Cardiogenic shock

Abstract

Cardiogenic shock (CS) is defined as end-organ hypoperfusion as the consequence of primary myocardial dysfunction. Among the diagnostic criteria are a systolic blood pressure < 90 mmHg, acute renal failure (oligoanuria), ischemic hepatitis, cyanosis and cold, clammy skin. Accepted hemodynamic cutoffs are a cardiac index < 2,2 (l/min)/m2 and a pulmonary capillary wedge pressure > 15 mmHg. It should be acknowledged, that a normal blood pressure does not rule out CS; there is a nonhypotensive variant of CS demonstrating all the signs mentioned above (including elevated lactate levels) while the blood pressure is compensated due to vasoconstriction. The single most frequent cause of CS is pump failure in the setting of an acute myocardial infarction and its mortality rate has been lowered to 40-50%, owing to the widespread availability of primary PCI. Regarding PCI, it has been demonstrated recently that a “culprit-lesion only strategy” should be followed in the setting of CS. Other important causes of CS to take into account are mechanical complications of myocardial infarction (papillary and ventricular septal rupture as well as rupture of the myocardial free wall leading to tamponade), valvular heart disease (mostly decompensated aortic stenosis) as well as myocarditis and end stage cardiomyopathy. The diagnosis of CS is made by patient history, physical examination, ECG, echocardiography and coronary angiography. Echocardiography should always be performed before coronary angiography because, in the case of mechanical complications, it significantly alters the management of the patients. Patients with clinical signs of CS but paradoxically preserved ejection fraction must be thoroughly evaluated for the presence of a papillary muscle rupture, particularly in the setting of a lateral wall infarction. Noradrenaline and dobutamine are the first-line agents for medical stabilization. When such conventional measures fail, extracorporeal support devices such as ECMO or Impella© may be used. Currently, trials are underway to assess wheter these devices confer a survival benefit in this high-risk population.