Pulmonary arterial hypertension in adults: novel drugs and catheter ablation techniques show promise? Systematic review on pharmacotherapy and interventional strategies

MicroRNA and lncRNA as the Future of Pulmonary Arterial Hypertension Treatment

Pulmonary hypertension (PH) is characterized by a progressive increase in pulmonary arterial pressure and pulmonary vascular resistance. In a short time, it leads to right ventricular failure and, consequently, to death. The most common causes of PH include left heart disease and lung disease. Despite the significant development of medicine and related sciences observed in recent years, we still suffer from a lack of effective treatment that would significantly influence the prognosis and prolong life expectancy of patients with PH. One type of PH is pulmonary arterial hypertension (PAH). The pathophysiology of PAH is based on increased cell proliferation and resistance to apoptosis in the small pulmonary arteries, leading to pulmonary vascular remodeling. However, studies conducted in recent years have shown that epigenetic changes may also lie behind the pathogenesis of PAH. Epigenetics is the study of changes in gene expression that are not related to changes in the sequence of nucleotides in DNA. In addition to DNA methylation or histone modification, epigenetic research focuses on non-coding RNAs, which include microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Preliminary research results give hope that targeting epigenetic regulators may lead to new, potential therapeutic possibilities in the treatment of PAH.

Transcatheter interventions in refractory pulmonary artery hypertension and pulmonary embolism

Pulmonary artery hypertension causes remodeling of distal pulmonary arterial vasculature leading to increased resistance of the pulmonary arterial system, right ventricular dysfunction, and sudden cardiac death. The diagnosis of pulmonary arterial hypertension (PAH) diagnosis is made when mean pulmonary artery pressure during catheterization is ≥25 mmHg at rest, pulmonary vascular resistance (PVR) more than 3 wood units, a pulmonary capillary wedge pressure of <15 mmHg. One year survival rate is 86.3% and 5 year survival rate in PAH is 61.2%, and only 7 years of median survival. Although several breakthrough advances are made in the medical management for PAH, there are some patients who do not respond to medications and continue to detoriate despite optimal medical therapy. The non-responders to medical management are those patients whose right atrial pressure is >20 mmHg or cardiac index is <2.0 L/min/m2, which are pointers of poor prognosis. For medical refractory patients invasive procedures such as atrial septostomy, Potts shunt, and pulmonary artery denervation are a therapeutic or palliative strategy in the treatment of pulmonary artery hypertension and serve as a bridge before surgery and heart lung transplantation.

[Pulmonary artery denervation in pulmonary hypertension: physiological and clinical aspects]

This article is a review of the findings of experimental and clinical studies of a new method of treatment of pulmonary hypertension - pulmonary artery denervation with the help of radiofrequency ablation, cryodenervation and ultrasonic impact. Pulmonary artery denervation results in decreased neurogenic tonic sympathetic and, probably, increased parasympathetic effects on pulmonary vessels. On models of experimental monocrotaline-induced pulmonary hypertension in various-species animals, it was determined that pulmonary artery denervation is followed by decreased activity of local pulmonary renin-angiotensin system, slowed processes of remodeling of pulmonary vessels, hypertrophy and fibrosis of the right ventricle, with inhibition of progression of pulmonary hypertension by means of suppression of extracellular signal-regulated kinase 1/2 (ERK 1/2) which regulates differentiation, proliferation and migration of smooth muscle cells. However, the problem of the pattern of pulmonary microcirculation changes (pre- and postcapillary resistance, capillary filtration coefficient) after pulmonary artery denervation warrants further study. The findings of clinical studies in patients with pulmonary hypertension suggest that pulmonary artery denervation inducing a decrease of pressure therein, as well as pulmonary vessel resistance did not lead to normalization of pulmonary haemodynamics.The mentioned impact partially removes the neurogenic component of multicircuit and multifactorial regulation of pulmonary circulation. Therefore, along with pulmonary artery denervation, further search for pharmacological agents selectively influencing pulmonary vessels remains a problem of current importance.

