Anatomy Of Great Vessels Research Articles

3D Printing of Subclavian Artery: Utility for Preprocedural Planning and Correlation With Subclavian Artery Percutaneous Vascular Interventions.

Three-dimensional (3D) printing for subclavian artery (SA) percutaneous vascular interventions (PVI) may allow superior understanding of patient specific complex anatomy and aid with preprocedural planning. Five patients with computed tomography angiography (CTA) of the neck who underwent SA PVI were queried retrospectively. 3D printing of aortic arch and great vessels was accomplished with 3D slicer software and painted with acrylic paint to highlight anatomic features. The aortic arch type and implications for preprocedural planning for SA interventions including complex chronic total occlusion (CTO) lesions were determined. Comparisons were made with SA angiograms and 3D-CTA. Of the 5 patients, type I (n = 2), type II (n = 1), and type III (n = 2) aortic arches were identified. Proximal and distal reference vessel size and total lesion length were determined using a digital millimeter caliper and correlated with intraprocedural balloons and stents. In 3D-printed models (3D-PMs) of patients with SA-CTO (n = 2), cap morphology (tapered vs blunt) and distal vessel filling were visualized, permitting optimal arterial access site selection for successful cap crossing. The vertebral arteries (VAs) were also 3D printed which further allowed the ability to delineate optimal stent deployment site (proximal or distal to VA), a common dilemma that is faced intraprocedurally. The 3D-PMs also allowed preprocedural precision in stent and balloon size and length, potentially leading to procedural efficiency and cost-effectiveness. 3D printing of aortic arch and great vessel anatomy for SA-PVI allows multiple procedure-related factors to be predicted in advance, translating to decrease in contrast volume, radiation time, procedure and fluoroscopic time, thereby improving procedure and cost efficiency.

The Effect of Intraoperative Prone Position on Psoas Morphology and Great Vessel Anatomy: Consequences for Prone Lateral Approach to the Lumbar Spine

This study sought to quantify radiographic differences in psoas morphology, great vessel anatomy, and lumbar lordosis between supine and prone intraoperative positioning to optimize surgical planning and minimize the risk of neurovascular injury. Measurements on supine magnetic resonance imaging and prone intraoperative computed tomography with O-arm from L2 to L5 levels included the anteroposterior and mediolateral proximity of the psoas, aorta, inferior vena cava (IVC), and anterior iliac vessels to the vertebral body. Psoas transverse and longitudinal diameters, psoas cross-sectional area, total lumbar lordosis, and segmental lordosis were assessed. Prone position produced significant psoas lateralization, especially at more caudal levels (P < 0.001). The psoas drifted slightly anteriorly when prone, which was non-significant, but the magnitude of anterior translation significantly decreased at more caudal segments (P= 0.038) and was lowest at L5 where in fact posterior retraction was observed (P= 0.032). When prone, the IVC (P < 0.001) and right iliac vein (P= 0.005) migrated significantly anteriorly, however decreased anterior displacement was seen at more caudal levels (P < 0.001). Additionally, the IVC drifted significantly laterally at L5 (P= 0.009). Mean segmental lordosis significantly increased when prone (P < 0.001). Relative to the vertebral body, the psoas demonstrated substantial lateral mobility when prone, and posterior retraction specifically at L5. IVC and right iliac vein experienced significant anterior mobility-particularly at more cephalad levels. Prone position enhanced segmental lordosis and may be critical to optimizing sagittal restoration.

73. The effect of intraoperative prone position on psoas morphology and great vessel anatomy: consequences for prone lateral approach to the lumbar spine

