduction surgery.

DESIGN, PATIENTS, AND INTERVENTIONS

We evaluated 37 patients with severe COPD (FEV(1) < 40%) before and after 6 to 8 weeks of outpatient PR. The following frequently used tools were evaluated: the 6-min walk distance (6MWD); functional dyspnea with the Medical Research Council (MRC) scale; baseline and transitional dyspnea index (BDI/TDI); resting and 6MWD visual analog scale (VAS); quality of life with a generic tool (the Short Form-36 [SF-36]); and two disease-specific tools, the Chronic Respiratory Disease Questionnaire (CRQ) and the St. George's Respiratory Questionnaire (SGRQ).

RESULTS

After PR, mean +/- SD 6MWD increased in 33 of 37 patients (89%), from 285 +/- 97 to 343 +/- 92 m (p = 0.009). Improvements were seen also in the MRC scale in 23 of 37 patients (62%; from 2.27 +/- 0.8 to 1.86 +/- 0.6; p = 0.01); in CRQ dyspnea in 25 of 37 patients (67%; from 3.25 +/- 0.9 to 3.90 +/- 1.4; p = 0.02); in CRQ mastery in 22 of 37 patients (60%; from 4.37 +/- 1.4 to 5.14 +/- 1.3; p = 0.01); and in BDI/TDI functional in 24 of 37 patients (64%; from 1.4 +/- 0.8 to 0.7 +/- 1.1; p = 0.002). There were smaller improvements in the SGRQ in 18 of 37 patients (48%) and in the SF-36 in 19 of 37 patients (51%), but they were not statistically significant. There were good correlations between the dyspnea components of all the tools. The 6MWD change did not correlate with the changes in the other outcomes. Clinically significant changes in the values for those outcome tools were detected in > 50% of patients for the BDI/TDI, 29% of patients for the MRC scale, in 37% of patients for the 6MWD, in 48% of patients for the VAS at peak exercise, in > 50% of patients for the CRQ, and in 40% of patients for the SGRQ.

CONCLUSIONS

We conclude that the VAS peak exercise, BDI/TDI, and CRQ adequately reflect the beneficial effects of PR. The 6MWD evaluates a unique domain not related to quality of life. Due to their simplicity and sensitivity, VAS at peak exercise, 6MWD, and CRQ may be the best practical tools to evaluate responsiveness to PR.

Bosentan therapy for pulmonary arterial hypertension

BACKGROUND

Endothelin-1 is a potent vasoconstrictor and smooth-muscle mitogen. In a preliminary study, the orally administered dual endothelin-receptor antagonist bosentan improved exercise capacity and cardiopulmonary hemodynamics in patients with pulmonary arterial hypertension. The present trial investigated the effect of bosentan on exercise capacity in a larger number of patients and compared two doses.

METHODS

In this double-blind, placebo-controlled study, we randomly assigned 213 patients with pulmonary arterial hypertension (primary or associated with connective-tissue disease) to receive placebo or to receive 62.5 mg of bosentan twice daily for 4 weeks followed by either of two doses of bosentan (125 or 250 mg twice daily) for a minimum of 12 weeks. The primary end point was the degree of change in exercise capacity. Secondary end points included the change in the Borg dyspnea index, the change in the World Health Organization (WHO) functional class, and the time to clinical worsening.

RESULTS

At week 16, patients treated with bosentan had an improved six-minute walking distance; the mean difference between the placebo group and the combined bosentan groups was 44 m (95 percent confidence interval, 21 to 67; P<0.001). Bosentan also improved the Borg dyspnea index and WHO functional class and increased the time to clinical worsening.

CONCLUSIONS

The endothelin-receptor antagonist bosentan is beneficial in patients with pulmonary arterial hypertension and is well tolerated at a dose of 125 mg twice daily. Endothelin-receptor antagonism with oral bosentan is an effective approach to therapy for pulmonary arterial hypertension.

Continuous subcutaneous infusion of treprostinil, a prostacyclin analogue, in patients with pulmonary arterial hypertension: a double-blind, randomized, placebo-controlled trial

Pulmonary arterial hypertension is a life-threatening disease for which continuous intravenous prostacyclin has proven to be effective. However, this treatment requires a permanent central venous catheter with the associated risk of serious complications such as sepsis, thromboembolism, or syncope. Treprostinil, a stable prostacyclin analogue, can be administered by a continuous subcutaneous infusion, avoiding these risks. We conducted a 12-week, double-blind, placebo-controlled multicenter trial in 470 patients with pulmonary arterial hypertension, either primary or associated with connective tissue disease or congenital systemic-to-pulmonary shunts. Exercise capacity improved with treprostinil and was unchanged with placebo; the between treatment group difference in median six-minute walking distance was 16 m (p = 0.006). Improvement in exercise capacity was greater in the sicker patients and was dose-related, but independent of disease etiology. Concomitantly, treprostinil significantly improved indices of dyspnea, signs and symptoms of pulmonary hypertension, and hemodynamics. The most common side effect attributed to treprostinil was infusion site pain (85%) leading to premature discontinuation from the study in 8% of patients. Three patients in the treprostinil treatment group presented with an episode of gastrointestinal hemorrhage. We conclude that chronic subcutaneous infusion of treprostinil is an effective treatment with an acceptable safety profile in patients with pulmonary arterial hypertension.

The prognostic role of the ECG in primary pulmonary hypertension

BACKGROUND/RATIONALE

Doppler echocardiography and invasive hemodynamic parameters reflective of right ventricular failure are associated with a poor prognosis in patients with primary pulmonary hypertension (PPH). The aims of the present study were to examine whether ECG features in patients with PPH are associated with a decrease in survival, and to determine the value of the ECG in risk stratification.

