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Background and Aims: Obstructive sleep apnea (OSA) may accelerate arterial calcification, but the relation remains unexplored in diabetic kidney disease (DKD). We examined the associations between OSA, coronary calcification and large artery stiffness in patients with DKD and reduced renal function., Methods: Patients with type 2 diabetes, estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m 2 and urine albumin-creatinine ratio (UACR) > 30 mg/g were tested for OSA quantified by the apnea-hypopnea index (AHI, events/hour). Patients without OSA (AHI< 5) were compared to patients with moderate (AHI 15-29) or severe (AHI ≥30) OSA and underwent computed tomography angiography with coronary Agatston scoring (CAS) to quantify coronary calcification. Arterial stiffness was determined as carotid-femoral pulse wave velocity (PWV)., Results: Among 114 patients with acceptable AHI recordings had 43 no OSA, 33 mild OSA and 38 moderate-severe OSA. Mean age of the 74 patients completing the study was 71.5 ± 9.4 years (73% males), eGFR 32.2 ± 12.3 ml/min/1.73 m 2 and UACR 533 (192-1707) mg/g. CAS (ln-transformed) was significantly higher in patients with OSA compared to patients without (6.6 ± 1.7 vs. 5.6 ± 2.4, p = 0.04), and the same was observed for PWV (11.9 ± 2.7 vs. 10.5 ± 2.2 m/s, p = 0.02). In multivariable linear regression analyses adjusted for sex, age, body mass index, UACR, and mean arterial pressure, moderate-severe OSA remained significantly associated with PWV but not with CAS. Dominance analysis revealed OSA as the third and second most important factor relative to CAS and PWV respectively., Conclusions: In DKD patients, moderate-severe OSA is a significant predictor of arterial stiffness but is not independently associated with coronary calcification., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Introduction: Central aortic blood pressure (BP) could be a better risk predictor than brachial BP. This study examined whether invasively measured aortic systolic BP improved outcome prediction beyond risk prediction by conventional cuff-based office systolic BP in patients with and without chronic kidney disease (CKD)., Methods: In a prospective, longitudinal cohort study, aortic and office systolic BPs were registered in patients undergoing elective coronary angiography (CAG). CKD was defined as estimated glomerular filtration rate (eGFR) <60 ml/min per 1.73 m 2 . Multivariable Cox models were used to determine the association with incident myocardial infarction (MI), stroke, and death., Results: Aortic and office systolic BPs were available in 39,866 patients (mean age: 64 years; 58% males; 64% with hypertension) out of which 6605 (17%) had CKD. During a median follow-up of 7.2 years (interquartile range: 4.6-10.1 years), 1367 strokes (CKD: 353), 1858 MIs (CKD: 446), and 7551 deaths (CKD: 2515) occurred. CKD increased the risk of stroke, MI, and death significantly. Office and aortic systolic BP were both associated with stroke in non-CKD patients (adjusted hazard ratios with 95% confidence interval per 10 mm Hg: 1.08 [1.05-1.12] and 1.06 [1.03-1.09], respectively) and with MI in patients with CKD (adjusted hazard ratios: 1.08 [1.03-1.13] and 1.08 [1.04-1.12], respectively). There was no significant difference between prediction of outcome with office or aortic systolic BP when adjusted models were compared with C-statistics., Conclusion: Regardless of CKD status, invasively measured central aortic systolic BP does not improve the ability to predict outcome compared with brachial office BP measurement., (© 2023 International Society of Nephrology. Published by Elsevier Inc.)

Objective: Uremic myopathy is a condition seen in end-stage renal disease (ESRD), characterized by muscle weakness and muscle fatigue, in which the pathophysiology is uncertain. The aim of this study was to assess the role of abnormal serum constituents in ESRD patients by relating them to the excitability properties of the tibialis anterior muscle, at rest and during electrically induced muscle activation, by recording muscle velocity recovery cycles (MVRC) and frequency ramp responses., Methods: Eighteen ESRD patients undergoing hemodialysis were evaluated by blood sample, MVRC, and frequency ramp (before and near the end of dialysis treatment), quantitative electromyography, and nerve conduction studies. Patients were compared to 24 control subjects., Results: In patients, muscle relative refractory period, early supernormality, late supernormality after 5 conditioning stimuli, and latency of the last of 15 and 30 frequency ramp pulses were strongly associated with potassium levels (p < 0.01), showing depolarization before and normalization in the end of hemodialysis., Conclusions: In ESRD patients, the muscle membrane is depolarized, mainly due to hyperkalemia., Significance: Since normal muscle fatigue has been attributed to potassium-induced depolarization, it seems likely that this mechanism is also a major cause of the exaggerated muscle fatigue and weakness in ESRD patients., Competing Interests: Declaration of Competing Interest Professor Hugh Bostock receives royalties from UCL for sales of his Qtrac software used in this study. The other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 International Federation of Clinical Neurophysiology. All rights reserved.)

