[Clinical Study of Peripherally Inserted Central Catheter-Related Thrombosis and Its Influence on the Blood Flow Status of the Inserted Veins in Cancer Patients]

Objective

To investigate the clinical features of peripherally inserted central catheter (PICC)-related thrombosis (PICCRT) within 2 weeks after PICC placement in cancer patients and its dynamic influence on the blood flow status of veins inserted with catheter, and to provide support for implementing thrombosis prevention and control measures.

Methods

Between May 2019 and July 2020, patients who had solid tumors and who had PICC were prospectively enrolled at West China Hospital, Sichuan University. Scheduled color Doppler imaging was performed to examine the status of PICCRT formation at 8 points of time, with the first one conducted one day before the insertion of PICC and the other 7 completed within 2 weeks after the insertion of PICC. Then, based on whether patients had PICCRT, the patients were divided into two groups, a non-PICCRT group and a PICCRT group. The PICCRT group was further divided into two subgroups, an asymptomatic PICCRT group and a symptomatic PICCRT group, according to whether the patients had thrombosis-related symptoms and signs. Comparisons were made to study the incidence of PICCRT and the vascular diameter and the blood flow velocity in the veins inserted with catheters at different points of time in the patients of different groups.

Results

Among 173 cancer patients in the cohort, 126 (72.8%) developed PICCRT, all of which occurred within 1 week after PICC insertion. There were 95 cases of asymptomatic PICCRT and 31 cases of symptomatic PICCRT. Before and after PICC insertion, the vascular diameter of both the asymptomatic and symptomatic PICCRT groups was significantly smaller than that of the non-PICCRT group and the blood flow velocity was significantly slower than that of the non-PICCRT group, with the difference continuing to increase with the prolongation of catheter indwelling time.

Conclusion

Inserting catheters in veins with bigger vascular diameter and faster blood flow velocity may help reduce the incidence of PICCRT. The first week post catheter insertion is the key intervention period for the prevention of PICCRT.

Vascular diameter and intima-media thickness to diameter ratio values of the carotid artery in 642 healthy children

In children, arterial alterations occur with increased intima-media thickness as well as vascular diameter enlargement. Both conditions correlate with higher cardiovascular risk in adults, and both the array and proportion of these alterations are important hemodynamic parameters. In terms of functional adaptation processes, they influence several arterial wall properties as for example the shear and tensile stress of the vessel. There are no reference values for the vascular diameter and intima-media thickness/diameter ratio of the carotid artery in children. Therefore, this study aimed to assess vascular diameter, intima-media thickness/diameter ratio and related tensile stress values in children and to further investigate the influence of sex, age, body mass index, and blood pressure. The parameters were measured with high-resolution semi-automated ultrasound. Sex- and age-dependent values were calculated with the LMS method for a cross-sectional sample of 642 healthy, non-obese children aged 8-17 years. The mean vascular diameter was 5.45 ± 0.46 mm; the median intima-media thickness/diameter ratio was 0.085 (0.079-0.092); the median tensile stress was 105.4 (95.2-116.4) kPa. The vascular diameter and the tensile stress were higher, and the intima-media thickness/diameter ratio was lower in boys than in girls. In comparison to the normal weight study population the excludedobese children had a significantly higher diameter, a lower intima-media thickness/diameter ratio, and a higher tensile stress. In multiple regression analyses of diameter, intima-media thickness/diameter ratio, and tensile stress, all parameters were influenced by sex and body mass index. Furthermore, systolic and diastolic blood pressure significantly influenced the vascular diameter, and systolic blood pressure significantly influenced the intima-media thickness/diameter ratio. Conclusion: This study is the first to report values for the diameter, the intima-media thickness/diameter ratio of the carotid artery, and the related tensile stress allowing a more differentiated view of cardiovascular adaptations as it combines structural and functional vascular parameters. What is known: • Intima-media thickness and vascular diameter are related to a higher cardiovascular risk in adults • The intima-media thickness/diameter ratio gives information about hemodynamic and functional vessel adaptation What is new: • Values for vascular diameter, intima-media thickness/diameter ratio, and tensile stress of the carotid artery in children are presented in this study • Intima-media thickness as a surrogate marker for arterial health in children should be complemented by intima-media thickness/diameter ratio measurement.

