ecg-blood speckle image acquisition of newborns

Advancements in Echocardiography-Derived Blood Speckle Imaging Technology

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 genes2,3. 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 blood passing along a vessel wall move slower when closest to the wall and faster when in the center of a vessel, where resistance is lower. This phenomenon can be demonstrated in any large vessel with pulse wave Doppler as the typical Doppler velocity time integral envelope4. When blood enters a larger cavity such as the heart, the blood farthest from the endocardial surface continues to increase its velocity relative to the blood closest to that surface and create a rotational body of fluid, known as a vortex. Once created, vortices are self-propelling flow structures that typically draw in surrounding fluid via negative pressure gradients. Thus, a vortex can move a greater volume of blood than an equivalent straight jet of fluid, promoting greater cardiac efficiency4,5.
The literature suggests that the evolutionary purpose of vortices is to conserve kinetic energy, minimize shear stress, and maximize flow efficiency4,5,6. Specifically for the heart, this includes storing hemodynamic energy in a rotary motion, facilitating valve closure, and the propagation of blood flow toward the outflow tract, as seen in Figure&#160;1. Altered intracardiac blood flow patterns are expected in pathological situations such as volume-overloaded states and in cases with artificial valves7,8. Thus, herein lies the true diagnostic potential of vortices as early predictors of cardiovascular outcomes in adults.
Intracardiac hemodynamics have gained increasing interest in the literature in both adult and pediatric populations. Several modalities are available for the qualitative and quantitative assessment of intracardiac hemodynamics and were comprehensively summarised in a recent review, with a specific emphasis on the intracardiac vortex9. One modality with great promise is echocardiography-derived blood speckle imaging (BSI), which offers the ability to noninvasively measure a number of qualitative and quantitative vortex characteristics, described below, at a relatively low cost and with excellent reproducibility10. BSI is currently commercially available using a high-end cardiac ultrasound system with an S12 or S6 MHz probe. The speckle-tracking features are analogous to those used in tissue speckle tracking to study myocardial deformation11,12,13. Since red blood cells tend to move faster and with a higher Doppler frequency than the surrounding tissue, the two signals can be separated by applying a temporal filter. BSI uses a best-match algorithm to quantify the movement of blood speckles directly without using contrast agents. The blood velocity measurements can be visualized as arrows, streamlines, or path lines with or without underlying color Doppler images, and can highlight areas of complex flow10.
BSI has been shown to have good feasibility and accuracy for quantifying intracardiac blood flow patterns, with excellent validity compared to a reference phantom instrument and pulsed-Doppler7,10,11. Whilst still very novel, BSI is a promising clinical tool for the early diagnosis of various cardiac pathophysiologies. The clinical application of vortex imaging has shown promise in newborn infants. Specifically, the behavior of a vortex in the left ventricle (LV) may have long-term implications on cardiac remodeling and predisposition toward heart failure.
The mechanism linking vortices to left ventricular remodeling is still relatively unexplored, but has been recently investigated in our laboratory and is the subject of ongoing work11. This methodology article aims to describe the use of BSI in exploring intracardiac vortices and discuss the practical and clinical uses of vortices in assessing diastolic function in various populations. A secondary aim is to discuss the clinical relevance of BSI and present some of the work previously performed in neonates.

Author Spotlight: Advancing Neonatal Cardiac Diagnostics with Echocardiography-Derived Blood Speckle Imaging 