Background: Microvascular impairment is well documented in hypertension. We investigated the effect of renal sympathetic denervation (RDN) on cardiac and peripheral microvasculature in patients with treatment-resistant essential hypertension (TRH)., Methods: A randomized, single centre, double-blinded, sham-controlled clinical trial. Fifty-eight patients with TRH (ambulatory systolic BP (ASBP) ≥ 145mmHg) despite stable treatment were randomized to RDN or SHAM. RDN was performed with the unipolar Medtronic Flex catheter. Coronary flow reserve (CFR) and coronary- and forearm minimum vascular resistance (C-Rmin and F-Rmin) were determined using transthoracic Doppler echocardiography and F-Rmin with venous occlusion plethysmography at baseline and at six-months follow-up., Results: RDN was performed with 5.3±0.2 lesions in the right renal artery and 5.4±0.2 lesions in the left. Baseline ASBP was 152±2mmHg (RDN, n=29) and 154±2mmHg (SHAM, n=29). Similar reductions in MAP were seen at follow up (-3.5±2.0 vs. -3.2±1.8, P=0.92). Baseline CFR was 2.9±0.1 (RDN) and 2.4±0.1 (SHAM), with no significant change at follow-up (0.2±0.2 vs. -0.1±0.2, P=0.57). C-Rmin was 1.9±0.3 (RDN) and 2.7±0.6 (SHAM) (mmHgmin/ml pr. 100g) and did not change significantly (0.3±0.5 vs. -0.4±0.8, P=0.48). F-Rmin was 3.6±0.2 (RDN) and 3.6±0.3 (SHAM) (mmHgmin/ml pr. 100ml tissue) and unchanged at follow-up (4.2±0.4 vs. 3.8±0.2, P=0.17). Left ventricular mass index was unchanged following RDN (-4±7 (RDN) vs. 3±5 (SHAM) (g/m 2 ) P=0.38)., Conclusion: The current study does not support positive effects of RDN on microvascular impairment in TRH., (Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.)

Central blood pressure (BP) can be assessed noninvasively based on radial tonometry and may potentially be a better predictor of clinical outcome than brachial BP. However, the validity of noninvasively obtained estimates has never been examined in patients with chronic kidney disease (CKD). Here we compared invasive aortic systolic BP (SBP) with estimated central SBP obtained by radial artery tonometry and examined the influence of renal function and arterial stiffness on this relationship. We evaluated 83 patients with stage 3 to 5 CKD (mean estimated glomerular filtration rate [eGFR] 30 ml/min/1.73 m(2)) and 41 controls without renal disease undergoing scheduled coronary angiography. BP in the ascending aorta was measured through the angiography catheter and simultaneously estimated using radial tonometry. The mean difference between estimated central and aortic SBP was -13.2 (95% confidence interval -14.9 to -11.4) mm Hg. Arterial stiffness was evaluated by carotid-femoral pulse wave velocity (cf-PWV) and was significantly increased in CKD patients compared with (versus) control patients (mean 10.7 vs. 9.3 m/s). The difference in BP significantly increased 1.0 mm Hg for every 10 ml/min decrease in eGFR and by 1.6 mm Hg per 1 m/s increase in cfPWV. Using multivariate regression analysis including both eGFR and cfPWV, the difference between estimated central and invasive aortic SBP was significantly increased by 0.7 mm Hg. For the entire cohort brachial SBP significantly better reflected invasive SBP than estimated SBP. Thus, tonometry-based estimates of central BP progressively underestimate invasive central SBP with decreasing renal function and increasing arterial stiffness in CKD patients., (Copyright © 2016 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.)