Wall-to-lumen Ratio Of Retinal Arterioles Research Articles

RETINAL ARTERIOLAR REMODELING IN PRIMARY ALDOSTERONISM: A STUDY WITH ADAPTIVE OPTICS

Objective: Primary aldosteronism (PA) represents the most frequent form of secondary hypertension. In previous studies an hypertrophic remodeling, with smooth muscle cell growth and an increase in media to lumen ratio (MLR), has been shown in patients with primary aldosteronism (Rizzoni D et al. Hypertension 1996;28:785–790.). To date, Adaptive Optics (AO) is one of the most innovative and non-invasive methods for studying the wall-to-lumen ratio of retinal arterioles (WLR), which directly correlates with the MLR of subcutaneous small arteries (De Ciuceis C et al. J Hypertens. 2018;36(5):1154-1163.). Design and method: Therefore, the aim of this study was to evaluate microvascular structure of retinal arterioles by Adaptive Optics in PA patients, before and after pharmacological or surgical treatment, compared to essential hypertensive patients (EH). Eleven patients with PA before treatment have been matched with 11 patients with EH and 11 patients with treated PA in follow up. All patients underwent assessment of retinal microcirculation morphology with AO (RTX-1, Imagine Eyes; Orsay, FR) in order to calculate WLR and wall cross sectional area (WCSA). Results: A total of 33 patients was enrolled in the study. PA patients at the baseline showed a significant higher WLR compared to EH and to PA in follow-up (Figure 1; 0.31±0.03 vs 0.27±0.04 vs 0.275±0.03 respectively; p = 0.01). Otherwise, differences between WCSA turned out to be less relevant with no significant differences among the three groups (4500.85±879.9 vs 4195.96±553.3 vs 4278.52±836.6 respectively; p = ns). Conclusions: Our data confirm with a non-invasive technique the presence of a more evident retinal arterioles remodeling in PA patients compared to EH patients, as suggested by the increased WLR, and an improvement in WLR after PA surgical or pharmacological treatment. Further studies in a larger population are needed in order to confirm these data.

Early microvascular modifications in patients previously hospitalized for COVID-19: comparison with healthy individuals

BackgroundSARS-CoV2 infection has been associated to a wide range of clinical scenarios, named COVID-19, ranging from acute respiratory distress syndrome to blood coagulation abnormalities and vascular manifestations related to hyper-inflammation. Recent focus has been addressed to study of microvascular alterations which may explain COVID-19 pathophysiology. Alterations in microvascular structure, identified as increased wall to lumen ratio (WLR) of retinal arterioles, have been extensively described in patients with cardiovascular diseases, such as hypertension or diabetes mellitus. Both inflammation and immune system dysregulation seem to play a role in the pathogenesis of these morphological changes.PurposeAim of this study was to evaluate through Adaptive Optics microvascular differences of retinal arterioles between patients experienced COVID-19 and controls.MethodsPatients were hospitalized between 28th February and 15th April at a Internal Medicine ward in a tertiary care hospital. All patients tested positive for a SARS-CoV-2 nasopharyngeal swab at admission and showed signs of pneumonia and respiratory insufficiency. Adaptive Optics, which allows a non-invasive evaluation of retinal arteriole structure, and blood chemistry exams were performed as part of follow up visits between 2 to 3 months after hospitalization. Baseline characteristics were collected through medical records. COVID-19 patients were compared to age- and sex-matched healthy subjects referred to our center between 2018 and 2019.ResultsA total of 80 patients were included in this study (of which 40 were COVID-19 patients). Apart from smoking habit, other baseline characteristics (sex, age, cardiovascular risk factors and main comorbidities) did not differ between the two groups. At follow up visit COVID-19 patients showed lower values for leukocytes (6.2 vs. 7.5x103/μL, p=0.015) and lymphocytes (1.9 vs. 2.8x103/μL, p=0.002). Creatinine values were higher in patients who suffered from COVID-19 (1.0 vs 0.8 mg/dl, p=0.004 – Figure 1, panel A). Adaptive Optics showed no differences in terms of internal lumen, wall thickness and WLR of retinal arterioles. However, the wall cross-sectional area (WCSA) was found to be higher in COVID-19 patients (p=0.039 – Figure 1, panel B). Hypertension significantly affected both WCSA and WLR between COVID-19 and healthy individuals, while diabetes only impacted on WLR (Figure 2).ConclusionPrevious studies described the presence of leukopenia and lymphopenia during the acute phase of SARS-CoV2 infection. Our study demonstrates that these alterations persist several weeks after symptoms onset. Adaptive Optics showed microvascular alterations occurring in these patients: in particular, higher wall cross-sectional area of retinal arterioles were observed in patients after COVID-19 hospitalization, reflecting the complex pathogenic mechanisms which may explain the wide range of symptoms and clinical severity.Funding AcknowledgementType of funding sources: None. Figure 1Figure 2

