A reappraisal of pediatric thoracic surface anatomy.

Accurate knowledge of surface anatomy is essential for physical examination, invasive procedures, and anatomy education. Individual factors such as age make surface landmarks variable so accurate descriptions are needed. The aim of this study is to describe age-related surface landmarks for intrathoracic structures in children. A total of 156 thoracic computed tomography scans of children aged 0-18 years were categorized into six groups, and the associations between major intrathoracic structures and surface landmarks were analyzed. Sternal angle is an accurate surface landmark for the azygos vein-superior vena cava junction in all age groups. However, the aortic arch (except in the 0-1 year group), the bifurcation of the pulmonary trunk and the tracheal bifurcation in those aged 15-18 years were not within this plane. The left brachiocephalic vein was located behind the ipsilateral sternoclavicular joint except in the 1-3 years group, and the right was behind it in children older than 6 years. The apex of heart was at the 5th intercostal space level in the 0-1 and 12-18 years groups; however, it was higher in the other groups. The lower borders of the lungs were at the sixth costal cartilage level in the midclavicular line, eighth intercostal space level in the midaxillary line, and T12 adjacent to the vertebral column in the 15-18 years group; the lower borders were at higher levels in younger children. Defining the variations in surface anatomy by in vivo studies will increase its clinical and pedagogical value.

Clinical relevance of the left brachiocephalic vein anatomy for vascular access in dialysis patients.

INTRODUCTION: Most hemodialysis patients start renal replacement therapy with a central venous catheter (CVC). The left internal jugular vein (LIJV) is the second-choice vein for CVC positioning, after the right IJV. However, to reach the right atrium, the CVC must pass through the left brachiocephalic vein (LBV), which also drains blood from the left arm through the subclavian vein. The purpose of this study is to describe how the anatomy of the central venous system and in particular that of the LBV affects vascular access in hemodialysis patients. MATERIALS AND METHODS: Three-dimensional (3D) virtual model reconstructions of the central thoracic veins of three hemodialysis patients were obtained from contrast-enhanced computed tomography scans acquired in the venous phase. The images were exported as DICOM files and loaded on open-source software for visualizing and analyzing the medical imaging (3D Slicer, Windows version 4.8.1). RESULTS: As expected, the 3D reconstructions showed that the LBV has a tortuous path with three main angulations that could be associated with external compression and stenosis. These could determine the difficulties and increased risks of venous injury during CVC placement, and an increased risk of medium to long-term catheter-associated vein thrombosis and stenosis. CONCLUSIONS: The anatomical features of the LBV indicate that the path of a CVC from the LIJV to the right atrium is tortuous and can easily be complicated by vein injury, negatively affecting the creation of future arterio-venous vascular accesses in the left arm.

A Systematic Ultrasound Evaluation of the Diameter of Deep Veins in the Newborn: Results and Implications for Clinical Practice.

BACKGROUND: In adults and children, current guidelines recommend measuring the diameter of the vein before the insertion of central catheters, in order to match vein diameter with catheter caliber and thus reduce the risk of venous thrombosis. In the neonatal intensive care unit, central catheters are often used but the vein diameter is usually not considered. METHOD: We assessed the diameter of the most relevant deep veins in 100 newborns, using a strict protocol of ultrasound evaluation. RESULTS: Mean gestational age of studied infants was 32 weeks and mean weight was 1,690 g. The mean diameter of the brachiocephalic vein was consistently ≥3 mm, with no significant difference between the right and the left side. The femoral vein diameter, on the other hand, was considerably smaller than 3 mm for infants with a weight < 2,000 g. Interobserver repeatability was found to be very high. CONCLUSION: Preprocedural ultrasound scan of veins is feasible and easy, also in newborns, and it should be recommended for optimizing central venous catheterization.

Apprasial of the surface anatomy of the Thorax in an adolescent population.

