ABC of Arterial and Venous Disease

Tim England, Akhtar Nasim, Tim England, Akhtar Nasim

• Publisher: BMJ Books
• Year: 2014
• Print ISBN: 9781118740682
• eBook ISBN: 9781118741900
• Edition: 3
• Topic: Medicine
• Subtopic: Surgery & Surgical Medicine

ABC of Arterial and Venous Disease provides a structured, practical approach to clinical assessment, investigation and management of the most commonly presenting arterial and venous disorders.

Structural and functional abnormalities of arteries and veins manifest clinically in a broad spectrum of disorders, including cerebrovascular and carotid artery disease, abdominal aortic aneurysms, acute and chronic limb ischaemia, vasculitis and varicose veins. This revised edition incorporates new chapters on coronary artery disease and acute coronary syndrome, visceral artery stenosis and mesenteric ischaemia, and arteriovenous malformations. Many of these common or chronic conditions first present for initial assessment by primary health care professionals. Case vignettes have been added to relevant chapters to aid understanding and decision making.

Fully up to date and from an expert editor and contributor team, ABC of Arterial and Venous Disease remains a useful resource for non-specialist doctors such as general practitioners, family physicians and junior doctors in training. It is also a relevant guide for all other primary health care professionals working within the multidisciplinary teams responsible for patients with chronic arterial and venous disorders.

Chapter 1
Pathogenesis of Atherosclerosis and Methods of Arterial and Venous Assessment

Mario De Nunzio¹ and Timothy J. England²

¹Derby Hospitals NHS Foundation Trust, Royal Derby Hospital, UK

²Division of Medical Sciences & GEM, School of Medicine, University of Nottingham, UK

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Overview

• Atherosclerosis is a chronic inflammatory disorder
• The ankle–brachial pressure index (ABPI), calculated from the ratio of ankle systolic blood pressure (SBP) to brachial SBP, is a sensitive marker of arterial insufficiency in the lower limb
• Blood velocity increases through an area of narrowing. Typically, a 2-fold increase in peak systolic velocity compared with the velocity in a proximal adjacent segment of the same artery usually signifies a stenosis of 50% or more
• In detecting femoral and popliteal artery disease, duplex ultrasonography has a sensitivity of 80% and a specificity of 90–100%
• The introduction of multidetector computed tomography (MDCT) has had a dramatic effect on vascular imaging. Computed tomography pulmonary angiography (CTPA) for suspected pulmonary embolism (PE) is a good example, but computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are widely used to investigate large artery pathology
• Colour duplex scanning is both sensitive and specific (90–100% in most series) for detecting proximal deep vein thrombosis (DVT).

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Pathogenesis of atherosclerosis

Atherosclerosis is a chronic inflammatory disorder that results in hardening and thickening of arterial walls. Although it inevitably accompanies aging, it is not a degenerative process. The initial insult, called a ‘fatty streak’, is a purely inflammatory lesion and has been observed in infants. Over many years, circulating monocyte-derived macrophages adhere to and invade the arterial wall. An inflammatory response, proliferation of vascular smooth muscle cells and deposition of cholesterol and other lipids create arterial plaques. The insult creates a prothrombotic environment and induces the release of inflammatory mediators including cytokines, growth factors and hydrolytic enzymes. Over time, the plaques narrow the arterial lumen (and at times dilate it) and subsequently rupture, causing platelet activation, aggregation and resultant thrombus and embolus formation (Figure 1.1). It remains unclear as to what causes a stable plaque to rupture but it may be due to mechanical stress (e.g. hypertension) and the large lipid core redistributing shear stress over weakened areas of a thin fibrous cap.

Figure 1.1 Spontaneous rupture or fissuring of an atherosclerotic plaque exposes the lipid-rich core and triggers platelet activation and platelet aggregation. The platelet GP IIb/IIIa receptor activation binds fibrinogen and leads to intravascular thrombus formation, resulting in complete or near-complete vessel occlusion. Clinically, this often presents with a life-threatening unstable event such as an acute coronary syndrome, acute limb ischaemia or stroke.

It is recognised that increasing age, a genetic predisposition, male sex, hypertension, lipid abnormalities (in particular, LDL-cholesterol), diabetes, chronic high alcohol intake and cigarette smoking (causing an increase in free radicals) increase the risk of atherogenesis and endothelial dysfunction. Atherosclerosis mainly affects large and medium-sized arteries at places of arterial branching (e.g. carotid bifurcation). Symptoms occur when there is insufficient blood flow to the vascular bed as a result of

1. in situ thrombotic arterial occlusion,
2. low flow distal to an occluded or severely narrowed artery or
3. embolism from an atherosclerotic plaque or thrombus.

Clots occurring in the venous system are often evaluated referencing the principles of Virchow's triad, the three broad categories that contribute to thrombosis: venous stasis due to prolonged immobility, endothelial and vessel wall injury, for example, due to radiation or medical devices, and hypercoagulability states such as patients with malignancy or clotting factor deficiency.

Investigating vascular disease

Diagnostic and therapeutic decisions in patients with vascular disease are guided primarily by the history and physical examination. However, the accuracy and accessibility of non-invasive investigations have greatly increased due to technological advances in computed tomography (CT) and magnetic resonance (MR) scanning. Computed tomography angiography (CTA) and magnetic resonance angiography (MRA) continue to evolve rapidly and are best described as ‘minimally invasive’ techniques when used with intravenous (i.v.) contrast. This chapter describes the main investigative techniques used in arterial and venous diseases.

Principles of vascular ultrasound

In its simplest form, ultrasound is transmitted as a continuous beam from a probe that contains two piezoelectric crystals. The tra...

Table of contents

• Cover
• Series Page
• Title Page
• Copyright
• Preface
• Contributors
• Chapter 1: Pathogenesis of Atherosclerosis and Methods of Arterial and Venous Assessment
• Chapter 2: Cerebrovascular and Carotid Artery Disease
• Chapter 3: Coronary Artery Disease and Acute Coronary Syndrome
• Chapter 4: Abdominal Aortic Aneurysms
• Chapter 5: Visceral Artery Stenosis and Mesenteric Ischaemia
• Chapter 6: Acute Limb Ischaemia
• Chapter 7: Chronic Lower Limb Ischaemia
• Chapter 8: Venous Thromboembolic Disease
• Chapter 9: Varicose Veins
• Chapter 10: Lower Limb Ulceration
• Chapter 11: Lymphoedema
• Chapter 12: Vasculitis
• Chapter 13: Vascular Anomalies
• Chapter 14: Secondary Prevention and Antiplatelet Therapy in Peripheral Arterial Disease
• Chapter 15: Anticoagulants in Venous and Arterial Disease
• Index
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• End User License Agreement