Nailfold capillary patterns correlate with age, gender, lifestyle habits, and fingertip temperature

Quantitative image analysis of nailfold capillaries during an in-hospital education program for type 2 diabetes or obesity

Nailfold capillaries are small U-shaped vessels located beneath the skin at the proximal part of the fingernail, and their morphology changes owing to various diseases. This study quantitatively analyzed nailfold capillaries using microscopy in patients hospitalized for 2 weeks for education and treatment of type 2 diabetes (T2D) or obesity. Our results suggest that nailfold arterial diameter and smoking history are useful predictors of diabetic neuropathy. An elevated urinary albumin-to-creatinine ratio correlated with decreased venous diameter during hospitalization, reflecting latent intravascular hypoalbuminemia in patients with diabetic nephropathy. Both body mass index and short-term weight reduction during hospitalization correlated with the color contrast between the capillaries and the perivascular zone, defined as delta E. These results suggest that the morphology of nailfold capillaries in T2D and obesity could be useful indicators of diabetic neuropathy and nephropathy, with delta E being a useful indicator of extracellular water volume in these populations. This is the first study to observe short-term changes in nailfold capillary morphology in relation to interventions for lifestyle-related diseases.

Significant Microvascular Abnormalities Present in Autonomic Nervous System Dysfunction: Results of a Cross-Sectional Study

Purpose: The prevalence and phenotype of capillaroscopic abnormalities in patients with autonomic nervous system dysfunction have not yet been investigated. Multiorgan involvement in dysautonomia entails abnormal vasoreactivity. We aim to correlate the diagnosis of autonomic dysfunction with certain clinical manifestations, which may provide prognostic or diagnostic information using a noninvasive technique, i.e., nailfold video capillaroscopy (NVC). Methods: Patients with autonomic nervous system dysfunction were recruited from rheumatology and neurology clinics with voluntary NVC procedures from 31 January 2024 to 10 January 2024, and a comparison with normal controls was performed. Additional recorded information include demographics and diagnoses of autonomic dysfunction types by autonomic testing, including, but not limited to, the following: reflex screen, sweat test, Valsalva maneuver, nerve fiber density, electromyography (EMG), serology, and history of autoimmune diseases. NVC was performed on a total of 27 patients. This study was approved by the Mayo Clinic Institutional Review Board. Results: The autonomic dysfunction group consisted of small-fiber neuropathy (37%), orthostatic hypotension (48%), autonomic neuropathy (30%), limited autonomic neuropathy (7%), postural orthostatic tachycardia syndrome (POTS) (7%), and connective tissue disease (7%), among other types. Patients with autonomic dysfunction had statistically significant increases in microhemorrhages, dilated capillaries, and ramifications when compared to controls. Conclusions: Autonomic dysfunction was associated with statistically significant microvascular abnormalities compared to normal controls with a distinct NVC pattern. There was a statistically significant correlation between age and BMI with microvascular abnormalities. Here, we demonstrate the diagnostic potential of NVC in autonomic dysfunction and advocate for further study of capillary structures in autonomic dysfunction.

Association between nailfold capillaroscopic findings and diabetes: a systematic review and meta-analysis

PURPOSE

People with diabetes often experience abnormal microcirculation, which can lead to various complications. This study aimed to investigate the relevance of nailfold capillaroscopy-a non-invasive imaging modality-in characterizing microvascular alterations specific to diabetes mellitus (DM).

METHODS

PubMed, Web of Science, and Baidu Academic were searched for relavant studies that investigated the associations between nailfold microcirculation abnormalities and DM. The quality of included studies was assessed using the National Institutes of Health (NIH) Quality Assessment tool for Observational Cohort and Cross-Sectional Studies. Meta-analysis was conducted to assess the relationship of various nailfold capillaroscopic findings with DM, and subgroup analysis was used to explore heterogeneity.

