Right ventricular load and contractility in HIV-associated pulmonary hypertension.

BACKGROUND: People living with human immunodeficiency virus (PLWH) are at risk of developing pulmonary hypertension (PH) and right ventricular (RV) dysfunction, but understanding of the relationship of RV function to afterload (RV-PA coupling) is limited. We evaluated the clinical and hemodynamic characteristics of human immunodeficiency virus (HIV)-associated PH. METHODS: We performed a retrospective review of patients with a diagnosis of HIV undergoing right heart catheterization (RHC) from 2000-2016 in a tertiary care center. Inclusion criteria were diagnosis of HIV, age ≥ 18 years and availability of RHC data. PH was classified as either pulmonary arterial hypertension (PAH; mean pulmonary arterial pressure [mPAP] ≥ 25mmHg with pulmonary artery wedge pressure [PAWP] ≤ 15mmHg) or pulmonary venous hypertension (PVH; mPAP ≥ 25mmHg with PAWP > 15). We collected demographics, CD4 cell count, HIV viral load, RHC and echocardiographic data. The single beat method was used to calculate RV-PA coupling from RHC. RESULTS: Sixty-two PLWH with a clinical likelihood for PH underwent RHC. Thirty-two (52%) met PH criteria (15 with PAH, 17 with PVH). Average time from diagnosis of HIV to diagnosis of PH was 11 years. Eleven of 15 individuals with PAH were on antiretroviral therapy (ART) while all 17 patients with PVH were on ART. Compared to PLWH without PH, those with PH had an increased likelihood of having a detectable HIV viral load and lower CD4 cell counts. PLWH with PAH or PVH had increased RV afterload with normal RV contractility, and preserved RV-PA coupling. CONCLUSION: PLWH with PH (PAH or PVH) were more likely to have a detectable HIV viral load and lower CD4 count at the time of RHC. PLWH with PAH or PVH had increased RV afterload, normal RV contractility, with preserved RV-PA coupling suggestive of an early onset, mild, and compensated form of PH. These results should be confirmed in larger studies.

Pulmonary veno-occlusive disease is highly prevalent in scleroderma patients undergoing lung transplantation.

There is an unexpectedly high incidence of PVOD in patients with SSc-PH-ILD. Presence of PVOD may be an unrecognised contributor to the dismal prognosis of these patients. Early transplant referral should be considered for those with SSc-PH-ILD. http://ow.ly/vPvc30neJZV.

Fatal air embolism following local anaesthetisation: does needle size matter?

A 76--year--old male cigarette smoker presented with a 2-week history of cough and haemoptysis. Chest CT on admission revealed multiple new lung nodules concerning for malignancy. CT--guided biopsy of the nodule in left lower lobe was attempted in prone oblique position for tissue diagnosis. Local anaesthetic (lidocaine) was administered using a 25--gauge (1.5-inch) needle to anaesthetise the skin and subcutaneous tissue. This was followed by insertion of a 25-gauge (3.5-inch) Whitacre needle to anaesthetise deeper tissues and parietal pleura. Due to patient's coughing and proximity of the nodule to the diaphragm, the circumstances were judged to be too risky for a needle biopsy. Therefore, it was decided to biopsy another nodule in the left lung that was visible on the same CT section. During this portion of the procedure, the patient became hypoxic and developed pulseless electrical activity arrest. Cardiopulmonary resuscitation was unsuccessful and the efforts ceased after 45 min. Subsequent review of CT scan revealed air in the left ventricle.

Vascular stiffness mechanoactivates YAP/TAZ-dependent glutaminolysis to drive pulmonary hypertension.

Dysregulation of vascular stiffness and cellular metabolism occurs early in pulmonary hypertension (PH). However, the mechanisms by which biophysical properties of the vascular extracellular matrix (ECM) relate to metabolic processes important in PH remain undefined. In this work, we examined cultured pulmonary vascular cells and various types of PH-diseased lung tissue and determined that ECM stiffening resulted in mechanoactivation of the transcriptional coactivators YAP and TAZ (WWTR1). YAP/TAZ activation modulated metabolic enzymes, including glutaminase (GLS1), to coordinate glutaminolysis and glycolysis. Glutaminolysis, an anaplerotic pathway, replenished aspartate for anabolic biosynthesis, which was critical for sustaining proliferation and migration within stiff ECM. In vitro, GLS1 inhibition blocked aspartate production and reprogrammed cellular proliferation pathways, while application of aspartate restored proliferation. In the monocrotaline rat model of PH, pharmacologic modulation of pulmonary vascular stiffness and YAP-dependent mechanotransduction altered glutaminolysis, pulmonary vascular proliferation, and manifestations of PH. Additionally, pharmacologic targeting of GLS1 in this model ameliorated disease progression. Notably, evaluation of simian immunodeficiency virus-infected nonhuman primates and HIV-infected subjects revealed a correlation between YAP/TAZ-GLS activation and PH. These results indicate that ECM stiffening sustains vascular cell growth and migration through YAP/TAZ-dependent glutaminolysis and anaplerosis, and thereby link mechanical stimuli to dysregulated vascular metabolism. Furthermore, this study identifies potential metabolic drug targets for therapeutic development in PH.