Arterial Variations in Humans: Key Reference for Radiologists and Surgeons E-Book

• Herausgeber: Thieme
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 273

Veröffentlichungsjahr: 2017

Beschreibung

Based on the landmark work Arterial Variations in Man: Classification and Frequency by Lippert and Pabst, this atlas presents the full range of arterial variations that occur in the human body. Adding an interdisciplinary perspective to the original text, Arterial Variations in Humans: Key Reference for Radiologists and Surgeons shows variations of the arteries with schematic diagrams alongside their corresponding radiological images. Chapters begin with schematic and radiological depictions of normal arterial blood supply, followed by images of the arterial variation, to enable rapid identification of individual variations. This unique resource also includes statistics on the frequency of specific arterial variations and explanations of their embryologic origins.

Special Features:

• Coverage of arterial variations in the head, neck, spine, thorax, abdomen and pelvis, and upper and lower extremities with separate chapters devoted to each major artery
• Clearly drawn schematic outlines and their correlating high-quality radiological scans-more than 900 illustrations in total-highlight arterial variations

Images of the "normal" arterial anatomy as described in standard textbooks are provided for side-by-side comparison with the arterial variation
Percentages for the frequency of occurrence of arterial variations with references to the source of the data
Concise and lucid descriptions in each chapter facilitate complete comprehension of normal and abnormal vascular anatomy
With Arterial Variations in Humans: Key Reference for Radiologists and Surgeons, radiologists will gain a full understanding of the diversity of arterial anatomy-essential knowledge for the accurate interpretation of pathological changes in diagnostic imaging. Interventional radiologists and vascular and general surgeons will also find this book valuable for planning and performing procedures safely and effectively.

Leseprobe

Arterial Variations in Humans:Key Reference for Radiologists and Surgeons

Classification and Frequency

1st Edition

Frank Wacker, MD

Professor and DirectorDepartment of Diagnostic and Interventional RadiologyHannover Medical SchoolHannover, Germany

Herbert Lippert, MD

ProfessorFormerly Institute of AnatomyHannover Medical SchoolHannover, Germany

Reinhard Pabst, MD

ProfessorInstitute of AnatomyHannover Medical SchoolHannover, Germany

924 illustrations

Thieme

Stuttgart • New York • Delhi • Rio de Janeiro

Library of Congress Cataloging-in-Publication Data is available from the publisher.

