Arterial Diseases: A Comprehensive USMLE Guide

Introduction

Arterial diseases refer to a group of medical conditions that affect the arteries, the blood vessels responsible for carrying oxygen-rich blood from the heart to various tissues and organs in the body. Understanding the pathophysiology, clinical presentation, diagnosis, and management of arterial diseases is crucial for medical students preparing for the United States Medical Licensing Examination (USMLE). This guide aims to provide a comprehensive overview of arterial diseases, focusing on key concepts that are frequently tested on the USMLE.

Table of Contents

1. Anatomy and Physiology of Arteries
2. Atherosclerosis
   • Pathophysiology
   • Risk Factors
   • Clinical Manifestations
   • Diagnosis
   • Management
3. Peripheral Arterial Disease (PAD)
   • Pathophysiology
   • Risk Factors
   • Clinical Presentation
   • Diagnosis
   • Management
4. Aortic Aneurysm
   • Pathophysiology
   • Risk Factors
   • Clinical Presentation
   • Diagnosis
   • Management
5. Dissection of Arteries
   • Pathophysiology
   • Risk Factors
   • Clinical Presentation
   • Diagnosis
   • Management

1. Anatomy and Physiology of Arteries

Arteries are thick-walled blood vessels that carry oxygenated blood away from the heart. They consist of three layers: the intima, media, and adventitia. The intima is the innermost layer composed of endothelial cells, which provide a smooth surface for blood flow. The media is a thick layer of smooth muscle cells that regulate vessel diameter. The adventitia is the outermost layer, composed of connective tissue.

2. Atherosclerosis

Pathophysiology

Atherosclerosis is a chronic inflammatory disease characterized by the formation of plaques within arterial walls. It involves the accumulation of cholesterol, fats, calcium, immune cells, and fibrous tissue, leading to the narrowing and hardening of arteries.

Risk Factors

• Modifiable risk factors: smoking, hypertension, hyperlipidemia, diabetes mellitus, obesity, sedentary lifestyle, and poor diet.
• Non-modifiable risk factors: age, gender (males > females), family history, and genetic predisposition.

Clinical Manifestations

• Coronary artery disease: angina, myocardial infarction.
• Carotid artery disease: transient ischemic attacks (TIAs), strokes.
• Peripheral arterial disease: claudication, non-healing ulcers, gangrene.
• Aneurysm formation: aortic aneurysms, peripheral aneurysms.

Diagnosis

• Physical examination: auscultation of carotid and peripheral arteries for bruits, assessing peripheral pulses.
• Laboratory tests: lipid panel, fasting blood glucose, HbA1c.
• Imaging: coronary angiography, carotid ultrasound, ankle-brachial index (ABI).

Management

• Lifestyle modifications: smoking cessation, regular exercise, healthy diet, weight management.
• Pharmacotherapy: statins, antiplatelet agents, antihypertensives, and hypoglycemic agents as needed.
• Invasive interventions: coronary angioplasty, stenting, bypass surgery.

3. Peripheral Arterial Disease (PAD)

Pathophysiology

PAD refers to the obstruction of arterial blood flow to the extremities, primarily caused by atherosclerosis. The narrowing of arteries reduces blood supply to the legs, leading to claudication (pain with exertion) and tissue ischemia.

Risk Factors

• Similar to atherosclerosis: smoking, hypertension, hyperlipidemia, diabetes mellitus, obesity, sedentary lifestyle, and poor diet.

Clinical Presentation

• Intermittent claudication: cramping leg pain during exercise, relieved by rest.
• Non-healing ulcers: particularly over bony prominences.
• Gangrene: advanced disease, tissue necrosis.

Diagnosis

• Ankle-brachial index (ABI): ratio of systolic blood pressure in the ankle to that in the arm.
• Doppler ultrasound: assesses blood flow and detects stenosis or occlusion.
• Angiography: visualizes arterial blockages.

Management

• Lifestyle modifications: smoking cessation, regular exercise, foot care, and wound management.
• Pharmacotherapy: antiplatelet agents, cilostazol (improves walking distance), statins.
• Revascularization procedures: angioplasty, stenting, bypass surgery.

4. Aortic Aneurysm

Pathophysiology

Aortic aneurysm involves the dilation of the aorta, predisposing it to rupture. Two common types include abdominal aortic aneurysm (AAA) and thoracic aortic an