Guideline on the Clinical Use of Ultrasound-Enhancing Agents in Cardiology Applications – 2026

Introduction

In the last two decades, new perspectives have opened for a better evaluation of cardiovascular pathophysiology, especially coronary macro- and microvascular pathophysiology, due to the development of ultrasound-enhancing agents (UEAs) based on encapsulated microbubbles prepared for intravascular injections.

These microbubbles behave similarly to red blood cells, remain exclusively intravascular, and freely circulate through the macro-and microcirculation, causing opacification of cardiac chambers and the capillary microcirculation. The primary mechanism whereby these microbubbles produce blood-pool enhancement is the introduction of multiple gas-liquid interfaces into the circulation, increasing ultrasound reflection by creating small areas with significant differences in impedance. Modern microbubbles used for diagnostic purposes are approximately 2µm in diameter (smaller than half the width of a human capillary) and resonate at frequencies used in diagnostic ultrasound for humans, around 2 MHz.
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