© 2018 by Georg Thieme Verlag KG

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Contents

Foreword

Preface

Contributors

Abbreviations

  1 Introduction

I Heart and Thorax

  2 Aortic Arch

  3 Coronary Arteries

  4 Posterior Intercostal Arteries

  5 Esophageal Arteries

  6 Bronchial Arteries (Rami Bronchiales)

  7 Pulmonary Arteries

II Pelvis and Abdomen

  8 Development of the Abdominal Aorta

  9 Inferior Phrenic Arteries

10 Suprarenal Arteries

11 Renal Artery

12 Testicular Artery

13 Celiac Trunk

14 Hepatic Arteries

15 Cystic Artery

16 Splenic Artery

17 Gastric Arteries

18 Pancreatic Arteries

19 Superior Mesenteric Artery and Celiac Trunk

20 Superior Mesenteric Artery and Colic Arteries

21 Appendicular Artery

22 Inferior Mesenteric Artery

23 Internal Iliac Artery

24 Arteries of the Female Genital Tract

25 Obturator Artery

III Lower Limbs

26 Development of the Arteries of the Lower Limb

27 The Profunda Femoris Artery

28 Popliteal Artery

29 Arteries of the Lower Leg

30 Dorsal Arteries of the Foot

31 Plantar Arch

IV Upper Limbs

32 Axillary Artery

33 Development of the Arteries of the Arm

34 Brachial Artery and Superficial Brachial Artery

35 Arteries of the Forearm

36 Superficial Palmar Arch

37 Deep Palmar Arch and Palmar Digital Arteries

38 Arteries on the Dorsal Side of the Hand

V Head and Spinal Cord

39 Subclavian Artery

40 Inferior Thyroid Artery

41 Vertebral Artery

42 External Carotid Artery

43 Maxillary Artery

44 Development of the Arteries of the Head

45 Ophthalmic Artery

46 Cerebral Arterial Circle (Circle of Willis)

47 Arteries of the Spinal Cord

Index

Foreword

Arterial Variations in Humans: Key Reference for Radiologists and Surgeons is based on the landmark work Arterial Variations in Man: Classification and Frequency by Lippert and Pabst, first published in 1985. With the collaboration of German radiologist Frank Wacker and his team, the original atlas has now been expanded. The schematic drawings have been enhanced with angiograms from digital subtraction angiography, computed tomography, and magnetic resonance imaging.

The beauty and diversity of the human body is one of the first things medical students learn, and the complexity is something that both students and experts appreciate greatly. Although detailed anatomic knowledge is a cornerstone of medical education, the wide range of basic facts and more advanced scientific findings that accumulate over the course of a doctor’s medical life increase the likelihood that only “normal” textbook anatomy remains in focus at later stages of a medical career. However, not infrequently, basic anatomic, surgical, and radiologic textbook knowledge does not meet the needs of addressing the complex reality of an individual patient’s anatomy, creating significant challenges for medical professionals. In imaging, such anatomic findings should be recognized and reported in a manner similar to pathologic changes. In surgery and interventional radiology, variants must be accurately recognized to avoid patient harm if they are not correctly addressed during a procedure.

Therefore, a comprehensive and illustrative summary of arterial variants beyond the “normal” anatomy described in textbooks helps not only radiologists in describing such variants, but also interventional radiologists, surgeons, and others who rely on arterial access. The exquisite combination of angiograms and schematic drawings in this book is an invaluable resource to understand and visually memorize patterns we might encounter during our daily work.

Jonathan S. Lewin, MD, FACR

Executive Vice President for Health Affairs, Emory University

Executive Director, Woodruff Health Sciences Center

President, CEO, and Chairman of the Board, Emory Healthcare

Atlanta, Georgia, USA

Preface

During my angiography and interventional radiology rotation as a radiology resident I was fascinated by the delicate arteries one could see when contrast medium was injected into them. At the same time, I was often disappointed that many arteries did not follow the course given in standard anatomy textbooks. The remarkable diversity of arterial anatomy sometimes made me feel lost for words when it came to the reports we had to write after the procedure. At that time, there was a small reference library in our radiology department and I was quite grateful that it included a thin book by Lippert and Pabst, published in 1985 and entitled Arterial Variations in Man: Classification and Frequency, which helped me to understand the complexity of arterial anatomy. The sketches in this book nicely delineated a multitude of variants in many arterial territories. The bundled information on the frequency of arterial anomalies, often hidden in old and inaccessible journals and books, was an important asset for my studies. Not only radiology residents but also many of our colleagues from the surgical field cherished this book. Variations in the arteries supplying a given organ are usually harmless; however, the correct detection and interpretation of pathologic changes requires knowledge of both the normal and the anomalous arterial blood supply. In addition, under certain circumstances some variants can have a negative effect. This is especially relevant for therapy planning in surgery, endoscopy, and interventional radiology, where an intimate knowledge and an understanding of the blood supply prior to a procedure helps to avoid unpleasant surprises during intervention.

