Right ventricular contractility in systemic sclerosis-associated and idiopathic pulmonary arterial hypertension

Exercise in Pulmonary Hypertension

In healthy subjects, exercise causes a complex cardiovascular and ventilatory response that allows for a 20-fold increase of oxygen consumption as compared to rest. In pulmonary hypertension (PH) this response is very much limited by a restriction of the maximum cardiac output (CO). This restriction is caused by a massively increased afterload of the right ventricle (RV) despite an adaptation that doubles right ventricular contractility as compared to normal controls.1

Pulmonary arterial hypertension in connective tissue diseases

Pulmonary arterial hypertension (PAH) may complicate diverse connective tissue diseases (CTDs). Approximately 10% of patients with systemic sclerosis develop PAH, the prevalence being much lower in other CTDs. However, PAH is an important contributor to morbidity and mortality in all forms of CTD. Despite similarities in presentation, hemodynamic perturbations, and pathogenesis, patients with CTD-associated PAH (CTD-PAH) usually have a poorer response to PAH-specific medications and poorer prognosis than patients with idiopathic PAH (IPAH). Select patients with CTD-PAH may be candidates for lung transplantation, but results are less favorable than for IPAH because of comorbidities and complications specifically associated with CTD.

Three-dimensional analysis of right ventricular shape and function in pulmonary hypertension

Right ventricular (RV) failure is a key determinant of morbidity and mortality in pulmonary hypertension (PH). The present study aims to add to existing descriptions of RV structural and functional changes in PH through a comprehensive three-dimensional (3D) shape analysis. We performed 3D echocardiography on 53 subjects with PH and 19 normal subjects. Twenty short-axis slices from apex to tricuspid centroid were measured to characterize regional shape: apical angle, basal bulge, eccentricity, and area. Transverse shortening was assessed by fractional area change (FAC) in each short-axis slice, longitudinal contraction was assessed by tricuspid annular plane systolic excursion (TAPSE) and global function by RV ejection fraction. Multivariate logistic analysis was used to compare the association of RV parameters with New York Heart Association (NYHA) class. Compared to normal, RV function in PH is characterized by decreased stroke volume index (SVi), fractional area change and ejection fraction. Increased eccentricity, apical rounding and bulging at the base characterize the shape of the RV in PH. Increased SVi, ejection fraction and mid-ventricular FAC were associated with less severe NYHA class in adjusted analyses. The RV in idiopathic PH (iPAH) was observed to have a larger end-diastolic volume and decreased function compared with connective tissue disease associated PH (ctd-PH). This work describes increased eccentricity and decreased systolic function in subjects with PH. Functional parameters were associated with NYHA class and heterogeneity in the phenotype was noted between subjects with iPAH and ctd-PH.

Pulmonary circulation at exercise

The pulmonary circulation is a high-flow and low-pressure circuit, with an average resistance of 1 mmHg/min/L in young adults, increasing to 2.5 mmHg/min/L over four to six decades of life. Pulmonary vascular mechanics at exercise are best described by distensible models. Exercise does not appear to affect the time constant of the pulmonary circulation or the longitudinal distribution of resistances. Very high flows are associated with high capillary pressures, up to a 20 to 25 mmHg threshold associated with interstitial lung edema and altered ventilation/perfusion relationships. Pulmonary artery pressures of 40 to 50 mmHg, which can be achieved at maximal exercise, may correspond to the extreme of tolerable right ventricular afterload. Distension of capillaries that decrease resistance may be of adaptative value during exercise, but this is limited by hypoxemia from altered diffusion/perfusion relationships. Exercise in hypoxia is associated with higher pulmonary vascular pressures and lower maximal cardiac output, with increased likelihood of right ventricular function limitation and altered gas exchange by interstitial lung edema. Pharmacological interventions aimed at the reduction of pulmonary vascular tone have little effect on pulmonary vascular pressure-flow relationships in normoxia, but may decrease resistance in hypoxia, unloading the right ventricle and thereby improving exercise capacity. Exercise in patients with pulmonary hypertension is associated with sharp increases in pulmonary artery pressure and a right ventricular limitation of aerobic capacity. Exercise stress testing to determine multipoint pulmonary vascular pressures-flow relationships may uncover early stage pulmonary vascular disease.

