Primary cutaneous microangiopathy in heart recipients

History of the cutaneous microcirculation from antiquity to modern times

 This review spans a wide arc from the first observations of the early anatomists to the present day. William Harvey was the first to describe the heart as the centre of the large and small circulatory system. He thus replaced the previously valid system of Galenos, It was Marcello Malpighi who first described that the capillary system connects the arteries with the veins. In 1688 Antoni van Leeuwenhoek (1632-1686) confirmed these results with a paper on capillary perfusion in the caudal fin of the glass eel. It was then Hermann Boerhave (1668-1738, Leiden) who was the first to carry out microcirculation tests on patients. He studied the microcirculation in the human bulbar conjunctiva. Even today, microcirculation studies in the conjunctiva bulbi of patients are carried out today. Until 1831, it was never quite clear whether the observations reported belonged mainly to the field of microcirculation, which had not yet been defined. This was done in Great Britain by Marshall Hall (1790-1857). Technical Improvements allowed increasingly sophisticated studies of the morphological structure of the terminal vasculature. According to Gustav Ricker (1870-1948, Vienna), the terminal vasculature comprises the functional unit of the smallest arteries, arterioles, capillaries and venules. In 1921 it was still thought that the blood circulation was the sole response to the pumping action of the heart. Even the classic work by Bayliss on the myogenic hypothesis (later referred to as "blood flow autoregulation") initially received little attention. More strikingly, even the findings of August Krogh, for which he received the Nobel Prize in Medicine in 1920 (for his discovery of the mechanisms of capillary motor regulation), were ignored. During an outstanding autoregulation symposium held in 1963 a broad consensus was reached on active and passive mechanisms, which is more or less valid till today. The mechanisms of regulation of capillary blood flow are now largely understood, although not completely resolved. The development of video systems with recording capability and automated off-line recording of capillary erythrocyte velocities allowed the application of morphological and dynamic studies of cutaneous capillaries in humans. These reopened the field of physiological or pathophysiological questions again for many groups worldwide. Since 1955, many publications on "microcirculation (5423)" and "capillary microscopy (2195)" have been listed in pubmed.

Effect of sacubitril valsartan on cardiac function and endothelial function in patients with chronic heart failure with reduced ejection fraction

OBJECTIVE

The aim of the present study was to observe the effect of sacubitril valsartan on cardiac function and vascular endothelial function in patients with chronic heart failure with reduced ejection fraction (HFrEF).

METHODS

A total of 80 patients with HFrEF were randomly divided into an observation group and a control group, with 40 patients in each group. Sacubitril valsartan was added to the conventional treatment in the observation group, and perindopril was added to the conventional treatment in the control group. Both groups were treated continuously for 12 weeks. The left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter (LVEDD), flow-mediated vasodilatory function (FMD) of the brachial artery, and levels of plasma Ang II, endothelin 1 (ET-1), and calcitonin gene-related peptide (CGRP), together with the serum nitric oxide (NO) and NO synthase (NOS) were compared before and after treatment in the groups.

RESULTS

Before the treatment, the levels of LVEF, LVEDD, FMD, Ang II, ET-1, CGRP, NO, and NOS in the observation group were not significantly different from those in the control group (P > 0.05). However, the levels of LVEF, FMD, CGRP, NO, and NOS in both groups were significantly higher after the treatment than those before the treatment (P < 0.05) and significantly higher in the observation group than those in the control group. The difference was statistically significant (P < 0.05). Meanwhile, the levels of LVEDD, Ang II, and ET-1 in both groups decreased significantly after the treatment (P < 0.05) and were significantly lower in the observation group than those in the control group. The difference was statistically significant (P < 0.05).

CONCLUSION

Sacubitril valsartan might improve endothelial function while increasing cardiac function in HFrEF patients.

Abnormal nailfold videocapillaroscopic findings in heart failure patients with preserved ejection fraction

BACKGROUND

Microvascular dysfunction is one of the pathophysiological mechanisms in heart failure. Nailfold videocapillaroscopy is a noninvasive technique used to examine the microvasculature.

OBJECTIVE

In this study, we aimed to investigate the nailfold capillaroscopic abnormalities in heart failure patients with reduced and preserved ejection fraction and compare those with control group.