Surface anatomy is considered a fundamental part of anatomy curricula and clinical practice. Recent studies have reappraised surface anatomy using CT, but the adolescent age group has yet to be appraised. Sixty adolescent thoracoabdominal CT scans (aged 12-18 years) were examined. The surface anatomy of the central veins, cardiac apex, diaphragmatic openings, and structures in relation to the sternal angle plane were analyzed. The results showed that the brachiocephalic vein (left and right) formed mostly posterior to the sternoclavicular joint. The superior vena cava formed close to the second costal cartilage, ±16.3 mm to the right of the midline. The apex of the heart was located in relation to the fifth intercostal space; ±78.6 mm to the left of the midline. The caval hiatus was in relation to T9 and T10; the esophageal hiatus was at T10; whereas the aortic hiatus was at T11. The sternal angle plane was in relation to the upper half of T5, which was also where the bifurcations of the trachea and pulmonary trunk were observed. The SVC/azygos vein junction and the concavity of the aortic arch were observed to be more than 10 mm superior to this plane. The results of this study further highlight the substantial variability of the surface anatomy between age groups. It also emphasizes the notion that surface anatomy is a dynamic variable and cannot be treated as a static observation. Clin. Anat. 32:762-769, 2019. © 2019 Wiley Periodicals, Inc.

Anatomical variations of the thymus in relation to the left brachiocephalic vein, findings of necropsia.

Two cases of anatomical variations of the thymus are presented with respect to the anatomical relations with the left brachiocephalic vein and found during the necropsy process. Less than 2 days after birth with Noonan Syndrome, when the left brachiocephalic vein was scanning behind the upper thymus horns, there were other adjacent lesions consisting of three supernumerary spleens and three hepatic veins. The second case was an 8-year-old infant with child malpractice who died from urinary sepsis due to obstructive uropathy, in which case the upper lobes of the thymus were fused and formed a ring through which the left brachiocephalic vein passed.

Double left brachiocephalic vein with a preaortic course: a rare finding.

A double left brachiocephalic vein is an uncommon anatomic variation. Among these, a accessory branch with preaortic course is extremely rare. In this case, both branches of the left brachiocephalic vein were anterior to the aortic arch. We describe the computed tomography findings with volume-rendering imaging of this rare anatomic variation.

Anatomical variations of the left anonymous trunk are associated with central venous catheter dysfunction.

BACKGROUND: Internal jugular vein cannulation has become increasingly widespread. Compared to the left internal jugular vein (LIJV), the right internal jugular vein (RIJV) is the preferred choice for the placement of central venous catheter (CVC) for hemodialysis, mostly due to the major technical difficulties and higher rate of complications of the LIJV approach. We aimed to investigate whether variability in the direction of the LIJV/brachiocephalic vein (BV) axis on the frontal plane could be a decisive factor in determining CVC dysfunctions. METHODS: Retrospective cohort study. From our Register, a total of 1489 consecutive patients (age 69 ± 9 years, males 60%) in whom a CVC for hemodialysis was placed from January 2012 to June 2014 were selected. RESULTS: LIJV cannulation, compared with RIJV, was associated with a higher rate of catheter dysfunction during an observational period of 2 weeks after catheter placement (16 vs.12%; p = 0.005). This complication was strongly correlated with the amplitude of the angle between the LIJV and the ipsilateral BV axis on the frontal plane; an angle ≤ 110° was associated with a higher rate of catheter dysfunction (78 vs.16%; p < 0.001). CONCLUSIONS: The anatomical clarification presented in our study provides useful data that could explain the dysfunction rate of CVC inserted in the LIJV. Clinicians who insert high-flow catheters (such as hemodialysis catheters) should be aware of LIJV/BV axis variability and of the possible risks of CVC dysfunction when the angle between the LIJV and ipsilateral BV is ≤ 110°.

Selective venous sampling for primary hyperparathyroidism: how to perform an examination and interpret the results with reference to thyroid vein anatomy.