RESULTS

Ten studies with 1,423 participants were included. The quality of two studies was rated as Good, one as Poor, and the other seven were rated as Normal. The pooled analysis revealed significant correlations between various nailfold capillaroscopic findings and DM, including tortuosity (odds ratio [OR] 8.33, 95% confidence interval [CI]: 2.31-30.04), abnormal morphology (OR 5.00, 95% CI 3.03-8.26), ectasia (OR 4.86, 95% CI 2.56-9.20), bushy capillaries (OR 29.09, 95% CI 5.90-143.55), hemorrhage (OR 5.33, 95% CI 2.31-12.34), avascular areas (OR 6.14, 95% CI 1.40-26.86), bizarre capillaries (OR 10.33, 95% CI 2.79-38.31), and meander capillaries (OR: 2.84, 95% CI 1.25-6.45). Subgroup analysis showed strong associations between nailfold capillaroscopic findings and type 2 diabetes mellitus (T2DM).

CONCLUSION

Our findings demonstrated that distinct nailfold capillary abnormalities aresignificantly correlated with DM, particularly T2DM.

PROTOCOL REGISTRATION

Protocol registered in PROSPERO (registration number: CRD42024608214).

Nailfold capillary patterns in ballgame and endurance athletes

Purpose

Nailfold capillary patterns can be observed noninvasively using light microscopy. Nailfold capillaries are straight, U-shaped, and densely looped in healthy individuals and may be altered by disease or lifestyle factors, such as diet. However, the effects of daily physical activity and exercise training on nailfold capillary patterns remain unclear. This study aimed to examine the effects of exercise training on nailfold capillary patterns by investigating these patterns in endurance athletes, ballgame athletes, and sedentary healthy men.

Methods

Five healthy men participated in nailfold capillary pattern measurements on three consecutive days to test the reproducibility and bilateral differences in the nailfold capillary loop density, length, and width measured using light microscopy and a commercial analysis system. The nailfold capillaries of 10 endurance athletes (endurance group; eight long-distance runners and two triathletes), 10 ballgame athletes (ballgame group; seven soccer players and three basketball players), and nine sedentary healthy men (sedentary group) were then examined using light microscopy.

Results

The day-to-day coefficient of variation for the nailfold capillary loop density, length, and width were 4.9% ± 1.6%, 7.5% ± 1.3%, and 4.2% ± 1.5%, respectively. No significant differences in these measurements were observed between the dominant and non-dominant hands. Nailfold capillary density was greater in the ballgame group than in the endurance and sedentary groups. Capillary loop length was shorter in the ballgame group than in the endurance and sedentary groups. No significant differences in capillary loop density and length were observed between the endurance and sedentary groups. No significant intergroup differences were observed in capillary loop width.

Conclusion

These results suggest that the nailfold capillary patterns of male ballgame athletes differ from those of endurance athletes and sedentary healthy men. Ballgame training may affect nailfold capillary patterns in sedentary healthy men.

Nailfold videocapillaroscopy - a novel method for the assessment of hemodynamic incoherence on the ICU

BACKGROUND

Loss of hemodynamic coherence is a phenomenon in critically ill patients. Due to inflammatory events and endothelial remodeling, macro- and microhemodynamics are decoupled from each other, resulting in microcirculatory disturbances and end organ ischemia despite adequate vital parameters. So far, quantification of perfusion of vessels with < 100 μm diameter on the intensive care unit (ICU) was regularly performed with incident darkfield (IDF) microscopy. Nailfold videocapillaroscopy (NVC), however, is an established and easy method for visualization of the microcirculation in chronic diseases. We here evaluated NVC in critically ill patients and compared its use with consensus microcirculatory assessment of IDF-microscopy.

METHODS

A new score, the capillary microcirculation (CapMic) score summarizing the microcirculation of the nail fold at four regions of digitus III, IV and V in a number between 0 (= no microcirculation) and 1 (= completely preserved microcirculation) was first established in 10 healthy volunteers and compared to the Microangiopathy Evolution Score (MES) standardized for NVC in chronic diseases. Then, n = 60 critically ill patients were recruited from a surgical ICU. Consensus-defined IDF scores and NCV data were compared at a single time point.