METHODS

Three groups of patients were recruited for the study: HFrEF group includes the patients with heart failure with reduced ejection fraction (HFrEF), HFpEF group, patients with heart failure with preserved ejection fraction (HFpEF) and control group, healthy asymptomatic individuals. Nailfold videocapillaroscopy was performed with a videodermatoscope and all nailfold images were evaluated for enlargement and hemorrhages.

RESULTS

Abnormal videocapillaroscopic findings including enlargement and/or hemorrhages were present in 7 (24%) patients in HFrEF group, 19 (66%) patients in HFpEF group and 11 (37%) in control group. The number of patients with abnormal videocapillaroscopic findings were significantly greater in HFpEF group compared to HFrEF (p < 0.05) and control groups (p < 0.05). However, no significant difference was observed in videocapillaroscopic findings between HFrEF and control groups.

CONCLUSIONS

Our study showed that microvascular abnormalities demonstrated by videodermatoscopic examination of nailfold capillaries are considerably more common in HFpEF patients compared to HFrEF and control groups.

HELP-(Heparin-induced Extracorporeal LDL Precipitation)-apheresis in heart recipients with cardiac allograft vasculopathy and concomitant hypercholesterolemia: Influence of long-term treatment on the microcirculation

Hyperlipidemic heart transplant patients who develop cardiac allograft vasculopathy (CAV) benefit from HELP-apheresis (Heparin-induced Extracorporeal LDL Precipitation) which enables drastic lowering of plasma low-density lipoprotein, lipoprotein (a), and fibrinogen. There is evidence that HELP-apheresis also improves microcirculation by an immediate improvement of impaired endothelial-dependent vasodilatation and additive hemorheological effects.Therefore, cutaneous microcirculation was examined before, during, and after the first HELP-apheresis in eight hyperlipidemic cardiac transplant recipients with CAV. To study the long-term effect the intravital microscopy was repeated after three and 12 months of weekly apheresis treatment.In CAV patients the baseline mean erythrocyte velocity was pathologically reduced with 0.13±0.07 mm/s. During the first HELP-apheresis the erythrocyte velocity increased significantly (p = 0.0001) and remained increased until the end of the HELP procedure (p < 0.05). After three months of weekly apheresis treatment a decrease of temporary flow stops in the capillaries with a progressive homogenization (concordance) of the cutaneous microcirculation was observed. After one year of weekly treatment a markedly increase in mean erythrocyte velocity under resting conditions occurred. In addition, a reactive post-ischemic hyperemia could be established for the first time.Even the first single HELP-apheresis resulted in a significant improvement of the cutaneous microcirculation. The long-term treatment of these patients resulted in a marked improvement of the cutaneous microcirculation with the tendency to a normalization of the regulation of the capillary perfusion.

The Venoarteriolar Reflex Significantly Reduces Contralateral Perfusion as Part of the Lower Limb Circulatory Homeostasis in vivo

Perfusion at microvascular level involves the contribution of both local and central regulators, under a complex vascular signaling frame. The venoarteriolar reflex (VAR) is one of such regulatory responses, of particular relevance in the lower limb to prevent edema. Although known for quite some time, many of the complex interactions involving all of these regulatory mechanisms still need clarification. Our objective was to look deeper into VAR through modern photoplethymography (PPG). Twelve healthy subjects (both sexes, 26.0 ± 5.0 y.o.) were enrolled in this study after informed written consent. Subjects were submitted to a leg lowering maneuver while lying supine to evoke the VAR, involving three phases-10 min baseline register, both legs extended, 10 min challenge, with one randomly chosen leg (test) pending 50 cm below heart level, while the contralateral (control) remained in place, and 10 minutes recovery, resuming the initial position. PPG signals were collected from both feet and treated by the wavelet transform (WT) revealing six spectral bands in frequency intervals comprising the cardiac [1.6-0.7 Hz], respiratory [0.4-0.26 Hz], myogenic [0.26-0.1 Hz], neurogenic/sympathetic [0.1-0.045 Hz], endothelial NO-dependent (NOd) [0.045-0.015 Hz], and NO-independent (NOi) [0.015-0.007 Hz] activities. For the first time, this approach revealed that, with VAR, perfusion significantly decreased in both limbs, although the change was more pronounced in the test foot. Here, a significant decrease in myogenic, neurogenic and NOd, were noted, while the control foot recorded a decrease in neurogenic and an increase in NOd. These results confirm the utility of WT spectral analysis for flowmotion. Further, it strongly suggests that VAR results from a complex cooperation between local myogenic-endothelial responses, where a central neurogenic reflex might also be involved.