<h3>BACKGROUND CONTEXT</h3> Lateral lumbar interbody fusion (LLIF) was initially developed to be performed in the lateral decubitus position, facilitating indirect neural decompression and interbody cage insertion while obviating the need for paraspinal musculature dissection. Nevertheless, this technique may limit segmental lordotic correction and–when posterior instrumentation is indicated–requires either procedure staging or lateral decubitus placement of pedicle screws. To address these drawbacks, attention has recently shifted toward the prone transpsoas technique. However, anatomical relationships between the vertebral column and adjacent anatomy may be affected by prone positioning. <h3>PURPOSE</h3> To quantify radiographic differences in psoas morphology, lumbar plexus, great vessel anatomy and lumbar lordosis between supine and prone positioning to optimize surgical planning and minimize the risk of neurovascular injury. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort study. <h3>PATIENT SAMPLE</h3> Consecutive single-surgeon cohort with lumbar degenerative pathologies undergoing posterior spinal fusion between June 2020 and December 2021. Any patient with intraoperative computed tomography (CT) imaging obtained using O-arm spinal navigation while positioned extended-prone on an open Jackson table was included. <h3>OUTCOME MEASURES</h3> Psoas morphology, iliac vasculature anatomy, lumbar lordosis. <h3>METHODS</h3> Measurements were made on supine preoperative magnetic resonance imaging (MRI) and prone intraoperative CT from L2 to L5 levels. These included the anteroposterior and mediolateral proximity of the psoas, aorta, inferior vena cava (IVC), and anterior iliac vessels to the vertebral body. Psoas transverse and longitudinal diameters, psoas cross-sectional area (CSA), total lumbar lordosis, and segmental lordosis were assessed. Supine and prone anatomies were compared via paired t-test, while ANOVA and the Spearman correlation coefficient evaluated the relationship between lumbar level and the magnitude of translation. <h3>RESULTS</h3> Twenty patients were included for analysis. Prone positioning led to significant psoas anterior translation (5.14 mm prone vs. 1.5 mm supine, P < 0.001), although the magnitude of anterior translation significantly decreased at more caudal segments (ρ: -0.39, P = 0.002) and was lowest at L5 where slight posterior retraction was observed (-0.31 mm, P = 0.024). No positional differences were observed in psoas lateralization, CSA, longitudinal diameter or transverse diameter. When prone, IVC was found to significantly migrate anteriorly (7.24 mm prone vs 2.56 mm supine, P < 0.001). However, decreased anterior displacement was demonstrated at more caudal levels (ρ: -0.38, P = 0.004). There were no significant differences in the anatomic locations of the aorta and iliac vasculature. Average segmental lordosis significantly increased when prone (14.62° prone vs 11.39° supine, P < 0.001). <h3>CONCLUSIONS</h3> This study suggests that anatomical relationships between the vertebral column, psoas muscle, and great vessels may change in the prone position and differ intraoperatively from supine imaging. Relative to the vertebral body, the psoas and IVC demonstrated substantial anterior mobility when prone– particularly at more cephalad levels– thereby promoting a safer intraoperative environment. Additionally, prone position enhanced segmental lordosis may be critical to optimizing sagittal restoration pre-discectomy. Further clinical investigations are necessary to corroborate these findings in a prone lateral cohort. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Unilateral Branch Pulmonary Artery Origin From a Solitary Arterial Trunk With Major Aortopulmonary Collaterals to the Contralateral Lung: Anatomic and Developmental Considerations

In both truncus arteriosus communis (TAC) and tetralogy of Fallot (TOF), there is a rare phenotype that includes a single branch pulmonary artery (PA) arising from a solitary great artery and major aortopulmonary collaterals (MAPCAs) supplying the contralateral lung. We describe the intracardiac and great vessel anatomy of infants with this phenotype, consider rationale for classifying patients as TOF vs TAC, and describe surgical outcomes. Our institution's surgical database was reviewed for patients with a single branch PA from a solitary arterial trunk and contralateral MAPCAs from 2007 to 2019. Demographic, imaging, and surgical data were collected and described. All 11 patients underwent complete repair with a median right ventricular to aortic pressure ratio of 0.36 (range 0.26-0.50). At 0.1-9.1 years after repair (median 0.8 years) there was approximately balanced left-right lung perfusion (median 52% to the right lung, range 34-74%). The MAPCA lungs exemplified the full spectrum of PA and MAPCA anatomy, from absent intrapericardial PAs with all single supply MAPCAs to a normally arborizing PA with all dual supply MAPCAs and present pulmonary valve leaflet tissue. All patients had a systemic semilunar valve with 3 thin and similarly sized leaflets and fibrous continuity with the tricuspid valve, and all had coronary origins and outflow tract morphology more consistent with TOF. It is appropriate to classify all patients with a single anomalous PA from a solitary arterial trunk and MAPCAs to the contralateral lung as TOF rather than TAC Type A3. All variants were amenable to surgical repair.

Impact of Aortic Arch Anatomy on Technical Performance and Clinical Outcomes in Patients with Acute Ischemic Stroke.