Salvianolic acid A attenuates vascular remodeling in a pulmonary arterial hypertension rat model

AIM

The current therapeutic approaches have a limited effect on the dysregulated pulmonary vascular remodeling, which is characteristic of pulmonary arterial hypertension (PAH). In this study we examined whether salvianolic acid A (SAA) extracted from the traditional Chinese medicine 'Dan Shen' attenuated vascular remodeling in a PAH rat model, and elucidated the underlying mechanisms.

METHODS

PAH was induced in rats by injecting a single dose of monocrotaline (MCT 60 mg/kg, sc). The rats were orally treated with either SAA (0.3, 1, 3 mg·kg(-1)·d(-1)) or a positive control bosentan (30 mg·kg(-1)·d(-1)) for 4 weeks. Echocardiography and hemodynamic measurements were performed on d 28. Then the hearts and lungs were harvested, the organ indices and pulmonary artery wall thickness were calculated, and biochemical and histochemical analysis were conducted. The levels of apoptotic and signaling proteins in the lungs were measured using immunoblotting.

RESULTS

Treatment with SAA or bosentan effectively ameliorated MCT-induced pulmonary artery remodeling, pulmonary hemodynamic abnormalities and the subsequent increases of right ventricular systolic pressure (RVSP). Furthermore, the treatments significantly attenuated MCT-induced hypertrophic damage of myocardium, parenchymal injury and collagen deposition in the lungs. Moreover, the treatments attenuated MCT-induced apoptosis and fibrosis in the lungs. The treatments partially restored MCT-induced reductions of bone morphogenetic protein type II receptor (BMPRII) and phosphorylated Smad1/5 in the lungs.

CONCLUSION

SAA ameliorates the pulmonary arterial remodeling in MCT-induced PAH rats most likely via activating the BMPRII-Smad pathway and inhibiting apoptosis. Thus, SAA may have therapeutic potential for the patients at high risk of PAH.

The Characteristics of Treated Pulmonary Arterial Hypertension Patients in Ontario

Background. There are no Canadian prevalence studies on pulmonary arterial hypertension (PAH) to date. We described the characteristics of treated PAH patients and the healthcare utilization and costs associated with PAH in a population of public drug plan beneficiaries in Ontario, Canada. Methods. A retrospective cross-sectional analysis was conducted between April 2010 and March 2011 to identify treated PAH patients using population-based health administrative databases. We investigated demographic and clinical characteristics of treated PAH patients and conducted a cohort study to determine treatment patterns, healthcare utilization, and associated costs, over a one-year follow-up period (March 2012). Results. We identified 326 treated PAH cases in Ontario's publicly funded drug plan. Overall mean age was 59.4 years (±20.3 years) and over 77% of cases were women (n = 251). Combination therapy was used to treat 22.9% (n = 69) of cases, costing an average of $4,569 (SD $1,544) per month. Median monthly healthcare costs were $264 (IQR $96-$747) for those who survived and $2,021 (IQR $993-$6,399) for those who died over a one-year period, respectively (p < 0.01). Conclusions. PAH care in Ontario is complex and has high healthcare costs. This data may help guide towards improved patient management.

New Therapeutic Paradigms and Guidelines in the Management of Pulmonary Arterial Hypertension

BACKGROUND

Recent and ongoing developments in the diagnosis, treatment, and management of pulmonary arterial hypertension (PAH) provide deeper insights into pathogenic mechanisms. Approvals of new pharmacotherapies that improve function and reduce morbidity and mortality risks; advances in clinical trial methods, including long-term, event-driven studies with clinically relevant and patient-centered endpoints; and trial results support a new therapeutic management strategy. This new paradigm involves initial treatment with combined therapies that act through different disease pathways. In addition, 2 new sets of clinical practice guidelines for PAH have been published since June 2014. Despite these advances, major gaps have been documented in the diagnosis, treatment, and management of patients with PAH.

OBJECTIVE

To present current knowledge and evidence on PAH to support managed care professionals and providers in achieving accurate differential diagnosis, promptly referring patients to specialists as necessary, and ensuring that patients receive appropriate, guideline-directed therapies.