Many years after my first contact with Lippert and Pabst’s book, I became Chairman of Radiology at Hannover Medical School in Germany, the alma mater of Professors Lippert and Pabst, and I got to know them in person. I expressed my appreciation for their book and we discussed the substantial advances that had been made in both invasive and noninvasive vascular imaging since its publication. In digital subtraction angiography (DSA), improved tubes and detectors offer high-spatial-resolution angiography. In computed tomography (CT), data sets with submillimeter voxel size in combination with postprocessing tools such as multiplanar reconstruction, maximum intensity projection, and volume rendering have become clinical standard. In magnetic resonance imaging (MRI), higher field strengths and fast imaging techniques offer excellent spatial and temporal resolution. These technical improvements offer an excellent delineation of the vascular anatomy with almost every DSA scan and with many CT and MRI recordings. We all agreed that, owing to the more detailed visualization of the arteries on routine imaging, familiarity with both normal anatomy and its variants is becoming more important. Based on these interdisciplinary discussions between a radiologist and two anatomists, the idea was born to publish a new atlas.

We decided to keep the schematic drawings of the arteries from the original book. The artists at Thieme redrew the schematics and added some color for a crisper layout. We added radiologic images for the more common variants visible with CT, MRI, and DSA. Given the small frequencies of some of the variants, we were not able to provide radiologic images for every schematic drawing.

We are greatly indebted to many colleagues and coauthors at Hannover Medical School who contributed to our project. We also received some sample images, even images for entire chapters, from colleagues at other institutions. The support of our colleagues and friends who supplied images is greatly appreciated. We would also like to thank Martina Habeck for editorial support and all the staff at Thieme for their help and patience.

We would be delighted if colleagues and readers of this atlas would send us additional CTA, MRA, or DSA images of variants. In addition, we would appreciate any information on recent or upcoming papers on arterial variations, and we will be more than happy to start a discussion on frequencies as well as on the relevance of certain findings in this field.

Frank Wacker, MD

Herbert Lippert, MD

Reinhard Pabst, MD

Contributors

Anja Giesemann, MD

Associate Professor

Department of Diagnostic and Interventional Neuroradiology

Hannover Medical School

Hannover, Germany

(Chapters 39–47)

Friedrich Goetz, MD

Department of Diagnostic and Interventional Neuroradiology

Hannover Medical School

Hannover, Germany

(Chapters 39–47)

Dagmar Hartung, MD

Associate Professor

Department of Diagnostic and Interventional Radiology

Hannover Medical School

Hannover, Germany

(Chapters 2–7)

Katja Hueper, MD

Associate Professor

Department of Diagnostic and Interventional Radiology

Hannover Medical School

Hannover, Germany

(Chapters 2–7)

Thomas Kroencke, MD, MBA, EBIR FCIRSE, FSIR

Professor

Department of Diagnostic and Interventional Radiology and Neuroradiology

Klinikum Augsburg

Augsburg, Germany

(Chapter 24)

Michael Lee, MSc, FRCPI, FRCR, FFR(RCSI), EBIR, FSIR

Professor

RCSI Radiology

Royal College of Surgeons in Ireland

Beaumont, Ireland

(Chapters 26–31)

Herbert Lippert, MD, PhD

Professor

Formerly Institute of Anatomy

Hannover Medical School

Hannover, Germany

(Editor)

Bernhard Meyer, MD

Professor

Department of Diagnostic and Interventional Radiology

Hannover Medical School

Hannover, Germany

(Chapters 32–38)

Simone Meyer

Department of Diagnostic and Interventional Radiology

Hannover Medical School

Hannover, Germany

(Chapters 8, 10, 15–18, 21–23)

Reinhard Pabst, MD

Professor

Institute of Anatomy

Hannover Medical School

Hannover, Germany

(Editor)

Kristina Imeen Ringe, MD

Associate Professor

Department of Diagnostic and Interventional Radiology

Hannover Medical School

Hannover, Germany

(Chapters 8–23, 25)

Thomas Rodt, MD

Associate Professor

Department of Diagnostic and Interventional Radiology

Hannover Medical School

Hannover, Germany

(Chapters 26–31)

Lena Sonnow, MD

Department of Diagnostic and Interventional Radiology

Hannover Medical School

Hannover, Germany

(Chapters 32–38)