Arterial access is a technical consideration of mechanical thrombectomy that may affect procedural time, but few studies exist detailing the relationship of anatomy to procedural times and patient outcomes. We sought to investigate the respective impact of aortic arch and carotid artery anatomy on endovascular procedural times in patients with large-vessel occlusion. We retrospectively reviewed imaging and medical records of 207 patients from 2 academic institutions who underwent mechanical thrombectomy for anterior circulation large-vessel occlusion from January 2015 to July 2018. Preintervention CTAs were assessed to measure features of the aortic arch and ipsilateral great vessel anatomy. These included the cranial-to-caudal distance from the origin of the innominate artery to the top of the aortic arch and the takeoff angle of the respective great vessel from the arch. mRS scores were calculated from rehabilitation and other outpatient documentation. We performed bootstrap, stepwise regressions to model groin puncture to reperfusion time and binary mRS outcomes (good outcome, mRS ≤ 2). From our linear regression for groin puncture to reperfusion time, we found a significant association of the great vessel takeoff angle (P = .002) and caudal distance from the origin of the innominate artery to the top of the aortic arch (P = .05). Regression analysis for the binary mRS revealed a significant association with groin puncture to reperfusion time (P < .001). These results demonstrate that patients with larger takeoff angles and extreme aortic arches have an association with longer procedural times as approached from transfemoral access routes.

Arch Repair Technique (Pulmonary Artery Trunk Saving) in the Norwood Procedure

The classic first stage of the Norwood procedure uses a homograft patch enlargement to obtain an unobstructed aorta and coronary arteries due to insufficient native tissue to reconstruct a neo aorta. However, there are some possible disadvantages of the homograft, such as lack of growth, degeneration, calcification, and unavailability. The pulmonary artery trunk saving technique was developed as a no-patch technique to minimize patch augmentation during the reconstruction of the neo aorta in the Norwood procedure. The pulmonary artery trunk was longer and narrowed, to make the left aortopulmonary space wider, to avoid extrinsic compression of the left pulmonary artery and bronchus by the neo aorta. This technique was developed based on the advantages of the anatomy of specific great vessels in patients with hypoplastic left heart syndrome.

Retroperitoneal tumors and congenital variations in vascular anatomy of retroperitoneal great vessels

Background/objectivesVariations in vascular anatomy (VIVAs) of the retroperitoneal great vessels are uncommon but can potentially complicate surgical procedures and negatively affect treatment outcomes, yet their incidence and clinical impact are poorly studied. We sought to assess the incidence and clinical impact of VIVAs of retroperitoneal great vessels in patients with retroperitoneal tumors. MethodsWe retrospectively analyzed imaging, surgical, treatment and survival data of all pediatric patients with retroperitoneal tumors who underwent resection between January 2007 and October 2016, comparing preoperative scans with corresponding intraoperative observations, and subsequent surgical outcomes. ResultsAmong 66 children with renal, adrenal and paravertebral tumors, 6 (9%) had retroperitoneal VIVAs. Retroperitoneal VIVAs were present only with right-sided tumors and significantly associated with more frequent intraoperative complications (P = 0.013). While the presence of retroperitoneal VIVAs was not directly associated with survival outcomes, relapse was more frequent in patients with VIVAs (33%) than those without (18.3%, P = 0.378), and relapse was also associated with lower overall and event-free survival (P < 0.001). ConclusionsVIVAs of retroperitoneal great vessels occurred in 9% of our patients with retroperitoneal tumors. Retroperitoneal VIVAs were associated with higher rates of intraoperative complications and disease relapse but was not directly related to survival outcomes. Type of Study: Retrospective review study. Level of evidenceLevel III Retrospective comparative study.

Transthoracic echocardiographic evaluation of the heart and great vessels.

Transthoracic examination of the heart and great vessels is an essential skill that allows the anesthesiologist to evaluate cardiac function. In this article, we describe a pragmatic technique to obtain the essential views to evaluate normal or abnormal cardiac function and to appreciate great vessel anatomy and physiology. The cardiac anatomy and function can be described using standard parasternal, apical, and subcostal views. These windows can also be used to assess the aorta, pulmonary artery, and vena cavae; however, other transthoracic and abdominal windows can be used to complete the evaluation of the great vessels. The integration of the echocardiographic information particularly from the heart and great vessels with the case story, physical examination, laboratory data, and other relevant clinical information should become the way of the future, and this will benefit the patients under our care.

