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Journal of the American Society of... May 2023Greater interest in imaging the superior vena cava (SVC) in recent years has arisen because of increased focus on disorders of the right heart; the growing use of... (Review)
Review
Greater interest in imaging the superior vena cava (SVC) in recent years has arisen because of increased focus on disorders of the right heart; the growing use of transvenous access lines, dialysis catheters, and device leads; and the emergence of right ventricular mechanical circulatory support systems via the transcatheter approach. As a low-pressure venous conduit in the right upper mediastinum, the SVC is prone to compression by various pathologic processes, to invasion by malignancies originating in nearby structures, and to complications arising from intraluminal device leads and indwelling catheters. Computed tomography and magnetic resonance venography are the modalities of choice for structural imaging of the SVC. Ultrasound allows a reasonable, yet less detailed anatomic assessment of this venous conduit. Spectral and color Doppler imaging by ultrasound are the most valuable noninvasive tools for the interrogation of SVC blood flow, a marker of the filling pattern of the right heart. Analysis of the velocity, duration, and direction of the Doppler waveforms and their phasic response to respiration makes it possible to distinguish normal from abnormal flow patterns and offers diagnostic insights into disorders that affect right heart function. The aims of this review are to demonstrate the added value SVC imaging provides during transthoracic and transesophageal echocardiographic studies, to outline its usefulness for the detection and evaluation of structural abnormalities, and to detail the role of spectral Doppler imaging in aiding the diagnosis of various disorders that affect the right heart.
Topics: Humans; Vena Cava, Superior; Echocardiography, Transesophageal; Heart Ventricles; Ultrasonography, Doppler
PubMed: 36754099
DOI: 10.1016/j.echo.2023.01.017 -
Journal of Cardiovascular Development... May 2021The aortic root has long been considered an inert unidirectional conduit between the left ventricle and the ascending aorta. In the classical definition, the aortic... (Review)
Review
The aortic root has long been considered an inert unidirectional conduit between the left ventricle and the ascending aorta. In the classical definition, the aortic valve leaflets (similar to what is perceived for the atrioventricular valves) have also been considered inactive structures, and their motion was thought to be entirely passive-just driven by the fluctuations of ventricular-aortic gradients. It was not until the advent of aortic valve-sparing surgery and of transcatheter aortic valve implantation that the interest on the anatomy of the aortic root again took momentum. These new procedures require a systematic and thorough analysis of the fine anatomical details of the components of the so-called aortic valve apparatus. Although holding and dissecting cadaveric heart specimens remains an excellent method to appreciate the complex "three-dimensional" nature of the aortic root, nowadays, echocardiography, computed tomography, and cardiac magnetic resonance provide excellent images of cardiac anatomy both in two- and three-dimensional format. Indeed, modern imaging techniques depict the aortic root as it is properly situated within the thorax in an attitudinally correct cardiac orientation, showing a sort of "dynamic anatomy", which admirably joins structure and function. Finally, they are extensively used before, during, and after percutaneous structural heart disease interventions. This review focuses on the anatomy of the aortic root as revealed by non-invasive imaging techniques.
PubMed: 34064421
DOI: 10.3390/jcdd8050051 -
Advanced Functional Materials Jan 2020Neural regeneration devices interface with the nervous system and can provide flexibility in material choice, implantation without the need for additional surgeries, and...
Neural regeneration devices interface with the nervous system and can provide flexibility in material choice, implantation without the need for additional surgeries, and the ability to serve as guides augmented with physical, biological (e.g., cellular), and biochemical functionalities. Given the complexity and challenges associated with neural regeneration, a 3D printing approach to the design and manufacturing of neural devices could provide next-generation opportunities for advanced neural regeneration via the production of anatomically accurate geometries, spatial distributions of cellular components, and incorporation of therapeutic biomolecules. A 3D printing-based approach offers compatibility with 3D scanning, computer modeling, choice of input material, and increasing control over hierarchical integration. Therefore, a 3D printed implantable platform could ultimately be used to prepare novel biomimetic scaffolds and model complex tissue architectures for clinical implants in order to treat neurological diseases and injuries. Further, the flexibility and specificity offered by 3D printed platforms have the potential to be a significant foundational breakthrough with broad research implications in cell signaling and drug screening for personalized healthcare. This progress report examines recent advances in 3D printing strategies for neural regeneration as well as insight into how these approaches can be improved in future studies.