Cooling Effect on Skin Microcirculation in Asphyxiated Newborn Infants with Increased C-Reactive Protein

BACKGROUND

Therapeutic hypothermia is presumed to suppress inflammatory processes after perinatal asphyxia. In a previous study of neonatal hypoxic-ischemic encephalopathy (HIE) we found altered skin microcirculation in about a third of the infants after rewarming. We speculated whether this could be linked to increased inflammatory responses, such as high C-reactive protein (CRP). The present study further explored this question.

OBJECTIVE

The aim of this study was to explore the differences in skin microcirculation and its oxygen delivery ability during cooling and after rewarming in HIE infants with or without high CRP.

METHODS

A previously studied population of 28 HIE infants was divided into two subgroups depending on low or high CRP (repeated values above 30 mg/l for more than 24 h). The differences between the two groups regarding laser Doppler perfusion measurements (LDPMs), computer-assisted video microscopy and diffuse reflectance spectroscopies during cooling on days 1 and 3 and after rewarming on day 4 were assessed.

RESULTS

After rewarming, infants with high CRP showed significantly higher skin LDPM perfusion, lower functional vessel density and larger heterogeneity of capillary flow velocities as compared to infants with low CRP, while no such differences were found during cooling.

CONCLUSION

Skin microcirculatory responses differed significantly after rewarming, but not during cooling, between asphyxiated neonates with or without high CRP. We speculate whether cooling influences the inflammatory skin microcirculatory response and the ability of oxygen delivery to the cells. Further studies are needed to investigate this as well as its applicability to other vascular beds in the body.

Vascular and Microvascular Endothelial Function in Heart Failure With Preserved Ejection Fraction

BACKGROUND

Assessment of vascular endothelial function lacks consistency, and microvascular endothelial function has been only partly assessed in heart failure with preserved ejection fraction (HFpEF).

METHODS

The study population consisted of 90 patients: 45 had well documented HFpEF, and 45 had hypertension and no history or evidence of heart failure. Patients with hypertension but no heart failure were matched with HFpEF patients for age, sex, and diabetes. They served as control subjects. All patients underwent 2-dimensional Doppler echocardiography and vascular function measurements, including assessment of arterial wave reflections and arterial stiffness, brachial artery flow-mediated dilation (FMD), and forearm cutaneous blood flow with the use of a laser Doppler flow probe at rest and after release of arterial occlusion for 5 minutes.

RESULTS

Brachial artery FMD was lower in HFpEF than in control subjects (median (IQR) 3.6 (0.4-7.4) vs. 7.2 (3.2-17.2)%, P = .001). Forearm cutaneous blood flow at rest was similar in HFpEF and control subjects (P = .68). After release of arterial occlusion, forearm cutaneous peak blood flow was lower in HFpEF than in control subjects (P = .03). Estimated aortic systolic and mean blood pressures were similar in HFpEF and control subjects, whereas pulse pressure and pressure augmentation were greater in HFPEF than in control subjects (both P < .05).

CONCLUSION

Compared with hypertensive control subjects, patients with HFpEF had a depressed endothelial function in the forearm vasculature and microvasculature.

Ergocalciferol and microcirculatory function in chronic kidney disease and concomitant vitamin d deficiency: an exploratory, double blind, randomised controlled trial

BACKGROUND AND OBJECTIVES

Vitamin D deficiency and endothelial dysfunction are non-traditional risk factors for cardiovascular events in chronic kidney disease. Previous studies in chronic kidney disease have failed to demonstrate a beneficial effect of vitamin D on arterial stiffness, left ventricular mass and inflammation but none have assessed the effect of vitamin D on microcirculatory endothelial function.

STUDY DESIGN

We conducted a randomised controlled trial of 38 patients with non diabetic chronic kidney disease stage 3-4 and concomitant vitamin D deficiency (<16 ng/dl) who received oral ergocalciferol (50,000 IU weekly for one month followed by 50,000 IU monthly) or placebo over 6 months. The primary outcome was change in microcirculatory function measured by laser Doppler flowmetry after iontophoresis of acetylcholine. Secondary endpoints were tissue advanced glycation end products, sublingual functional capillary density and flow index as well as macrovascular parameters. Parallel in vitro experiments were conducted to determine the effect of ergocalciferol on cultured human endothelial cells.

