Cardio-Ankle Vascular Index and Indices of Diabetic Polyneuropathy in Patients with Type 2 Diabetes

Relationship between reduced heart rate variability and increased arterial stiffness evaluated by the cardio-ankle vascular index in people with type 2 diabetes

Objective

Cardiac autonomic neuropathy (CAN) is an independent risk factor for cardiovascular mortality and also is associated with a high risk of lethal arrhythmias and sudden death in people with type 1 or 2 diabetes. Heart rate variability (HRV) is an index of cardiac autonomic function. To investigate the relationship between HRV and arterial stiffness evaluated by the cardio-ankle vascular index (CAVI), a relatively new marker for arterial stiffness and a predictor of cardiovascular disease, in patients with type 2 diabetes.

Materials and methods

We studied consecutive 313 patients with type 2 diabetes in a cross-sectional design. HRV was estimated by the coefficient of variation of 100 R-R intervals (CVR-R) at rest and during deep breathing (DB). The difference in CVR-R was defined as CVR-R during DB minus CVR-R at rest. Arterial stiffness was evaluated by CAVI, which is independent of blood pressure (BP). A CAVI greater than or equal to 9.0 was defined as significant arterial stiffening.

Results

Linear regression analysis showed that CAVI correlated positively with age, duration of diabetes, urinary albumin creatinine ratio (UACR), CVR-R during DB, and the difference in CVR-R and negatively with body mass index (BMI), estimated glomerular filtration rate, and sensory nerve conduction velocity and action potential of the sural nerve. Multivariate analysis found that age, BMI, systolic blood pressure, UACR, and CVR-R during DB were independently associated with arterial stiffness determined by CAVI. The CVR-R at rest and during deep breathing was significantly lower in the patients with arterial stiffness than in those without it.

Conclusion

Low HRV estimated by CVR-R during DB is closely associated with arterial stiffness measured by CAVI in people with type 2 diabetes, suggesting that arterial stiffness associated with CAN may be an independent risk factor for cardiovascular disease in people with type 2 diabetes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13340-022-00604-y.

Impact of Plasma Xanthine Oxidoreductase Activity on the Mechanisms of Distal Symmetric Polyneuropathy Development in Patients with Type 2 Diabetes

To unravel associations between plasma xanthine oxidoreductase (XOR) and diabetic vascular complications, especially distal symmetric polyneuropathy (DSP), we investigated plasma XOR activities using a novel assay. Patients with type 2 diabetes mellitus (T2DM) with available nerve conduction study (NCS) data were analyzed. None were currently taking XOR inhibitors. XOR activity of fasting blood samples was assayed using a stable isotope-labeled substrate and LC-TQMS. JMP Clinical version 5.0. was used for analysis. We analyzed 54 patients. Mean age was 64.7 years, mean body mass index was 26.0 kg/m², and mean glycated hemoglobin was 9.4%. The logarithmically transformed plasma XOR activity (ln-XOR) correlated positively with hypoxanthine, xanthine, visceral fatty area, and liver dysfunction but negatively with HDL cholesterol. ln-XOR correlated negatively with diabetes duration and maximum intima-media thickness. Stepwise multiple regression analysis revealed ln-XOR to be among selected explanatory factors for various NCS parameters. Receiver operating characteristic curves showed the discriminatory power of ln-XOR. Principal component analysis revealed a negative relationship of ln-XOR with F-waves as well as positive relationships of ln-XOR with hepatic steatosis and obesity-related disorders. Taken together, our results show plasma XOR activity to be among potential disease status predictors in T2DM patients. Plasma XOR activity measurements might reliably detect pre-symptomatic DSP.

[Cardio-ankle vascular index (CAVI) in diagnostics, risk and severity evaluation of magistral vessels lesion in patients with cardio-vascular diseases and type 2 diabetes]

Assesment of arterial stiffness the substantional prognostic factor for evaluating complications of cardiovascular diseases (CVD) in patients with atherosclerosis, hypertension and type 2 diabetes, may be performed using different parameters, including cardio-ankle vascular index (CAVI). The main purpose of this review is to analyze data from studies where CAVI is used to test the arterial wall stiffness in magistral vessels. CAVI measurement is non-invasive and performed by portable devices which makes it comfortable for ambulatory use in patients who come for a check-up and also in those who already are hospitalized. It does not require any special knowledge from investigator and the test lasts a couple of minutes long. CAVI does not depend on blood pressure changes and is more specific in structural changes of arterial wall assessment than brachial-ankle pulse wave velocity (baPWV). CAVI shows considerable correlation with markers of CVD like atherosclerotic plaques in vessels, diastolic disfunction of left ventricle and angina pectoris. CAVI may be used for early monitoring and assessing the lesions of target organs in patients with atherosclerosis, chronic hypertension and type 2 diabetes. Establishing CAVI as a standart parameter in assessing patients who are at risk of CVD can help to improve complications prevention, reduce mortality and prolong their lifespan.