PubMed: 32038121
DOI: 10.1002/adfm.201906237 -
JAMA Psychiatry Dec 2023Psychotic illness is associated with anatomically distributed gray matter reductions that can worsen with illness progression, but the mechanisms underlying the specific... (Randomized Controlled Trial)
Randomized Controlled Trial
IMPORTANCE
Psychotic illness is associated with anatomically distributed gray matter reductions that can worsen with illness progression, but the mechanisms underlying the specific spatial patterning of these changes is unknown.
OBJECTIVE
To test the hypothesis that brain network architecture constrains cross-sectional and longitudinal gray matter alterations across different stages of psychotic illness and to identify whether certain brain regions act as putative epicenters from which volume loss spreads.
DESIGN, SETTINGS, AND PARTICIPANTS
This case-control study included 534 individuals from 4 cohorts, spanning early and late stages of psychotic illness. Early-stage cohorts included patients with antipsychotic-naive first-episode psychosis (n = 59) and a group of patients receiving medications within 3 years of psychosis onset (n = 121). Late-stage cohorts comprised 2 independent samples of people with established schizophrenia (n = 136). Each patient group had a corresponding matched control group (n = 218). A sample of healthy adults (n = 356) was used to derive representative structural and functional brain networks for modeling of network-based spreading processes. Longitudinal illness-related and antipsychotic-related gray matter changes over 3 and 12 months were examined using a triple-blind randomized placebo-control magnetic resonance imaging study of the antipsychotic-naive patients. All data were collected between April 29, 2008, and January 15, 2020, and analyses were performed between March 1, 2021, and January 14, 2023.
MAIN OUTCOMES AND MEASURES
Coordinated deformation models were used to estimate the extent of gray matter volume (GMV) change in each of 332 parcellated areas by the volume changes observed in areas to which they were structurally or functionally coupled. To identify putative epicenters of volume loss, a network diffusion model was used to simulate the spread of pathology from different seed regions. Correlations between estimated and empirical spatial patterns of GMV alterations were used to quantify model performance.
RESULTS
Of 534 included individuals, 354 (66.3%) were men, and the mean (SD) age was 28.4 (7.4) years. In both early and late stages of illness, spatial patterns of cross-sectional volume differences between patients and controls were more accurately estimated by coordinated deformation models constrained by structural, rather than functional, network architecture (r range, >0.46 to <0.57; P < .01). The same model also robustly estimated longitudinal volume changes related to illness (r ≥ 0.52; P < .001) and antipsychotic exposure (r ≥ 0.50; P < .004). Network diffusion modeling consistently identified, across all 4 data sets, the anterior hippocampus as a putative epicenter of pathological spread in psychosis. Epicenters of longitudinal GMV loss were apparent in posterior cortex early in the illness and shifted to the prefrontal cortex with illness progression.
CONCLUSION AND RELEVANCE
These findings highlight a central role for white matter fibers as conduits for the spread of pathology across different stages of psychotic illness, mirroring findings reported in neurodegenerative conditions. The structural connectome thus represents a fundamental constraint on brain changes in psychosis, regardless of whether these changes are caused by illness or medication. Moreover, the anterior hippocampus represents a putative epicenter of early brain pathology from which dysfunction may spread to affect connected areas.
Topics: Male; Adult; Humans; Female; Gray Matter; Antipsychotic Agents; Cross-Sectional Studies; Case-Control Studies; Psychotic Disorders; Brain; Magnetic Resonance Imaging
PubMed: 37728918
DOI: 10.1001/jamapsychiatry.2023.3293 -
Colorectal Disease : the Official... Jul 2020To provide a comprehensive evidence-based assessment of the anatomical variations of the left colic artery (LCA). (Meta-Analysis)
Meta-Analysis Review
AIM
To provide a comprehensive evidence-based assessment of the anatomical variations of the left colic artery (LCA).
METHOD
A thorough systematic search of the literature up until 1 April 2019 was conducted on the electronic databases PubMed, SCOPUS and Web of Science (WOS) to identify studies eligible for inclusion. Data were extracted and pooled into a meta-analysis using the Metafor package in R. The primary outcomes of interest were the absence of the LCA and the anatomical variants of its origin. The secondary outcomes were the distance (mean ± SD) between the origin of the inferior mesenteric artery (OIMA) and the origin of the left colic artery (OLCA).