Did the use of the Guideliner V2TM guide catheter extension increase complications? A review of the incidence of complications related to the use of the V2 catheter, the influence of right brachiocephalic arterial anatomy and the redesign of the V3TM Guideliner and clinical outcomes

ObjectiveWe sought to investigate the incidence of complications associated with V2 Guideliner, understand the mechanisms and evaluate the impact of alterations made to the V3 Guideliner.MethodsRetrospective analysis of consecutive cases...

Abstract 18686: Serial Two Dimensional Echocardiographic Observations and Measurements Obtained by Fetal Echocardiograms: Correlation With Gestational Age

Objective: The purpose of the study was to establish changes that may occur between 20 and 34 weeks of pregnancy in linear measurements of the cardiac chambers, great vessels, aortic isthmus, descending aorta and foramen ovale by fetal echocardiography (FE). Regression analysis was utilized to determine any possible correlation between the linear measurements and gestational age. Methods: Serial FEs were obtained on 2573 normal single pregnancies with accurate gestational ages. FEs obtained using ASE guidelines were divided into 15 groups according to gestational age. Results: Measurements of thoracic diameter, total cardiac diameter, left atrial (LA) and right atrial (RA) diameters, left ventricular (LV) and right ventricular (RV) diameters, and aortic and pulmonary artery diameters significantly increased between 22 and 28 weeks (p &lt; 0.01). Aortic arch isthmus (AoAI), descending Ao diameter, left and right pulmonary artery (PA) diameters and foramen ovale diameter did not change significantly. Between 20 and 34 weeks of pregnancy, RA and RV diameters were always greater than LA and LV diameters, the PA diameter was always greater than Ao diameter, and the AoAI diameter was always greater than the ductal artery (p &lt; 0.01). The ductal artery diameter was always greater than left and right PA Regression analysis between FE dimensions and gestational age showed a significant progressive increase in thoracic and total cardiac diameters, LA and RA diameters, LV and RV diameters, AoAI and descending Ao diameters and ductal artery diameter. Conclusion: FE can accurately assess cardiac structure and is capable of establishing normal reference values of cardiac and great vessel anatomy. As expected, most measurements statistically increase with increasing gestational age.

Heart valve disease: investigation by cardiovascular magnetic resonance.

Cardiovascular magnetic resonance (CMR) has become a valuable investigative tool in many areas of cardiac medicine. Its value in heart valve disease is less well appreciated however, particularly as echocardiography is a powerful and widely available technique in valve disease. This review highlights the added value that CMR can bring in valve disease, complementing echocardiography in many areas, but it has also become the first-line investigation in some, such as pulmonary valve disease and assessing the right ventricle. CMR has many advantages, including the ability to image in any plane, which allows full visualisation of valves and their inflow/outflow tracts, direct measurement of valve area (particularly for stenotic valves), and characterisation of the associated great vessel anatomy (e.g. the aortic root and arch in aortic valve disease). A particular strength is the ability to quantify flow, which allows accurate measurement of regurgitation, cardiac shunt volumes/ratios and differential flow volumes (e.g. left and right pulmonary arteries). Quantification of ventricular volumes and mass is vital for determining the impact of valve disease on the heart, and CMR is the 'Gold standard' for this. Limitations of the technique include partial volume effects due to image slice thickness, and a low ability to identify small, highly mobile objects (such as vegetations) due to the need to acquire images over several cardiac cycles. The review examines the advantages and disadvantages of each imaging aspect in detail, and considers how CMR can be used optimally for each valve lesion.

Right ventricular function by MRI

For years, the right ventricle (RV) has been deemed 'unnecessary', as shown by procedures such as Fontan surgery. More recently, right ventricular dysfunction has been recognized as a prognostic factor in many cardiovascular diseases. Supported by advances in echocardiography and MRI, assessment of right ventricular function and morphology has gained interest. The goal of this review is to offer a current clinical perspective on right ventricular function as assessed by MRI. MRI has progressed towards a fast and reliable technique for assessing right ventricular morphology, volumes and function. Strain-encoded techniques and single breath-hold four-dimensional acquisition techniques are promising, but need to be confirmed in patient studies. Continuous improvement in postprocessing software has further reduced analysis time and effort. Our understanding of right ventricular behavior even in complex heart disease has taken substantial benefit from modern cardiac MRI techniques. MRI imaging of the RV is patient-tailored, integrating right ventricular volumetric and functional analysis in a comprehensive approach, including assessment of cardiac morphology, myocardial tissue characteristics, flow patterns and great vessel anatomy. This approach provides the clinician a complete view, not only of the RV as such, but also of the RV being an essential part of the cardiopulmonary system.

