Microvascular optical assessment confirms the presence of peripheral autonomic dysfunction in primary biliary cirrhosis

Capabilities of photoplethysmography as a method for screening of cardiovascular system pathology

Currently, vegetative dysfunction considered to be one of principal mechanisms in the pathogenesis of cardiovascular pathology, which causes a cascade of events leading to changes in the properties and a structure of vascular wall. This review article contains literature from various databases (Russian science citation index, PubMed, Google Shcolar, Scopus). It presents the methods for assessing vegetative imbalance. In particular, the method of photoplethysmography (PPGV) is considered for recording periodic fluctuations at various frequencies in the distal vascular bed which characterize physiological processes (cardiac activity, respiratory influences, neurogenic, myogenic and endothelial activity). In addition, other diagnostic capabilities of PPGV such as heart rate (HR) assessment, determining the properties of vascular wall and the level of blood saturation are elucidated. This paper demonstrates a wide range of PPGV applications. The simplicity of PPGV reproduction and its cost-effectiveness make it feasible both in routine clinical practice for the purposes of screening for cardiovascular pathology, and for individual health monitoring incorporated in smart devices.

Fatigue in chronic liver disease: New insights and therapeutic approaches

The management of fatigue associated with chronic liver disease is a complex and major clinical challenge. Although fatigue can complicate many chronic diseases, it is particularly common in diseases with an inflammatory component. Fatigue can have both peripheral (i.e., neuromuscular) and central (i.e., resulting from changes in neurotransmission within the brain) causes. However, fatigue in chronic liver disease has strong social/contextual components and is often associated with behavioural alterations including depression and anxiety. Given the increasing awareness of patient-reported outcomes as important components of treatment outcomes and clinical research, there is a growing need to better understand and manage this poorly understood yet debilitating symptom. Although several pathophysiological mechanisms for explaining the development of fatigue have been generated, our understanding of fatigue in patients with chronic liver disease remains incomplete. A better understanding of the pathways and neurotransmitter systems involved may provide specific directed therapies. Currently, the management of fatigue in chronic liver disease can involve a combined use of methods to beneficially alter behavioural components and pharmacological interventions, of which several treatments have potential for the improved management of fatigue in chronic liver disease. However, evidence and consensus are lacking on the best approach and the most appropriate biochemical target(s) whilst clinical trials to address this issue have been few and limited by small sample size. In this review, we outline current understanding of the impact of fatigue and related symptoms in chronic liver disease, discuss theories of pathogenesis, and examine current and emerging approaches to its treatment.

Cholinergic Anti-Inflammatory Pathway and the Liver

The hepatic vagus branches innervate the liver and serve an important role in liver-brain connection. It appears that brain modulates inflammatory responses by activation of vagal efferent fibers. This activation and subsequent acetylcholine releases from vagus nerve terminals leads to inhibition of inflammatory cytokines through α7 nicotinic acetylcholine receptors (α7nAChRs) which located on the surface of different cell types such as liver Kupffer cells. This protective role of vagus-α7nAChR axis in liver diseases has been shown in several experimental studies. On the other hand, accumulated evidence clearly demonstrate that, autonomic dysfunction which is reduced functioning of both vagal and sympathetic nervous system, occurs during chronic liver disease and is well-known complication of patients suffering from cirrhosis. This review describes the impact and significance of cholinergic anti-inflammatory pathway in the liver and discusses about its disease-related dysfunction on the progression of cirrhosis. Considering the fact that sepsis is major cause of death in cirrhotic patients, convergence of these findings, may lead to designing novel therapeutic strategies in the field of chronic liver diseases management involving selective drug targeting and electrical nerve stimulation.

Early primary biliary cholangitis is characterised by brain abnormalities on cerebral magnetic resonance imaging

BACKGROUND

Brain change can occur in primary biliary cholangitis (PBC), potentially as a result of cholestatic and/or inflammatory processes. This change is linked to systemic symptoms of fatigue and cognitive impairment.

AIM

To identify whether brain change occurs early in PBC. If the change develops early and is progressive, it may explain the difficulty in treating these symptoms.

METHODS

Early disease brain change was explored in 13 patients with newly diagnosed biopsy-proven precirrhotic PBC using magnetisation transfer, diffusion-weighted imaging and ¹ H magnetic resonance spectroscopy. Results were compared to 17 healthy volunteers.

RESULTS

Cerebral magnetisation transfer ratios were reduced in early PBC, compared to healthy volunteers, in the thalamus, putamen and head of caudate with no greater reduction in patients with greater symptom severity. Mean apparent diffusion coefficients were increased in the thalamus only. No ¹ H magnetic resonance spectroscopy abnormalities were seen. Serum manganese levels were elevated in all PBC patients, but no relationship was seen with imaging or symptom parameters. There were no correlations between neuroimaging data, laboratory data, symptom severity scores or age.

