Assessment Of Microcirculation Research Articles

Wearable laser Doppler flowmetry for non-invasive assessment of diabetic foot microcirculation: methodological considerations and clinical implications.

Type 2 diabetes mellitus (T2DM) is a global health concern with significant implications for vascular health. The current evaluation methods cannot achieve effective, portable, and quantitative evaluation of foot microcirculation. We aim to use a wearable device laser Doppler flowmetry (LDF) to evaluate the foot microcirculation of T2DM patients at rest. Eleven T2DM patients and twelve healthy subjects participated in this study. The wearable LDF was used to measure the blood flows (BFs) for regions of the first metatarsal head (M1), fifth metatarsal head (M5), heel, and dorsal foot. Typical wavelet analysis was used to decompose the five individual control mechanisms: endothelial, neurogenic, myogenic, respiratory, and heart components. The mean BF and sample entropy (SE) were calculated, and the differences between diabetic patients and healthy adults and among the four regions were compared. Diabetic patients showed significantly reduced mean BF in the neurogenic () and heart () components at the M1 and M5 regions () compared with healthy adults. Diabetic patients had significantly lower SE in the neurogenic () and myogenic () components at the M1 region, as well as in the endothelial () component at the M5 region and in the myogenic component at the dorsal foot (), compared with healthy adults. The SE in the myogenic component at the dorsal foot was lower than at the M5 region () and heel area (). Similarly, the SE in the heart component at the dorsal foot was lower than at the M5 region () and heel area () in diabetic patients. This study indicated the potential of using the novel wearable LDF device for tracking vascular complications and implementing targeted interventions in T2DM patients.

Microvascular dysfunction associated with reduced nailfold capillary density in patients with ischemia with no obstructive coronary artery disease

Abstract Funding Acknowledgements None. Introduction The impairment of microvascular function present in coronary microcirculation with chronic angina without obstructive coronary arteries. There are insufficient data in the literature regarding possible generalized microangiopathy in this population. Aim The aim of this study is to demonstrate whether patients with Angina with No Obstructive Coronary Artery Disease (ANOCA) compared to individuals without coronary microvascular dysfunction (CMD) are characterized by a different level of nailfold capillaroscopy abnormalities. Methods We examined 18 participants without CMD - non-CMD group [9 female, 50%, mean age: 54.4±8.1 years) and 26 patients with ANOCA - CMD group (22 female, 84,6%, mean age : 53.2±10.7 years). Functional coronary angiography was performed for the assessment of coronary microcirculation in all patients. Coronary flow reserve (CFR) and index of microvascular resistance (IMR) were measured in the left anterior descending coronary artery using a temperature/pressure sensor-tipped guidewire. In addition, the assessment of skin microcirculation was performed by capillaroscopy, a non-invasive technique to evaluate small vessels of the microcirculation in the nailfold, using stereomicroscope in all patients. Results In CMD group, mean CFR and IMR were 1.34±0.6 and 44.8±28, respectively. Out of the 26 MVD patients with abnormal CFR, 7 of them (27%) had a normal value of IMR, indicating functional microvascular dysfunction. On the other hand, 18 patients (69%) had an abnormal IMR, indicating structural microvascular dysfunction. Capillary density in patients with MVD was significantly decreased compared to the control group (7.6±2.2 vs 10.9±1.8 vessels/mm, p=0.04). The difference in capillary density between the two groups was statistically significant after adjustment for multiple comparisons (p<0.05). No significant difference was found in body mass index, renal function, medical history of dyslipidemia, diabetes mellitus and smoking status between the two groups (p<0.05). Conclusion Nailfold capillary density was reduced in ANOCA patients compared to control group. These data may provide new insights regarding possible generalized microangiopathy in CMD patients. These results suggest that there is an association between microcirculatory impairment at both heart and peripheral vascular bed level.

Endothelial function in patients with chronic myeloid leukemia treated with tyrosine kinase inhibitors is not related to cardiovascular risk assessed by SCORE2 algorithm.

