Acute mechanical circulatory support for cardiogenic shock: the "door to support" time

Abstract

Cardiogenic shock (CS) remains a major cause of in-hospital mortality in the setting of acute myocardial infarction. CS begins as a hemodynamic problem with impaired cardiac output leading to reduced systemic perfusion, increased residual volume within the left and right ventricles, and increased cardiac filling pressures. A critical step towards the development of future algorithms is a clear understanding of the treatment objectives for CS. In this review, we introduce the "door to support" time as an emerging target of therapy to improve outcomes associated with CS, define four key treatment objectives in the management of CS, discuss the importance of early hemodynamic assessment and appropriate selection of acute mechanical circulatory support (AMCS) devices for CS, and introduce a classification scheme that identifies subtypes of CS based on cardiac filling pressures.

Keywords: acute mechanical circulatory support; cardiogenic shock; hemodynamics; percutaneous ventricular assist device; ventricular unloading.

Figure 1.. The hemodynamic support equation.

The Hemodynamic Support Equation encompasses the four major management objectives for patients with cardiogenic shock, which include: circulatory support, ventricular unloading, myocardial perfusion, and decongestive strategies. BNP, brain natriuretic peptide; CK-MB, creatinine kinase and its MB isozyme; EDP, end-diastolic pressure; ESP, end-systolic pressure; LFT, liver function test; LV, left ventricle; MAP, mean arterial pressure; PA, pulmonary artery; RA, right atrium; RV, right ventricle.

Figure 2.. Left ventricular acute mechanical circulatory support devices.

Contemporary acute mechanical circulatory support devices for left ventricular support are illustrated and categorized by mode of action (pulsatile or continuous-flow pumps), type of rotary flow pump (axial- or centrifugal flow), and pump location (intracorporeal or extracorporeal). IABP, intra-aortic balloon counter-pulsation pump; PHP, percutaneous heart pump; VA-ECMO, veno-arterial extracorporeal membrane oxygenation.

Figure 3.. Right ventricular acute mechanical circulatory support devices.

Contemporary acute mechanical circulatory support devices for right ventricular support are illustrated and categorized by type of rotary flow pump (axial- or centrifugal-flow). pRVAD, percutaneous right ventricular assist device; VA-ECMO, veno-arterial extracorporeal membrane oxygenation.

Figure 4.. Congestive profiles in cardiogenic shock.

Clinical assessment of hemodynamic conditions in decompensated heart failure is traditionally categorized into four groups based on systemic perfusion and congestive status using a two-by-two table. We now propose a similar two-by-two construct to define hemodynamic profiles in cardiogenic shock based on congestive state using measures of left and right heart filling pressures. Cardiogenic shock is categorized as having LV-, RV-, or BiV-dominant congestion or hypovolemia. Treatment approaches may be tailored to each of these four categories. BiV, biventricular; CVP, central venous pressure; LV, left ventricular; PCWP, pulmonary capillary wedge pressure; RA, right atrial; RV, right ventricular.