CONCLUSIONS

This is the first study to be performed in this precirrhotic patient population, and we have highlighted that neuroimaging changes are present at a much earlier stage than previously demonstrated. The neuroimaging abnormalities suggest that the brain changes seen in PBC occur early in the pathological process, even before significant liver damage has occurred. If such changes are linked to symptom pathogenesis, this could have important implications for the timing of second-line-therapy use.

The role of autonomic dysfunction in cirrhotic patients before and after liver transplantation. Review of the literature

In patients affected by hepatic cirrhosis, autonomic dysfunction is a common finding; usually it is asymptomatic but it may correlate with increased mortality and morbidity before, during and after liver transplant, due to hemodynamic instability in the course of stressful events like sepsis, gastrointestinal bleeding and reperfusion after transplantation surgery. Hyperdynamic circulation and hepatic dysfunction seem to play a role in the pathogenesis of autonomic dysfunction, even if pathophysiological mechanisms are not completely known. We present a revision of previous literature about prevalence, pathophysiological mechanisms, clinical features, and mortality and morbidity of autonomic dysfunction secondary to hepatic cirrhosis.

Shared symptoms and putative biological mechanisms in chronic liver disease: implications for biobehavioral research

Liver disease affects over 25 million people in the United States and, despite advances in medical management resulting in increased survival, a majority of these individuals report multiple co-occurring symptoms that severely impair functioning and quality of life. The purpose of this review is to (1) propose defining these co-occurring symptoms as a symptom cluster of chronic liver disease (CLD), (2) discuss putative underlying biological mechanisms related to CLD, including the liver-gut-brain axis and influence of the microbiome, and (3) discuss the implications for biobehavioral research in this patient population. Biobehavioral research focusing on the interrelated, and possibly synergistic, mechanisms of these symptoms may lead to the development and testing of targeted symptom management interventions for improving function and quality of life in this growing patient population.

Novel photoplethysmography cardiovascular assessments in patients with Raynaud's phenomenon and systemic sclerosis: a pilot study

OBJECTIVE

Multisite photoplethysmography (PPG) cardiovascular assessments can evaluate endothelial, peripheral autonomic and arterial dysfunction. The aim of this pilot study was to investigate the potential clinical utility of the technology in assessing patients with SSc and primary RP (PRP).

METHODS

Multisite PPG pulse measurements, a reference ankle brachial pressure index (ABPI) and a full clinical assessment were undertaken for three subject groups: SSc, PRP and controls. Endothelial and autonomic function and arterial disease measures were obtained using pulse wave analysis.

RESULTS

Nineteen SSc, 19 PRP and 23 control subjects were assessed and compared. Endothelial function was significantly impaired in SSc (P < 0.02), but with no difference between controls and PRP. Receiver operating characteristic-based classification accuracy was 81% (sensitivity 90%, specificity 74%) for separating SSc from controls and 82% (sensitivity 84%, specificity 79%) for separating SSc from PRP. SSc patients with digital ulcers had significantly lower endothelial function compared with those without ulcers (P < 0.05). Autonomic dysfunction was suggested in both SSc and PRP and was most exaggerated in patients with diffuse SSc. All groups had overall normal ABPI and arterial stiffness timing measures. Bilateral timing differences at the toes, which represents peripheral occlusive arterial disease, did show increased asymmetry in SSc (P < 0.02).

CONCLUSION

Multisite PPG pulse technology showed potential diagnostic ability. By using measures of endothelial function, it differentiated SSc from control and PRP subjects with an accuracy of at least 81%. Objective pulse-derived measures of autonomic function and arterial disease in SSc have also been reported in this pilot study.

Primary Sjogrens syndrome is associated with impaired autonomic response to orthostasis and sympathetic failure

BACKGROUND

Symptoms in keeping with autonomic dysfunction are commonly described by primary Sjögrens syndrome patients (pSS); whether objective abnormalities of autonomic function occur is unclear. This study set out to explore dynamic cardiovascular autonomic responses in pSS and their relationship with symptoms and quality of life.

METHODS

Twenty-one people from the UK pSS registry, 21 community controls and 21 patients with the autoimmune liver disease primary biliary cirrhosis (PBC) (matched case-wise for age and sex) attended for assessment of autonomic responses to orthostasis and Valsalva manoeuvre (VM). pSS patients also completed EULAR Sjögrens Syndrome patient-reported index (ESSPRI), EULAR Sjögren's syndrome disease activity index (ESSDAI), fatigue impact scale and EURO-QOL 5-dimension (EQ-5D).