Primary hyperparathyroidism (pHPT) causes hypercalcemia. The treatment for pHPT is surgical dissection of the hyperfunctioning parathyroid gland. Lower rates of hypocalcemia and recurrent laryngeal nerve injury imply that minimally invasive parathyroidectomy (MIP) is safer than bilateral neck resection. Current trends in MIP use can be inferred only by reference to preoperative localization studies. Noninvasive imaging studies (typically preoperative localization studies) show good detection rates of hyperfunctioning glands; however, there have also been cases of nonlocalization or discordant results. Selective venous sampling (SVS) is an invasive localization method for detecting elevated intact parathyroid hormone in the thyroid and/or internal jugular and brachiocephalic veins. SVS was developed mainly for postoperative patients with persistent or recurrent pHPT; however, SVS could also be useful before initial operations due to its high sensitivity to pHPT. Currently, SVS is generally indicated for recurrent HPT, and for cases with negative imaging study results for HPT or discordant results. Multi-detector row helical CT is useful for imaging the anatomy of the jugular and thyroid veins. Knowledge of the thyroid vein anatomy enables the creation of sampling points in the internal jugular and brachiocephalic veins for catheterization of the thyroid veins and venous anastomoses.

A supraclavicular cephalic vein drained into the subclavian vein.

Although the cephalic vein follows a fairly consistent course, numerous variants have been reported. We found a rare anatomical presentation of the cephalic vein in a 75-year-old Korean male cadaver. The left cephalic vein was identified in the deltopectoral groove, ascended over the clavicle, and terminated into the left subclavian vein just before its union with the left internal jugular vein. The detailed knowledge on the variations of the cephalic vein is important for clinicians as well as anatomists since the approach through the axillary base is favored in many invasive clinical procedures.

Biometric measurements involving the terminal portion of the thoracic duct on left cervical level IV: an anatomic study.

To determine the point of entrance of the thoracic duct in the venous system, as well as to evaluate some biometric measurements concerning its terminal portion, we conducted an anatomic study on 25 non-preserved cadavers. The termination of the thoracic duct occurred on the confluence between the left internal jugular vein and the left subclavian vein in 60 % of the individuals. The average results for the biometric measurements were: distance between the end of left internal jugular vein and omohyoid muscle 31.2 ± 2.7 mm; distance between the end of thoracic duct and the left internal jugular vein 0.0 ± 0.0 mm; distance between the end of thoracic duct and the left subclavian vein 3.6 ± 1.0 mm; distance between the end of thoracic duct and the left brachiocephalic vein 10.7 ± 3.1 mm. Moreover, it was identified that the left internal jugular vein length in level IV, measured between its entrance in the left subclavian vein and the omohyoid muscle, was able to predict the termination of the thoracic duct on the junction between the left internal jugular vein and the left subclavian vein (OR = 2.99) with high accuracy (79.3 %). In addition, the left internal jugular vein length at level IV was able to predict the localization of thoracic duct termination. Thus, this finding has practical value in minimizing the risk for a potential chyle leak during or after a left-sided neck dissection.

Defining the surface anatomy of the central venous system in children.

Pediatric emergency physicians, pediatric critical care specialists, and pediatric surgeons perform central venous catheterization in many clinical settings. Complications of the procedure are not uncommon and can be fatal. Despite the frequency of application, the evidence-base describing the surface landmarks involved is missing. The aim of the current study was to critically investigate the surface markings of the central venous system in children. The superior vena cava/right atrial (SVC/RA) junction, superior vena cava (SVC) formation, and brachiocephalic vein (BCV) formation were examined independently by two investigators. Three hundred computed tomography (CT) scans collected across multiple centers were categorized by age group into: 0-3 years, 4-7 years, and 8-11 years. Scans with pathology that distorted or obscured the regional anatomy were excluded. The BCV formation was commonly found behind the ipsilateral medial clavicular head throughout childhood. This contrasts with the variable levels of SVC formation, SVC length, and SVC/RA junction. In the youngest group, SVC formation was most commonly at the second costal cartilage (CC), but moved to the first CC/first intercostal space (ICS) as the child grew. The SVC/RA junction was at the fourth CC in the youngest group and moved to the third CC/third ICS as the child grew. This study demonstrates the variable anatomy of SVC formation and the SVC/RA junction with respect to rib level. This variability underscores the unreliability of surface anatomical landmarks of the SVC/RA junction as a guide to catheter tip position.

