THE COMPLETE GUIDE TO VASCULAR ULTRASOUND PETER H. ARGER, M.D., SUZANNE DEBARI IYOOB, F.A.I.U.M., F.A.C.R. B.S., R.D.M.S., R.V.T. Professor Emeritus Technical Director-Vascular Laboratory Department of Radiology Department of Radiology University of Pennsylvania Medical Center University of Pennsylvania Medical Center Hospital of the University of Pennsylvania Hospital of the University of Pennsylvania Philadelphia, Pennsylvania Philadelphia, Pennsylvania THE COMPLETE GUIDE TO VASCULAR ULTRASOUND To Christopher, my parents Susan and Robert, my brother Chris, my grandmother Edith, and to all the rest of my family and friends (especially Susan Schultz and Bonnie Brake) for their love, guidance, and support. S.D.I. To Afento, Harry, Donald, Anastasia, Eugenia, and Nicholas, to whom I am immensely grateful, as they have profoundly influenced my whole approach to life. P.H.A. CONTENTS Preface ix 4 Grafts 45 I. Hemodialysis Grafts 45 Acknowledgments xi II. Bypass Grafts 48 1 Blood Vessels: Anatomy and Physiology 1 5 Peripheral Venous Systems 55 2 Abdominal Vasculature 6 I. Lower Extremity Veins 55 I. Abdominal Aorta 6 II. Upper Extremity Veins 69 II. Inferior Vena Cava 10 6 Penile Vessels 75 III. Hepatic Veins, Portal Veins, and Hepatic Arteries 11 7 Cerebrovascular System 84 IV. Superior Mesenteric Artery 17 8 Test Validation and Statistics 108 V. Renal Arteries and Renal Veins 19 9 A Word About Doppler Controls 109 3 Peripheral Arterial Systems 26 I. Lower Extremity Arteries 26 Appendix 121 II. Upper Extremity Arteries 41 I. Review Questions 121 II. Answer Key 129 Subject Index 131 PREFACE Vascular ultrasound has expanded to become an inte- 2. Pathology. Briefly discusses the pathologic processes, gral component of nearly every aspect of diagnostic ultra- which can affect the vessels being examined. Outlines sound. The complexity of vascular ultrasound has increased important associated pathophysiologic information nec- as the technology has increased, along with the ability of essary for good analysis. ultrasound equipment to visualize more and more vessels as 3. History/Questions to Ask the Patient. Details symp- well as a wider range of flow variables. The increased capa- toms associated with potential vascular disease of the bility and utilization of color, power, and duplex Doppler vessels being evaluated. are examples of this. 4. Diagnostic Examinations. Details necessary technical Understanding both the technical and diagnostic aspects of the examination tailored to the specific vessel aspects of vascular ultrasound is essential to obtaining the being evaluated. This may include commonly per- maximum information that can be acquired and to making formed but non-ultrasound tests. the most cogent and informative diagnosis of a given prob- 5. Diagnostic Analysis. Includes Doppler waveform images lem. and illustrations. Discusses in a detailed outline form of The Complete Guide to Vascular Ultrasound has a differ- the relevance of various clinical findings. ent approach to vascular ultrasound, that combines the 6. Other Diagnostic Tests related to the clinical problem “technique know-how” and “diagnostic analysis”. This including nonultrasound diagnostic tests. approach results in a better diagnosis of pathology at mul- We believe the information in this book speaks to a tiple levels. To promote a comprehensive approach to in- wide audience including physicians, i.e., radiologists, vascu- depth knowledge of any given vascular problem, most chap- lar surgeons, and cardiologists, as well as sonographers, ters are divided into a six-part approach: whose work is vital to the field of ultrasound. 1. Anatomy. Graphically demonstrates the general anatomy of the vascular area to be examined as well as the anatomy Peter H. Arger of individual vessels. Suzanne DeBari Iyoob ACKNOWLEDGMENTS We would like to extend our sincere thanks to Patricia Hartman whose invaluable help was a key factor in the production of this book. Her computer skills and typing of the many modifications and re-modifications were a constant source of strength. We also extend our gratitude to Philips Ultrasound, Scott Leonard, and all of the sonographers and physicians in the Ultrasound section at the Hospital of the University of Pennsylvania. We appreciate their help in acquiring the ultrasound images included in this book. We would also like to thank Steven Horii for sharing his technical expertise. 