Frank Wacker, MD

Professor

Director, Department of Diagnostic and Interventional Radiology

Hannover Medical School

Hannover, Germany

(Editor)

Abbreviations

3D

three-dimensional

AvIP

average intensity projection

CT

computed tomography

CTA

computed tomography angiography

DSA

digital subtraction angiography

MIP

maximum intensity projection

MRA

magnetic resonance angiography

MRI

magnetic resonance imaging

VR

volume-rendered

1 Introduction

Textbooks on anatomy, radiology, and surgery usually describe only the “normal” arterial blood supply. However, for some arteries this “normality” is found in less than 30% of all patients, whereas for other arteries it is found in over 95% of patients. Rarely mentioned are deviations in an artery’s origin, its topographical localization, or the area it supplies. Such deviations can be classified into two groups: malformations and variations. Malformations often have a negative influence on the function of the given organ under normal circumstances—for example, this is the case if both coronary arteries originate from the pulmonary artery. In the current book, this group will be dealt with in only a few instances. Variations, by contrast, generally have no effect on the function of the organ under normal circumstances—for example, a superficial brachial artery does not have a negative effect on the function of the forearm and hand. However, should the superficial artery be mistaken for a vein and should a thiobarbiturate be injected, severe necrosis of the hand would result. Thus, even a harmless variation can have negative effects under certain circumstances.

The basis for the current book is a surge of clinical interest in the topographical anatomy of the arterial blood supply, the origin of arteries, and the areas supplied by individual vessels. Every day, superselective angiography and angiographic interventions are performed on many organs in many angiography labs. Given the striking improvements in imaging technology, it has now become possible to visualize in vivo smaller arteries and branches that could formerly only be identified in carefully dissected anatomical preparations. Modern surgical techniques depend on the intimate knowledge of both the “normal” and the anomalous arterial blood supply. For instance, when selective transarterial chemoembolization or radioembolization is used for the treatment of hepatic cancer, even small aberrant hepatic arteries can cause significant side effects due to off-target embolization. Microsurgical techniques employed in vascularized transplants and repairs after trauma also depend on the sound knowledge of arterial variations.

Many terms are found in the literature to describe the variations of arteries, such as aberrant, replaced, supplementary, or accessory arteries. We have used the term replaced artery to refer to a single artery that supplies an organ in place of the artery that normally supplies it. An accessory artery is a second artery in addition to the one normally present, without any specification of size. There is no general agreement on whether minute vessels with very small diameters and hardly any significant blood flow should also be considered.

The determination of the frequency of arterial variations poses some obvious problems, especially when combining anatomic dissections and angiographic techniques ex vivo and in vivo. First, there is a broad spectrum of techniques between radiology, anatomy, and pathology labs that might show different aspects of the vasculature. Second, patient selection bias might be present. In radiology, the patients examined with CT or MRI are usually sick, and in many instances the examination is targeted toward an organ with pathology. Smaller variant arteries might be missed owing to limited spatial resolution or simply overlooked because they were not expected. In certain diseases, small branches increase in size, making it difficult to define whether they are variants of the normal blood supply or represent a pathologic condition. Invasive angiographic data are never based on a representative group of patients because there was of course an indication for the angiography. Although selection bias is also present in pathology when the cause of a patient’s death is determined, unaffected organs can also be examined. In anatomy, many dissected corpses are from rather old patients with some kind of pathology, which also introduces selection bias.

The frequencies of variant arteries can be underestimated because small accessory vessels may be missed or cut, and not all arteries are filled in corrosion cast preparations. Therefore, different observations and different frequencies of anatomical variants are to be expected. Some variations are well-studied, with the frequencies of the replaced arteries statistically reliable. A good example is the liver supply (because of the increasing number of transarterial therapies and liver donor evaluations). In other cases, case reports with rare arterial findings make it difficult to give reliable numbers.