RESULTS

Evaluation of the CapMic score in 10 healthy volunteers at rest and under iatrogenic limb ischemia showed robust changes (0.80 ± 0.03 vs. 0.51 ± 0.12, p < 0.001). In critically ill patients, the IDF microscopy parameters "proportion of perfused vessels" (PPV) and "microvascular flow index" (MFI) inversely correlated with the MES (Spearman's R = -0.590, p < 0.001; Spearman's R = -0.585, p < 0.001). There was a positive correlation between PPV and the CapMic score (Spearman's R = 0.714, p < 0.001) and between MFI and the CapMic score (Spearman's R = 0.711, p < 0.001) and an inverse correlation between MES and the CapMic score (Spearman's R = -0.610, p < 0.001). Both sublingual and nailfold microcirculation deteriorated under rising norepinephrine- and crystalloid volume-requirements.

CONCLUSION

NVC-imaging provides comparable information on the microcirculation in critically ill patients compared to sublingual IDF microscopy. NCV could represent a new, additional method for diagnosing microcirculatory parameters on the ICU.

Nail fold capillaroscopy in leprosy: Unveiling the microvascular changes

BACKGROUND

Leprosy, a chronic infectious disease, is associated with various nail changes. Its etiopathogenesis is multifaceted, with microvascular damage being crucial. Nail fold capillaroscopy (NFC) emerges as a novel tool for detecting early vascular deficits in leprosy. The study aimed to assess and provide a complete clinical characterization of NFC changes in leprosy patients.

METHODS

It is an observational cross-sectional study, done over a period of 1.5 year (January 2021 to august 2022) in a tertiary care hospital, encompassing 60 patients diagnosed with leprosy (18-60 years). After obtaining informed consent; detailed history, complete cutaneous and neurological examinations were conducted. All fingernails and toenails were examined for clinical changes. Subsequently, onychoscopy was performed using USB type of video-dermatoscope (Model AM7115MZT Dino-lite), a non-invasive tool. This was followed by NFC which was done for all fingernails and images were recorded by single operator, which were then assessed for quantitative and qualitive changes and statistical analysis was conducted using SPSS v20, with mean capillary density compared using Student's t-test, morphological change frequencies assessed by proportions, and group comparisons made using Chi-square or Fischer exact tests, with a significance threshold of p < 0.05.

RESULTS

Among the 60 patients, 39 were in the lepromatous group, which included both borderline lepromatous (BL) and lepromatous leprosy (LL) patients, and 17 were in the tuberculoid group, which included borderline tuberculoid (BT) leprosy patients; 23.3 % had Type 1 reactions, and 18.3 % had Type 2 reactions. Nail fold capillaroscopy (NFC) showed microvasculature changes in 93.3 % of patients. The average capillary density was 6.8 ± 1.5 capillaries per mm, with the lepromatous group having a lower density (6.5 ± 1.09) compared to the tuberculoid group (7.0 ± 0.86). The most common NFC changes in the tuberculoid group were tortuous capillaries (70 %), capillary dropouts, and dilated capillaries (both 64.7 %). In the lepromatous group, capillary dropouts (82 %) were most frequent, followed by tortuous (69 %), receding (69 %), and dilated capillaries (66 %). A dilated and prominent subpapillary plexus was more common in the lepromatous group (35 %, p = 0.04). Patients with trophic changes in the lepromatous group had more capillary dropouts and bizarre capillaries. Capillary dropouts, dilated capillaries, and visible subpapillary venous plexus were more prevalent in patients with Type 2 reactions.

CONCLUSION

NFC changes are prevalent in both tuberculoid and lepromatous leprosy, which may be an indicator of peripheral vascular compromise and trophic changes, especially in lepromatous leprosy. NFC can be an auxiliary tool for detecting microvascular abnormalities in leprosy patients.