Tricuspid annular plane systolic excursion is a robust outcome measure in systemic sclerosis-associated pulmonary arterial hypertension

OBJECTIVE

The tricuspid annular plane systolic excursion (TAPSE) strongly reflects right ventricular (RV) function and predicts survival in idiopathic pulmonary arterial hypertension (PAH). But its role in systemic sclerosis (SSc)-associated PAH has not been established. Our objective was to validate the TAPSE in the assessment of RV function and prediction of survival in SSc-PAH.

METHODS

Fifty consecutive patients with SSc-PAH who underwent echocardiography with TAPSE measurement within 1 h of clinically indicated right heart catheterization were followed prospectively. The relationship between TAPSE and measures of RV function and measures of survival was assessed.

RESULTS

The majority of the cohort were women in New York Heart Association class III/IV with severe PAH (mean cardiac index 2.4 ± 0.8 l/min/m(2)). RV function was significantly impaired (mean cardiac index 2.1 ± 0.7 vs 2.9 ± 0.8 l/min/m(2); p < 0.01) and RV afterload was significantly greater (mean pulmonary vascular resistance 11.1 ± 5.1 vs 5.8 ± 2.5 Wood units; p < 0.01) in subjects with a TAPSE ≤ 1.7 cm. The proportion surviving in the low TAPSE group was significantly lower [0.56 (95% CI 0.37-0.71) and 0.46 (95% CI 0.28-0.62) vs 0.87 (95% CI 0.55-0.96) and 0.79 (95% CI 0.49-0.93), 1- and 2-year survival, respectively]. TAPSE ≤ 1.7 cm conferred a nearly 4-fold increased risk of death (HR 3.81, 95% CI 1.31-11.1, p < 0.01).

CONCLUSION

TAPSE is a robust measure of RV function and strongly predicts survival in patients with PAH-SSc. Future studies are needed to identify the responsiveness of TAPSE to PAH-specific therapy and to assess its diagnostic utility in PAH-SSc.

Cardiac complications of systemic sclerosis: recent progress in diagnosis

PURPOSE OF REVIEW

Systemic sclerosis (SSc), a collagen vascular disease characterized by diverse organ system involvement, is associated with serious cardiac complications. Cardiac symptoms are much less frequent than autopsy-demonstrated cardiac involvement. Although frequent calls for early diagnosis have been made, validated strategies for assessment of scleroderma cardiac disease are not yet well established, mainly because the right ventricle, a common target of the disease, presents considerable obstacles to simple and reliable appraisal of its structure and function. This article reviews the current information about cardiac dysfunction in scleroderma, with special emphasis on its detection and prognostic implications.

RECENT FINDINGS

Cardiac involvement is a harbinger of poor prognosis in patients with SSc. Recent progress in its diagnosis has been made with the availability of more sophisticated diagnostic tools.

SUMMARY

Early detection of scleroderma heart disease will allow exploration of novel therapies with potential positive impact on the quality of life and life expectancy of this patient population.

Platelet-derived growth factor receptor-β and epidermal growth factor receptor in pulmonary vasculature of systemic sclerosis-associated pulmonary arterial hypertension versus idiopathic pulmonary arterial hypertension and pulmonary veno-occlusive disease: a case-control study

Introduction

Systemic sclerosis (SSc) complicated by pulmonary arterial hypertension (PAH) carries a poor prognosis, despite pulmonary vascular dilating therapy. Platelet-derived growth factor receptor-β (PDGFR-β) and epidermal growth factor receptor (EGFR) are potential therapeutic targets for PAH because of their proliferative effects on vessel remodelling. To explore their role in SScPAH, we compared PDGFR- and EGFR-mmunoreactivity in lung tissue specimens from SScPAH. We compared staining patterns with idiopathic PAH (IPAH) and pulmonary veno-occlusive disease (PVOD), as SScPAH vasculopathy differs from IPAH and sometimes displays features of PVOD. Immunoreactivity patterns of phosphorylated PDGFR-β (pPDGFR-β) and the ligand PDGF-B were evaluated to provide more insight into the patterns of PDGFR-b activation.