Tyrosine kinase inhibitors (TKIs) revolutionized the treatment of chronic myeloid leukemia (CML) but are endowed with negative effects on endothelial function. To characterize endothelial function in patients with CML treated with various TKIs. Forty-eight patients diagnosed with chronic phase CML treated with TKIs, such as imatinib, bosutinib, nilotinib, ponatinib, and asciminib were included. Endothelial function was assessed in the brachial artery and microcirculation based on flow-mediated dilation (FMD), reactive hyperemia peripheral arterial tonometry (RH-PAT) and Flow Mediated Skin Fluorescence (FMSF). Reactive Hyperemia Index (RHI), FMD [%], Reactive Hyperemia Response (RHR [%]), Normoxia Oscillatory index (NOI [%]) and Hyperemic Response index (HR index [%]) did not differentiate between the group of patients with low / moderate risk in the Systemic Coronary Risk Estimation 2 (SCORE2), SCORE2-Older Persons (SCORE2-OP) and those with high / very high-risk scores. Among patients with low/intermediate risk based on the SCORE2 algorithms, some had lower (<Q1) values of endothelial parameters, reflecting impaired endothelial function, when compared with the whole population. Lower values of endothelial function parameters were associated with overall long-term treatment with TKIs or ponatinib treatment. Importantly, endothelial function assessed by FMSF (RHR [%]) negatively correlated with the total duration of TKI treatment, also after adjustment for age. Endothelial function in CML patients treated with TKIs was not related to cardiovascular risk based on SCORE2/SCORE2-OP algorithms but CML-specific factors, including duration of TKI treatment. FMSF-based assessment of skin microcirculation was a sensitive method for detecting the vascular effects of TKIs.

Comprehensive Angiography-Derived Functional Assessment of Epicardial and Microvascular Coronary Disease. Correlation With Non-invasive Myocardial Stress Imaging

Coronary angiography (CA) is poorly correlated with non-invasive myocardial stress imaging (NSI) and myocardial ischemia is often observed in patients with unobstructed coronary arteries. Moreover, the diagnostic performance of combined epicardial and microcirculatory angiography-derived physiological assessment and its correlation with NSI remains unknown. Nine-hundred-seventeen coronary vessels in 319 patients who underwent both CA and NSI were included in this multicenter observational retrospective analysis. Quantitative flow ratio (QFR) and angiography-derived index of microcirculatory resistance (IMRangio) analyses were performed to estimate coronary epicardial and microcirculatory function respectively. NSI demonstrated evidence of myocardial ischemia in 76% of the cases. IMRangio (36 [22-50] vs 29 [21-41], p<0.001) was significantly higher and QFR (0.92 [0.78-0.99] vs 0.97 [0.91-0.99], p<0.001) was significantly lower in vessels subtending ischemic territories. Overall, the diagnostic accuracy of QFR was moderate (AUCROC 0.632 [95% CI 0.589-0.674], p<0.0001) but it was higher in patients with normal microcirculatory function (AUCROC = 0.726 [95% CI 0.669-0.784], p<0.0001, p-value for AUCROC comparison=0.009). Combined QFR/IMRangio assessment provided incremental diagnostic performance compared with the evaluation of epicardial or microcirculatory districts in isolation (p-value for AUC comparison <0.0001) and it was able to identify the predominant mechanism of myocardial ischemia in 77% of the patients with positive NSI. Our study suggests the value of a combined angiography-derived assessment of epicardial and microvascular function for the definition of the predominant mechanism of myocardial ischemia in patients with suspected coronary artery disease.

Implementation of Microcirculation Examination in Clinical Practice-Insights from the Nationwide POL-MKW Registry.

