Microvascular Disease After Renal Transplantation.

BACKGROUND/AIMS: Individuals who reach end-stage kidney disease (CKD5) have a high risk of vascular events that persists even after renal transplantation. This study compared the prevalence and severity of microvascular disease in transplant recipients and patients with CKD5. METHODS: Individuals with a renal transplant or CKD5 were recruited consecutively from renal clinics, and underwent bilateral retinal photography (Canon CR5-45, Canon). Their retinal images were deidentified and reviewed for hypertensive/microvascular signs by an ophthalmologist and a trained grader (Wong and Mitchell classification), and for vessel caliber at a grading centre using a computer-assisted method and Knudtson's modification of the Parr-Hubbard formula. RESULTS: Ninety-two transplant recipients (median duration 6.4 years, range 0.8 to 28.8) and 70 subjects with CKD5 were studied. Transplant recipients were younger (p<0.001), with a higher eGFR (p< 0.001), but were just as likely to have a moderate-severe hypertensive/microvascular retinopathy (46/92, 50%) as subjects with CKD5 (38/70, 54%; OR 0.84, CI 0.45 to 1.57, p=0.64), and had similar mean arteriole and venular calibres (135.1 ± 7.5 µm and 137.9 ± 14.9 µm, p=0.12; and 199.1 ± 17.8 µm and 202.4 ± 27.8 µm, p=0.36, respectively). Arteriole and venular caliber were not different in nine patients examined before and after transplantation (p=0.62 and p=0.11, respectively). CONCLUSIONS: Hypertensive/microvascular disease occurred just as often and was generally as severe in transplant recipients and subjects with CKD5. Microvascular disease potentially contributes to increased cardiac events post-transplantation.

Microvascular dilatation after haemodialysis is determined by the volume of fluid removed and fall in mean arterial pressure.

BACKGROUND/AIMS: The effects of haemodialysis on the microcirculation are poorly understood. This study examined the changes in small vessel calibre. METHODS: 24 patients (including 12 males, median age 62.5 years, range 30-87) underwent digital retinal photography immediately before and after routine haemodialysis. Arteriolar and venular calibres were measured from the images by a trained grader using a highly reproducible, computer-assisted method. RESULTS: Patients had an average 2.0 ± 0.3 litres of fluid removed with dialysis, and their mean arterial blood pressure fell by 6.8 mm Hg (CI 13.8-0.2, p = 0.06). Retinal arteriole calibre did not change (mean difference 2.3 µm, CI -1.1 to 5.7, p = 0.17) but the venules dilated (mean difference 12.7 µm, CI 7.3-18.3, p < 0.001). Calibre returned to baseline by 2 h. Venules dilated less in diabetics than non-diabetics (mean difference -6.2 µm, CI -9.6 to -2.9, p < 0.01). Retinal venular dilatation correlated positively with the volume of fluid removed per kilogramme body weight (5.9, CI 0.2-11.5, p = 0.04), and negatively with the fall in mean arterial pressure (-0.36, CI -0.72 to -0.01, p < 0.05) after adjusting for age, gender, diabetes and dyslipidaemia. CONCLUSION: Haemodialysis is associated with systemic venular dilatation.

Vision-threatening retinal abnormalities in chronic kidney disease stages 3 to 5.

BACKGROUND AND OBJECTIVES: Retinal abnormalities are common in inherited and acquired renal disease. This study determined the prevalence of retinal abnormalities in chronic kidney disease (CKD) stages 3 to 5. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: One hundred fifty patients with CKD stages 3 to 5 and 150 age- and gender-matched hospital patients with CKD stages 1 to 2 underwent bilateral retinal photography. These images were reviewed for incidental abnormalities, microvascular (Wong and Mitchell classification) and diabetic retinopathy (Airlie House criteria), and macular degeneration (Seddon classification). RESULTS: Three (2%) patients with CKD stages 3 to 5 had retinal features characteristic of inherited renal disease (atrophy in Myopathy, Encephalopathy, Lactic Acidosis, Stroke-like episodes [MELAS] syndrome; and 2 with drusen in dense deposit disease). Fifty-nine (39%) patients had moderate-severe microvascular retinopathy (hemorrhages, exudates, etc.) compared with 19 (13%) with CKD stages 1 to 2. Forty-one (28%) had moderate-severe diabetic retinopathy (microaneurysms, exudates, etc.) compared with 16 (11%) with CKD stages 1 to 2. Ten (7%) had severe macular degeneration (geographic atrophy, hemorrhage, exudates, membranes) compared with one (1%) with CKD stages 1 to 2. Renal failure was an independent risk factor for microvascular retinopathy, diabetic retinopathy, and macular degeneration. Eleven (7.3%) patients with renal failure and one (0.7%) with CKD stages 1 to 2 had previously unrecognized vision-threatening retinal abnormalities that required immediate ophthalmologic attention. CONCLUSIONS: Retinal abnormalities are common in CKD stages 3 to 5, and are more severe and more likely to threaten vision than in hospital patients with CKD stages 1 to 2.

The microvasculature in chronic kidney disease.

BACKGROUND AND OBJECTIVES: Individuals with chronic kidney disease (CKD) stages 3 to 5 have an increased risk of cardiac and other vascular disease. Here we examined the association of CKD 3 to 5 with small vessel caliber. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This was a cross-sectional observational study of 126 patients with CKD stages 3 to 5 (estimated GFR [eGFR] <60 ml/min per 1.73 m(2)) and 126 age- and gender-matched hospital patients with CKD 1 or 2. Retinal vessel diameters were measured from digital fundus images by a trained grader using a computer-assisted method and summarized as the central retinal artery equivalent (CRAE) and central retinal vein equivalent (CRVE). RESULTS: Patients with CKD 3 to 5 had a smaller mean CRAE and CRVE than hospital controls (139.4 ± 17.8 µm versus 148.5 ± 16.0 µm, P < 0.001; and 205.0 ± 30.7 µm versus 217.4 ± 25.8 µm, respectively; P = 0.001). CRAE and CRVE decreased progressively with each stage of renal failure CKD1-2 to 5 (P for trend = 0.08 and 0.04, respectively). CKD and hypertension were independent determinants of arteriolar narrowing after adjusting for age, gender, diabetes, dyslipidemia, and smoking history. Patients with CKD 5 and diabetes had a larger mean CRAE and CRVE than nondiabetics (141.4 ± 14.9 µm versus 132.9 ± 14.2 µm; 211.1 ± 34.4 µm versus 194.8 ± 23.8 µm). CONCLUSIONS: The microvasculature is narrowed in patients with reduced eGFR.