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

We're try to explore why preterm babies when they're born preterm and grow into adults have a significant higher risk of heart failure. We think it has to do with an abnormal cardiac development because they were born 10 or sometimes 15 weeks early and where pressure in the heart has changed. We can now capture this kind of changes with looking at intracardiac blood flow patterns with blood speckle imaging.Hopefully we'll be able to select babies very early on in this crucial period of cardiac development and maybe apply some preventive strategies with a future goal to also prevent heart failure when they grow up to be adults. Well, from a practical point of view, the challenges always fall back on image quality and the acquisition of clear cardiac structures in an echo. And what's more, it's additionally challenging because we're dealing with babies and we sometimes have very unsettled patients.So we did two studies with blood speckle imaging, one to look if the technique was actually feasible in this population and the answer was yes, it's very feasible. It's very nice images of intracardiac blood flow patterns in these preterm population. And the second we followed the cohort of 80 preterm infant, and we measured them at day five to seven and then again at discharge.And then we categorized them in the babies who had this cardiac remodeling of prematurity and the ones who did not. And we found out that the babies who had cardiac modeling also had abnormal vortex formations at day seven. The vortexes were way more larger and rounder than in the babies who did not develop cardiac remodeling.This might be a very important clue moving forward in exploring which babies might be amenable to preventive treatments. Well, currently there's limited research available on the use of echo derived blood speckle imaging and neonates. So what we've currently been doing is looking at cardiac development after preterm birth.But what remains to be explored is the association between diastolic dysfunction and intracardiac blood flow, like vortices and vortex exclamation. Echo derived blood speckle imaging is a completely non-invasive tool compared to other technologies like MRI. It's also fairly cheap to use and it's very useful as a bedside tool, meaning it can be brought into the rooms next to patients and minimizing inconvenience to the patients.

Watch this Scientific Journal Video about ECG-Blood Speckle Image Acquisition of Newborns at JoVE.com

ECG-Blood Speckle Image Acquisition of Newborns  

Begin by setting up the ultrasound machine next to the patient's cot and connect a three lead electrocardiogram. Next, perform the echocardiogram. To begin blood speckle image specific acquisition, obtain a shallow view of the left ventricle in the apical four chamber view with a narrow section width.Open a color box over the left ventricular cavity and narrow it maximally to include only the region from the mitral valve to the endocardial apex and from the septal to the lateral wall endocardial border. Increase the color game to the point of speckling and reduce it slightly. Set the color Doppler velocity scale limit to the appropriate diastolic velocity.Tap the BSI mode on the touchscreen control panel of the equipment to reveal the intracardiac flow directions and vortices in raw color format. Adjust the BSI box position and size to include the flow region of interest and record at least two cardiac cycles.

ecg-blood-speckle-image-acquisition-of-newborns

Research

JoVE Journal

Medicine

186 Views.  University of Newcastle. Begin by setting up the ultrasound machine next to the patient's cot and connect a three lead electrocardiogram. Next, perform the echocardiogram. To begin blood speckle image specific acquisition, obtain a shallow view of the left ventricle in the apical four chamber view with a narrow section width.Open a color box over the left ventricular cavity and narrow it maximally to include only the region from the mitral valve to the endocardial apex and from the septal to the lateral wall e...

Video: ECG-Blood Speckle Image Acquisition of Newborns  

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.

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.

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 ...

Newborn Blood-Speckle Image Analyses 

Begin by saving two cardiac cycles from each patient to the external media in its raw DICOM format and transfer to a laboratory station with image processing software for detailed offline analyses. Once offline, identify the most prominent or main vortex. Record the number of independent, complete oval-shaped vortices forming throughout the cardiac cycle for each clip.Measure the position of the main vortex relative to known landmarks within the left ventricle. For measuring the vortex depth, use the distance measurement tool to measure the vertical distance from the vortex eye to the middle of the mitral valve annulus. For the vortex transverse position, measure the horizontal distance between the vortex eye and the endocardial border of the interventricular septum.Obtain the vortex shape by measuring the vertical and horizontal edge-to-edge distances of the main vortex relative to the left ventricular length and width. Next, use the tracing measurement tool to click on and trace the outermost vortex ring from the most prominent point of the main vortex to obtain the vortex area. Assess the peak vortex formation time by recording the cardiac frame when the vortex is most prominent and calculate the number of frames relative to the total number of frames in one cardiac cycle of the patient.Assess the vortex duration by measuring the frames from which the vortex first appears to when the vortex loses its circular ring formation. Preterm neonate comprehensive echocardiograms with BSI assessment showed a strong positive correlation between the vortex area and LV and diastolic dimension. The vortex duration and eon ePrime ratio were inversely correlated.BSI application in characterizing cardiac landmarks with unique flow patterns was explored to describe venous return flow in neonates. In the right ventricle, the main vortex is seen as a clockwise rotating structure that rolls along the septum with its maximum area just before the pulmonary valve and artery. A main vortex is formed due to the mixing of inflow via the inferior vena cava and superior vena cava in the right atrium.The left atrium has limited areas where the flow of the four pulmonary veins is not directly mixing and vortices can be difficult to capture.