Background and Objectives: The assessment of coronary microcirculation may facilitate risk stratification and treatment adjustment. The aim of this study was to evaluate patients' clinical presentation and treatment following coronary microcirculation assessment, as well as factors associated with an abnormal coronary flow reserve (CFR) and index of microcirculatory resistance (IMR) values. Materials and Results: This retrospective analysis included 223 patients gathered from the national registry of invasive coronary microvascular testing collected between 2018 and 2023. Results: The frequency of coronary microcirculatory assessments in Poland has steadily increased since 2018. Patients with impaired IMR (≥25) were less burdened with comorbidities. Patients with normal IMR underwent revascularisation attempts more frequently (11.9% vs. 29.8%, p = 0.003). After microcirculation testing, calcium channel blockers (CCBs) and angiotensin-converting enzyme inhibitors were added more often for patients with IMR and CFR abnormalities, respectively, as compared to control groups. Moreover, patients with coronary microvascular dysfunction (CMD, defined as CFR and/or IMR abnormality), regardless of treatment choice following microcirculation assessment, were provided with trimetazidine (23.2%) and dihydropyridine CCBs (26.4%) more frequently than those without CMD who were treated conservatively (6.8%) and by revascularisation (4.2% with p = 0.002 and 0% with p < 0.001, respectively). Multivariable analysis revealed no association between angina symptoms and IMR or CFR impairment. Conclusions: The frequency of coronary microcirculatory assessments in Poland has steadily increased. Angina symptoms were not associated with either IMR or CFR impairment. After microcirculation assessment, patients with impaired microcirculation, expressed as either low CFR, high IMR or both, received additional pharmacotherapy treatment more often.

The association between prolonged capillary refill time and microcirculation changes in children with sepsis

BackgroundsIn children with sepsis, circulatory shock and multi-organ failure remain major contributors to mortality. Prolonged capillary refill time (PCRT) is a clinical tool associated with disease severity and tissue hypoperfusion. Microcirculation assessment with videomicroscopy represents a promising candidate for assessing and improving hemodynamic management strategies in children with sepsis. Particularly when there is loss of coherence between the macro and microcirculation (hemodynamic incoherence). We sought to evaluate the association between PCRT and microcirculation changes in sepsis.MethodsThis was a prospective cohort study in children hospitalized with sepsis. Microcirculation was measured using sublingual video microscopy (capillary density and flow and perfused boundary region [PBR]—a parameter inversely proportional to vascular endothelial glycocalyx thickness), phalangeal tissue perfusion, and endothelial activation and glycocalyx injury biomarkers. The primary outcome was the association between PCRT and microcirculation changes.ResultsA total of 132 children with sepsis were included, with a median age of two years (IQR 0.6–12.2). PCRT was associated with increased glycocalyx degradation (PBR 2.21 vs. 2.08 microns; aOR 2.65, 95% CI 1.09–6.34; p = 0.02) and fewer 4–6 micron capillaries recruited (p = 0.03), with no changes in the percentage of capillary blood volume (p = 0.13). Patients with hemodynamic incoherence had more PBR abnormalities (78.4% vs. 60.8%; aOR 2.58, 95% CI 1.06–6.29; p = 0.03) and the persistence of these abnormalities after six hours was associated with higher mortality (16.5% vs. 6.1%; p < 0.01). Children with an elevated arterio-venous CO2 difference (DCO2) had an abnormal PBR (aOR 1.13, 95% CI 1.01–1.26; p = 0.03) and a lower density of small capillaries (p < 0.05). Prolonged capillary refill time predicted an abnormal PBR (AUROC 0.81, 95% CI 0.64–0.98; p = 0.03) and relative percentage of blood in the capillaries (AUROC 0.82, 95% CI 0.58–1.00; p = 0.03) on admission. A normal CRT at 24 h predicted a shorter hospital stay (aOR 0.96, 95% CI 0.94–0.99; p < 0.05).ConclusionsWe found an association between PCRT and microcirculation changes in children with sepsis. These patients had fewer small capillaries recruited and more endothelial glycocalyx degradation. This leads to nonperfused capillaries, affecting oxygen delivery to the tissues. These disorders were associated with hemodynamic incoherence and worse clinical outcomes when the CRT continued to be abnormal 24 h after admission.

Non-invasive assessment of sublingual microcirculation using flow derived from green light PPG: evaluation and reference values.