RESULTS

Twenty patients received ergocalciferol and 18 patients received placebo. After 6 months, there was a significant improvement in the ergocalciferol group in both endothelium dependent microcirculatory vasodilatation after iontophoresis of acetylcholine (p = 0.03) and a reduction in tissue advanced glycation end products (p = 0.03). There were no changes in sublingual microcirculatory parameters. Pulse pressure (p = 0.01) but not aortic pulse wave velocity was reduced. There were no significant changes in bone mineral parameters, blood pressure or left ventricular mass index suggesting that ergocalciferol improved endothelial function independently of these parameters. In parallel experiments, expression of endothelial nitric oxide synthase and activity were increased in human endothelial cells in a dose dependent manner.

CONCLUSIONS

Ergocalciferol improved microcirculatory endothelial function in patients with chronic kidney disease and concomitant vitamin D deficiency. This process may be mediated through enhanced expression and activity of endothelial nitric oxide synthase.

TRIAL REGISTRATION

Clinical trials.gov NCT00882401.

Dynamic microvascular blood flow analysis during post-occlusive reactive hyperemia test in patients with schizophrenia

Patients suffering from schizophrenia have an increased mortality risk due to cardiovascular events. Recently the analysis of peripheral circulation has revealed interesting results in the study of vascular pathological conditions assuming that the state of microcirculation of the skin is at least partly representative for the constitution of other vascular beds including those of the cardiac muscle and arteries. The objective of this study was to investigate the microcirculation in patients with acute schizophrenia (PAT, n = 15, mean age 33.0 years, 7 male, 8 female) to identify whether spectral features from blood flow signals derived through laser Doppler spectrometry are significantly altered compared to healthy subjects (CON, n = 15, mean age 32.4 years, 7 male, 8 female) by means of the post-occlusive reactive hyperemia test. It was also explored if a segmentation of the post-ischemic stage can disclose more detailed and additional information about the dynamic behavior of the blood flow during hyperemic response. For this reason, time-frequency analyses were performed to observe the course of the blood flow frequency components over time. Our results indicate significant differences in the patients group, already detectable under baseline conditions but also in the hyperemic phase. The main modifications affect the respiratory (p = 0.006) as well as the cardiac (p = 0.001) activity. It was further shown that the application of a segmented analysis of the post-ischemic state considerably improves the differentiation between both groups. Only with the introduced segmentation algorithm using a window length of 2048 samples and a shift of 128 and 256 samples we could demonstrate influences of the disease on the endothelial (p = 0.029), the sympathetic (p = 0.019) and the myogenic (p = 0.029) mechanisms. These information provide further insights into the appearance of schizophrenia and could lead to an improvement of the patients' treatment to avoid the occurrence of cardiovascular events.

Impairment of skin blood flow during post-occlusive reactive hyperhemy assessed by laser Doppler flowmetry correlates with renal resistive index

We lack non-invasive tools for evaluating the coronary and renal microcirculations. Since cutaneous Doppler laser exploration has evidenced impaired cutaneous microvascular responses in coronary artery disease and in impaired renal function, we wanted to find out if there was a link between the impairments in the cutaneous and renal microcirculations. To specify the significance of the rise in the renal resistive index (RI), which is still unclear, we also sought relations between RI and arterial stiffness. We conducted a cross-sectional controlled study in a heterogeneous population including hypertensive patients of various ages with or without a history of cardiovascular disease along with a healthy control group. The cutaneous microcirculation was evaluated by laser Doppler flowmetry of the post-occlusive reactive hyperhemy (PORH) and of the hyperhemy to heat. The renal microcirculation was evaluated by measurement of the RI. Arterial stiffness was evaluated from an ambulatory measurement of the corrected QKD(100-60) interval. We included 22 hypertensives and 11 controls of mean age 60.6 vs 40.8 years. In this population, there was a correlation between RI and basal zero to peak flow variation (BZ-PF) (r=-0.42; P=0.02) and a correlation between RI and rest flow to peak flow variation (RF-PF) (r=-0.44; P=0.01). There was also a significant correlation between RI and the corrected QKD(100-60) (r=-0.47; P=0.01). The significant correlation between PORH parameters and RI indicates that the functional modifications of the renal and cutaneous microcirculations tend to evolve in parallel during ageing or hypertension. The relation between RI and arterial stiffness shows that RI is a compound index of both renal microvascular impairment and the deterioration of macrovascular mechanics.