Late-age onset systemic sclerosis-clinical and serological characteristics

The clinical course and serological profile of the late-age onset systemic sclerosis (LAO SSc) and the early-age onset SSc (EAO SSc) was compared. The study enrolled 157 patients that fulfilled the American College of Rheumatology (ACR)/European League against Rheumatism (EULAR) classification criteria for systemic sclerosis (SSc). Among them, 69 had diffuse cutaneous SSc (dcSSc) and 88 limited cutaneous SSc (lcSSc). Within this population, 39 patients developed the disease over the age of 60 years old (LAO SSc) and 118 prior to that age (EAO SSc). The subtype of SSc, the incidence of internal organ involvement, the prevalence of malignancy, mortality, and serological profile were compared between both groups. The LAO SSc was observed in 39 of total 157 patients with SSc and exhibited a notably higher prevalence of pulmonary arterial hypertension (p = 0.014), heart involvement (p = 0.0014), and renal involvement (p = 0.0002). The occurrence of arthralgias was less common in the LAO SSc group (p = 0.02) than in the EAO SSc group. Furthermore, in the LAO SSc group, the prevalence of anti -RNA polymerase III antibodies (p = 0.008) and antiPM/Scl antibodies (p = 0.048) were significantly lower than in the EAO SSc group. On the other hand, higher anti-Th/To antibody levels (p = 0.014) were recorded in the LAO SSc group. Approximately 25% of SSc patients experienced a delayed onset of the disease after the age of 60 years old. Some clinical and serological features of late-onset SSc were markedly different from that in early-onset disease. Particularly noteworthy is the fact that involvement of internal organs such as heart and kidneys, as well as pulmonary arterial hypertension were much more often observed among patients with LAO SSc which in our suggestion may be referred to age-related co-morbidities. Key Points • Significant differences in clinical and serological profile of the disease were found between late-age onset (LAO) and early-age onset (EAO) SSc. • Incidence of dcSSc as well as prevalence of anti-RNA polymerase III and anti-PM/Scl antibodies were found to be lower in patients over 60 years old compared to those before 60, but regardless of the age of the disease onset. • Internal organ morbidity, notably pulmonary arterial hypertension, renal impairment and heart disease were significantly more common in elder SSc patients as well as in those with late disease onset. • These findings may suggest an impact of age-related co-morbidities on the course of late-age onset SSc.

Relationship between nailfold videocapillaroscopic findings and cardiovascular risk factors

BACKGROUND

Nailfold Videocapillaroscopy (NVC) is a valuable tool in the differential diagnosis of Raynaud's phenomenon (RP), present in certain Rheumatic diseases (RD). Knowing that many people have cardiovascular risk factors (CVRF), the main objective was to demonstrate that CVRF and carotid plaques produce NVC alterations.

METHODS

Cross-sectional unicentric study carried out from 2020 to 2023. Four groups were formed: subjects with RD and RP, participants with RD without RP, subjects with RP without RD and finally participants without RP or RD (study group). Each subject exhibiting CVRF presented only a single risk factor. The variables collected were: sociodemographic, CVRF (diabetes, tobacco, alcohol (ALC), obesity (OBE), dyslipidemia and arterial hypertension (AH)), diseases, RP, treatments, tortuosities and NVC alterations (ramified capillaries, enlarged capillaries, giant capillaries, haemorrhages and density loss) and carotid ultrasound (CU).

RESULTS

402 subjects were included (76 % women, mean age 51 ± 16 years), 67 % had CVRF, 50 % RP and 38 % RD. Tortuosities were present in 100 % of CVRF participants. A statistically significant association was found between the presence of CVRF and all the NVC alterations: ramified capillaries (OR = 95.6), enlarged capillaries (OR = 59.2), giant capillaries (OR = 8.32), haemorrhages (OR = 17.6) and density loss (OR = 14.4). In particular, an association was found between giant capillaries with AH (p = 0,008) and OBE (p 〈0,001), and haemorrhages and density loss with ALC and OBE (p < 0,001). On the other hand, 40 subjects presented CU plaques (9.9 %), associated with enlarged capillaries (OR = 8.08), haemorrhages (OR = 4.04) and ramified capillaries (OR = 3.01). The pathological intima-media thickness was also associated with haemorrhages (OR = 3.14).