1 BLOOD VESSELS: ANATOMY AND PHYSIOLOGY I. ANATOMY OF BLOOD VESSELS C. Types of Blood Vessels A. Three Layers (Tunicae) of Blood Vessels (Fig. 1.1) 1. Arteries are blood vessels that transport blood 1. Tunica interna or intima. This is the innermost from the heart to the tissues of the body. They contain layer and is composed of endothelial cells. all three layers of tunicae. The tunica interna and 2. Tunica media. This is the middle layer and is com- media is thicker than in veins. The tunica externa is posed of smooth muscle and elastic fibers. It is thicker thinner than in veins. These divide into smaller and in arteries, can change the size and shape of arteries, smaller branches, eventually dividing into arterioles. gives arteries their rigidity and round shape, and is 2. Arterioles. These small vessels are regulators of influenced by hormones and other chemicals. blood flow from the arteries into the capillaries. As 3. Tunica externa or adventitia. This is the outer layer they get closer to the capillaries, the layers of arteriole and is composed of collagenous and elastic fibers. It decrease to consist only of an endothelial layer sur- protects and anchors the vessel to surrounding tissues. rounded by a few smooth muscle fibers. Vasoconstric- B. Circulatory System (Fig. 1.2) tion (when the smooth muscle constricts) decreases 1. Systemic circulation refers to the flow of blood blood flow into the capillaries. Vasodilation (when the from the left ventricle of the heart through the body smooth muscle relaxes) increases blood flow into the (except for the lungs) and back to the right atrium of capillaries. Arterioles have the highest resistance in the the heart. The blood carries oxygen and nutrients to circulatory system. They account for one half of the the tissues of the body. It also removes wastes, carbon total resistance to blood flow. dioxide, and heat from the tissues of the body. The 3. Capillaries. These microscopic vessels only have a blood leaves the left ventricle of the heart, and goes single layer of endothelium and a basement mem- through the aorta, arteries, arterioles, venules, veins, brane. They allow exchange of nutrients and waste and vena cava to enter the right atrium of the heart: products between the blood and the cells of tissue. → → → → Capillaries (sometimes extensive networks of capillar- Heart Aorta Arteries Arterioles ies) usually connect arterioles and venules. Capillaries → Venules → Veins → → 4. Venules. These vessels drain blood from the capil- Vena cava Heart laries into the veins. Close to the capillaries, venules 2. Pulmonary circulation refers to the flow of blood may only consist of an endothelial layer surrounded by from the right ventricle of the heart, through the right the tunica externa. Closer to the veins, venules consist and left pulmonary arteries, to the alveoli (air sacs) in of all three layers. the lungs, then from the alveoli of the lungs, through 5. Veins. Veins are blood vessels that transport blood the right and left pulmonary veins, and back to the left from the tissues of the body back to the heart. They atrium. The blood is deoxygenated when it enters the are composed of all three layers of tunicae, although alveoli from the right ventricle (as it has already gone the tunica intima and tunica media are thinner than in through the rest of the body through the systemic cir- arteries. The tunica externa is thicker than in arteries. culation) and is oxygenated when it leaves the alveoli Veins contain valves to prevent backflow of the blood, of the lungs to go into the left atrium. which has lower pressure at this point. 6. Vasa vasorum. This is a network of minute blood Heart → Pulmonary arteries → Alveoli → vessels that perfuse the tissues of blood vessels them- Pulmonary veins → Heart selves. 2 The Complete Guide to Vascular Ultrasound 3. Blood pressure starts off high as the blood leaves the left ventricle to go into the systemic circulation (mean pressure of 100 mm Hg) as it progresses down to 0 mm Hg when the blood returns to the heart in the right atrium. 4. Principal factors that affect arterial blood pressure: a. Cardiac output. Cardiac output is determined by multiplying the stroke volume (which is the amount of blood ejected from either ventricle in one systole, typically 70 mL) by the heart rate. This is 5.25 L/min in a normal, resting adult. Cardiac output is directly proportional to blood pressure. When one increases, so does the other. When one decreases, so does the other. b. Blood volume. The volume of the blood is also directly proportional to the blood pressure. When FIGURE 1.1. Three layers of a vessel wall. one increases, so does the other. When one decreases, so does the other. Normally, the volume of blood in an adult is about 5 L. Hemorrhage decreases blood volume and thus the blood pressure II. PHYSIOLOGY AND CHARACTERISTICS OF also decreases. High salt intake (water retention) BLOOD FLOW increases blood volume, and thus the blood pressure A. Blood flow is the amount of blood that passes also increases. through a vessel during an episode of time. Blood flows c. Peripheral resistance is defined as all the factors in a laminar flow pattern in most vessels (Fig. 1.3). A that oppose blood flow in the circulatory system. laminar flow pattern is a stable pattern consisting of Arterioles change their diameters to affect the resis- many laminae (layers) that are concentric.