Literature review on the cross-link between ocular and renal disease: renin angiotensin aldosterone system is a main actor.

OBJECTIVE: Chronic kidney disease (CKD) and ocular disease share several cardiovascular risk factors as well as pathogenetic mechanisms having Renin-Angiotensin-Aldosterone System (RAAS) as main actor. Moreover, kidney and eyes have common genetic and embryonic origin. In this literature review, we present main evidence supporting this association for early identifying diseases affecting both systems and evaluating potential multi-target therapeutic strategies. MATERIALS AND METHODS: We performed a literature review of the current peer-reviewed English-language randomized controlled studies (RCTs), reference lists of nephrology or ophthalmology textbooks, review articles and relevant studies with ocular or eye and kidney or renal diseases as keywords until March 2020. Prospective and retrospective studies as well as meta-analyses and latest systematic reviews were included. RESULTS: We evaluated a total of 683 records, finally selecting 119 articles related to ocular and renal diseases. Records were divided into two areas: chronic and acute kidney disease and ocular or eye diseases. Some of the examined studies were discarded for population biases/intervention or deemed unfit. CONCLUSIONS: Based on our results, we conclude that there is evidence of a clear association between kidney and eye diseases, being this cross-link mainly based on RAAS dysregulation. Our review suggests that it may be useful to screen CKD patients for associated ocular diseases, such as cataract, glaucoma, diabetic retinopathy and age-related macular degeneration. A comprehensive study of CKD and proteinuric patients should include careful eye examination. Renal impairment in young patients should prompt a search for ocular disease, such as TUNA syndrome or oculo-renal syndrome, in particular if family history of concurrent ocular and renal disease is present. Anti-RAAS agents are mostly recommended in patients with renal and ocular impairment.

Screening of QTc interval and global autonomic activity in autosomal dominant polycystic kidney disease and atherosclerotic renal artery stenosis hypertensive patients.

OBJECTIVE: Arterial hypertension (AH) represents a major risk factor for cardiovascular disease and is associated to several complications, such as prolonged corrected QT (QTc) interval and impaired heart rate variability (HRV). Secondary causes of AH include autosomal dominant polycystic kidney disease (ADPKD) and atherosclerotic renal artery stenosis (ARAS), both known to be related to arrhythmic risk and autonomic imbalance. The aim of the study is to evaluate whether global autonomic activity and QTc interval differently affect ADPKD and ARAS hypertensive patients. PATIENTS AND METHODS: An observational study was performed on 59 patients: 16 ADPKD patients and 19 diagnosed with ARAS, compared to 24 healthy controls (HC). All patients underwent clinical evaluation, biochemical lab tests, 24-hour electrocardiogram (ECG) and renal Doppler ultrasound. HRV was assessed through the analysis of 24-hour ECG to detect standard deviation of normal-to-normal RR intervals (SDNN). QTc interval was defined as prolonged when > 440 msec. RESULTS: SDNN was significantly lower in ADPKD and ARAS patients than HC (p < 0.0001) and no significant differences were found between ADPKD and ARAS patients (p > 0.05). QTc was found significantly higher in ARAS patients than HC (p = 0.001) and in ARAS patients than ADPKD patients (p = 0.004). CONCLUSIONS: The pathogenesis of hypertension in ADPKD and ARAS patients is related to the activation of the renin angiotensin aldosterone system (RAAS). In ADPKD, cyst enlargement leads to kidney ischemia and renin release, associated to endothelial dysfunction, low nitric oxide and sympathetic tone activation. Differently, reduction in renal perfusion pressure activates RAAS and renal adrenergic nerves in ARAS patients. We can speculate that prolonged QTc interval is more present in ARAS vs. ADPKD hypertensive patients due to a greater activation of RAAS. We suggest adding 24-hour HRV evaluation in association with traditional risk factors in course of ADPKD and ARAS hypertension to better stratify cardiovascular risk in these groups of patients.

Autonomic dysfunction in kidney diseases.

Kidney diseases are associated with many cardiovascular risk factors, such as anaemia, inflammation and chronic volume overload. Changes in the sympathovagal balance are common findings in patients with end-stage renal disease (ESRD). In particular, sympathetic hyperactivity is linked with an increase in resting heart rate leading to myocardial hypertrophy and fibrosis. The latter increases the risk of sudden cardiac death from fatal arrythmias and therefore assessment of both sympathetic and parasympathetic tones could be clinically relevant in ESRD patients. Heart rate variability and other indices are currently used to evaluate the functionality of the autonomic nervous system. Some of these have emerged as potential diagnostic tools that can support clinical decision-making processes and therapeutic strategies in patients with renal disease, including those who are on dialysis replacement therapy. In this review, we summarize the impact and the relationships between sympathovagal disturbances and kidney diseases, replacement therapies and transplantation.