Comprehensive Imaging Review of the Superior Vena Cava.

The superior vena cava (SVC) is the largest central systemic vein in the mediastinum. Imaging (ie, radiography, computed tomography [CT], magnetic resonance [MR] venography, and conventional venography) plays an important role in identifying congenital variants and pathologic conditions that affect the SVC. Knowledge of the basic embryology and anatomy of the SVC and techniques for CT, MR imaging, and conventional venography are pivotal to accurate diagnosis and clinical decision making. Congenital anomalies such as persistent left SVC, partial anomalous pulmonary venous return, and aneurysm are asymptomatic and may be discovered incidentally in patients undergoing imaging evaluation for associated cardiac abnormalities or other indications. Familiarity with congenital abnormalities is important to avoid image misinterpretation. Acquired abnormalities such as intrinsic and extrinsic strictures, fibrin sheath, thrombus, primary neoplasms, and trauma can produce mild narrowing to complete occlusion, the latter leading to SVC syndrome. Each imaging modality plays a role in evaluation of the SVC, helping to determine the site, extent, and cause of pathologic conditions and guide appropriate management. Commonly performed interventional procedures for fibrin sheath and benign and malignant strictures include low-dose thrombolytic infusion, fibrin sheath disruption, venous angioplasty, and stent placement.

Respiratory-gated noncontrast SPACE MR angiography sequence at 3T for evaluation of the central veins of the chest: a feasibility study.

PURPOSE: To evaluate the feasibility of a respiratory-gated noncontrast magnetic resonance angiography (MRA) sequence for imaging the central veins of the chest. MATERIALS AND METHODS: Eleven healthy subjects underwent MRA of the central veins of the chest with a respiratory-gated noncontrast (SPACE) sequence. Qualitative visualization and signal homogeneity of each central venous segment were scored by two radiologists on a scale of 1-4. Signal-to-noise and contrast-to-noise ratios (SNR and CNR) were also calculated. Retrospective review of our imaging database revealed 13 patients with suspected pathology of the central veins who underwent a clinical MRA examination using the SPACE sequence as well as reference standard central venous imaging with contrast-enhanced MRA or conventional venography. RESULTS: In healthy subjects, all central venous segments demonstrated good to excellent venous visualization and homogeneity scores with the noncontrast SPACE sequence. The mean SNR and CNR of the central venous system were 192.7 and 175.0, respectively. In the 13 clinical examinations, the sensitivity and specificity for detection of stenosis or occlusions was 100% and 100% for reader 1 and 95% and 91% for reader 2, respectively. CONCLUSION: The respiratory-gated noncontrast SPACE sequence provided excellent imaging characteristics of the central veins in healthy subjects with promising diagnostic accuracy in patients with central venous pathology.

Normative MDCT cross-sectional data estimation of superior vena cava and innominate vein in growing children using age as a predictor.

