CHAPTER 62: Advances in the Management of Ischemic Pain

INTRODUCTION

Ischemic pain affects millions of people worldwide. It is a detriment to quality of life and carries with it significant morbidity and mortality. Ischemic pain occurs when there is obstruction of the circulation to an area of the body. The myocardium, lower extremities, and mesentery can be affected primarily from the development of atherosclerosis obliterans. Pain management centers are becoming more involved in the care of patients with ischemic diseases because the centers can offer interventional procedures applicable to these diseases. This chapter provides a review of the pathophysiology of ischemic disease, existing and emerging therapies available and their efficacy, and the role of the pain specialist in the management of patients with peripheral, coronary, and mesenteric ischemic disease.

PERIPHERAL ARTERY DISEASE

CHARACTERISTICS

Limb ischemia can be caused by atherosclerosis obliterans as well as atheroembolic or thromboembolic disease, vasculitis, trauma, and other disease processes. Limb ischemia affects macrovascular and microvascular circulation. Peripheral artery disease (PAD) is a marker for cardiovascular disease (CVD) and affects 8 million Americans.

Ischemic pain in PAD is insidious and gradual in onset. The pain is described as an aching and cramping sensation that is worse at night and improves when the legs are in a dependent position, which improves blood flow. Most patients have atherosclerotic changes for 5 to 10 years before they have symptoms. Intermittent claudication is the earliest sign of vascular insufficiency, which is characterized by cramping, tightness, and heaviness that increase with exercise. The pain is relieved with rest and the claudication distance remains fairly constant until further progression of the disease. The differential diagnosis for intermittent claudication is listed in Table 62-1.

In the early stages of PAD, collateral circulation develops and may maintain adequate perfusion to the affected limb, but may not provide sufficient blood flow to prevent symptoms, especially during exercise. Approximately 25% of patients with intermittent claudication will progress to critical ischemia and pain at rest, secondary to the primary and collateral vessels becoming stenotic or occluded. When rest pain occurs, the degree of vascular insufficiency is severe. When ischemic pain at rest, tissue necrosis, and/or gangrene develop, patients fall into the category of critical limb ischemia (CLI) and will likely require surgery or endovascular procedures for pain control, limb salvage, and wound healing. Diagnosis and treatment is essential to minimize these sequelae (Table 62-2).