The study of sublingual microcirculation offers valuable insights into vascular changes and overcomes some limitations of peripheral microcirculation assessment. Videomicroscopy and pulse oximetry have been used to assess microcirculation, providing insights into organ perfusion beyond macrohemodynamics parameters. However, both techniques have important limitations that preclude their use in clinical practice. To address this, we propose a non-invasive approach using photoplethysmography (PPG) to assess microcirculation. Two experiments were performed on different samples of 31 subjects. First, multi-wavelength, finger PPG signals were compared before and while applying pressure on the sensor to determine if PPG signals could detect changes in peripheral microcirculation. For the second experiment, PPG signals were acquired from the ventral region of the tongue, aiming to assess the microcirculation through features calculated from the PPG signal and its first derivative. In experiment 1, 13 out of 15 features extracted from green PPG signals showed significant differences () before and while pressure was applied to the sensor, suggesting that green light could detect flow distortion in superficial capillaries. In experiment 2, 15 features showed potential application of PPG signal for sublingual microcirculation assessment. The PPG signal and its first derivative have the potential to effectively assess microcirculation when measured from the fingertip and the tongue. The assessment of sublingual microcirculation was done through the extraction of 15 features from the green PPG signal and its first derivative. Future studies are needed to standardize and gain a deeper understanding of the evaluated features.

Invasive Assessment of Coronary Microcirculation: A State-of-the-Art Review.

A significant proportion of patients presenting with signs and symptoms of myocardial ischemia have no "significant" epicardial disease; thereby, the assessment of coronary microcirculation gained an important role in improving diagnosis and guiding therapy. In fact, coronary microvascular dysfunction (CMD) could be found in a large proportion of these patients, supporting both symptoms and signs of myocardial ischemia. However, CMD represents a diagnostic challenge for two main reasons: (1) the small dimension of the coronary microvasculature prevents direct angiographic visualization, and (2) despite the availability of specific diagnostic tools, they remain invasive and underused in the current clinical practice. For these reasons, CMD remains underdiagnosed, and most of the patients remain with no specific treatment and quality-of-life-limiting symptoms. Of note, recent evidence suggests that a "full physiology" approach for the assessment of the whole coronary vasculature may offer a significant benefit in terms of symptom improvement among patients presenting with ischemia and non-obstructive coronary artery disease. We analyze the pathophysiology of coronary microvascular dysfunction, providing the readers with a guide for the invasive assessment of coronary microcirculation, together with the available evidence supporting its use in clinical practice.

Using Signal Features of Functional Near-Infrared Spectroscopy for Acute Physiological Score Estimation in ECMO Patients.

Extracorporeal membrane oxygenation (ECMO) is a vital emergency procedure providing respiratory and circulatory support to critically ill patients, especially those with compromised cardiopulmonary function. Its use has grown due to technological advances and clinical demand. Prolonged ECMO usage can lead to complications, necessitating the timely assessment of peripheral microcirculation for an accurate physiological evaluation. This study utilizes non-invasive near-infrared spectroscopy (NIRS) to monitor knee-level microcirculation in ECMO patients. After processing oxygenation data, machine learning distinguishes high and low disease severity in the veno-venous (VV-ECMO) and veno-arterial (VA-ECMO) groups, with two clinical parameters enhancing the model performance. Both ECMO modes show promise in the clinical severity diagnosis. The research further explores statistical correlations between the oxygenation data and disease severity in diverse physiological conditions, revealing moderate correlations with the acute physiologic and chronic health evaluation (APACHE II) scores in the VV-ECMO and VA-ECMO groups. NIRS holds the potential for assessing patient condition improvements.

Skin microcirculatory responses: A potential marker for early diabetic neuropathy assessment using a low-cost portable diffuse optical spectrometry device.

Diffuse optical measurement is an evolving optical modality providing a fast and portable solution for microcirculation assessment. Diffuse optics in static and dynamic modalities are combined here in a system to assess hemodynamics in skin tissues of control and diabetic subjects. The in-house developed system consists of a laser source, fiber optic probe, a low-cost avalanche photodiode, a finite element model (FEM) derived static optical property estimator, and a software correlator for continuous flow monitoring through microvasculature. The studies demonstrated that the system quantifies the changes in blood flow rate in the immediate skin subsurface. The system is calibrated with in vitro flow models and a proof-of-concept was demonstrated on a limited number of subjects in a clinical environment. The flow changes in response to vasoconstrictive and vasodilative stimuli were analyzed and used to classify different stages of diabetes, including diabetic neuropathy.