This retrospective study aimed to determine the superior vena cava (SVC) and left innominate vein (INV) normative cross-sectional area in children noninvasively using age as a predictor and also to compare the correlation of the area measured with the diameter on multidetector computed tomography (MDCT). Analysis of the SVC-INV cross-sectional area was performed for 73 consecutive patients. The cross-sectional area of the SVC-INV was manually estimated. A regression analysis was performed for the cross-sectional area and age separately, and regression equations were compared. One-way analysis of variance (ANOVA) was performed to evaluate significant differences in the area means according to age groups. Regression analysis showed that age can be a predictor for the area of the SVC (50.6 mm(2) + 1.01 × age), te INV (48.3 mm(2) + 0.93 × age), and the left SVC-INV junction (47.2 mm(2) + 0.92 × age), with respective R(2) values of 93, 88 and 94%. The comparative evaluation of the cross-sectional area and the diameter measurement of SVC showed that the cross-sectional area was more closely associated with the increasing age of the cohort (R(2) of 68 vs. 61%) than the measured diameter. For a cohort of patients without congenital or acquired heart disease, MDCT can be used as a complementary test for a normative cross-sectional normogram area database of SVC-INV using age as a predictor.

Anatomical factors associated with left innominate vein stenosis in hemodialysis patients.

Central venous stenosis remains a challenge in hemodialysis patients. Venograms have shown that left innominate vein (LIV) stenosis often occurs in front of the trachea, where it crosses the aortic arch, suggesting that there may be an anatomical factor involved, such as iliac vein compression syndrome. The goal of this study was to determine whether LIV stenosis can be attributed to compression. From September 2008 to December 2011, 19 hemodialysis patients (ten women, nine men) with symptomatic venous hypertension of the upper-left extremity were enrolled in this study. Venography and multidetector computed tomography were used to determine the location of the venous stenosis and to assess LIV anatomy. LIV diameter and the space between the sternum and aortic arch were compared between the LIV stenosis (LIVS) group (n = 9) and the non-LIV-stenosis (NLIVS) group (n = 10). The mean age of the cohort was 63 ± 17.3 years. The mean LIV diameter was 1.69 ± 1.55 mm in the LIVS group and 8.71 ± 2.33 mm in the NLIVS group. The space between the aortic arch and sternum was smaller in the LIVS group (4.55 ± 2.67 mm) than in the NLIVS group (15.25 ± 6.12 mm, P < 0.001). A contributing factor to LIV stenosis may be due to anatomical compression of the aortic arch behind the sternum. Preoperative noncontrast computed tomography is recommended for hemodialysis patients to exclude extrinsic compression.

Lymph node distribution in the central compartment of the neck: an anatomic study.

BACKGROUND: Dissection of the central compartment of the neck (CCN) is performed for proven or suspected lymph node metastases of thyroid carcinoma. During this procedure, the recurrent laryngeal nerves and the parathyroid glands are at risk. The purpose of this study was to determine the anatomic distribution of the lymph nodes in the CCN. METHODS: The anatomic distribution of the lymph nodes in the CCN was studied by dissection of 30 fresh cadavers. The soft tissue between the cricoid cartilage and the innominate vein, carotid arteries, and prevertebral fascia was removed and divided according to CCN sublevels. Nodules were identified by palpation in the specimen and sent for pathological examination. RESULTS: Three to 44 (18.5 ± 10.29) nodules were identified macroscopically. Two to 42 nodules were confirmed as lymph nodes after microscopic examination. The lymph node distribution was as follows: precricoid: 0 to 2 (0.9 ± 0.72); pretracheal: 1 of 35 (12.4 ± 8.19); lateral to the right recurrent laryngeal nerve (RLN): 0 to 11 (3.4 ± 2.34); and lateral to the left: 0 to 4 (1.7 ± 1.30). Twenty-six parathyroid glands were removed by 14 dissections. The innominate vein was found at 15 mm above the superior border of the clavicles to 35 mm below on the left side of the neck and 5 to 45 mm on the right side. CONCLUSION: The number of confirmed lymph nodes in the central neck varied from 2 to 42. Sixty-seven percent of the lymph nodes were in the pretracheal sublevel. There was no division between level VI and VII lymph nodes. Additionally, the innominate vein was found to be from 15 mm above the superior border of the clavicles to 35 mm below on the left side of the neck and 5 to 45 mm on the right side. Parathyroid glands were identified to be far away from the thyroid gland.