CONCLUSIONS

There is a clear association between CVRF and ultrasound atherosclerotic findings in carotid with NVC alterations. These findings are of special interest for a correct NVC interpretation and to avoid false positives in the diagnosis of primary and secondary RP.

Nailfold Capillaroscopy: A Comprehensive Review on Its Usefulness in Both Clinical Diagnosis and Improving Unhealthy Dietary Lifestyles

Since the 1970s, the utility of nailfold capillaroscopy (NFC) in diagnosing rheumatological disorders such as systemic sclerosis has been well established. Further studies have also shown that NFC can detect non-rheumatic diseases such as diabetes, glaucoma, dermatitis, and Alzheimer disease. In the past decade, nailfold capillary morphological changes have also been reported as symptoms of unhealthy lifestyle habits such as poor diet, smoking, sleep deprivation, and even psychological stress, all of which contribute to slow blood flow. Therefore, studying the relationships between the morphology of nailfold capillaries and lifestyle habits has a high potential to indicate unhealthy states or even pre-disease conditions. Simple, inexpensive, and non-invasive methods such as NFC are important and useful for routine medical examinations. The present study began with a systematic literature search of the PubMed database followed by a summary of studies reporting the assessment of morphological changes detected by NFC, and a comprehensive review of NFC's utility in clinical diagnosis and improving unhealthy dietary lifestyles. It culminates in a summary of dietary and lifestyle health promotion strategy, assessed based on NFC and other related measurements that indicate healthy microvascular blood flow and endothelial function.

Prototype and evaluation of automatic fingertip-blood-sampling system that uses fingertip blood-vessel images to determine puncture position

We are developing an automatic fingertip-blood-sampling system to reduce the burden on trained medical personnel. For this system to withdraw a consistent volume of sampled blood for blood tests, we developed a mechanism for our system to select and puncture the vicinity of a large blood vessel from the blood-vessel image of an individual's fingertip. We call this mechanism the fingertip-vessel-puncture mechanism. From the results of an experiment in which the fingertips of 20 individuals (men and women in their 20 s to 60 s) were manually punctured at near and far locations from the blood vessel selected with our mechanism, the following conclusions were obtained. The fingertip-vessel-puncture mechanism tends to increase the volume of sampled blood, thus is effective in sampling more than 650 µL of blood for automatic blood analyzers. It was also found that it is more effective in increasing the volume of sampled blood in the men and those who were younger.

Relationship between nailfold capillaroscopy parameters and the severity of diabetic retinopathy

PURPOSE

To determine whether non-invasive measurements of the nailfold capillaries (NCs) are associated with the presence and severity of diabetic retinopathy (DR) in patients with type 2 diabetes.

METHODS

Eighty-three eyes of 83 patients with type 2 diabetes were enrolled. Sixty-three age-matched non-diabetic subjects served as controls. Diabetic patients were classified by the severity of their DR: non-DR (NDR), non-proliferative DR (NPDR), and proliferative DR (PDR). We used nailfold capillaroscopy to measure NC parameters, including number, length, width, and turbidity.

RESULTS

Four NC parameters in the diabetic patients were significantly lower than in the controls (all P < 0.001). There was a statistically significant decrease in the NC parameters along with the increasing severity of DR (number: P = 0.02; all others: P < 0.001). Logistic regression analysis revealed that combining the systemic characteristics of age, sex, systolic blood pressure, estimated glomerular filtration rate, hemoglobin A1c level, and history of hypertension and dyslipidemia could indicate the presence of DR and PDR (the area under the receiver operating characteristic curve [AUC] = 0.81, P = 0.006; AUC = 0.87, P = 0.001, respectively). Furthermore, the discriminative power of DR was significantly improved (P = 0.03) by adding NC length to the systemic findings (AUC = 0.89, P < 0.001).

CONCLUSION

NC measurement is a simple and non-invasive way to assess the risk of DR and its severity.

