Updated treatment algorithm of pulmonary arterial hypertension

The demands on a pulmonary arterial hypertension (PAH) treatment algorithm are multiple and in some ways conflicting. The treatment algorithm usually includes different types of recommendations with varying degrees of scientific evidence. In addition, the algorithm is required to be comprehensive but not too complex, informative yet simple and straightforward. The type of information in the treatment algorithm are heterogeneous including clinical, hemodynamic, medical, interventional, pharmacological and regulatory recommendations. Stakeholders (or users) including physicians from various specialties and with variable expertise in PAH, nurses, patients and patients' associations, healthcare providers, regulatory agencies and industry are often interested in the PAH treatment algorithm for different reasons. These are the considerable challenges faced when proposing appropriate updates to the current evidence-based treatment algorithm.The current treatment algorithm may be divided into 3 main areas: 1) general measures, supportive therapy, referral strategy, acute vasoreactivity testing and chronic treatment with calcium channel blockers; 2) initial therapy with approved PAH drugs; and 3) clinical response to the initial therapy, combination therapy, balloon atrial septostomy, and lung transplantation. All three sections will be revisited highlighting information newly available in the past 5 years and proposing updates where appropriate. The European Society of Cardiology grades of recommendation and levels of evidence will be adopted to rank the proposed treatments.

Characterization of altered patterns of endothelial progenitor cells in sickle cell disease related pulmonary arterial hypertension

Endothelial dysfunction plays an important role in the pathogenesis of pulmonary arterial hypertension (PAH) in sickle cell disease (SCD). A variety of evidence suggests that circulating endothelial progenitor cells (EPCs) play an integral role in vascular repair. We hypothesized that SCD patients with PAH are deficient in EPCs, potentially contributing to endothelial dysfunction and disease progression. The number of circulating CD34+/CD14−/CD106+ EPCs was significantly lower in SCD patients with PAH than without PAH (P=0.025). CD34+/CD14−/CD106+ numbers significantly correlated with tricuspid regurgitation velocity (TRV, r=−0.44, P=0.033) 6-minute walk distance (6MWD, r= 0.72, P=0.001), mean pulmonary artery pressure (mPAP, r= −0.43, P=0.05), and pulmonary vascular resistance (PVR, r=−0.45, P=0.05). Other EPC subsets including CD31+/CD133+/CD146+ were similar between both groups. Numbers of EPCs did not correlate with age, sex, hemoglobin, WBC count, reticulocyte count, lactate dehydrogenase (LDH), iron/ferritin levels, and serum creatinine. These data indicate that subsets of EPC are lower in SCD patients with PAH than in those without PAH. Fewer EPCs in PAH patients may contribute to the pulmonary vascular pathology. Reduced number of EPCs in SCD patients with PAH might not only give potential insight into the pathophysiological mechanisms but also might be useful for identifying suitable therapeutic targets in these patients.

Associated pulmonary arterial hypertension in connective tissue diseases

In recent years, major advances have been achieved in the understanding of pulmonary arterial hypertension (PAH) patho-physiology. Associated pulmonary arterial hypertension (APAH) can occur in a variety of other conditions and circumstances including a number of systemic autoimmune diseases. As with PAH in general, clinical symptoms of APAH in systemic autoimmune diseases are unspecific. In addition, there is a long standing association between autoimmunity and APAH. It has been postulated that autoimmunity may play a role in the pathogenesis of APAH. This argument has been based on frequent coexisting clinical and serological rheumatic findings. There is no experimental model of immune mechanism-dependent severe APAH. The loss of self-tolerance could initiate a process which ultimately results in APAH. It is possible that T-cell deficiencies (in either function or number) may contribute to pulmonary vascular injury or disease. These conditions are often associated with autoantibodies as well as defects in the CD4 T-cell compartiment. However, it remains uncertain how autoimmune mechanisms contribute to the pathogenesis of APAH. There are data that show a significant association between APAH and connective tissue diseases (CTD). In this regard, systemic sclerosis, mixed connective tissue disease, systemic lupus erythematosus, dermato/polymyositis and primary Sjögren's syndrome are associated with APAH. The study of APAH in the systemic autoimmune diseases and its relation to basic immunologic disturbances may yet bring effective therapies in the future. APAH can be a severe complication attracting a high excess mortality in autoimmune diseases. The present review will focus on what is known about autoimmune phenomena in APAH patients.