Chapter 64: Emergency Resuscitation Measures

INTRODUCTION

Sudden cardiac death (SCD) is the leading cause of cardiovascular death and remains an important public health issue. The definition of SCD includes death from natural causes within an hour of a change in cardiovascular status and can occur in patients with or without preexisting cardiovascular disease. Incidence estimates for SCD in the United States vary from 250,000 to 450,000 cases a year, with most estimates in the range of 300,000 to 350,000 per year.¹ Although the worldwide incidence of SCD is difficult to estimate, several studies have shown the rate of SCD is approximately 50 to 100 per 100,000 people.² In the United States, SCD accounts for about half of cardiovascular deaths and 15% to 20% of all deaths.² In this chapter, we will briefly review the most common etiologies of SCD as well as outline treatment strategies for dealing with patients who present with SCD because these commonly fall under the realm of the interventional cardiologist. A thorough knowledge of emergency resuscitation measures is critical for the interventional cardiologist who is often called to potentially treat patients with SCD, whether this occurs out of or within the hospital (even within the cardiac catheterization laboratory).

Pathophysiology

Diseases of the coronary arteries account for the majority of SCD (Table 64-1). In the Western world, approximately 80% of SCD is caused by coronary artery abnormalities.³ Coronary artery disease can precipitate SCD by several mechanisms. Acute coronary plaque instability leading to cardiac ischemia or infarction can lead to electrical instability and ventricular fibrillation (VF). Previously infarcted myocardium can precipitate ventricular arrhythmias around areas of scar. Adverse remodeling after a myocardial infarction (MI) can create another substrate for ventricular arrhythmias. Furthermore, stable coronary disease can precipitate SCD. In an autopsy study of 90 cases of SCD attributed to coronary artery disease (CAD), 17 of the 90 cases (19%) had no evidence of prior MI or active coronary plaque.⁴ While the majority of patients with SCD from CAD will have VF as their initial cardiac rhythm, VF will degrade to asystole in a short period of time. Therefore, even though the initial rhythm documented by emergency medical systems can be asystole, coronary abnormalities may still be the primary etiology of the arrest.