Nocturnal hypercapnia with daytime normocapnia in patients with advanced pulmonary arterial hypertension awaiting lung transplantation

BACKGROUND

Pulmonary arterial hypertension (PAH) is frequently complicated by sleep disordered breathing (SDB), and previous studies have largely focused on hypoxemic SDB. Even though nocturnal hypercapnia was shown to exacerbate pulmonary hypertension, the clinical significance of nocturnal hypercapnia among PAH patients has been scarcely investigated.

METHOD

Seventeen patients with PAH were identified from 246 consecutive patients referred to Kyoto University Hospital for the evaluation of lung transplant registration from January 2010 to December 2017. Included in this study were 13 patients whose nocturnal transcutaneous carbon dioxide partial pressure (PtcCO2) monitoring data were available. Nocturnal hypercapnia was diagnosed according to the guidelines of the American Academy of Sleep Medicine. Associations of nocturnal PtcCO2 measurements with clinical features, the findings of right heart catheterization and pulmonary function parameters were evaluated.

RESULTS

Nocturnal hypercapnia was diagnosed in six patients (46.2%), while no patient had daytime hypercapnia. Of note, nocturnal hypercapnia was found for 5 out of 6 patients with idiopathic PAH (83.3%). Mean nocturnal PtcCO2 levels correlated negatively with the percentage of predicted total lung capacity (TLC), and positively with cardiac output and cardiac index.

CONCLUSION

Nocturnal hypercapnia was prevalent among advanced PAH patients who were waiting for lung transplantation, and associated with %TLC. Nocturnal hypercapnia was associated with the increase in cardiac output, which might potentially worsen pulmonary hypertension especially during sleep. Further studies are needed to investigate hemodynamics during sleep and to clarify whether nocturnal hypercapnia can be a therapeutic target for PAH patients.

Extensive pulmonary sarcoid reaction in a patient with BMPR-2 associated idiopathic pulmonary arterial hypertension

Pulmonary arterial hypertension is a progressive life-threatening disease characterized by vascular remodeling. There is evidence that varied immune mechanism play an important role in progression of pulmonary hypertension.  We describe a case of a 35-year-old woman with idiopathic pulmonary arterial hypertension (IPAH) and a novel BMPR2 mutation, who underwent a successful lung transplantation.  Extensive granulomatous inflammation was seen in the resected lungs. The granulomatous inflammation found in the histology supports  a sarcoid-like reaction due to pulmonary hypertension in the context of the BMPR2 mutation.

BMPR2 mutations and survival in pulmonary arterial hypertension: an individual participant data meta-analysis

BACKGROUND

Mutations in the gene encoding the bone morphogenetic protein receptor type II (BMPR2) are the commonest genetic cause of pulmonary arterial hypertension (PAH). However, the effect of BMPR2 mutations on clinical phenotype and outcomes remains uncertain.

METHODS

We analysed individual participant data of 1550 patients with idiopathic, heritable, and anorexigen-associated PAH from eight cohorts that had been systematically tested for BMPR2 mutations. The primary outcome was the composite of death or lung transplantation. All-cause mortality was the secondary outcome. Hazard ratios (HRs) for death or transplantation and all-cause mortality associated with the presence of BMPR2 mutation were calculated using Cox proportional hazards models stratified by cohort.

FINDINGS

Overall, 448 (29%) of 1550 patients had a BMPR2 mutation. Mutation carriers were younger at diagnosis (mean age 35·4 [SD 14·8] vs 42·0 [17·8] years), had a higher mean pulmonary artery pressure (60·5 [13·8] vs 56·4 [15·3] mm Hg) and pulmonary vascular resistance (16·6 [8·3] vs 12·9 [8·3] Wood units), and lower cardiac index (2·11 [0·69] vs 2·51 [0·92] L/min per m(2); all p<0·0001). Patients with BMPR2 mutations were less likely to respond to acute vasodilator testing (3% [10 of 380] vs 16% [147 of 907]; p<0·0001). Among the 1164 individuals with available survival data, age-adjusted and sex-adjusted HRs comparing BMPR2 mutation carriers with non-carriers were 1·42 (95% CI 1·15-1·75; p=0·0011) for the composite of death or lung transplantation and 1·27 (1·00-1·60; p=0·046) for all-cause mortality. These HRs were attenuated after adjustment for potential mediators including pulmonary vascular resistance, cardiac index, and vasoreactivity. HRs for death or transplantation and all-cause mortality associated with BMPR2 mutation were similar in men and women, but higher in patients with a younger age at diagnosis (p=0·0030 for death or transplantation, p=0·011 for all-cause mortality).