The microvascular extracellular matrix in brains with Alzheimer's disease neuropathologic change (ADNC) and cerebral amyloid angiopathy (CAA)

BACKGROUND

The microvasculature (MV) of brains with Alzheimer's disease neuropathologic change (ADNC) and cerebral amyloid angiopathy (CAA), in the absence of concurrent pathologies (e.g., infarctions, Lewy bodies), is incompletely understood.

OBJECTIVE

To analyze microvascular density, diameter and extracellular matrix (ECM) content in association with ADNC and CAA.

METHODS

We examined samples of cerebral cortex and isolated brain microvasculature (MV) from subjects with the National Institute on Aging-Alzheimer's Association (NIA-AA) designations of not-, intermediate-, or high ADNC and from subjects with no CAA and moderate-severe CAA. Cases for all groups were selected with no major (territorial) strokes, ≤ 1 microinfarct in screening sections, and no Lewy body pathology. MV density and diameter were measured from cortical brain sections. Levels of basement membrane (BM) ECM components, the protein product of TNF-stimulated gene-6 (TSG-6), and the ubiquitous glycosaminoglycan hyaluronan (HA) were assayed by western blots or HA ELISA of MV lysates.

RESULTS

We found no significant changes in MV density or diameter among any of the groups. Levels of BM laminin and collagen IV (col IV) were lower in MV isolated from the high ADNC vs. not-ADNC groups. In contrast, BM laminin was significantly higher in MV from the moderate-severe CAA vs. the no CAA groups. TSG-6 and HA content were higher in the presence of both high ADNC and CAA, whereas levels of BM fibronectin and perlecan were similar among all groups.

CONCLUSIONS

Cortical MV density and diameter are not appreciably altered by ADNC or CAA. TSG-6 and HA are increased in both ADNC and CAA, with laminin and col IV decreased in the BM of high ADNC, but laminin increased in moderate-severe CAA. These results show that changes in the ECM occur in AD and CAA, but independently of one another, and likely reflect on the regional functioning of the brain microvasculature.

A novel computer-aided diagnosis system for the early detection of hypertension based on cerebrovascular alterations

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3-D CNN segmentation succeeded in delineating cerebrovasculature accurately.

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Segmentation approach is automatic and applicable on healthy/pathological vessels.

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Blood flow variability challenge was addressed by processing MRA scans locally.

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Proposed vascular features were efficient to quantify cerebral changes.

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Proposed CAD system could help clinicians predict hypertension before its onset.

Hypertension is a leading cause of mortality in the USA. While simple tools such as the sphygmomanometer are widely used to diagnose hypertension, they could not predict the disease before its onset. Clinical studies suggest that alterations in the structure of human brains’ cerebrovasculature start to develop years before the onset of hypertension. In this research, we present a novel computer-aided diagnosis (CAD) system for the early detection of hypertension. The proposed CAD system analyzes magnetic resonance angiography (MRA) data of human brains to detect and track the cerebral vascular alterations and this is achieved using the following steps: i) MRA data are preprocessed to eliminate noise effects, correct the bias field effect, reduce the contrast inhomogeneity using the generalized Gauss-Markov random field (GGMRF) model, and normalize the MRA data, ii) the cerebral vascular tree of each MRA volume is segmented using a 3-D convolutional neural network (3D-CNN), iii) cerebral features in terms of diameters and tortuosity of blood vessels are estimated and used to construct feature vectors, iv) feature vectors are then used to train and test various artificial neural networks to classify data into two classes; normal and hypertensive. A balanced data set of 66 subjects were used to test the CAD system. Experimental results reported a classification accuracy of 90.9% which supports the efficacy of the CAD system components to accurately model and discriminate between normal and hypertensive subjects. Clinicians would benefit from the proposed CAD system to detect and track cerebral vascular alterations over time for people with high potential of developing hypertension and to prepare appropriate treatment plans to mitigate adverse events.