Methods and potential biomarkers for the evaluation of endothelial dysfunction in chronic kidney disease: a critical approach

The impressive cardiovascular morbidity and mortality of chronic kidney disease (CKD) patients is attributable in a significant proportion to endothelial dysfunction (ED), arterial stiffness, and vascular calcifications. Abnormal vascular reactivity in these patients is more pronounced compared with other high-risk populations, but remains undiagnosed in the usual clinical setting. We briefly review the most important causes and risk factors of ED, oxidative stress, and inflammation related to arterial stiffness. We describe the main methods of ED investigation and the importance of using potential biomarkers together with classic techniques for a more comprehensive assessment of this condition. These methods include evaluation of: forearm blood flow by plethysmography, skin microcirculation by laser Doppler, and flow-mediated vasodilation by Doppler ultrasound imaging. Applanation tonometry is an easy-to-handle tool that allows a clinically reliable assessment of arterial stiffness and is also useful in quantifying endothelium-dependent and -independent vascular reactivity. We also discuss the diagnostic and therapeutic impact of new markers of ED in the CKD population. Improvement of endothelial function is an important challenge for clinical practice, and there are relatively few therapeutical strategies available. Therefore, a combined biomarker and bedside investigational approach could be a starting point for developing optimal therapeutic tools.

Relationship between peripheral and coronary function using laser Doppler imaging and transthoracic echocardiography

Vascular dysfunction in the coronary and peripheral circulations is an early prognostic marker of future cardiovascular events. Measurements of coronary and peripheral vascular function in resistance vessels can be made, but rely on invasive procedures, which make them unsuitable for routine application. An assessment of the direct correlation between vascular responses in skin and coronary vessels has not been made previously. In 27 normal healthy subjects (18-55 years of age), we examined the relationship between peripheral and coronary vascular function. Cutaneous perfusion was measured using the non-invasive technique of laser Doppler imaging during iontophoresis of acetylcholine and sodium nitroprusside, and cutaneous vascular conductance was calculated (laser Doppler perfusion/mean arterial pressure). Coronary flow reserve was measured using transthoracic echocardiography during intravenous adenosine infusion. Mean diastolic velocities were measured at baseline and peak hyperaemic conditions from the Doppler signal recordings. CVR (coronary velocity reserve) was defined as the ratio of hyperaemic to basal mean diastolic velocities. There were significant positive correlations between CVR and cutaneous vascular conductance for acetylcholine (r=0.399, P=0.039) and sodium nitroprusside (r=0.446, P=0.020). These results support the idea that peripheral measurements of skin blood flow are representative of generalized microvascular function including that of the coronary circulation in normal healthy subjects.

Vascular calcification is associated with impaired microcirculatory function in chronic haemodialysis patients

Although vascular calcification (VC) in dialysis patients is associated with increased cardiovascular events, the pathophysiology is still largely obscure. Microcirculatory dysfunction may contribute to demand myocardial ischaemia. We have studied cutaneous microcirculatory function in haemodialysis (HD) patients with and without large-vessel VC. 37 non-diabetic subjects (20 HD and 17 healthy controls) were studied. VC was assessed using CT scanning of a standardised segment of superficial femoral artery (11 VC+, 9 VC-). Laser Doppler imaging was undertaken using a Periscan PIM II(R) at rest and under vasodilator challenge. Baseline perfusion was not statistically different in VC+ patients than VC- patients or controls (1.03 +/- 0.2, 1.08 +/- 0.2, 0.93 +/- 0.3 PU respectively). Overall, the maximum vasodilatory response to both ACh (p < 0.001) and SNP (p = 0.004) was lower in the HD than the control group. In addition, the HD patients took longer to reach a maximum vasodilatation than the controls (p = 0.008 for ACh, n.s. for SNP). Further, the maximum vasodilatory response in the VC+ patients was lower and patients took longer to reach maximum vasodilatation than the VC- group. We have demonstrated, for the first time, impaired and dysregulated microcirculatory function in patients with VC. This may be important in understanding the pathophysiology of the complications and cardiovascular consequences of VC.