Assessment of macular microcirculation in patients with multiple sclerosis by swept-source optical coherence tomography angiography

Objective: To investigate the changes in the retinal microcirculation in multiple sclerosis (MS) patients by swept-source optical coherence tomography angiography (SS-OCTA). Patients and Methods: Thirty-seven patients with relapsing-remitting MS and 40 healthy volunteers were included into this crosssectional study. Clinical history, Expanded Disability Status Scale and duration of MS were collected. SS-OCTA by deep range imaging (DRI) OCT measurements were performed on all subjects. Macular perfusion parameters including superficial and deep foveal avascular zones (FAZs, FAZd, respectively) (%), vascular densities of superficial capillary plexus (SCP) (%), deep capillary plexus (DCP) (%) and choriocapillaris (CC) (%) were compared with healthy subjects. Results: Vascular densities of SCP, DCP and CC were found to be statistically lower in the study group compared to the control group (p = 0.02, p = 0.03, p = 0.03, respectively). FAZs and FAZd, areas were significantly higher in the study group (p = 0.02, p = 0.02, respectively). Central macular thickness and subfoveal choroidal thickness were significantly lower than in the control group (p = 0.015, p = 0.047, respectively). Conclusion: Evaluation of retinal blood flow in patients with MS is useful both for understanding the physiopathology of the disease and in the clinical follow-up.

The Haemodialysis Session Effect on the Choroidal Thickness and Retinal and Choroidal Microcirculation-A Literature Review.

Haemodialysis (HD) is currently the most commonly used method of renal replacement therapy. The process of dialysis involves numerous changes that affect many systems, including the eye. The changes occurring in the course of HD may affect the ocular parameters, such as intraocular pressure, central corneal thickness, retinal thickness, retinal nerve fibre layer thickness, and choroidal thickness (CT). The choroid, being one of the most vascularized tissues, is characterized by the highest ratio of blood flow to tissue volume in the entire body, may be particularly susceptible to changes occurring during HD, and at the same time reflect the microcirculatory status and its response to HD. Patients with end-stage renal disease subjected to dialysis are highly susceptible to systemic microvascular dysfunction. Moreover, it is considered that the process of HD itself contributes to vascular dysfunction. Nowadays, thanks to the development of imaging techniques, the widely available optical coherence tomography (OCT) tests allow for the assessment of CT, while OCT-angiography allows for a quick, non-invasive, and repeatable assessment of the condition of retinal and choroidal microcirculation, which significantly expands our knowledge regarding the reaction of ocular microcirculation due to HD. The assessment of both retinal and choroidal circulation is even more attractive because retinal circulation is autoregulated, while choroidal circulation is mainly controlled by extrinsic autonomic innervation. Thus, assessment of the choroidal response to an HD session may provide the possibility to indirectly evaluate the functions of the autonomic system in patients subjected to HD. At a time when the importance of microcirculation in systemic and renal diseases is becoming increasingly evident, the assessment of ocular microcirculation appears to be a potential biomarker for assessing the condition of systemic microcirculation. In this work, we present a review of the literature on the effect of the HD session on CT and the retinal and choroidal microcirculation.

Noninvasive evaluation of dynamic microvascular dysfunction in ischemia and no obstructive coronary artery disease patients with suspected vasospasm.

In patients with ischemia and no obstructive coronary artery disease (INOCA), a dynamic coronary microvascular dysfunction (CMD) is frequent but difficult to capture by noninvasive means.The aim of our study was to assess dynamic CMD in INOCA patients with stress echocardiography after vasoconstrictive and vasodilator stimuli. In this prospective single-center study, we have enrolled 40 INOCA patients (age 56.3 ± 13 years, 32 women). All participants underwent stress echocardiography with hyperventilation (HYP), followed by supine bicycle exercise (HYP+EXE) and adenosine (ADO). Stress echocardiography included an assessment of regional wall motion abnormality (RWMA) and coronary flow velocity (CFV) in the distal left anterior descending (LAD) coronary artery. HYP induced a 30% increase in rate pressure product (rest = 10 244 ± 2353 vs. HYP = 13 214 ± 3266 mmHg x bpm, P < 0.001) accompanied by a paradoxical reduction in CFV (HYP< rest) in 21 patients (52%). HYP alone was less effective than HYP+EXE in inducing anginal pain (6/40, 15% vs. 10/40, 25%, P = 0.046), ST segment changes (6/40, 15% vs. 24/40, 60%, P < 0.001), and RWMA (6/40, 15% vs. 13/40, 32.5%, P = 0.008). ADO-induced vasodilation was preserved (≥2.0) in all patients. In patients with INOCA, a coronary vasoconstriction after HYP is common, in absence of structural CMD detectable with ADO. HYP+EXE test represents a more powerful ischemia inducer than HYP alone. Stress echocardiography with LAD-CFV may allow the noninvasive assessment of dynamic and structural coronary microcirculation during stress.