Computerized nailfold video-capillaroscopy in type 2 diabetes: A cross-sectional study on 102 outpatients

BACKGROUND

Type 2 diabetes (T2D) is a chronic disease that negatively affects vascular health. A careful assessment of chronic complications, including microcirculation, is mandatory. The computerized nailfold video-capillaroscopy (CNVC) accurately examines the nailfold microvasculature, but its suitability in T2D is currently under investigation.

AIMS

To describe nailfold microvasculature in T2D patients regarding the level of glucose control and chronic microvascular and macrovascular complications.

METHODS

This is a cross-sectional study on 102 consecutive and unselected outpatients with T2D who had undergone CNVC examination. The examination was carried out by using an electronic video-capillaroscope with 300x magnification. Capillaroscopic appearance and capillary changes were described according to well-established parameters. Capillaroscopic parameters were compared between patients with poor glucose control (HbA1c ≥7%) and those with better glucose control (HbA1c <7%) and between patients with chronic complications and those without. Chronic complications were deduced from the anamnestic, laboratory, and instrumental data and the five-item International Index of Erectile Function (IIEF-5) questionnaire.

RESULTS

Nailfold capillaries in patients with HbA1c ≥7% were thicker (p = .019) and longer (p = .021) than in those with better glucose control. Ectasias (p = .017) and microaneurysms (p = .045) were more frequently observed in patients with HbA1c ≥7.0% than those with HbA1c <7.0%. Patients with ED, compared to those without, had a lower frequency of bizarre-shaped capillaries (p = .02). Microaneurysms (p = .02) were more frequently described in patients with carotid stenosis (>20%) than those without.

CONCLUSION

Relevant nailfold microvascular alterations were observed in T2D, most of which were associated with poor glycemic control, ED, and carotid stenosis. Further investigation is needed to recognize the role of CNVC in predicting the onset and evolution of chronic complications and monitoring the effectiveness of antihyperglycemic treatments on microcirculation.

Nailfold capillaroscopy in Egyptian systemic lupus erythematosus (SLE) patients: correlation with demographic features and serum levels of IL 17A and IFNs I

Background

In SLE patients, cytokines are linked to endothelial cell damage. Nailfold capillaroscopy (NFC) is a simple method for evaluating micro-vascular abnormalities in different connective tissue diseases (CTDs). The study aimed to detect the levels of interleukin 17A (IL 17A), type I interferons (IFNs I) in the serum, and NFC changes in Egyptian SLE patients compared to a control group and to correlate NFC findings with patients’ demographic features and serum levels of IL 17A and IFNs I.

Results

Serum levels of IL 17A, IFN α, and IFN β were significantly higher in SLE patients than in control group (P < 0.0001). About thirty nine patients (73.6%) of the 53 SLE patients showed abnormal NFC changes. Egyptian SLE patients had a high prevalence of the NFC non-specific pattern, with 32 (60.4%) patients showing non-specific changes and 7 (13.2%) patients showing scleroderma pattern, including 3 (5.6%) patients with active scleroderma pattern and 4 (7.55%) patients with late scleroderma pattern. Furthermore, Raynaud’s phenomenon (RP) was observed in 8 (15.1%) SLE patients, with 3 (5.6%) having normal NFC pattern and 5 (9.4%) having scleroderma pattern. All controls (n = 20) showed normal hairpin shape capillaries. Except for SLEDAI (P = 0.03) and the presence of RP (P < 0.0001), there were no significant differences in demographic and laboratory parameters between the three NFC patterns (normal, non-specific, and scleroderma); additionally, NFC score correlated significantly with SLEDAI (P = 0.021).

Conclusion

As a result of the high disease activity, Egyptian SLE patients had elevated serum levels of IL 17A and IFNs I. The most common NFC pattern in Egyptian SLE patients was a non-specific pattern. NFC abnormalities in Egyptian SLE patients were correlated with disease activity but not with patients’ ages, disease duration, or serum levels of IL 17A and IFNs I. SLE patients with scleroderma NFC pattern and RP should be closely followed for the possibility of appearance of anti-U1 RNP antibodies and MCTDS.