RESULTS
A total of 19 studies (n = 2040 patients) were included. The pooled prevalence estimate (PPE) of LCA absence was 1.2% (95% CI 0.0-3.6%). Across participants with either a Type I or Type II LCA, the PPE of a Type I LCA was 49.0% (95% CI 40.2-57.8%). The PPE of a Type II LCA was therefore 51.0%. The pooled mean distance from the OIMA to the OLCA was 40.41 mm (95 CI% 38.69-42.12 mm). The pooled mean length of a Type I LCA was 39.12 mm (95% CI 36.70-41.53 mm) while the pooled mean length of a Type IIa and Type IIb LCA was 41.43 mm (95% CI 36.90-43.27 mm) and 39.64 mm (95% CI 37.68-41.59 mm), respectively.
CONCLUSION
Although the absence of the LCA is a rare occurrence (PPE 1.2%), it may be associated with an important risk of anastomotic leakage as a result of insufficient vascularization of the proximal colonic conduit. It is also necessary to distinguish variants I and II of Latarjet, the frequency of which is identical, with division of the LCA being technically more straightforward in variant I of Latarjet. Surgeons should be aware that technical difficulties are likely to be more common with variant II of Latarjet, as LCA ligation may be more difficult due to its close proximity to the inferior mesenteric vein (IMV).
Topics: Anastomotic Leak; Humans; Laparoscopy; Mesenteric Artery, Inferior; Mesenteric Veins; Rectal Neoplasms; Retrospective Studies
PubMed: 31655010
DOI: 10.1111/codi.14891 -
Clinical Anatomy (New York, N.Y.) Nov 2020The mandibular canal is a conduit that allows the inferior alveolar neurovascular bundle to transverse the mandible to supply the dentition, jawbone and soft tissue... (Review)
Review
The mandibular canal is a conduit that allows the inferior alveolar neurovascular bundle to transverse the mandible to supply the dentition, jawbone and soft tissue around the gingiva and the lower lip. It is not a single canal but an anatomical structure with multiple branches and variations. The branches are termed accessory, bifid or trifid canals depending on their number and configuration. A bifid mandibular canal is an anatomical variation reported more commonly than the trifid variant. Because of these variations, it is of the utmost importance to determine the exact location of the mandibular canal and to identify any branches arising from it prior to performing surgery in the mandible. This article reviews the prevalence, classification and morphometric measurements of these accessory mandibular canals, emphasizing their clinical significance.
Topics: Anatomic Variation; Anesthesia, Dental; Humans; Mandible; Radiography, Panoramic; Tomography, X-Ray Computed
PubMed: 31943382
DOI: 10.1002/ca.23567 -
The New Phytologist Aug 2021Wood anatomical traits shape a xylem segment's hydraulic efficiency and resistance to embolism spread due to declining water potential. It has been known for decades...
Wood anatomical traits shape a xylem segment's hydraulic efficiency and resistance to embolism spread due to declining water potential. It has been known for decades that variations in conduit connectivity play a role in altering xylem hydraulics. However, evaluating the precise effect of conduit connectivity has been elusive. The objective here is to establish an analytical linkage between conduit connectivity and grouping and tissue-scale hydraulics. It is hypothesized that an increase in conduit connectivity brings improved resistance to embolism spread due to increased hydraulic pathway redundancy. However, an increase in conduit connectivity could also reduce resistance due to increased speed of embolism spread with respect to pressure. We elaborate on this trade-off using graph theory, percolation theory and computational modeling of xylem. The results are validated using anatomical measurements of Acer branch xylem. Considering only species with vessels, increases in connectivity improve resistance to embolism spread without negatively affecting hydraulic conductivity. The often measured grouping index fails to capture the totality of the effect of conduit connectivity on xylem hydraulics. Variations in xylem network characteristics, such as conduit connectivity, might explain why hypothesized trends among woody species, such as the 'safety-efficiency' trade-off hypothesis, are weaker than expected.
Topics: Acer; Water; Wood; Xylem
PubMed: 33908055
DOI: 10.1111/nph.17429 -
Physiologia Plantarum 2023Interconduit pit membranes, which are permeable regions in the primary cell wall that connect to adjacent conduits, play a crucial role in water relations and the...