Laser speckle contrast imaging for intraoperative assessment of intestinal microcirculation in normo- and hypovolemic circulation in a porcine model

Introduction: Healing is essential for successful colorectal surgery. Optimal microcirculation is needed to ensure this; however, this is only subjectively assessed by the surgeon. Laser Speckle Contrast Imaging (LSCI) is an objective non-contact, image-based method to quantify microcirculation in bowel ends. This study aimed to evaluate the application of LSCI in an open surgery porcine model, determine differences between normal and impaired microcirculation, and test the LSCI applicability to repeated measurements. Method: A midline laparotomy was made in ten healthy female pigs to expose the colon and small intestine. Subsequently, baseline measurements were conducted. A local arteria supplying the colonic or small intestine mesentery was clamped for 5 min. and LSCI measures were made again. After an hour’s rest, LSCI measurements were done in two unaffected areas on the colon and the small intestine, and baseline values were recorded. Hypotension was induced with rapid bleeding and LSCI measurements were done. After the mean arterial blood pressure (MAP) dropped to 50-60 mmHg, norepinephrine infusion was started. At a stable MAP of 85-100 mmHg, LSCI measurements were repeated at 0 min. and 30 min. during continuous norepinephrine infusion. Results: Cross-clamping caused LSCI levels to drop equally in both the colon and small intestine by 60% in the entire the clamped zone. Compared to baseline, the microcirculation measured by LSCI in the unclamped adjacent transition zone was diminished by 33% and 40%, colon and small intestines, respectively. During hypotension due to bleeding, LSCI decreased as expected. When MAP was stabilized by norepinephrine infusion, LSCI values dropped further: compared to baseline, measurements decreased with 24% and 20% in colon and small intestines, respectively. Conclusion: LSCI can be used as a quantitative, real-time, non-contact method to detect changes in the microcirculation during open intestinal surgery with large changes in microcirculation due to e.g., hypovolemic and norepinephrine infusion. It is simple to use and in contrast to the existing intraoperative microcirculation assessment techniques, LSCI stands out primarily for its elimination of the requirement for a dye. As our study has shown, this feature allows us to perform time-independent measurements and repeat them indefinitely in nearby regions without compromising the effectiveness of the method.

The effect of transdermal combined product on the state of microcirculatory blood flow in patients with chronic venous insufficiency

Introduction. Treatment of patients with severe chronic venous insufficiency of the lower extremities is complex and along with compression therapy includes transdural use of drugs. Aim. To study the microcirculatory blood flow of the tissues of the distal segments of the lower limbs in patients with severe chronic venous insufficiency and the possibility of its correction with the use of a combined product for local application.Materials and мethods. The study included 40 patients suffering from varicose vein disease with chronic venous insufficiency of C3-C5 stages according to CEAP. In the main group of patients (n = 30) the transdermal combined product Detragel® was used; patients of the comparison group (n = 10) received only basic compression therapy of functional class II. The basis for the assessment of microcirculation of the lower limbs soft tissues was the analysis of the results of laser doppler flowmetry. Results. At local use of Detragel® in combination with elastic bandage in 91% of observations, there was a statically significant decrease of basal blood flow less than 4.0 pf. units (p &lt; 0.05). The mean basal blood flow was 2.7 ± 0.6 pf. units (1.6–3.9 pf. units, 95% CI), which was consistent with normal values. Statistically significant decrease in veno-arteriolar response to 51.5 ± 10.8% (36.0–68.8%, 95% CI) was recorded in 75% of cases after 14 days of topical treatment, although veno-arteriolar response decreased to normal in only 53% of cases. Conclusion. Correction of microcirculatory disorders in patients with varicose vein disease should include local use of medicine.