Vasoreactivity of the optic nerve head, nailfold, and facial skin in response to cold provocation in normal-tension glaucoma patients

BACKGROUND

The dysfunction of optic nerve head (ONH) hemodynamics has been suggested to be involved in the pathogenesis of normal-tension glaucoma (NTG). The aim of this study was to compare vasoreactivity in the ONH, nailfold, and facial skin in response to cold-water provocation in NTG patients and healthy controls.

METHODS

We performed cold-water provocation in 14 eyes of 14 NTG patients and 15 eyes of 15 age-matched control subjects. Laser speckle flowgraphy-derived tissue-area mean blur rate (MT), skin blood flowmetry-derived pulse wave amplitude (PA), nailfold capillaroscopy-derived nailfold capillary diameter, and other clinical parameters were recorded at baseline and 4 and 6 min after the cold stimulus. We compared changes (as percentages) in these variables in the NTG and control subjects with a linear mixed-effects model and evaluated correlations between these changes with Spearman's rank correlation coefficient.

RESULTS

The interaction term between the NTG group (reference, control group) and the 4-min protocol step (reference, baseline) significantly affected the changes in MT, nailfold capillary diameter and PA (β = -9.51%, P = 0.017, β = -20.32%, P = 0.002; β =  + 18.06%, P = 0.017, respectively). The change in MT was positively correlated with the change in nailfold capillary diameter, and negatively correlated with the change in PA (r = 0.39, P = 0.036; r = -0.40, P = 0.031, respectively).

CONCLUSION

NTG patients showed abnormal vasoconstriction in the ONH and nailfold and vasodilation in the facial skin in response to cold-water provocation.

Nailfold Videocapillaroscopy for Non-Invasive Assessment of Microcirculation and Prognostic Correlation with Endothelial Dysfunction, Cardiovascular Risk Factors, and Non-HLA Antibodies in Heart Transplant Recipients: A Pilot Study

Early identification of allograft vasculopathy and the concomitant elimination of adverse risk factors is essential for improving the long-term prognosis of heart transplant (HTx) recipients with underlying cardiovascular disease (CVD). The major aim of this pilot study was to conduct a non-invasive imaging evaluation of the HTx patient microcirculation by employing nailfold video-capillaroscopy (NVC) in a well-characterized patient and control cohort, and to correlate these data with endothelial cell function, accompanied by studies of traditional cardiovascular risk factors and non-HLA antibodies in HTx recipients. Ten patients undergoing HTx (mean age of 38 ± 14 years) were recruited for the study and compared to a control group of 12 well-matched healthy volunteers (mean age 35 ± 5 years) with normal body mass index (BMI). Detailed medical records were collected from all individuals. NVC was performed using CapillaryScope 200 MEDL4N microscope. For functional readout and correlation analysis, endothelial cell network formation in conjunction with measurements of patient serum levels of vascular endothelial growth factor (VEGF) and non-HLA autoantibodies directed against the angiotensin II type-1-receptor (anti-AT1R-Ab), endothelin-1 type-A-receptor (anti-ETAR-Ab), protease-activated receptor-1 (anti-PAR-1-Ab), and VEGF-A (anti-VEGF-A-Ab) were studied. Our NVC analysis found that the average apical loop diameter of nailfold capillaries was significantly increased in HTx recipients (p = 0.001). In addition, HTx patients with more prominent changes in capillaroscopic patterns were characterized by the presence of traditional cardiovascular risk factors, and HTx patients had increased levels of anti-AT1R-ab, anti-ETAR-ab, and anti-VEGF-A-Ab (p = 0.017, p = 0.025, and p = 0.003, respectively). Capillary diameters most strongly correlated with elevated serum levels of troponin T and triglycerides (R = 0.69, p = 0.028 and R = 0.81, p = 0.004, respectively). In conclusion, we found that an abnormal NVC pattern in HTx patients is associated with traditional CVD risk factors and that NVC is a useful non-invasive tool to conveniently monitor changes in the microvasculature of HTx patients.