Lung transplantation and atrial septostomy in pulmonary arterial hypertension

Assessment and treatment of the failing right heart: considerations for transplantation referral

Long considered an insignificant chamber, the right ventricle has been recently under spotlight, especially with emerging data supporting its critical role in disease progression. The right ventricle is a triangular heart chamber with complex physiology and pathophysiology. In this review, we discuss the normal physiology of the right ventricle, right ventricular failure, and recent advances in treatment with emphasis on optimal timing for transplantation referral.

A Focus on Macitentan in the Treatment of Pulmonary Arterial Hypertension

The approval of macitentan has increased the number of pharmacological treatments of pulmonary arterial hypertension (PAH). Here, we review the effect on PAH of macitentan compared to other endothelin receptor antagonists. Drugs targeting the endothelin (ET) pathway include the selective ET_A receptor antagonist ambrisentan, the ET_A /ET_B receptor antagonists, bosentan and macitentan, which were recently approved for PAH treatment. Macitentan exhibits higher antagonistic potency than bosentan and ambrisentan in pulmonary smooth muscle cells. Compared to ambrisentan and bosentan, macitentan has a longer duration of action, reflected by the longer half-life, as well as pharmacodynamics attributed to its active metabolite, ACT-132577. The efficacy of macitentan on PAH was investigated in the phase III SERAPHIN trial (NCT00660179). Macitentan significantly reduced morbidity and mortality. It improved the 6-min. walk distance (6MWD) among PAH patients. In the AMB-320/321-E (NCT00578786) study, ambrisentan improved exercise capacity. In the EARLY study (NCT00091715), bosentan showed improvements in 6MWD which were not statistically significant. Bosentan had an effect on PAH in patients with Eisenmenger syndrome (ES) in the BREATHE-5 study (NCT00367770), while macitentan did not improve 6MWD in these patients, but there are differences regarding study size and functional class, and that 30% of the patients treated with macitentan were already in treatment with a phosphodiesterase type 5 inhibitor. Macitentan revealed a lower risk of developing peripheral oedema and hepatotoxicity in the SERAPHIN study. In summary, macitentan has an efficiency comparable to bosentan and ambrisentan in the treatment of PAH. Patients treated with macitentan exhibited less adverse effects compared to bosentan and ambrisentan. In patients with PAH associated with ES, the trials with bosentan and macitentan do not seem comparable, and it needs to be clarified whether these drugs are effective when administered as part of a combination treatment in this condition.

Pulmonary Hypertension: Scientometric Analysis and Density-Equalizing Mapping

Pulmonary hypertension (PH) is characterized by the increase of the mean pulmonary arterial pressure in the lung circulation. Despite the large number of experimental and clinical studies conducted on pulmonary hypertension, there is no comprehensive work that analyzed the global research activity on PH so far. We retrieved the bibliometric data of the publications on pulmonary hypertension for two periods from the Web of science database. Here, we set the first investigation period from 1900 to 2007 (t1) due to the cited half life of articles and the relating difficulties to interpret the citation parameters. The second evaluation period (t2) covers the time interval from 2008 onwards including the year 2015. The data were analyzed and processed to density-equalizing maps using the NewQIS platform. A total number of 18,986 publications were identified in t1 that come from 85 countries. The US published the highest number of publications (n = 7,290), followed by the UK, Germany, Japan and France. In t2 19,676 items could be found worked out by 130 countries. The raking started just the same with the USA as most publishing nation with 7,127 publications on PH, followed by the UK and Germany. Japan fell back on 6^th place, whereas China came into view on the 5^th position. Analyzing the average citation rate as a parameter for research quality, Mexico reached the highest value in t1 and Ireland in t2. While, the country specific h-index underlined the leading position of the US research in both evaluation periods again. The average number of international collaboration items was expanding from none in 1978 to 530 items in 2015 with the USA as the country with the highest number of collaboration articles. The present study is the first large scale density-equalizing mapping and scientometric analysis of global PH research activity. Our data draw a sketch of the global research architecture in this field, indicating a need for specific research programs in countries with a lower human development index.

Pulmonary Thromboendarterectomy for Pulmonary Hypertension Before Considering Transplant

BACKGROUND

In cases of chronic thromboembolic pulmonary hypertension (CTEPH), referral for possible surgical intervention is important because surgery can be curative. Surgery necessitates cardiopulmonary bypass and deep circulatory arrest with pulmonary thrombectomy and bilateral endarterectomy (PTE). If surgery fails, lung transplant is the next best surgical option. Medical treatment is also an important adjunct.

CASE REPORT

A 35-year-old female presented 3 months after a pulmonary embolus was found to be completely occluding her left pulmonary artery. She was found to have pulmonary hypertension with a pulmonary artery pressure of 81/33 mmHg, with a mean pressure of 52 mmHg. The right atrial pressure was also severely elevated at 29 mmHg, and her echocardiogram revealed severe tricuspid regurgitation and severe right ventricular dysfunction. She underwent PTE and postoperatively was followed by the heart failure team. Her 6-minute walk distance improved from 396 meters at 1 month to 670 meters at 7 months, and her pulmonary artery pressure improved significantly to 55/17 mmHg with a mean pressure of 31 mmHg. The patient's right atrial pressure also improved significantly from 29 mmHg to 13 mmHg.

CONCLUSION

CTEPH is likely underrecognized, and patients with pulmonary hypertension or a history of pulmonary embolism should be screened for CTEPH. This case illustrates the surgical treatment for CTEPH and discusses alternative and adjunctive treatments. Residual pulmonary hypertension after PTE occurs in approximately 35% of patients. Overall, 4-year mortality rates after surgery appear to be approximately 15%, and mortality rates correlate with the postoperative pulmonary vascular resistance. Recognition of chronic pulmonary thromboembolic disease as the etiology of pulmonary hypertension warrants evaluation for surgery.