Improvement of microcirculatory vessel density in the early post-operative period of heart valve surgery: an observational study

Abstract Introduction Cardiac surgery with cardiopulmonary bypass (CPB) is associated with microcirculatory perfusion disturbances that persist after the surgery and that can cause multiple organ dysfunction. Little is known about the effects of heart surgery on the microcirculation of patients in the postoperative period of heart valve surgery. Purpose The purpose of the study is to identify the alterations that occur in the sublingual microcirculation of patients submitted to heart valve surgery using cardiopulmonary bypass. Such findings may guide future implementation of routine microcirculation assessment in the postoperative period of cardiac surgery. Methods This was a single-center cross-sectional observational study that included thirty patients aged 52 ± 14 years and enrolled during a period of four months, scheduled for heart valve surgery with CPB at a quaternary public hospital. Sublingual microcirculatory density and perfusion were assessed using a handheld camera based on incident dark-field (IDF) imaging. Each recruited patient was evaluated in two stages: 1) during hospitalization, in the preoperative period of cardiac surgery to be performed within the next 48 hours; 2) in the early postoperative phase of cardiac surgery, within the first four hours of the patient's arrival at the intensive care unit. At least three videos of 5 seconds each were obtained in both stages. Images were analyzed using automated software as well as visual analysis. For analysis purposes, we considered vessels as capillaries if diameter ranges between 6.04-15.9 µm and non-capillaries if diameter ranges between 16-50 µm. Results We observed a statistically significant increase in the total number of vessels (TVN) after surgery (1076 ± 156) compared to values obtained before surgery (943 ± 117, P=0.0004). In addition, the total number of capillaries vessels (TNCV) was also greater after surgery (998 ± 132) compared to the preoperative period (877 ± 106; P=0.0001), the same being observed in the total length of capillaries vessels (TLCV) after surgery (28.7 ± 3.3 mm) compared to before surgery (25.8 ± 3.0 mm; P=0.0005) and capillary vessel density (CVD) (16.4 ± 1.9 and 14.8 ± 1.7 mm/mm2) after and before surgery, respectively (P=0.0005). With regard to non-capillary vessels, no difference was observed in total number of non-capillary vessels (TNNCV) after [68 (49-104)] and before surgery [69 (49-78)] (P=0.21), as well as in total length of non-capillary vessels (TLNCV) after [1.6 (1.2-2.4)] mm and before [1.5 (1.1-1.8.)] mm (P=0.25) surgery. Finally, non-capillary vessel density (NCVD) was also similar after [0.89 (0.67-1.36)] mm/mm2 and before surgery [0.83 (0.66-1.06)] mm/mm2 (P=0.34). Conclusion In patients undergoing heart valve surgery, there was a significant increase in postoperative microvessel number, mainly due to the increase in the density of capillaries vessels.

Assessment of retinal and choroidal microcirculation after unilateral recession–resection surgery for horizontal strabismus by swept-source optical coherence tomography angiography

This study explored the possible hemodynamic changes of the retina and choroid after horizontal strabismus surgery using swept-source optical coherence tomography angiography (SS-OCTA). 32 eyes of 32 patients who underwent unilateral horizontal rectus muscle recession–resection surgery were included. SS-OCTA examinations were performed preoperatively and one week postoperatively. Several OCTA measurements were used, including vessel density (VD) of the superficial vascular complex (SVC), VD of the deep vascular complex (DVC), VD of the choriocapillaris (CC), choroidal vascular index (CVI) and choroidal thickness (CT). No significant change in VD of SVC, DVC, and CC was observed whereas CT increased significantly with CVI unchanged. Recession–resection surgery for horizontal strabismus seemed not to significantly influence the microcirculation of the retina and CC in the early postoperative period. However, choroidal thickening happened with a constant CVI probably due to the postoperative inflammation. Further studies are needed to investigate the long-term effects of unilateral recession–resection surgery for horizontal strabismus on the microcirculation of the retina and choroid.