Small Fibre Neuropathy Is Associated With Impaired Vascular Endothelial Function in Patients With Type 2 Diabetes

Diabetic polyneuropathy (DPN) and endothelial dysfunction are prevalent complications of diabetes mellitus. Currently, there are two non-invasive markers for endothelial dysfunction: flow-mediated dilation and reactive hyperaemia peripheral arterial tonometry (RH-PAT). However, the relationship between diabetic small fibre neuropathy and macroangiopathy remains obscure thus far. Corneal confocal microscopy (CCM) has emerged as a new diagnostic modality to assess DPN, especially of small fibre. To clarify the relationship between diabetic small fibre neuropathy and vascular dysfunction, we aimed to determine the functions of peripheral nerves and blood vessels through clinical tests such as nerve conduction study, coefficient of variation in the R-R interval, CCM, and RH-PAT in 82 patients with type 2 diabetes. Forty healthy control subjects were also included to study corneal nerve parameters. Correlational and multiple linear regression analyses were performed to determine the associations between neuropathy indices and markers for vascular functions. The results revealed that patients with type 2 diabetes had significantly lower values for most variables of CCM than healthy control subjects. RH-PAT solely remained as an explanatory variable significant in multiple regression analysis for several CCM parameters and vice versa. Other vascular markers had no significant multiple regression with any CCM parameters. In conclusion, endothelial dysfunction as revealed by impaired RH-PAT was significantly associated with CCM parameters in patients with type 2 diabetes. This association may indicate that small fibre neuropathy results from impaired endothelial dysfunction in type 2 diabetes. CCM parameters may be considered surrogate markers of autonomic nerve damage, which is related to diabetic endothelial dysfunction. This study is the first to report the relationship between corneal nerve parameter as small fibre neuropathy in patients with type 2 diabetes and RH-PAT as a marker of endothelial dysfunction.

[Possibilities of application of cardio-ankle vascular index in patients with cerebrovascular diseases]

This publication focuses on the feasibility of using the cardio-ankle vascular index (CAVI) in patients with cerebrovascular diseases. The authors consider the pathological conditions and risk factors of stroke associated with increased arterial stiffness, methods for its assessment, the advantages of using CAVI, the experience of using CAVI in patients with cardiovascular diseases, in particular, in neurological patients. The complexity of the application of CAVI in the Russian population, promising directions for determining the index in neurology as well as the importance of CAVI borderline indicators are shown. It is emphasized that stroke patients should be screened with a mandatory study of CAVI.

Association of decreased variation of coefficient R-R interval with ischemic colitis and small bowel obstruction

Background

The parasympathetic nervous system exerts and controls intestinal tone. Several studies have suggested that the coefficient of the R–R intervals (CVRR) is useful for evaluating the parasympathetic nervous system.

Objectives

This study aimed to evaluate the relationship between gastrointestinal emergencies, specifically ischemic colitis (IC) and small bowel obstruction (SBO), and the autonomic nervous system.

Methods

In this retrospective study, a total of 13 patients with IC or SBO aged ≧65 years were analyzed. CVRR was measured in patients with IC and SBO and controls.

Results

CVRR averaged to 8.8% ± 2.5% in controls, 1.4% ± 0.4% in patients with IC, and 2.4% ± 1.0% in SBO groups (p < 0.001). CVRR was significantly lower in patients with IC and SBO than that in controls.

Conclusion

The results of this study demonstrate the possibility that CVRR may serve as a clinical index for assessing the functioning of the parasympathetic nervous system in patients with IC or SBO.

Arterial Stiffness Assessed by Cardio-Ankle Vascular Index

Arterial stiffness is an age-related disorder. In the medial layer of arteries, mechanical fracture due to fatigue failure for the pulsatile wall strain causes medial degeneration vascular remodeling. The alteration of extracellular matrix composition and arterial geometry result in structural arterial stiffness. Calcium deposition and other factors such as advanced glycation end product-mediated collagen cross-linking aggravate the structural arterial stiffness. On the other hand, endothelial dysfunction is a cause of arterial stiffness. The biological molecular mechanisms relating to aging are known to involve the progression of arterial stiffness. Arterial stiffness further applies stress on large arteries and also microcirculation. Therefore, it is closely related to adverse outcomes in cardiovascular and cerebrovascular system. Cardio-ankle vascular index (CAVI) is a promising diagnostic tool for evaluating arterial stiffness. The principle is based on stiffness parameter β, which is an index intended to assess the distensibility of carotid artery. Stiffness parameter β is a two-dimensional technique obtained from changes of arterial diameter by pulse in one section. CAVI applied the stiffness parameter β to all of the arterial segments between heart and ankle using pulse wave velocity. CAVI has been commercially available for a decade and the clinical data of its effectiveness has accumulated. The characteristics of CAVI differ from other physiological tests of arterial stiffness due to the independency from blood pressure at the time of examination. This review describes the pathophysiology of arterial stiffness and CAVI. Molecular mechanisms will also be covered.