The classification of arterial variations is usually based on the normal embryological development. During ontogeny, rapid growth occurs with anastomoses between arteries disappearing. However, some of the arteries that are usually present for a short period only may remain throughout life. Furthermore, given that many organs such as the testes and the heart wander during their development, knowledge of their original location may explain certain abnormalities. In this book, no detailed descriptions of the different types are given, only brief explanations. More important are the schematic drawings and the radiographs, which show variations of the origin, the course of the artery, and sometimes the area or portion of the organ supplied. The figures and radiographs are mainly arranged by individual arteries or by the blood supply of a given organ. There is by necessity some overlap, especially in areas like the celiac trunk. The reader looking for a given artery in the index will find all variants of that vessel listed together on a few pages with the corresponding drawings.

The numerous descriptions of single cases of an abnormal artery could not all be cited in the references. Some case reports were selected if a rare individual type was of special interest for any clinical reason or to explain the development of variations of that artery in general. Preference was given to articles reporting large numbers of patients.

Part I

Heart and Thorax

2 Aortic Arch

3 Coronary Arteries

4 Posterior Intercostal Arteries

5 Esophageal Arteries

6 Bronchial Arteries (Rami Bronchiales)

7 Pulmonary Arteries

2  Aortic Arch

D. Hortung, K. Hueper

2.1  Development of the Aortic Arch

During the early stages of embryonic development two pairs of aortas are present. The anterior aortas ascend from the heart, turn posteriorly within the first branchial arch, and descend as the posterior aortas. Already in embryos with 3-mm crown-heel length, the beginnings and ends of the paired aortas merge, remaining separate only in the area of the foregut. In each of the six branchial arches, connections develop between the anterior and posterior aortas, the branchial arteries. These arteries do not coexist, the first branchial arteries having already disappeared before the fifth and sixth develop. The fifth branchial artery seems to be present for a few hours only, although a few instances of its persisting have been reported.1–3 The carotid arteries develop from the cranial part of the anterior and posterior aortas. The posterior aortas give off segmental branches along their segmented body wall: 3 occipital, 7 cervical, and 12 thoracic, etc. All cervical arteries disappear, except for the sixth, which forms the subclavian artery. A longitudinal anastomosis remains on both sides to form the vertebral artery.

Thus, as a rule, the human aortic arch develops in the following way:

1.The left side of the fourth branchial artery forms part of the aortic arch, and the right side forms the beginning of the subclavian artery.

2.Parts of the posterior aortas on both sides atrophy, that is, the area between the third and fourth branchial arteries (left) and the section between the sixth segmental artery and the merged descending aorta (right).

3.The sixth branchial arteries form the beginning of the pulmonary arteries and the ductus arteriosus (Botallo’s duct). The final topographical position of the aortic arch and its branches is a product of differential growth rates of various parts of the arteries, which results in a “migration” and “merging” of branches. The main force behind these changes seems to be the optimization of hemodynamic paths combined with the descending heart.

For developmental and general aspects of the aortic arch, see the literature.4–15

Fig. 2.1 Development of the aortic arch. I–VI, occipital segmental branches; C1–C7, cervical segmental branches; T1–T2, thoracic segmental branches; CCA, common carotid artery; ECA, external carotid artery; ICA, internal carotid artery; SA, subclavian artery; VA, vertebral artery.

2.2  “Normal” Situation (70%)

Fig. 2.2 “Normal” situation as given in textbooks (70%). Schematic (a) and MRA, VR 3D image, anterior view (b). 1 Right external carotid artery; 2 left external carotid artery; 3 left internal carotid artery; 4 left common carotid artery; 5 left vertebral artery; 6 left subclavian artery; 7 aorta; 8 right brachiocephalic trunk; 9 right common carotid artery; 10 right subclavian artery; 11 right vertebral artery; 12 right internal carotid artery.