METHODS/RESULTS

We analyzed the ECG, New York Heart Association (NYHA) class, and hemodynamic parameters in 51 untreated patients with PPH (88% women; mean age, 41.7 years; 79% NYHA classes III and IV) evaluated between 1992 and 1998. Subsequent treatment included epoprostenol in 37 patients, calcium channel blockers in 10 patients, epoprostenol and atrial septostomy in 2 patients, and lung transplant in 3 patients. As of 1999, 16 patients had died. Based on Kaplan-Meier estimates, median survival was > 6.5 years and estimated survival at 1 year, 3 years, and 5 years was 86%, 71%, and 57%, respectively. Significant predictors of decreased survival by Cox regression analysis include pulmonary vascular resistance (PVR; hazard ratio [HR], 1.11 per Wood unit), cardiac index (HR, 0.22 per L/min/m(2)), p wave amplitude in lead II (HR, 3.06 per mm), p > or = 0.25 mV in lead II (HR, 2.77), qR in V(1) (HR, 3.55), and World Health Organization criteria for right ventricular hypertrophy (HR, 4.26). After controlling for PVR, the HRs attributable to the ECG criteria were only slightly diminished. NYHA class and pulmonary artery pressures did not correlate with a decrease in survival.

CONCLUSIONS

ECG parameters reflective of physiologic and anatomic abnormalities in the right ventricle are associated with decreased survival in patients with PPH, and may be useful for deciding therapeutic choices including the timing for lung transplantation listing.

ET-1 stimulates pulmonary arterial smooth muscle cell proliferation via induction of reactive oxygen species

Recent studies implicate reactive oxygen species (ROS) such as superoxide anions and H(2)O(2) in the proliferation of systemic vascular smooth muscle cells (SMCs). However, the role of ROS in SMC proliferation within the pulmonary circulation remains unclear. We investigated the effects of endothelin-1 (ET-1), a potential SMC mitogen, on ROS production and proliferation of fetal pulmonary artery SMCs (FPASMCs). Exposure to ET-1 resulted in increases in superoxide production and viable FPASMCs after 72 h. These increases were prevented by pretreatment with PD-156707. Treatment with pertussis toxin blocked the effects of ET-1, whereas cholera toxin stimulated superoxide production and increased viable cell numbers even in the absence of ET-1. Wortmannin, LY-294002, diphenyleneiodonium (DPI), 4-(2-aminoethyl)benzenesulfonyl fluoride, and apocynin also prevented the ET-1-mediated increases in superoxide production and viable cell numbers. Exposure to H(2)O(2) or diethyldithiocarbamate increased viable cell number by 37% and 50%, respectively. Conversely, ascorbic acid and DPI decreased viable cell number, which appeared to be due to an increase in programmed cell death. Our data suggest that ET-1 exerts a mitogenic effect on FPASMCs via an increase in ROS production and that antioxidants can block this effect via induction of apoptosis. Antioxidant treatment may therefore represent a potential therapy for pulmonary vascular diseases.

Lung and heart-lung transplant practice patterns in pulmonary hypertension centers

BACKGROUND

Transplant practice patterns for pulmonary hypertension in the epoprostenol era are unknown.

METHODS

Thirty-five centers in North America, Europe, and Israel were surveyed regarding practice patterns for lung and heart-lung transplant.

RESULTS

New York Heart Association class and distance on a 6-minute walk were considered most useful for deciding who to refer for listing. Patients with New York Heart Association class I to II were referred for listing in 26% of centers, while 57% were classified as New York Heart Association class III or greater after epoprostenol failure. Twenty-nine of the 35 centers had transplant programs that performed approximately 75% of the International Registry volume annually. A double lung transplant was preferred by 83% of centers and heart-lung transplant in the remaining centers. The wait time for lung transplant averaged 16.8 months (range 4-36) and for heart-lung transplant averaged 21.3 months (range 6-36) and was significantly longer in the United States. The mean maximum age for heart-lung transplant was 51.4 years (range 35-65), double lung transplant 58.3 years (range 45-65), and single lung transplant 63.1 years (range 50-70). Fifty-three percent of centers transplant New York Heart Association class III or IV patients, 26% class IIIb-IV, and 21% only class IV. Eighty percent of centers use a transplant hold status. Major unqualified exclusions were hepatitis in 38%, 1 or more hepatic (90%) or renal (100%) criteria, smoking 97%, and obesity in 93%.

CONCLUSIONS

Physicians and patients should be aware of the considerable variability in practice patterns for transplantation in pulmonary hypertension, despite published guidelines.

Pulmonary function test abnormalities in pulmonary vascular disease and chronic heart failure

Diagnostic criteria based on pulmonary function testing for pulmonary vascular disease and CHF are imprecise. Although these tests constitute a necessary part of the work-up of a patient with dyspnea, additional studies are required to obtain a final diagnosis in the setting of cardiopulmonary vascular disease. In contrast, specific pulmonary function tests may offer an objective means of assessing severity of dysfunction resulting from pulmonary hypertension or CHE Serial measurements of pulmonary function offer insight into general and specific patterns of cardiopulmonary vascular disease and are useful in evaluating response to treatment.

Clinical exercise testing

Clinical exercise testing is increasingly being utilized in clinical practice because of the valuable, often unique information that it provides in patient diagnosis and management. This is also due to a growing awareness that resting cardiopulmonary measurements provide an unreliable estimate of functional capacity. A continuum of exercise testing modalities for functional evaluation from "low tech" to "high tech" will be discussed. These include the six minute walk test, shuttle walk test, exercise induced bronchoconstriction test, cardiac stress test, and cardiopulmonary exercise testing. The main focus of this article will be cardiopulmonary exercise testing including indications, important measurements, salient methodological considerations, and interpretation.