Beneficial Effects of Pulmonary Vasodilators on Pre-Capillary Pulmonary Hypertension in Patients with Chronic Kidney Disease on Hemodialysis.

BACKGROUND: In patients with chronic kidney disease (CKD) on hemodialysis, comorbid pulmonary hypertension (PH) aggravates exercise tolerance and eventually worsens the prognosis. The treatment strategy for pre-capillary PH, including combined pre- and post-capillary PH (Cpc-PH), has not been established. OBJECTIVES: This study aimed to evaluate the impact of pulmonary vasodilators on exercise tolerance and pulmonary hemodynamics in patients with CKD on hemodialysis. METHODS AND RESULTS: The medical records of 393 patients with suspected PH who underwent right heart catheterization were reviewed. Of these, seven patients had isolated pre-capillary PH and end-stage CKD on hemodialysis. Pulmonary vasodilators decreased pulmonary vascular resistance from 5.9 Wood units (interquartile range (IQR), 5.5-7.6) at baseline to 3.1 Wood units (IQR, 2.6-3.3) post-treatment (p = 0.02) as well as increased pulmonary capillary wedge pressure from 10 mmHg (IQR, 7-11) to 11 mmHg (IQR, 8-16) (p = 0.04). Pulmonary vasodilators increased the World Health Organization functional class I or II from 0% to 100% (p = 0.0002) and the 6 min walk distance from 273 m (IQR, 185-365) to 490 m (IQR, 470-550) (p = 0.03). CONCLUSIONS: Pulmonary vasodilators for PH in patients with CKD on hemodialysis decrease pulmonary vascular resistance and eventually improve exercise tolerance. Pulmonary vasodilators may help hemodialysis patients with pre-capillary PH, although careful management considering the risk of pulmonary edema is required.

Increased Lung Uric Acid Deteriorates Pulmonary Arterial Hypertension.

Background Recent studies have demonstrated that uric acid (UA) enhances arginase activity, resulting in decreased NO in endothelial cells. However, the role of lung UA in pulmonary arterial hypertension (PAH) remains uncertain. We hypothesized that increased lung UA level contributes to the progression of PAH. Methods and Results In cultured human pulmonary arterial endothelial cells, voltage-driven urate transporter 1 (URATv1) gene expression was detected, and treatment with UA increased arginase activity. In perfused lung preparations of VEGF receptor blocker (SU5416)/hypoxia/normoxia-induced PAH model rats, addition of UA induced a greater pressure response than that seen in the control and decreased lung cGMP level. UA-induced pressor responses were abolished by benzbromarone, a UA transporter inhibitor, or L-norvaline, an arginase inhibitor. In PAH model rats, induction of hyperuricemia by administering 2% oxonic acid significantly increased lung UA level and induced greater elevation of right ventricular systolic pressure with exacerbation of occlusive neointimal lesions in small pulmonary arteries, compared with nonhyperuricemic PAH rats. Administration of benzbromarone to hyperuricemic PAH rats significantly reduced lung UA levels without changing XOR (xanthine oxidoreductase) activity, and attenuated right ventricular systolic pressure increase and occlusive lesion development. Topiroxostat, a XOR inhibitor, significantly reduced lung XOR activity in PAH rats, with no effects on increase in right ventricular systolic pressure, arterial elastance, and occlusive lesions. XOR-knockout had no effects on right ventricular systolic pressure increase and arteriolar muscularization in hypoxia-exposed mice. Conclusions Increased lung UA per se deteriorated PAH, whereas XOR had little impact. The mechanism of increased lung UA may be a novel therapeutic target for PAH complicated with hyperuricemia.

Fatal Pulmonary Hemorrhagic Infarction Caused by Pulmonary Vein Thrombotic Occlusion During Venoarterial Extracorporeal Membrane Oxygenation.

A 20-year-old man with arrhythmogenic right ventricular cardiomyopathy (ARVC) was resuscitated from ventricular fibrillation. He was transferred to our hospital because of progressive multiorgan dysfunction despite mechanical circulatory support with peripheral venoarterial extracorporeal membrane oxygenation (VA-ECMO) and intra-aortic balloon pump (IABP). At admission to our hospital, chest X-ray showed bilateral complete lung opacification, and echocardiography revealed a massive thrombus occupying the left atrium (LA) and left ventricle (LV). Conversion to central ECMO with transapical LV venting and thrombectomy were performed. The huge LA thrombus occluded all pulmonary veins (PVs). Despite the surgery and intensive care, complete lung opacity remained, and he died of multiorgan failure associated with sepsis. Autopsy demonstrated bilateral pulmonary multiple red infarctions, and histopathology showed alveolar wall necrosis with extensive hemorrhage, confirming a diagnosis of pulmonary hemorrhagic infarction. Extensive pulmonary infarction was attributable to PV occlusion due to massive LA thrombus. PV thrombosis should be considered when refractory lung opacities are encountered during VA-ECMO and necessitates early intervention.

Radiofrequency catheter ablation of atrial fibrillation through an implanted inferior vena cava filter.

Pulmonary vein isolation (PVI), which creates electrical blocks between pulmonary veins and left atrium, is an established way of catheter ablation for atrial fibrillation (AF). PVI is usually performed via the femoral vein access, using two or three long preshaped sheaths, followed by atrial-septal puncture to approach the left atrium. Here, we treated an AF patient with a permanently implanted inferior vena cava filter (IVC-F) due to deep venous thrombosis (DVT) and pulmonary thromboembolism (PTE). The patient had symptomatic paroxysmal AF for over a decade, which was not controlled under antiarrhythmic drugs including beta-blockers. Therefore, we recommended PVI to treat the AF. However, as the IVC-F was an obstacle to perform conventional PVI, we changed the combination of vascular access sites and devices to perform it safely. Notably, insertions of a single steerable sheath through IVC-F and an intracardiac ultrasound catheter from the right internal jugular vein were useful for the successful completion of the procedure. .