Fig. 2.3 Common origin of the right brachiocephalic trunk and left common carotid artery (~13%). Schematic (a) and contrast-enhanced CT images of two patients (b–d). Patient 1: VR 3D image, anterior view (b); MIP at the level of the common origin of the right brachiocephalic trunk and the left common carotid artery, coronal view (c). Patient 2: MIP of the supra-aortic arteries, transverse views (d). Patient with left-sided pleural effusion. 1 Aorta; 2 left subclavian artery; 3 left common carotid artery; 4 right brachiocephalic trunk; 5 right subclavian artery; 6 right common carotid artery.

2.3  Anomalies of the Trunk (23%)

The frequencies of the different types depend largely on the method of examination and racial factors (the types illustrated in Fig 2.3 and Fig 2.4 seem to be present more often in blacks than in Caucasians). Some descriptions are difficult to classify and lie between the types shown in Fig. 2.2, Fig. 2.3, and Fig 2.4. According to the literature, the types shown in Figs. 2.2–2.11 cover approximately 93% of all humans.5,8,14,16–30

Some types that are considered anomalies in humans are the rule in other mammals; for example, Fig 2.4 occurs in rodents and carnivores, Fig 2.5 in insectivores, Fig 2.6 in elephants, and Fig 2.7 in paired and unpaired ungulates.

Fig. 2.4 Left common carotid artery originates from the right brachiocephalic trunk (~9%). Schematic (a) and contrast-enhanced CT of the thoracic aorta, VR 3D image, anterior view (b). 1 Right common carotid artery; 2 left common carotid artery; 3 left subclavian artery; 4 aorta; 5 right subclavian artery.

Fig. 2.5 Right and left brachiocephalic trunk (<1%). Schematic (a) and MRA, VR 3D image, sagittal oblique view (b). 1 Right brachiocephalic trunk; 2 left brachiocephalic trunk.

Fig. 2.6 Trunk formation of both carotid arteries (bicarotid) (<0.1%). Schematic.

Fig. 2.7 Common brachiocephalic trunk (<0.1%). Schematic (a) and contrast-enhanced CT of the thoracic aorta, VR 3D image, anterior view (b). The CT image shows the common brachiocephalic trunk in a 24-year-old woman with a truncus arteriosus as a congenital cardiac anomaly. 1 Right subclavian artery; 2 right common carotid artery; 3 left vertebral artery; 4 left common carotid artery; 5 left subclavian artery; 6 common brachiocephalic trunk.

Fig. 2.8 Right subclavian artery originates from a bicarotid trunk (<0.1%). Schematic.

Fig. 2.9 Left subclavian artery originates from a bicarotid trunk (<0.1%). Schematic.

Fig. 2.10 Only a left brachiocephalic trunk (<0.1%). Schematic.

Fig. 2.11 No brachiocephalic trunk (<0.1%). Schematic.

2.4  Vertebral Artery as a Direct Branch of the Aortic Arch (4%)

When a segmental artery persists more cranial than the sixth cervical artery, the left vertebral artery will branch from the aortic arch. In such cases, the vertebral artery enters the vertebral column through a more cranial transverse foramen. The vertebral artery can have two origins when the longitudinal anastomosis to the sixth segmental artery remains open. In extremely rare instances, the right vertebral artery originates from the aortic arch. In such cases, either all the beginning part of the right fourth branchial artery forms the aortic arch or there is a variety of the type shown in Section 2.6 with a subsequent “migration” of the origin of the artery.31–33

Fig. 2.12 Left vertebral artery as the penultimate branch of the aortic arch (3%). Schematics of the arterial variation (a), its development (b), and MRA images of the arterial variation (c,d), both of the same patient. MIP of the thoracic aorta and the supra-aortic vessels in an oblique sagittal view (c), VR 3D image in an oblique sagittal view (d). 1 Right vertebral artery; 2 right common carotid artery; 3 left common carotid artery; 4 left subclavian artery; 5 left vertebral artery; 6 right brachiocephalic trunk; 7 aorta.

