Assessing Intracardiac Vortices with High Frame-Rate Echocardiography-Derived Blood Speckle Imaging in Newborns

Summary

The present protocol uses echocardiography-derived blood speckle imaging technology to visualize intracardiac hemodynamics in newborns. The clinical utility of this technology is explored, the rotational body of fluid within the left ventricle (known as a vortex) is accessed, and its significance in understanding diastology is determined.

Abstract

The left ventricle (LV) has a unique pattern of hemodynamic filling. During diastole, a rotational body or ring of fluid known as a vortex is formed due to the chiral geometry of the heart. A vortex is reported to have a role in conserving the kinetic energy of blood flow entering into the LV. Recent studies have shown that LV vortices may have prognostic value in describing diastolic function at rest in neonatal, pediatric, and adult populations, and may help with earlier subclinical intervention. However, the visualization and characterization of the vortex remain minimally explored. A number of imaging modalities have been utilized for visualizing and describing intracardiac blood flow patterns and vortex rings. In this article, a technique known as blood speckle imaging (BSI) is of particular interest. BSI is derived from high-frame rate color Doppler echocardiography and provides several advantages over other modalities. Namely, BSI is an inexpensive and noninvasive bedside tool that does not rely on contrast agents or extensive mathematical assumptions. This work presents a detailed step-by-step application of the BSI methodology used in our laboratory. The clinical utility of BSI is still in its early stages, but has shown promise within the pediatric and neonatal populations for describing diastolic function in volume-overloaded hearts. A secondary aim of this study is thus to discuss recent and future clinical work with this imaging technology.

Introduction

Intracardiac blood flow patterns play a key role in cardiac development, starting in fetal morphogenesis and continuing throughout the lifespan¹. Hemodynamic shear stress plays a pivotal role in the stimulation of cardiac chamber growth and architecture via the activation of specific genes^2,3. This occurs at both the intrauterine stage and in the early stages of life, thus highlighting the importance of hemodynamic influence on early cardiac development and the carry-over into adulthood³.

The laws of fluid dynamics state that ....

Protocol

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants' families included in the study. All images and video clips were de-identified following the acquisition.

1. Patient preparation

1. Set up the ultrasound machine adjacent to the patient's cot and connect a three-lead electrocardiogram (see Table of Materials).

Results

The acquisition of vortex clips is comparable to the standard methodology universally employed in obtaining color Doppler clips. Pioneering studies in adults have described vortices using the apical two-, three-, and four-chamber views¹⁴. The LV vortex is a ring-like structure that moves from base to apex. BSI visualizes the internal diameter of the ring (Figure 2). A vortex ring is usually not symmetrical in shape, hence alternative imaging planes can show variable v.......

Discussion

The importance of visualizing and understanding the intracardiac vortex
There are many possible clinical applications of high-frame rate echocardiography-derived vortex imaging. Their ability to provide valuable insight into intracardiac flow dynamics has been the interest of recent studies¹⁶. Moreover, vortex imaging may allow the detection of pre-symptomatic changes in LV architecture and function in neonates, which may have a bearing on long-term cardiac remodeling into a.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Tomtec Imaging Systems GmbH	Phillips	GmbH Corporation	Offline ultrasound image processing tool, used for calculating all vortex measurements
Vivid E95	General Electrics	NA	Cardiac Ultrasound device used to capture Echocardiography-derived Blood Speckle Imaging