Methods

Lung tissue specimens from five SScPAH, nine IPAH, six PVOD patients and five controls were examined. Immunoreactivity was scored for presence, distribution and intensity.

Results

All SScPAH and three of nine IPAH cases (P = 0.03) showed PDGFR-β-immunoreactivity in small vessels (arterioles/venules); of five SScPAH vs. two of nine IPAH cases (P = 0.02) showed venous immunoreactivity. In small vessels, intensity was stronger in SScPAH vs. IPAH. No differences were found between SScPAH and PVOD. One of five normal controls demonstrated focally mild immunoreactivity. There were no differences in PDGF-ligand and pPDGFR-b-immunoreactivity between patient groups; however, pPDGFR-b-immunoreactivity tended to be more prevalent in SScPAH small vasculature compared to IPAH. Vascular EGFR-immunoreactivity was limited to arterial and arteriolar walls, without differences between groups. No immunoreactivity was observed in vasculature of normals.

Conclusions

PDGFR-β-immunoreactivity in SScPAH is more common and intense in small- and post-capillary vessels than in IPAH and does not differ from PVOD, fitting in with histomorphological distribution of vasculopathy. PDGFR-β immunoreactivity pattern is not paralleled by pPDGFR-β or PDGF-B patterns. PDGFR-β- and EGFR-immunoreactivity of pulmonary vessels distinguishes PAH patients from controls.

Pulmonary arterial hypertension associated with systemic sclerosis

Systemic sclerosis (SSc) is commonly complicated by pulmonary arterial hypertension (PAH), which is a leading cause of death in the SSc patient population. Owing to the fact that the risk of developing pulmonary hypertension is high, screening is important, although the optimal modality remains to be defined. Furthermore, despite recent advances in therapy for PAH, the response to these interventions in patients with PAH with SSc has been discouraging. The lack of clinical response to these therapies may merely reflect the limitations of traditionally employed PAH outcome measures in SSc-PAH patients or highlight the heterogeneity of the disease manifestations within SSc. Importantly, since extrapulmonary involvement of the GI tract and kidneys by SSc limit candidacy for lung transplantation, new therapies that target abnormal cellular proliferation in the pulmonary vasculature are currently under investigation and may be particularly relevant to SSc-PAH.

Lung involvement in systemic sclerosis

Scleroderma is a multisystem disease characterized by a severe inflammatory process and exuberant fibrosis. Lung involvement is a frequent complication and a leading cause of morbidity and mortality in this syndrome. Two major pulmonary syndromes are associated with scleroderma; a pulmonary vascular disorder evolving over time into relatively isolated pulmonary arterial hypertension (PAH), and interstitial lung disease (ILD). Each syndrome, when present, is a cause of morbidity and significantly reduces survival of scleroderma patients when compared to patients free of lung complication. When pulmonary hypertension and ILD are combined, survival is further reduced. Current therapy appears to have no meaningful effect on either condition and, thus, there is a need for better understanding of underlying pathogenic mechanisms. This review focuses on clinical, diagnostic, and therapeutic features of PAH and ILD as well as other frequent but less debilitating lung complications of scleroderma.

Pulmonary hypertension in systemic sclerosis

OBJECTIVES

To discuss the clinical subtypes, pathogenesis, pathology, diagnostic evaluation, treatment options, and prognosis of pulmonary hypertension in systemic sclerosis (SSc-PH) and highlight its fundamental differences from idiopathic pulmonary arterial hypertension (IPAH).

METHODS

A Medline search for articles published between January 1969 and June 2010 was conducted using the following keywords: scleroderma, systemic sclerosis, pulmonary hypertension, pulmonary arterial hypertension, pulmonary veno-occlusive disease, pathogenesis, pathology, investigation, treatment, and prognosis. The essential differences from IPAH in pathogenesis and histopathologic findings were highlighted and the limitations of some of the investigations used were emphasized. The differences in response to currently accepted therapy and prognosis were also reviewed.