Fig. 2.13 Left vertebral artery as the penultimate branch of the aortic arch; left common carotid artery originating from the brachiocephalic trunk (<1%). Schematic.

Fig. 2.14 Left vertebral artery as the last branch of the aortic arch (<1%). Schematic.

Fig. 2.15 Left vertebral artery as the last branch of the aortic arch; left common carotid artery originating from the brachiocephalic trunk (<0.1%). Schematic.

Fig. 2.16 Left vertebral artery as the last branch of the aortic arch; a common brachiocephalic trunk (<0.1%). Schematic.

Fig. 2.17 Vertebral artery branches before the left subclavian artery, but the last branch of the aortic arch is the right subclavian artery (<0.1%). Schematic (a) and MRA, VR 3D image, anterior view (b). 1 Right common carotid artery; 2 right subclavian artery; 3 left common carotid artery; 4 left vertebral artery; 5 left subclavian artery.

Fig. 2.18 Two roots of the vertebral artery, one penultimate branch of the aortic arch (<1%). Schematics of the arterial variation (a) and its development (b).

Fig. 2.19 Both vertebral arteries directly branch from the aortic arch (<0.1%). Schematic.

2.5  Arteria Thyroidea Ima as a Direct Branch of the Aortic Arch (1%)

The overall frequency of the lowest thyroid artery (arteria thyroidea ima) is approximately 6%: it arises from the brachiocephalic trunk in 3% of all cases; from the right common carotid artery in 1%; from the aortic arch in 1%; and less frequently from the internal thoracic artery, subclavian artery, and inferior thyroid scapular artery. Two arteria thyroidea ima have also been described. This artery is of importance in surgeries performed caudal to the isthmus of the thyroid gland. For general features, see the literature.8,9,34–40

Fig. 2.20 Arteria thyroidea ima as a direct branch of the aortic arch (1%). Schematic (a) and contrast-enhanced CT, VR 3D image, anterior view (b). 1 Right common carotid artery; 2 left common carotid artery; 3 left subclavian artery; 4 arteria thyroidea ima; 5 right brachiocephalic trunk; 6 right subclavian artery.

2.6  Right Subclavian Artery as the Last Branch of the Aortic Arch (Arteria Lusoria) (1%)

In this situation, the right subclavian artery always turns to the right behind the other branches. It is located behind the esophagus in 80% of all cases, between the esophagus and trachea in 15%, and in front of the trachea or the main bronchi in 5%. This position results in dysphagia or dyspnea.8,35,40–44 In most cases, the right recurrent laryngeal nerve is absent, but there are direct branches to the trachea and esophagus from the vagus. If the right vertebral artery branches from the right common carotid artery (see Fig. 2.24a), a nerve, comparable to the recurrent laryngeal nerve, winds around the artery.

Fig. 2.21 Right subclavian artery as the last branch of the aortic arch, other arteries originate normally (<1%). Schematics of the arterial variation (a), its development (b), and contrast-enhanced CT of the arterial variation (c), VR 3D image, anterior view. The scan field of view in c is limited to the thorax, so that the supra-aortic vessels are not displayed in their entire course. 1 Right brachiocephalic trunk; 2 left common carotid artery; 3 left subclavian artery; 4 right subclavian artery.

Fig. 2.22 Right subclavian artery as the last branch of the aortic arch combined with a bicarotid trunk (<1%). Schematic.

Fig. 2.23 Right subclavian artery as the last branch of the aortic arch combined with a left subclavian artery from the bicarotid trunk (<0.1%). Schematic.

Fig. 2.24 Right brachiocephalic trunk as the last branch of the aortic arch (<0.1%). Schematic of the arterial variation (a) and its development (b).

2.7  Right-Sided Aortic Arch (<0.1%)

The persistence of the right fourth branchial artery results in this anomaly, which is more frequent in Fallot’s tetralogy.5,45–54 The right-sided aortic arch is the rule in birds and in certain reptiles.