Interconduit pit membranes, which are permeable regions in the primary cell wall that connect to adjacent conduits, play a crucial role in water relations and the movement of nutrients between xylem conduits. However, how pit membrane characteristics might influence water-carbon coupling remains poorly investigated in cycads. We examined pit characteristics, the anatomical and photosynthetic traits of 13 cycads from a common garden, to determine if pit traits and their coordination are related to water relations and carbon economy. We found that the pit traits of cycads were highly variable and that cycads exhibited a similar tradeoff between pit density and pit area as other plant lineages. Unlike other plant lineages (1) pit membranes, pit apertures, and pit shapes of cycads were not coordinated as in angiosperms; (2) cycads exhibited larger pit membrane areas but lower pit densities relative to ferns and angiosperms, but smaller and similar pit membrane densities to non-cycad gymnosperms; (3) cycad pit membrane areas and densities were partially coordinated with anatomical traits, with hydraulic supply of the rachis positively coordinated with photosynthesis, whereas pit aperture areas and fractions were negatively coordinated with photosynthetic traits; (4) cycad pit traits reflected adaptation to wetter habitats for Cycadaceae and drier habitats for Zamiaceae. The large variation in pit traits, the unique pit membrane size and density, and the partial coordination of pit traits with anatomical and physiological traits of the rachis and pinna among cycads may have facilitated their dominance in a variety of ecosystems from the Mesozoic to modern times.
Topics: Ecosystem; Cycadopsida; Photosynthesis; Plants; Water; Carbon
PubMed: 37158623
DOI: 10.1111/ppl.13924 -
Cochlear Implants International Mar 2021This case study presents a rare anatomical anomaly complicating cochlear implantation in the form of patent periotic ducts and Hyrtl's (tympanomeningeal) fissures.... (Review)
Review
This case study presents a rare anatomical anomaly complicating cochlear implantation in the form of patent periotic ducts and Hyrtl's (tympanomeningeal) fissures. Hyrtl's fissures are transient anatomical conduits which normally ossify by the 24th week of gestation. Their persistence may cause inadvertent insertion of the cochlear implant electrode into this channel and prevent a successful outcome. This case study and a review of the relevant literature highlights the importance of recognizing this rare anomaly which is easily missed on preoperative imaging.
Topics: Cochlea; Cochlear Implantation; Cochlear Implants; Electrodes, Implanted; Humans; Temporal Bone
PubMed: 32967593
DOI: 10.1080/14670100.2020.1823127 -
The Canadian Journal of Cardiology May 2020Large conduit arteries and the microcirculation participate in the mechanisms of elevation of blood pressure (BP). Large vessels play roles predominantly in older... (Review)
Review
Large conduit arteries and the microcirculation participate in the mechanisms of elevation of blood pressure (BP). Large vessels play roles predominantly in older subjects, with stiffening progressing after middle age leading to increases in systolic BP found in most humans with aging. Systolic BP elevation and increased pulsatility penetrate deeper into the distal vasculature, leading to microcirculatory injury, remodelling, and associated endothelial dysfunction. The result is target organ damage in the heart, brain, and kidney. In younger individuals genetically predisposed to high BP, increased salt intake or other exogenous or endogenous risk factors for hypertension, including overweight and excess alcohol intake, lead to enhanced sympathetic activity and vasoconstriction. Enhanced vasoconstrictor responses and myogenic tone become persistent when embedded in an increased extracellular matrix, resulting in remodelling of resistance arteries with a narrowed lumen and increased media-lumen ratio. Stimulation of the renin-angiotensin-aldosterone and endothelin systems and inflammatory and immune activation, to which gut microbiome dysbiosis may contribute as a result of salt intake, also participate in the injury and remodelling of the microcirculation and endothelial dysfunction. Inflammation of perivascular fat and loss of anticontractile factors play roles as well in microvessel remodelling. Exaggerated myogenic tone leads to closure of terminal arterioles, collapse of capillaries and venules, functional rarefaction, and eventually to anatomic rarefaction, compromising tissue perfusion. The remodelling of the microcirculation raises resistance to flow, and accordingly raises BP in a feedback process that over years results in stiffening of conduit arteries and systo-diastolic or predominantly systolic hypertension and, more rarely, predominantly diastolic hypertension. Thus, at different stages of life and the evolution of hypertension, large vessels and the microcirculation interact to contribute to BP elevation.
Topics: Arteries; Blood Pressure; Humans; Hypertension; Microcirculation; Phenotype; Vascular Remodeling; Vascular Stiffness
PubMed: 32389338
DOI: 10.1016/j.cjca.2020.02.003