Nerve conduction velocity is negatively associated with intima-media thickness and brachial-ankle pulse wave velocity in men with type 2 diabetes mellitus

Objective

Previous studies suggest that the presence of diabetic peripheral polyneuropathy (DPN) is associated with atherosclerotic diseases; however, little is known about the relationship between diabetic nerve conduction velocity (NCV) versus arterial stiffness and atherosclerosis parameters.

Methods

The subjects in this study were 292 men with type 2 diabetes mellitus (T2DM). All subjects underwent NCV examination at median and tibial nerves as motor nerve (MCV) as well as median and sural nerves as sensory nerve (SCV). Brachial-ankle pulse wave velocity (baPWV) and carotid intima-media thickness (IMT) were evaluated as arterial stiffness and atherosclerosis parameters.

Results

Pearson’s correlation coefficient showed that NCV at all sites negatively correlated with baPWV, maximal and mean IMT (IMT-Max and IMT-Mean), and plaque score (all p values p<0.01 at least). Multiple regression analyses adjusted for confounding factors such as age, duration of diabetes, body mass index, HbA1c, fasting C-peptide, systolic blood pressure, HDL-cholesterol, LDL-cholesterol and albuminuria showed that the association of NCV with IMT-Max, ITM-Mean, and plaque score remained significant (all p values p<0.05 at least) except that between SCV at median and IMT-Max. Moreover, SCV at median (forearm) and sural were significantly associated with baPWV (p = 0.023 and p = 0.027, respectively).

Conclusion

The present study showed that DPN estimated by quantitative NCV is linearly associated with the deterioration of arterial stiffness and atherosclerosis parameters in T2DM independently of various diabetic and atherosclerotic factors.

Vascular factors and neuropathy in lower limb of diabetic patients

Asymmetric clinical presentation in some patients with diabetic polyneuropathy may result from the different vascular environments in both lower limbs. The aim of the study is to determine the association of neuropathy with vascular factors in each lower limb of diabetic patients. A total of 102 patients (204 lower limbs) given a diagnosis of diabetic polyneuropathy were enrolled. The primary end points are sensory nerve action potential (SNAP) amplitude and conduction velocity (CV) of the sural nerve and independent variables are vascular and nonvascular factors. Vascular factors include mean arterial pressure and pulse pressure at the ankle, ankle-brachial index, and arterial stiffness assessed by pulse wave velocity. Nonvascular factors include age, gender, height, body weight, body mass index, total cholesterol, and hemoglobin A₁C. Age, hemoglobin A₁C, and ankle pulse pressure were inversely correlated with SNAP amplitude of the sural nerve, while no factors were correlated with CV of the sural nerve. Increased arterial stiffness was significant in the limbs group with abnormal SNAP amplitude of the sural nerve, while increased height was significant in the limbs group with abnormal CV of the sural nerve. Vascular factors were more significantly associated with decreased SNAP amplitude rather than decreased CV of the sural nerve in the nerve conduction study of diabetic patients.

Relationship between Systemic Vascular Characteristics and Retinal Nerve Fiber Layer Loss in Patients with Type 2 Diabetes

Retinal nerve fiber layer (RNFL) loss in diabetic patients is especially common regardless of diabetic retinopathy (DR). The correlations between nonglaucomatous RNFL loss and systemic characteristics in diabetic patients have aroused interests in many aspects. 167 subjects with type 2 diabetes who underwent evaluation for arterial stiffness and cardiovascular autonomic function using heart rate variability (HRV) were included in this study. Arterial stiffness was measured using cardio-ankle vascular index (CAVI) and ankle-brachial index (ABI). Multivariate regression analysis was performed to determine factors influencing the presence of RNFL loss according to age. Factors determining the superior location of diabetic RNFL loss were also investigated. CAVI were worse in patients with RNFL loss, especially in those with old age (≥50 yrs) (p = 0.037). Influential factor of RNFL defect in old group was ABI (p = 0.007). However, in young group (<50 yrs), HRV parameter (low-frequency/high-frequency ratio) determined the presence of RNFL loss (p = 0.040). Significant determinants of superior RNFL defect in old subjects were CAVI and ABI (p = 0.032 and p = 0.024). For young diabetic patients, autonomic dysfunction may have relationship with RNFL loss, but as patients get older, arterial stiffness could aggravate vascular autoregulation and diabetic RNFL loss. RNFL loss in diabetes may be correlated with systemic vascular conditions.