Effect of aliskiren on vascular remodelling in small retinal circulation

In hypertension, changes in small arterial structure are characterized by an increased wall-to-lumen ratio (WLR). These adaptive processes are modulated by the rennin-angiotensin system. It is unclear whether direct renin inhibitors exert protective effects on small arteries in hypertensive patients. In this double-blind, randomized, placebo-controlled study (http://www.clinicaltrials.gov: NCT01318395), 114 patients with primary hypertension were randomized to additional therapy with either placebo or aliskiren 300 mg for 8 weeks after 4 weeks of standardized open-label treatment with valsartan 320 mg (run-in phase). Parameter of arteriolar remodelling was WLR of retinal arterioles (80 - 140 μm) assessed noninvasively and in vivo by scanning laser Doppler flowmetry (Heidelberg Engineering, Germany). In addition, pulse wave analysis (SphygmoCor, AtCor Medical, Australia) and pulse pressure (PP) amplification were determined. In the whole study population, no clear effect of additional therapy with aliskiren on vascular parameters was documented. When analyses were restricted to patients with vascular remodelling, defined by a median of WLR more than 0.3326 (n = 57), WLR was reduced after 8 weeks by the treatment with aliskiren compared with placebo (-0.044 ± 0.07 versus 0.0043 ± 0.07, P = 0.015). Consistently, after 8 weeks of on-top treatment with aliskiren, there was an improvement of PP amplification compared with placebo (0.025 ± 0.07 versus -0.034 ± 0.08, P = 0.013), indicative of less stiff arteries in the peripheral circulation. Thus, our data indicate that treatment with aliskiren, given on top of valsartan therapy, improves altered vascular remodelling in hypertensive patients.

Wall‐to‐lumen ratio of retinal vessels in patients with cerebrovascular damage

Abstract Purpose There is evidence that generalized retinal arteriolar narrowing, which can be measured by the arteriole‐to‐venule ratio (AVR) of retinal vessels, predicts cerebrovascular events. The wall‐to‐lumen ratio (WLR) and wall cross‐sectional area (WCSA) of retinal arterioles reflect structural arteriolar parameters. The primary objective was to test the association between WLR and AVR in patients with cerebrovascular damage. Methods In this cross‐sectional study, 23 patients (57.5 +/‐ 9.4 years) with acute transitory ischemic attack or lacunar cerebral infarct were compared with two age‐matched control groups: 83 subjects with essential hypertension (53.7 +/‐ 5.5 years) and 16 normotensive subjects (52.2 +/‐ 8.3 years). Retinal arteriolar parameters (WLR, WTH, and WCSA) were assessed in vivo with scanning laser Doppler flowmetry (SLDF). AVR and a qualitative evaluation of retinal vessels were obtained from digital retinal color photographs. The intima‐media thickness (IMT) of the carotid artery was measured. Results WLR (0.44 +/‐ 0.1 vs. 0.34 +/‐ 0.1 vs. 0.30 +/‐ 0.1, P < 0.001) and carotid IMT (P < 0.05) were significantly greater in the cerebrovascular event group compared with normotensive subjects. WLR and WCSA were significantly higher in the cerebrovascular event group compared with subjects with mild arterial hypertension. AVR was similar in all three study groups. Conclusion The increase in WLR and WCSA of retinal arterioles, as well as in IMT in patients with cerebrovascular damage suggests vascular hypertrophy in the microvascular and macrovascular bed. The lack of association between AVR of retinal vessels and WLR of retinal arterioles