RESULTS

In scleroderma, pulmonary hypertension can be present in isolation or along with interstitial lung disease and left heart disease. In SSc-PH, the unique histopathologic findings in the lungs include intimal fibrosis, absence of plexiform lesions, and a high prevalence of pulmonary veno-occlusive disease-like lesions. Both "6-minute walk test" and NT-proBNP have their limitations in the evaluation of SSc-PH. For treatment, calcium channel blockers are ineffective and anticoagulation should be used with caution. Currently approved therapies are not as effective and prognosis is much worse in SSc-PH compared with IPAH.

CONCLUSIONS

SSc-PH is a complex condition with poorer response to therapy and worse outcome compared with that of IPAH. Recent findings have shed some light about the pathophysiology and pathogenesis of SSc-PH. Further research in this area is warranted to better understand the complex pathogenesis and devise better therapeutic strategies.

Characteristics of interstitial fibrosis and inflammatory cell infiltration in right ventricles of systemic sclerosis-associated pulmonary arterial hypertension

Objective. Systemic sclerosis-associated pulmonary arterial hypertension (SScPAH) has a disturbed function of the right ventricle (RV) when compared to idiopathic PAH (IPAH). Systemic sclerosis may also affect the heart. We hypothesize that RV differences may occur at the level of interstitial inflammation and-fibrosis and compared inflammatory cell infiltrate and fibrosis between the RV of SScPAH, IPAH, and healthy controls. Methods. Paraffin-embedded tissue samples of RV and left ventricle (LV) from SScPAH (n = 5) and IPAH (n = 9) patients and controls (n = 4) were picrosirius red stained for detection of interstitial fibrosis, which was quantified semiautomatically. Neutrophilic granulocytes (MPO), macrophages (CD68), and lymphocytes (CD45) were immunohistochemically stained and only interstitial leukocytes were counted. Presence of epi- or endocardial inflammation, and of perivascular or intimal fibrosis of coronary arteries was assessed semiquantitatively (0-3: absent to extensive). Results. RV's of SScPAH showed significantly more inflammatory cells than of IPAH (cells/mm(2), mean ± sd MPO 11 ± 3 versus 6 ± 1; CD68 11 ± 3 versus 6 ± 1; CD45 11 ± 1 versus 5 ± 1 , P < .05) and than of controls. RV interstitial fibrosis was similar in SScPAH and IPAH (4 ± 1 versus 5 ± 1%, P = .9), and did not differ from controls (5 ± 1%, P = .8). In 4 SScPAH and 5 IPAH RV's foci of replacement fibrosis were found. No differences were found on epi- or endocardial inflammation or on perivascular or intimal fibrosis of coronary arteries. Conclusion. SScPAH RVs display denser inflammatory infiltrates than IPAH, while they do not differ with respect to interstitial fibrosis. Whether increased inflammatory status is a contributor to altered RV function in SScPAH warrants further research.

Hemodynamic predictors of survival in scleroderma-related pulmonary arterial hypertension

RATIONALE

Pulmonary arterial hypertension (PAH) related to systemic sclerosis (SSc) has a poorer prognosis compared with other forms of PAH for reasons that remain unexplained.

OBJECTIVES

To identify risk factors of mortality in a well-characterized cohort of patients with PAH related to systemic sclerosis (SSc-PAH).

METHODS

Seventy-six consecutive patients with SSc (64 women and 12 men; mean age 61 +/- 11 yr) were diagnosed with PAH by heart catheterization in a single center, starting in January 2000, and followed over time. Kaplan-Meier estimates were calculated and mortality risk factors were analyzed.

MEASUREMENTS AND MAIN RESULTS

Forty (53%) patients were in World Health Organization functional class III or IV. Mean pulmonary artery pressure was 41 +/- 11 mm Hg, pulmonary vascular resistance (PVR) was 8.6 +/- 5.6 Wood units, and cardiac index was 2.4 +/- 0.7 L/min/m(2). Median follow-up time was 36 months, with 42 deaths observed. Survival estimates were 85%, 72%, 67%, 50%, and 36% at 1, 2, 3, 4, and 5 years, respectively. Multivariate analysis identified PVR (hazard ratio [HR], 1.10; 95% confidence interval [CI], 1.03-1.18; P < 0.01), stroke volume index (HR, 0.94; 95% CI, 0.89-0.99; P = 0.02), and pulmonary arterial capacitance (HR, 0.43; 95% CI, 0.20-0.91; P = 0.03) as strong predictors of survival. An estimated glomerular filtration rate less than 60 ml/min/1.73 m(2) portended a threefold risk of mortality.