Fig. 2.25 Mirror image of the type shown in Fig. 2.2 (<0.1%). Schematics of the arterial variation (a) and its development (b), and MRA images showing the arterial variation (c–e). MIPs in coronal planes, anterior view (c), posterior view (d), and transverse view at the level of the aortic arch (e). 1 Right subclavian artery; 2 right vertebral artery; 3 superior vena cava; 4 right common carotid artery; 5 brachiocephalic trunk; 6 left common carotid artery; 7 left subclavian artery; 8 ascending aorta; 9 right descending aorta.

Fig. 2.26 Mirror image of the type shown in Fig. 2.21a (<0.1%). Schematics of the arterial variation (a) and its development (b), and MRA images of two patients showing the arterial variation (c-h). Patient 1: VR 3D images in anterior (c) and lateral (d) views, MIPs in coronal planes from anterior to posterior (e), and transverse views of the supra-aortic vessels and the aortic arch (f). Patient 2: VR 3D images in oblique views (g,h). 1 Right subclavian artery; 2 right common carotid artery; 3 left common carotid artery; 4 left subclavian artery; 5 right aortic arch; 6 ascending aorta; 7 right descending aorta.

Fig. 2.27 Mirror image of the type shown in Fig. 2.24a (<0.1%). Schematics of the arterial variation (a) and its development (b).

2.8  Double Aortic Arch (<0.1%)

Most of these cases must be classified as malformations, as they have been reported to cause severe functional disturbances of the trachea and esophagus. However, some rare cases were detected only by chance. Both arches often have different lumens or one aortic arch can be replaced by only a fibrous band. These malformations are often combined with heart defects or a patent ductus arteriosus.4,5,55–66 Double aortic arches are the rule in all branchial breathing vertebrates and also occur in some reptiles.

2.9  Circumflex Aortic Arch (<0.1%)

Paramedian merging of the primitive posterior aortas, the tension of an atypical ductus arteriosus (Botallo’s duct), or a rudimentary double aortic arch can all result in such a formation.5,45,48,67–71 Obviously, these types are more frequent in cases of an arteria lusoria (Section 2.6) or a right-sided aortic arch (Section 2.7) in which the caudal instead of the cranial part of the fourth branchial artery persists. The anomalies in Section 2.9 are extremes that have been described, also as regards the loss of the last branch (Fig. 2.30, Fig. 2.31, Fig. 2.33, and Fig 2.34).

Fig. 2.29 Left circumflex aortic arch, otherwise the type shown in Fig. 2.2 (<0.1%). Schematic.

Fig. 2.30 Left circumflex aortic arch, otherwise the type shown in Fig. 2.21a (<0.1%). Schematic.

Fig. 2.31 Left circumflex aortic arch, otherwise the type shown in Fig. 2.24a (<0.1%). Schematic.

Fig. 2.32 Right circumflex aortic arch, otherwise the type shown in Fig. 2.25a (<0.1%). Schematic.

Fig. 2.33 Right circumflex aortic arch, otherwise the type shown in Fig. 2.26a (<0.1%). Schematic.

Fig. 2.34 Right circumflex aortic arch, otherwise the type shown in Fig. 2.27a (<0.1%). Schematic.

2.10  Other Variations of the Aortic Arch (<0.1%)

The sequence of branches can vary due to the different growth rates of individual parts of the vessels. The subclavian arteries are pulled downward by the descending heart, although they are fixed at the upper outlet of the thorax. Many more combinations are possible than are listed. The so-called low division of the carotid artery can be explained by either the first part becoming part of the aortic arch or the third branchial artery disappearing and the part of the primitive posterior aorta between the third and fourth branchial arteries persisting. The latter possibility is supported by cases in which the internal carotid artery is totally absent and the common carotid artery alone forms the external carotid artery.