Wall-to-lumen ratio of retinal arterioles is related with urinary albumin excretion and altered vascular reactivity to infusion of the nitric oxide synthase inhibitor N-monomethyl-L-arginine

We hypothesized that wall-to-lumen ratio (WLR) of retinal arterioles might serve as an in-vivo parameter of vascular damage. To test this hypothesis we examined whether WLR of retinal arterioles is related with increased urinary albumin excretion and altered vascular reactivity to infusion of the nitric oxide synthase inhibitor N-monomethyl-L-arginine (L-NMMA). Thirty-nine never-treated male patients aged 18-65 years with a body mass index at least 25 kg/m(2) and without diabetes mellitus or secondary or stage 3 arterial hypertension were examined. WLR of retinal arterioles was assessed using scanning laser Doppler flowmetry. Urinary albumin-to-creatinine ratio (UACR) was measured from first morning spot urine. Vascular reactivity was measured by the change of aortic augmentation index (aAIx) to infusion of L-NMMA. UACR was related with WLR of retinal arterioles (r = 0.352, P = 0.032). In response to L-NMMA infusion aAIx increased (from 10.7 +/- 11 to 19.7 +/- 11%, P < 0.001). The change of aAIx to L-NMMA infusion was inversely related with WLR of retinal arterioles (r = -0.462, P = 0.003) even after adjustment for changes of hemodynamic parameters to L-NMMA infusion (partial r = -0.475, P = 0.005). The relationships of UACR and the change of aAIx to L-NMMA infusion with WLR of retinal arterioles were found to be independently of other cardiovascular risk factors (ss = 0.386, P = 0.006; ss = -0.369, P = 0.004, respectively) in multiple regression analyses with separate models for both parameters. Increased WLR of retinal arterioles may thus serve as an in-vivo marker of vascular damage.

Wall-to-Lumen Ratio of Retinal Arterioles and Arteriole-to-Venule Ratio of Retinal Vessels in Patients with Cerebrovascular Damage

There is evidence that generalized retinal arteriolar narrowing, which can be measured by the arteriole-to-venule ratio (AVR) of retinal vessels, predicts cerebrovascular events. The wall-to-lumen ratio (WLR) and wall cross-sectional area (WCSA) of retinal arterioles reflect structural arteriolar parameters. The primary objective was to test the association between WLR and AVR in a distinct cohort of patients with cerebrovascular damage. In this cross-sectional study, 23 patients (57.5 +/- 9.4 years) with acute transitory ischemic attack or lacunar cerebral infarct were compared with two age-matched control groups: 83 subjects with essential hypertension (53.7 +/- 5.5 years) and 16 normotensive subjects (52.2 +/- 8.3 years). Retinal arteriolar parameters (WLR, WTH, and WCSA) were assessed in vivo with scanning laser Doppler flowmetry (SLDF). AVR and a qualitative evaluation of retinal vessels were obtained from digital retinal color photographs. The intima-media thickness (IMT) of the carotid artery was measured. WLR (0.44 +/- 0.1 vs. 0.34 +/- 0.1 vs. 0.30 +/- 0.1, P < 0.001) and carotid IMT (P < 0.05) were significantly greater in the cerebrovascular event group compared with normotensive subjects. WLR and WCSA were significantly higher in the cerebrovascular event group compared with subjects with mild arterial hypertension. AVR was similar in all three study groups (0.75 +/- 0.07 vs. 0.74 +/- 0.07 vs. 0.78 +/- 0.1, P = 0.18). The increase in WLR and WCSA of retinal arterioles, as well as in IMT in patients with cerebrovascular damage suggests vascular hypertrophy in the microvascular and macrovascular bed. The lack of association between AVR of retinal vessels and WLR of retinal arterioles may point to different stages of cerebrovascular disease and/or different pathophysiological changes in the arteriolar wall.