Can 3D Ultrasound and Doppler Angiography of Great Arteries Be Included in Second Trimester Ecocardiographic Examination? A Prospective Study on Low‐Risk Pregnancy Population

The introduction of new applications such as the spatiotemporal image correlation (STIC) and the tomographic ultrasound imaging (TUI) has greatly enhanced the study of cardiac and vessels anatomy. The aim of our study was to assess the feasibility of including real-time volumetric 3D reconstruction of heart anatomy and Doppler angiography of great vessels during routine second trimester pregnancy scan, in a low-risk population. Visualization of the pulmonary veins, ductus venosus and inferior vena cava was significantly superior with 3D ultrasound. Therefore, STIC makes it possible to store heart beats for a mean time of 10 s, to replay acquired volumes in slow motion, to study the heart atrium along three axes and retrace volumetric image storage inversely from the apex to the base of the heart, making reconstruction of the four-chamber view and great artery outflow tract much easier and faster. Furthermore, the use of digital communication allow operators to store and send volume of images that can be postprocessed by external consultant specialists worldwide. Although 3D echocardiography is less time-consuming and independent of fetal positioning in utero when compared with 2D it may be premature to include 3D and 3D Doppler angiography among routine examination. However, the study of the outflow tracts by 2D echocardiography should be implemented in order to improve the diagnostic accuracy of CHDs. At present, only "targeted" cases in which a routine 2D scan has raised diagnostic doubts should undergo a second level sonography for a thorough 2D-3D examination of cardiac and vessels anatomy.

The Right Sided Great Vessels by Cardiac Multidetector Computed Tomography: Normative Reference Values among Healthy Adults Free of Cardiopulmonary Disease, Hypertension, and Obesity

We sought to derive normative reference values for the thoracic great vessels using multidetector computed tomography (MDCT) in a healthy normotensive non-obese population free of cardiovascular disease. Non-gated axial computed tomography (CT) of the chest has traditionally been used to evaluate normal great vessel anatomy for prognosis and management. However, non-gated axial chest CT cannot account for the obliquity, systolic expansion, and non-axial motion of the great vessels during the cardiac cycle and may misclassify patients as normal or abnormal for prognostic and management purposes. To date, normative reference values for double-oblique, short-axis great vessel diameters have not been established using current generation electrocardiogram (ECG)-gated 64-detector row MDCT. A total of 103 (43% women, age 51 +/- 14 years) consecutive normotensive, non-obese adults free of cardiopulmonary or great vessel structural disease, arrhythmias, or significant coronary artery disease were studied by MDCT. Individuals underwent examination for determination of end-diastolic (ED) pulmonary artery (PA) and superior vena cava (SVC) dimensions in double-oblique short axes for comparison with the ascending aorta and the right-sided cardiac chambers. For right sided great vessels, the 5th to 95th interval was 1.89-3.03 cm for ED PA diameter and 1.08-4.42 cm(2) for SVC cross-sectional area. The pulmonary artery to ascending aortic (PA-to-Ao) ratio was 0.66-1.13. In multivariate analysis, the PA was significantly associated with weight, whereas the PA-to-Ao ratio was inversely associated with age. Axial PA measurements were significantly higher and PA-to-Ao measurements significantly lower than corresponding short axis measurements (P = .04 and P < .001, respectively). This study establishes ECG-gated MDCT reference values for right-sided great vessel dimensions derived from a healthy population of individuals free of cardiovascular disease, hypertension, and obesity. The traditional axial PA-to-Ao discriminant value of 1 for pulmonary hypertension is a poor diagnostic tool because it encompasses normal patients and is negatively affected by age. Thoracic great vessels should be measured by CT in ECG-gated double-oblique short-axis for accurate quantitation. These data may serve as a reference to identify right-sided great vessel pathology in individuals being referred for ECG-gated MDCT imaging.

Technical factors for inserting a « Charité » type lumbar disc prosthesis

The implantation of a « Charite » prosthesis has to be solved through a biomechanical compromise between the size of the implants and it’s positioning in the intervertebral space. A retroperitoneal approach allows one to minimise complications and especially to see and protect the hypogastric nerve. Generally, the anatomy of the great vessels offers a wide approach on the anterior aspect of the disc, except in the case of a high bifurcation of the vena cava with a left iliac vena outside and over the iliac artery and having a straight downwards direction. This situation is infrequent, 1 for 1,000 anterior approaches in our experience.

