Recent advances in chronic thromboembolic pulmonary hypertension

P2Y Purinergic Receptors, Endothelial Dysfunction, and Cardiovascular Diseases

Purinergic G-protein-coupled receptors are ancient and the most abundant group of G-protein-coupled receptors (GPCRs). The wide distribution of purinergic receptors in the cardiovascular system, together with the expression of multiple receptor subtypes in endothelial cells (ECs) and other vascular cells demonstrates the physiological importance of the purinergic signaling system in the regulation of the cardiovascular system. This review discusses the contribution of purinergic P2Y receptors to endothelial dysfunction (ED) in numerous cardiovascular diseases (CVDs). Endothelial dysfunction can be defined as a shift from a “calm” or non-activated state, characterized by low permeability, anti-thrombotic, and anti-inflammatory properties, to a “activated” state, characterized by vasoconstriction and increased permeability, pro-thrombotic, and pro-inflammatory properties. This state of ED is observed in many diseases, including atherosclerosis, diabetes, hypertension, metabolic syndrome, sepsis, and pulmonary hypertension. Herein, we review the recent advances in P2Y receptor physiology and emphasize some of their unique signaling features in pulmonary endothelial cells.

Inflammatory response and pneumocyte apoptosis during lung ischemia-reperfusion injury in an experimental pulmonary thromboembolism model

Lung ischemia-reperfusion injury (LIRI) may occur in the region of the affected lung after reperfusion therapy. The inflammatory response mechanisms related to LIRI in pulmonary thromboembolism (PTE), especially in chronic PTE, need to be studied further. In a PTE model, inflammatory response and apoptosis may occur during LIRI and nitric oxide (NO) inhalation may alleviate the inflammatory response and apoptosis of pneumocytes during LIRI. A PTE canine model was established through blood clot embolism to the right lower lobar pulmonary artery. Two weeks later, we performed embolectomy with reperfusion to examine the LIRI changes among different groups. In particular, the ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO2/FiO2), serum concentrations of tumor necrosis factor-α (TNF-α), myeloperoxidase concentrations in lung homogenates, alveolar polymorphonuclear neutrophils (PMNs), lobar lung wet to dry ratio (W/D ratio), apoptotic pneumocytes, and lung sample ultrastructure were assessed. The PaO2/FiO2 in the NO inhalation group increased significantly when compared with the reperfusion group 4 and 6 h after reperfusion (368.83 ± 55.29 vs. 287.90 ± 54.84 mmHg, P < 0.05 and 380.63 ± 56.83 vs. 292.83 ± 6 0.34 mmHg, P < 0.05, respectively). In the NO inhalation group, TNF-α concentrations and alveolar PMN infiltration were significantly decreased as compared with those of the reperfusion group, 6 h after reperfusion (7.28 ± 1.49 vs. 8.90 ± 1.43 pg/mL, P < 0.05 and [(19 ± 6)/10 high power field (HPF) vs. (31 ± 11)/10 HPF, P < 0.05, respectively]. The amount of apoptotic pneumocytes in the lower lobar lung was negatively correlated with the arterial blood PaO2/FiO2, presented a positive correlation trend with the W/D ratio of the lower lobar lung, and a positive correlation with alveolar PMN in the reperfusion group and NO inhalation group. NO provided at 20 ppm for 6 h significantly alleviated LIRI in the PTE model. Our data indicate that, during LIRI, an obvious inflammatory response and apoptosis occur in our PTE model and NO inhalation may be useful in treating LIRI by alleviating the inflammatory response and pneumocyte apoptosis. This potential application warrants further investigation.

Beneficial effects of inhaled NO on apoptotic pneumocytes in pulmonary thromboembolism model

BACKGROUND

Lung ischemia-reperfusion injury (LIRI) may occur in the region of the affected lung after reperfusion therapy. Inhaled NO may be useful in treating acute and chronic pulmonary thromboembolism (PTE) due to the biological effect property of NO.

METHODS

A PTE canine model was established through selectively embolizing blood clots to an intended right lower lobar pulmonary artery. PaO2/FiO2, the mPAP and PVR were investigated at the time points of 2, 4, 6 hours after inhaled NO. Masson's trichrome stain, apoptotic pneumocytes and lung sample ultrastructure were also investigated among different groups.

RESULTS

The PaO2/FiO2 in the Inhaled NO group increased significantly when compared with the Reperfusion group at time points of 4 and 6 hours after reperfusion, mPAP decreased significantly at point of 2 hours and the PVR decreased significantly at point of 6 hours after reperfusion. The amounts of apoptotic type II pneumocytes in the lower lobar lung have negative correlation trend with the arterial blood PaO2/FiO2 in Reperfusion group and Inhaled NO group. Inhaled nitric oxide given at 20 ppm for 6 hours can significantly alleviate the LIRI in the model.

CONCLUSIONS

Dramatic physiological improvements are seen during the therapeutic use of inhaled NO in pulmonary thromboembolism canine model. Inhaled NO may be useful in treating LIRI in acute or chronic PTE by alleviating apoptotic type II pneumocytes. This potential application warrants further investigation.

Long-term psychological consequences of symptomatic pulmonary embolism: a qualitative study

OBJECTIVE

To explore the psychological consequences of experiencing symptomatic pulmonary embolism (PE).

DESIGN

Qualitative interview-based study using interpretative phenomenological analysis.

SETTING

Outpatients who attended an anticoagulation clinic in a district general hospital.

PARTICIPANTS

Patients attending an anticoagulation clinic following hospital admission for symptomatic PE were approached to participate. A total of 9 (4 women, 5 men) of 11 patients approached agreed to be interviewed. Participants were aged between 26 and 72 years and had previously experienced a PE between 9 and 60 months (median=26 months, mean=24 months).

INTERVENTION

Audiotaped semistructured qualitative interviews were undertaken to explore participants experiences of having a PE and how it had affected their lives since. Data were transcribed and analysed using interpretative phenomenological analysis to identify emergent themes.

RESULTS

Three major themes with associated subthemes were identified. Participants described having a PE as a life-changing experience comprising initial shock, followed by feeling of loss of self, life-changing decisions and behaviour modification. Features of post-traumatic stress disorder (PTSD) were described with flashbacks, hypervigilance and intrusive thoughts being most prevalent. Participants identified several areas of support needed for such patients including easier access to support through information giving and emotional support.

CONCLUSIONS

Long-term consequences of venous thromboembolism go beyond the physical alone. Patients describe experiencing symptomatic PE to be a life-changing distressing event leading to behaviour modification and in some PTSD. It is likely that earlier psychological intervention may reduce such long-term sequelae.