INTERPRETATION

Patients with PAH and BMPR2 mutations present at a younger age with more severe disease, and are at increased risk of death, and death or transplantation, compared with those without BMPR2 mutations.

FUNDING

Cambridge NIHR Biomedical Research Centre, Medical Research Council, British Heart Foundation, Assistance Publique-Hôpitaux de Paris, INSERM, Université Paris-Sud, Intermountain Research and Medical Foundation, Vanderbilt University, National Center for Advancing Translational Sciences, National Institutes of Health, National Natural Science Foundation of China, and Beijing Natural Science Foundation.

[Short-term efficacy of atrial septostomy in the treatment of idiopathic pulmonary arterial hypertension patients complicating with right heart failure]

OBJECTIVE

To evaluate the efficacy of atrial septostomy in idiopathic pulmonary arterial hypertension (IPAH) patients complicating right ventricular failure.

METHODS

This retrospective analysis included 5 IPAH patients (3 males, (29.3±15.2) years old) with right ventricular failure which were refractory to conventional and target-specific medication in Shanghai Chest Hospital from March to July 2014. Graded balloon dilation septostomy procedures were performed in all 5 patients.

RESULTS

Successful atrial septostomy was achieved in 5 attempts with no procedure-related complications. Immediately post procedure, the mean systemic oxygen saturation decreased from (98.0±1.8)% to (86.4±3.2)% (P = 0.002), while the mean right atrial pressure decreased from (18.9±1.7) mmHg (1 mmHg = 0.133 kPa) to (16.0±1.3) mmHg (P = 0.039) and the mean cardiac index increased from (2.1±0.3) L · min(-1) · m(-2) to (2.7±0.5) L · min(-1) · m(-2) (P = 0.029). Mean follow-up was (6.2 ±1.8) months. Cardiac functional class (WHO) was 3 in 3 patients and 4 in 2 patients before the procedure, and increased 1 class in all patients during follow-up (P = 0.062). Exercise endurance (6-min walk test) also improved from (289.2±16.9) m to (320.4±19.6) m (P = 0.019), while B-type natriuretic peptide (BNP) level declined from (550.0±35.7) ng/L to (218.0±36.2) ng/L (P < 0.001). Except one patient developed spontaneous closure of created defect, right to left shunt at atrial septal level was evidenced by echocardiography during follow-up in the rest 4 patients.

CONCLUSIONS

Atrial septostomy is safe and can improve hemodynamics and heart function in selected IPAH patients with right heart failure. Atrial septostomy can be used as a palliative treatment for IPAH and further study is warranted to evaluate the long-term efficacy of this procedure.

O-linked β-N-acetylglucosamine transferase directs cell proliferation in idiopathic pulmonary arterial hypertension

BACKGROUND

Idiopathic pulmonary arterial hypertension (IPAH) is a cardiopulmonary disease characterized by cellular proliferation and vascular remodeling. A more recently recognized characteristic of the disease is the dysregulation of glucose metabolism. The primary link between altered glucose metabolism and cell proliferation in IPAH has not been elucidated. We aimed to determine the relationship between glucose metabolism and smooth muscle cell proliferation in IPAH.

METHODS AND RESULTS

Human IPAH and control patient lung tissues and pulmonary artery smooth muscle cells (PASMCs) were used to analyze a specific pathway of glucose metabolism, the hexosamine biosynthetic pathway. We measured the levels of O-linked β-N-acetylglucosamine modification, O-linked β-N-acetylglucosamine transferase (OGT), and O-linked β-N-acetylglucosamine hydrolase in control and IPAH cells and tissues. Our data suggest that the activation of the hexosamine biosynthetic pathway directly increased OGT levels and activity, triggering changes in glycosylation and PASMC proliferation. Partial knockdown of OGT in IPAH PASMCs resulted in reduced global O-linked β-N-acetylglucosamine modification levels and abrogated PASMC proliferation. The increased proliferation observed in IPAH PASMCs was directly impacted by proteolytic activation of the cell cycle regulator, host cell factor-1.

CONCLUSIONS

Our data demonstrate that hexosamine biosynthetic pathway flux is increased in IPAH and drives OGT-facilitated PASMC proliferation through specific proteolysis and direct activation of host cell factor-1. These findings establish a novel regulatory role for OGT in IPAH, shed a new light on our understanding of the disease pathobiology, and provide opportunities to design novel therapeutic strategies for IPAH.

[Primary (idiopathic) pulmonary hypertension (Ayerza-Arrillaga syndrome) and pregnancy - intensive care and anesthesia management]

The lecture deals with detailed information about the etiology, pathogenesis and clinical manifestations of primary (idiopathic) pulmonaiy hypertension, intensive treatment and anesthesia in pregnancy.