Ryanodine-induced vasoconstriction of the gerbil spiral modiolar artery depends on the Ca2+ sensitivity but not on Ca2+ sparks or BK channels

Background

In many vascular smooth muscle cells (SMCs), ryanodine receptor-mediated Ca²⁺ sparks activate large-conductance Ca²⁺-activated K⁺ (BK) channels leading to lowered SMC [Ca²⁺]_i and vasodilation. Here we investigated whether Ca²⁺ sparks regulate SMC global [Ca²⁺]_i and diameter in the spiral modiolar artery (SMA) by activating BK channels.

Methods

SMAs were isolated from adult female gerbils, loaded with the Ca²⁺-sensitive flourescent dye fluo-4 and pressurized using a concentric double-pipette system. Ca²⁺ signals and vascular diameter changes were recorded using a laser-scanning confocal imaging system. Effects of various pharmacological agents on Ca²⁺ signals and vascular diameter were analyzed.

Results

Ca²⁺ sparks and waves were observed in pressurized SMAs. Inhibition of Ca²⁺ sparks with ryanodine increased global Ca²⁺ and constricted SMA at 40 cmH₂O but inhibition of Ca²⁺ sparks with tetracaine or inhibition of BK channels with iberiotoxin at 40 cmH₂O did not produce a similar effect. The ryanodine-induced vasoconstriction observed at 40 cmH₂O was abolished at 60 cmH₂O, consistent with a greater Ca²⁺-sensitivity of constriction at 40 cmH₂O than at 60 cmH₂O. When the Ca²⁺-sensitivity of the SMA was increased by prior application of 1 nM endothelin-1, ryanodine induced a robust vasoconstriction at 60 cmH₂O.

Conclusions

The results suggest that Ca²⁺ sparks, while present, do not regulate vascular diameter in the SMA by activating BK channels and that the regulation of vascular diameter in the SMA is determined by the Ca²⁺-sensitivity of constriction.

BK Channels in the Vascular System

Autoregulation of blood flow is essential for the preservation of organ function to ensure continuous supply of oxygen and essential nutrients and removal of metabolic waste. This is achieved by controlling the diameter of muscular arteries and arterioles that exhibit a myogenic response to changes in arterial blood pressure, nerve activity and tissue metabolism. Large-conductance voltage and Ca(2+)-dependent K(+) channels (BK channels), expressed exclusively in smooth muscle cells (SMCs) in the vascular wall of healthy arteries, play a critical role in regulating the myogenic response. Activation of BK channels by intracellular, local, and transient ryanodine receptor-mediated "Ca(2+) sparks," provides a hyperpolarizing influence on the SMC membrane potential thereby decreasing the activity of voltage-dependent Ca(2+) channels and limiting Ca(2+) influx to promote SMC relaxation and vasodilation. The BK channel α subunit, a large tetrameric protein with each monomer consisting of seven-transmembrane domains, a long intracellular C-terminal tail and an extracellular N-terminus, associates with the β1 and γ subunits in vascular SMCs. The BK channel is regulated by factors originating within the SMC or from the endothelium, perivascular nerves and circulating blood, that significantly alter channel gating properties, Ca(2+) sensitivity and expression of the α and/or β1 subunit. The BK channel thus serves as a central receiving dock that relays the effects of the changes in several such concomitant autocrine and paracrine factors and influences cardiovascular health. This chapter describes the primary mechanism of regulation of myogenic response by BK channels and the alterations to this mechanism wrought by different vasoactive mediators.

Assessing Direct Vascular Actions of Estrogens

Estrogens are known to affect vascular function. In order to decipher the underlying mechanisms, it is essential to study the direct actions of estrogenic substances on blood vessels. There are two widely used approaches to assess the effects of estrogenic substances directly on blood vessels, the isolated perfused intact mesenteric vascular bed (McGregor preparation) and the isolated perfused/pressurized vessel approach. The McGregor preparation relies on constant flow with vascular reactivity assessed as changes in perfusion pressure. The isolated perfused/pressurized vessel approach uses a single vessel mounted on glass micropipettes. The main readout in this approach is vascular diameter. This chapter describes these approaches which remain cornerstones in the investigation of direct vascular actions of estrogenic substances.