Blunted post-ischemic increase of the endothelial skin blood flowmotion component as early sign of endothelial dysfunction in chronic kidney disease patients

With the aim to investigate microvascular endothelial function in chronic kidney disease (CKD) patients on conservative treatment, skin blood flowmotion (SBF) was explored by spectral Fourier analysis of skin forearm laser Doppler tracing, registered before and following forearm ischemia in 32 III to V stage CKD patients (23 males, mean age: 52+/-12 years), without diabetes or cardiovascular disease, and in 32 age and sex matched healthy subjects. The power spectral density (PSD) of the 0.009-1.6 Hz total spectrum SBF, as well as of five sub-intervals, each of them related to endothelial (0.009-0.02 Hz), sympathetic (0.02-0.06 Hz), myogenic (0.06-0.2 Hz), respiratory (0.2-0.6 Hz) or cardiac (0.6-1.6 Hz) activity, was measured in PU(2)/Hz (PU=perfusion unit; 1 PU=10 mV). Under basal conditions CKD patients and controls did not differ in skin perfusion or in PSD of total spectrum SBF, as well as of each of the five subintervals considered. No substantial difference was also observed in skin post-ischemic hyperemia between patients and controls. A significant post-ischemic increase in the normalized value of endothelial sub-interval was observed in controls (p<0.05, GLM ANOVA analysis of variance), but not in CKD patients. A lower per cent increase in absolute PSD value of endothelial sub-interval was also observed in CKD patients compared to controls (185+/-98 % vs 279+/-243 %, p<0.05). The post-ischemic per cent increase in absolute PSD of endothelial sub-interval was negatively related to the systolic blood pressure (r=-0.45, p<0.01), to the mean arterial blood pressure (r=-0.40, p<0.05) and to the PTH serum levels (r=-0.38, p<0.05) in CKD patients. The blunted post-ischemic increase of the endothelial SBF sub-interval can be considered an early sign of microvascular endothelial dysfunction in the CKD studied patients. Arterial hypertension seems to be the main factor related to this SBF abnormality, together with the hormonal CKD related abnormalities.

Noninvasive interrogation of microvasculature for signs of endothelial dysfunction in patients with chronic renal failure

Endothelial cell dysfunction (ECD) has been demonstrated in patients with end-stage renal disease (ESRD) who have cardiovascular disease (CD) or diabetes mellitus (DM). While techniques to examine conduit arteries have been adapted to these patients, evaluation of microvascular function has lagged behind. Therefore, we used laser Doppler flowmetry (LDF) and scanned laser Doppler imaging (LDI) to quantify parameters of the postocclusion reactive hyperemia and thermal hyperemic responses (local heating to 43 degrees C) in ESRD patients (n=63) and healthy individuals (n=33). Patients with ESRD were partitioned among those with either CD or DM or both (designated CDorDM, n=30), patients with both CD and DM (designated CD+DM, n=12, statistically similar to CDorDM), and patients with neither CD or DM (designated approximately CDor DM, n=33). LDF during thermal hyperemia showed a decrease in the thermal peaks and plateau as well as a delay in plateau compared with control, consistent with ECD. LDF during reactive hyperemia showed a decrease in the pay-back area under the curve, also consistent with ECD. approximately CDorDM were heterogeneous: almost 50% contained flow abnormalities similar to CDorDM. There was also a reduction in the number of functional arterioles on LDI images. Fourier analysis of LDF oscillations showed that low-frequency oscillations characterizing endothelial function were impaired in CDorDM and in many approximately CDorDM. The data demonstrate that ESRD patients with expected ECD (CDorDM) are characterized by distinct abnormalities in LDF parameters. However, similar abnormalities are found in approximately one-half of ESRD patients without evidence for CD or DM. Postocclusive and thermal interrogation of the microvasculature with laser Doppler-resolved parameters of the microcirculation, followed by Fourier analysis of the very slow oscillations, may provide a valuable adjunct to early noninvasive diagnosis of ECD in ESRD, especially important in a subpopulation of ESRD patients with no known CD or DM, which could be at increased risk of impending clinical manifestations of vasculopathy.