RESULTS

Compared with controls, pSS patients had significantly lower baseline systolic blood pressure (SBP) (114 ± 13 vs. 127 ± 20; P = 0.02), which dropped to a significantly lower value (98 ± 22 vs. 119 ± 24, P = 0.009). When area under the curve (AUC) was calculated for when the SBP was below baseline this was significantly greater in pSS compared to both control groups (pSS vs. control vs. PBC: 153 ± 236 vs. 92 ± 85 vs. 1.2 ± 0.3, P = 0.005). Peak phase IV SBP during the VM was significantly lower in pSS (P = 0.007) indicating early sympathetic failure. Increased heart rate associated with fatigue (P = 0.02; r(2) = 0.2) and EQ-5D. A shift in sympathetic-vagal balance associated with overall symptom burden (ESSPRI) (P = 0.04, r(2) = 0.3) and EULAR sicca score (P = 0.016; r(2) = 0.3), the latter also correlated with baroreceptor effectiveness (P = 0.03; r(2) = 0.2) and diastolic blood pressure variability (P = 0.003; r(2) = 0.4).

CONCLUSION

pSS patients have impaired blood pressure response to standing. Dysautonomia correlates with PSS-associated symptoms and quality of life.

Managing systemic symptoms in chronic liver disease

Improved medical management and the changing disease demographic mean that the majority of patients with chronic liver disease are living with the disease rather than dying from it. Historically, the perception has been that the impact of chronic liver disease is related entirely to the consequences of endstage liver disease; however, more recently a number of systemic symptoms have been recognised that can occur at any point in the natural history of chronic liver disease and which can be associated with functional impairment and reduced quality of life. The most characteristic of these systemic symptoms is fatigue, which frequently associates with sleep disturbance and autonomic dysfunction, particularly manifest as abnormality of blood pressure regulation. Cognitive symptoms can occur even in non-cirrhotic patients. Falls can present in patients with autonomic dysfunction, complicated by the presence of peripheral muscle strength problems. Importantly for clinicians managing chronic liver disease, the severity of these systemic symptoms is typically not related to liver disease severity, and therefore despite optimal liver disease management, patients can often continue to experience debilitating symptoms. The similarity in systemic symptoms between different chronic liver diseases (and indeed chronic inflammatory conditions affecting other organs) suggests the possibility of shared pathogenetic processes and raises the possibility of common management strategies, although further research is urgently needed to confirm this. In primary biliary cirrhosis, where our understanding of systemic symptoms is arguably most developed, structured management strategies have been shown to improve the quality of life of patients. It is highly likely that similar approaches will have comparable benefits for other chronic liver disease groups. Here, we review the current understanding of systemic symptoms in chronic liver disease and offer recommendations regarding the successful management of these symptoms. Critical for successful treatment is use of a structured and systematic approach to management in which all contributing factors are addressed in an organised fashion. We believe that such a systematic approach, when applied to research as well as to clinical management, will allow us to reduce the overall burden of chronic liver disease, improve quality of life and enhance functional ability.

Impaired cardiovascular function in primary biliary cirrhosis

Cardiovascular system dysregulation in the form of autonomic dysfunction is common at all stages of the disease process in the autoimmune liver disease primary biliary cirrhosis (PBC) and associates with the symptom of fatigue. The mechanisms underpinning autonomic dysfunction in PBC are, however, at present unclear. In this study we set out to explore, for the first time, cardiac structure and function in PBC using impedance cardiography (ICG) and magnetic resonance methodologies. ICG was assessed beat to beat in response to orthostasis (by head-up tilt) in age and sex case-matched high-fatigue and low-fatigue PBC groups (assessed by Fatigue Impact Scale), normal control subjects (n = 15 each group) and a liver disease control cohort (primary sclerosing cholangitis). Cardiac structure and bioenergetics were examined in 15 of the PBC subjects and 8 of the normal control subjects by magnetic resonance spectroscopy and cine imaging. Capacity of the left ventricle to respond to orthostasis [left ventricular ejection time (LVET)] was impaired in PBC compared with matched normal control subjects (P = 0.05). This was a PBC-specific phenomenon unrelated to fatigue status. PBC patients exhibited significantly lower cardiac muscle phosphocreatine-to-ATP ratio (PCr/ATP ratio; measure of cardiac bioenergetic integrity) compared with control subjects (P < 0.01). PCr/ATP <1.6 (indicative of increased risk of death in cardiomyopathy) was present in 6/15 (40%) PBC patients (0/8 control subjects; P < 0.05). Cardiac structure and function were similar in all measures of left ventricular morphology between control subjects and PBC. The close relationship between PCr/ATP and LVET seen in normal subjects (r(2) = 0.6; P < 0.05) was lost in PBC patients, a finding compatible with myocardial dysfunction. Significant correlation was seen between fatigue severity in PBC and fall in cardiac output on orthostasis (r(2) = 0.25; P = 0.005). Our findings suggest the presence of altered myocardial function in PBC. Autonomic "dysfunction" may, rather than being an abnormal process, represent a compensatory mechanism to increase cardiac return to mitigate these effects.