Correlation between toe brachial index and walking ability in peripheral arterial disease with type 2 diabetes mellitus

BackgroundThe primary symptom of peripheral arterial disease (PAD) is intermittent claudication and the most common non-invasive diagnostic method is ankle brachial index. Peripheral arterial disease is usually accompanied by various other co-morbidities like type 2 diabetes mellitus, hypertension, and hypercholesterolemia. Literature suggests that when peripheral arterial disease is accompanied by type 2 diabetes mellitus, the ankle-brachial index can be falsely elevated due to medial calcification of the arteries. Therefore, an assessment of microcirculation using the toe brachial index is needed to diagnose PAD in these individuals. It has been well established that walking ability and ankle-brachial index are correlated in peripheral arterial disease. However, there is a dearth of literature on whether there is a correlation between toe brachial index (TBI) and walking ability. Therefore, the objective of the study is to find the correlation between toe brachial index and walking ability in type 2 diabetes mellitus with peripheral arterial disease. A total of 1485 participants were screened for the study, among which 133 met the inclusion criteria. Informed consent was obtained and the included participants were assessed for their demographic details. Toe brachial index was performed with the help of Doppler and 6-min walk test was performed to measure the claudication in the participants.ResultsIn the present study of 133 participants, we found a strong positive correlation between toe brachial index and 6-min walk distance (r = 0.911 p value < 0.05). The walking ability is directly proportional to the TBI, i.e., the lesser the values of TBI, the lesser the walking distance covered in peripheral arterial disease with type 2 diabetes mellitus.ConclusionThe present study concludes that there is a strong positive correlation between toe brachial index and 6-min walk distance.

Quantitative Flow Ratio-Derived Index of Microcirculatory Resistance as a Novel Tool to Identify Microcirculatory Function in Patients with Ischemia and No Obstructive Coronary Artery Disease

Background: Coronary microvascular disease (CMVD) is associated with adverse cardiovascular outcomes. However, there is no reliable and noninvasive quantitative diagnostic method available for CMVD. The use of a pressure wire to measure the index of microcirculatory resistance (IMR) is possible, but it has inevitable practical restrictions. We hypothesized that computation of the quantitative flow ratio could be used to predict CMVD with symptoms of ischemia and no obstructive coronary artery disease (INOCA). Methods: We retrospectively assessed the diagnostic efficiency of the quantitative flow ratio-derived index of microcirculatory resistance (QMR) in 103 vessels from 66 patients and compared it with invasive IMR using the thermodilution technique. Results: Patients were divided into the CMVD group (41/66, 62.1%) and non-CMVD group (25/66, 37.9%). Pressure wire IMR measurements were made in 103 coronary vessels, including 44 left descending arteries, 18 left circumflex arteries, and 41 right coronary arteries. ROC curve analysis showed a good diagnostic performance of QMR for all arteries (area under the curve = 0.820, 95% confidence interval 0.736–0.904, p < 0.001) in predicting microcirculatory function. The optimal cut-off for QMR to predict microcirculatory function was 266 (sensitivity: 82.9%, specificity: 72.6%, and diagnostic accuracy: 76.7%). Conclusion: QMR is a promising tool for the assessment of coronary microcirculation. The assessment of the IMR without the use of a pressure wire may enable more rapid, convenient, and cost-effective assessment of coronary microvascular function.

State-of-the-art methods of qualitative and quantitative assessment of eye microcirculation

Circulatory disorders in eye vessels play an important role in the development of ophthalmic pathologies, in particular socially significant diseases such as glaucoma, age-related macular degeneration, diabetic retinopathy, and retinal vascular occlusion. Eye hemodynamics features are an important diagnostic criterion for both ocular and systemic diseases. A comprehensive assessment of blood flow in various structures of the eyeball offers additional information on the pathogenesis of the diseases and helps develop new approaches to monitoring the effectiveness of treatment and vascular pathology prognostication. Thanks to the improved technologies, we have today a variety of invasive and non-invasive techniques for examining ocular hemoperfusion, including those intended for retrobulbar blood flow and intraocular blood circulation evaluation. The review article is focused on the state-of-the-art techniques: fluorescein angiography, ultrasound examination involving blood flow assessment by colour Doppler mapping and Dopplerography, optical coherence tomography in the angiographic mode and laser speckle flowgraphy. The role of these techniques in the diagnosis of vascular pathology and their advantages and disadvantages when used in ophthalmological practice is considered.