CHAPTER SUMMARY AND CENTRAL ILLUSTRATION
This chapter describes the pathophysiology, assessment, classification, and management of cardiogenic shock (see Fuster and Hurst’s Central Illustration). The pathophysiology of cardiogenic shock involves a maladaptive compensatory cycle triggered by acute reduction in cardiac output. All etiologies initiate a physiologic cascade rooted in three main pathways: (1) increase in left ventricular end diastolic pressure, (2) reduction of blood pressure, and (3) triggering of inflammatory responses. If left uninterrupted, the compensatory cycle will lead to progressive cardiac dysfunction and ultimately death. A thorough assessment of the patient with suspected cardiogenic shock is necessary to confirm diagnosis and inform treatment decisions, and involves physical examination, ultrasonography, laboratory studies, invasive hemodynamics, and coronary angiography, as appropriate. Cardiogenic shock with predominant left ventricular failure is more common than isolated right ventricular failure, and etiology can be categorized as primary, obstructive, or valvular. Etiology of cardiogenic shock with predominant right ventricular failure is usually primary or obstructive, often related to acute pulmonary embolism of hemodynamic significance. Concurrent left ventricular failure and right ventricular failure is relatively common among causes of cardiogenic shock and the underlying etiology is primary, obstructive, electrical, or structural. Treatment for cardiogenic shock depends on etiology, and may involve a combination of vasoactive agents (pressors and inotropes), treatment of myocardial ischemia and revascularization as appropriate, and mechanical circulatory support (e.g. intra-aortic balloon pump counterpulsation, percutaneous left ventricular assist device, and/or extracorporal membrane oxygenation) as needed.
eFig 62-01 Chapter 62: Circulatory and Cardiogenic Shock
Cardiogenic shock is diminished cardiac function resulting in life-threatening end-organ hypoperfusion and hypoxemia1 and is associated with major morbidity and frequent mortality.
There are varied definitions of cardiogenic shock. The most widely used are the entry criteria used in the SHOCK trial2 that highlight three hallmarks of cardiogenic shock: (1) a systolic blood pressure of <90 mm Hg for >30 minutes or vasopressor support to maintain a systolic blood pressure of >90 mm Hg, (2) evidence of end organ hypoperfusion, and (3) a measured cardiac index of <2.2 L/m/m2 and pulmonary capillary wedge pressure of >15 mm Hg. Since that time, there have been a number of randomized trials that used similar but slightly varied definitions of cardiogenic shock, many not requiring the measurement of invasive hemodynamic data to meet criteria.3–5
Most recently, the Society for Cardiovascular Angiography and Intervention (SCAI) proposed a new classification system.6 This system describes five stages of cardiogenic shock, from A to E, with A being “at risk,” B “beginning,” C “classic,” D “deteriorating,” and E “extremis” (Fig. 62–1). Cardiogenic shock begins at Stage C, which is defined by organ hypoperfusion. Stage D is defined by the failure of at least 30 minutes of initial interventions. ...