Beware of the Aberrant Innominate Artery

The anatomy of aortic great vessels is relevant in surgeries of the anterior neck, especially with a tracheostomy, thyroidectomy, or mediastinoscopy. Variations in their anatomy could lead to severe complications if not recognized. An aberrant high-riding innominate artery incidentally encountered during mediastinoscopy is presented.

Endovascular Exclusion Of Subclavian Artery Pseudoaneurysm

Subclavian artery pseudoaneurysms are typically a rare occurrence commonly caused by iatrogenic injury and trauma. We describe an endovascular approach employing a brachiofemoral through-wire technique for the treatment of a left subclavian artery pseudoaneurysm in the presence of a hostile aortic arch and great vessel anatomy.

Advances in cardiovascular CT imaging: CT clinical imaging

Recent advances in cardiovascular CT imaging have dramatically changed the way we evaluate cardiac and great vessel disease. The superb spatial and faster temporal resolutions of the newer scanners, have allowed CT to gain acceptance not only in defining cardiac and great vessel anatomy but also has allowed its entry into the field of functional and perfusion imaging. This paper reviews the current status of CT in clinical imaging of the heart and great vessels.

Re-evaluation of renal cell carcinoma tumor thrombus extension by intraoperative transesophageal echocardiography

T RANSESOPHAGEAL ECHOCARDIOGRAPHY (TEE) is well accepted and extensively used by cardiologists, anesthesiologists, and cardiothoracic surgeons perioperatively to monitor cardiac function and great vessel anatomy.’ TEE remains underused in noncardiac surgical procedures, however. This oversight may be due, in part, to inadequate resources or the specialized training and qualifications necessary to perform TEE.* Alternatively, other physicians may be unfamiliar with its diagnostic capabilities. This case report describes a patient whose treatment was dramatically altered by perioperative TEE. He was brought to the operating room with a diagnosis of renal cell carcinoma and his preoperative diagnostic evaluation revealed extension of the tumor thrombus into the inferior vena cava and intrahepatic vessels. There was no tumor thrombus extension visualized above the level of the diaphragm by magnetic resonance imaging (MRI) or transthoracic echocardiography. The patient was brought to the operating room for a planned surgical resection of the tumor and subdiaphragmatic tumor thrombus.

Left mainstem bronchial narrowing: a vascular compression syndrome? Evaluation by magnetic resonance imaging.

Vascular compression of the left mainstem bronchus (LMSB) between the descending aorta (DA) and pulmonary artery (PA) has been suggested as a cause for LMSB narrowing in children. These anatomic relationships have not been compared with those in children with a normal LMSB. Materials and methods. We undertook a retrospective review of the medical and radiologic records of 10 symptomatic young children (1-19 months, 5 boys, 5 girls) with MR demonstration of LMSB narrowing and compared them to 40 young children without great vessel or bronchial abnormality on MR (1 week-19 months, 28 boys, 12 girls). Chest MR evaluation included assessment of airway and great vessel anatomy with specific attention to the course of the LMSB and its relationship to the adjacent DA and PA. The position of the DA in relation to the spine was carefully evaluated. Five children had focal and five had diffuse LMSB narrowing. DA position at the level of the crossing LMSB: in 40% of symptomatic children the DA was located in front of the adjacent vertebral body; in 40%, 1/2-3/4 and in 20% 1/4-1/2 of the circumference of the DA was located anterior to the spine. In the control group, the DA was prespinal in 10%, with a trend toward a more paraspinal location of the DA. The trend toward a difference in position of the DA between symptomatic and control patients was statistically significant (P < 0.05). DA position was not related to age (up to 19 months). At the level where the LMSB crossed the DA, a segment of the PA was located anterior to the LMSB, more often the right PA (RPA) or pulmonary bifurcation in symptomatic children and the left PA (LPA) in controls. No correlation was apparent between length of LMSB narrowing and DA or PA position. Chest radiographic abnormalities, when present, were subtle. Excellent MR/bronchoscopic correlation of LMSB narrowing was found in nine of the ten symptomatic children. One child underwent posterior aortopexy and ligation of the ligamentum arteriosum. LMSB narrowing is well-defined by MR imaging. While a prespinal position of the DA occurs in some children as a normal variant, it is more common and more marked in children with LMSB narrowing. Vascular compression of the LMSB between an anteriorly positioned DA and the pulmonary artery appears to be important in children with symptomatic LMSB narrowing.