Basic Concepts of Echocardiography Hemodynamics

Echocardiography utilizes ultrasound to image the cardiovascular system from both an anatomical and a physiologic standpoint. The advances in echocardiography initially began with Inge Edler, often considered the father of echocardiography, who utilized an early motion-based technique called M-mode. In the 1970s, S.L. Johnson, Holen, and Hatle developed technological capabilities allowing the measurement of blood flow as well as the detection of pressure gradients between cardiovascular structures. Using concepts formulated by D. Bernoulli in 1738 and L. Euler in 1752, they developed one of the most utilized techniques used in modern-day echocardiography, the Bernoulli equation (see Bernoulli Equation). With its ability to assess real-time hemodynamics, echocardiography has played an important role in the modern-day management of patients. It involves several basic physical and mathematical principles (i.e., volume, velocity, area,  pressure, etc.). In this article, we will discuss the basics of echocardiography hemodynamics, specifically four major principles: the conservation of energy (Bernoulli’s principle), the hydraulic formula of flow, conservation of mass (the continuity equation), and proximal iso velocity surface area (PISA).