SUMMARY

Major gaps in the quality of care provided to patients with PAH include oversights in clinicians' recognition of symptoms, delays in diagnosis, and misdiagnosis ensuing from incomplete evaluations, delays in referral of patients to centers of expertise and initiation of therapy, and inappropriate treatment regimens. To address deficiencies in PAH diagnosis, new practice guidelines emphasize the essential role of right heart catheterization in characterizing and confirming the disease, as well as referral to expert pulmonary hypertension centers to ensure appropriate evaluation and treatment. Updated disease and functional classifications of PAH, along with new research findings on prognostic factors and effects of comorbid conditions, offer key support for making effective therapy and management decisions for patients with PAH at different risk levels and stages of the disease. Since 2013, the U.S. Food and Drug Administration has approved new PAH therapies in the classes of endothelin receptor antagonists, guanylate cyclase stimulators, prostacyclin analogues, and prostacyclin receptor agonists. As demonstrated through phase 3 clinical trials, these generally well-tolerated therapies delay disease progression, improve hemodynamic and functional status, and decrease numbers of hospitalizations. Moreover, 2 sets of recently published guidelines-developed by the American College of Chest Physicians and the European Society of Cardiology/European Respiratory Society-provide evidence-based and expert consensus recommendations for achieving PAH treatment goals. The most recent guidelines include a recommendation for upfront combination therapy for patients with moderate disease, which is supported by new comparative clinical trial evidence. As addressed in this article, these advances in the field of PAH have important implications for managed care and clinical practice, including considerations of cost-benefit outcomes associated with different management strategies.

Epigenetic modulation as a therapeutic approach for pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a rare but progressive and currently incurable disease, which is characterized by vascular remodeling in association with muscularization of the arterioles, medial thickening and plexiform lesion formation. Despite our advanced understanding of the pathogenesis of PAH and the recent therapeutic advances, PAH still remains a fatal disease. In addition, the susceptibility to PAH has not yet been adequately explained. Much evidence points to the involvement of epigenetic changes in the pathogenesis of a number of human diseases including cancer, peripheral hypertension and asthma. The knowledge gained from the epigenetic study of various human diseases can also be applied to PAH. Thus, the pursuit of novel therapeutic targets via understanding the epigenetic alterations involved in the pathogenesis of PAH, such as DNA methylation, histone modification and microRNA, might be an attractive therapeutic avenue for the development of a novel and more effective treatment. This review provides a general overview of the current advances in epigenetics associated with PAH, and discusses the potential for improved treatment through understanding the role of epigenetics in the development of PAH.

Activation of renin-angiotensin-aldosterone system (RAAS) in the lung of smoking-induced pulmonary arterial hypertension (PAH) rats

Objectives:

To explore the role of the renin–angiotensin–aldosterone system (RAAS) in the pathogenesis of pulmonary arterial hypertension (PAH) induced by chronic exposure to cigarette smoke.

Methods:

48 healthy male SD rats were randomly divided into four groups (12/group): control group (group A); inhibitor alone group (group B); cigarette induction group (group C); cigarette induction + inhibitor group (group D). After the establishment of smoking-induced PAH rat model, the right ventricular systolic pressure (RVSP) was detected using an inserted catheter; western blotting was used to detect the protein expression of angiotensin-converting enzyme-2 (ACE2) and angiotensin-converting enzyme (ACE); expression levels of angiotensin II (AngII) in lung tissue were measured by radioimmunoassay.

Results:

After six months of cigarette exposure, the RVSP of chronic cigarette induction group was significantly higher than that of the control group; expression levels of AngII and ACE increased in lung tissues, but ACE2 expression levels reduced. Compared with cigarette exposure group, after losartan treatment, RVSP, ACE and AngII obviously decreased (P<0.05), and ACE2 expression levels significantly increased.

Conclusion:

Chronic cigarette exposure may result in PAH and affect the protein expression of ACE2 and ACE in lung tissue, suggesting that ACE2 and ACE play an important role in the pathogenesis of smoking-induced PAH.

WITHDRAWN: The future of lung transplantation

This article has been withdrawn for editorial reasons because the journal will be published only in English. In order to avoid duplicated records, this article can be found at http://dx.doi.org/10.1016/j.rppnen.2014.09.006. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy.