Systemic Circulation in Advanced Heart Failure and Cardiogenic Shock: State-of-the-Art Review.

Abstract

The integrative physiology of the left ventricle and systemic circulation is fundamental to our understanding of advanced heart failure and cardiogenic shock. In simplest terms, any increase in aortic stiffness increases the vascular afterload presented to the failing left ventricle. The net effect is increased myocardial oxygen demand and reduced coronary perfusion pressure, thereby further deteriorating contractile function. Although mechanical circulatory support devices should theoretically work in concert with guideline-directed medical therapy, cardiac resynchronization and inotropic and vasopressor agents designed to support myocardial performance and enhance left ventricle recovery, this does not always occur. Each therapy and intervention may result in vastly different and sometimes deleterious effects on vascular afterload. Although best described by a combination of both steady-state and pulsatile components, the latter is frequently overlooked when mean arterial pressure or systemic vascular resistance alone is used to quantify vascular afterload in advanced heart failure and cardiogenic shock. In this state-of-the-art review, we examine what is known about vascular afterload in advanced heart failure and cardiogenic shock, including the use of temporary and permanent mechanical circulatory support systems. Importantly, we outline 4 key components for a more complete assessment of vascular afterload. Unlike previous discussions on this topic, we set aside considerations of venous return and ventricular preload, as important as they are, to focus exclusively on the hydraulic load within the systemic circulation against which the impaired left ventricle must contract.