CONCLUSIONS

Our results suggest that specific components of right ventricular dysfunction and renal impairment contribute to increased mortality in SSc-PAH. Understanding the mechanisms of right ventricular dysfunction in response to increased afterload should lead to improved targeted therapy in these patients.

Systemic sclerosis-associated pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a devastating vascular complication of a number of connective tissue diseases, including systemic sclerosis (SSc), where it has a dramatic impact on the clinical course and overall survival and is the single most common cause of death in patients afflicted with this syndrome. Although remarkable advances have been achieved in elucidating the pathogenesis of PAH over the past 2 decades, leading to the development of disease-targeted therapies for the idiopathic form of this condition (IPAH), the response to therapy is suboptimal in SSc-related PAH (SSc-PAH), and survival remains very poor. Factors accounting for striking clinical and prognostic differences between these two syndromes are unclear but may include a more pronounced autoimmune, cellular, and inflammatory response, and a higher prevalence of comorbidities in SSc-PAH, including cardiac and pulmonary venous and parenchymal involvement. Furthermore, currently available markers of disease severity and clinical tools to assess response to therapy, which may be reliable in IPAH, are either limited or lacking in SSc-PAH. Thus, a more focused approach, including a better understanding of the pathogenesis and genetic factors underlying the development of SSc-PAH, a search for more specific and reliable tools to adequately assess functional impairment and monitor therapy, as well as the design of novel targeted therapies, are all urgently required to alter the dismal course of this syndrome.

Right ventricular function in scleroderma-related pulmonary hypertension

SSc-associated pulmonary arterial hypertension (PAH) has a poorer prognosis than that of other types of pulmonary hypertension. Recent echocardiographic and haemodynamic studies suggest that right ventriculer (RV) pump function and filling characteristics are altered in SSc-PAH as compared with idiopathic PAH. This could be explained by intrinsic myocardial involvement of the disease, related to abnormal collagen deposition, also observed in the left ventricle, or an increased vulnerability to ischaemia due to coronary vasculopathy, abnormal collagen cross-linking and altered myocyte function. It is also possible that a relatively more important decrease in pulmonary arterial compliance as evidenced by recently reported increased characteristic impedance measurements, would contribute to RV-arterial decoupling. More pathological, imaging and haemodynamic studies are needed for a better understanding for relatively more important vulnerability of the RV in SSc-PAH.

Determinants of right ventricular ejection fraction in pulmonary arterial hypertension

BACKGROUND

Right ventricular function is a key determinant of exercise capacity and survival in pulmonary arterial hypertension (PAH). We aimed to study the predictors of right ventricular ejection fraction (RVEF) in patients with newly diagnosed PAH.

METHODS

We performed a cross-sectional analysis of a retrospective cohort of consecutive patients with idiopathic, familial, or anorexigen-associated PAH who underwent equilibrium radionuclide angiography for measurement of RVEF at baseline.

RESULTS

Of the 84 patients in the cohort, 63 underwent equilibrium radionuclide angiography and right heart catheterization and were included. The mean age was 41 +/- 13 years, and 79% of the patients were female. The mean RVEF was 30 +/- 8%. RVEF was directly associated with right ventricular stroke volume index and cardiac index, and inversely associated with pulmonary vascular resistance index from right heart catheterization (all p < 0.001). Older age and male sex were associated with lower RVEF (p < 0.05) after adjustment for pulmonary vascular resistance index and left ventricular ejection fraction. Higher plasma von Willebrand factor levels were also independently associated with lower RVEF (p = 0.01) (n = 55). Body size and type of PAH were not associated with RVEF.

CONCLUSIONS

Older patients and males with PAH had lower RVEF at baseline than younger patients and females, even after controlling for left ventricular function and hemodynamics. Higher plasma von Willebrand factor levels, a marker of endothelial dysfunction, were also associated with lower RVEF.