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\begin{document}

\title{Intracardiac Flow Visualization Using High-Frame Rate Blood Speckle
Tracking Echocardiography: Illustrations from infants with Congenital
Heart Disease}



\author[1]{Massimiliano Cantinotti}%
\author[1]{Pietro Marchese}%
\author[2]{Martin Koestenberger}%
\author[3]{Raffaele Giordano}%
\author[1]{Giuseppe Santoro}%
\author[1]{Nadia Assanta}%
\author[4]{Shelby  Kutty}%
\affil[1]{Stabilimento Ospedaliero di Massa Ospedale del Cuore G Pasquinucci}%
\affil[2]{University of Graz}%
\affil[3]{Universita degli Studi di Napoli Federico II}%
\affil[4]{Johns Hopkins Medicine}%


\vspace{-1em}



  
  \date{May 08, 2024}


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\selectlanguage{english}
\begin{abstract}
We report applications of novel high-frame rate blood speckle tracking
(BST) echocardiography in a series of infants with congenital heart
disease (CHD). BST echocardiography was highly feasible, reproducible,
and fast. High-frame rate BST provided complimentary information to
conventional color-Doppler data enhancing the visualization and
understanding of anomalous blood trajectories (e.g., shunt direction,
regurgitant volumes, and stenotic jets) and vortex formation. High-frame
rate BST echocardiography is a new, promising imaging tool that may be
helpful for deeper understanding of complex CHD physiology.%
\end{abstract}%



\sloppy


\textbf{Intracardiac Flow Visualization Using High-Frame Rate Blood
Speckle Tracking Echocardiography: Illustrations from infants with
Congenital Heart Disease}

Massimiliano Cantinotti, MD\textsuperscript{1,2}; Pietro Marchese,
MD\textsuperscript{1,3} Martin Koestenberger, MD4; Raffaele Giordano M.D
5, Giuseppe Santoro M.D. 1; Nadia Assanta, MD\textsuperscript{1}; Shelby
Kutty, MD, MS, PhD\textsuperscript{6}

\par\null

\textsuperscript{1} Stabilimento Ospedaliero di Massa Ospedale del Cuore
G Pasquinucci, Pediatric Cardiology and Cardiac Surgery, Massa, Toscana,
IT

\textsuperscript{2} Institute of Clinical Physiology (IFC), National
Research Institute (CNR), Pisa, Italy

\textsuperscript{3} Department of Pediatrics University of Pisa, Italy

\textsuperscript{4} Division of Pediatric Cardiology, Department of
Pediatrics Medical University Graz, Austria

5 University of Naples ``Federico II'', Italy,

\textsuperscript{6} Johns Hopkins Medicine, Pediatrics, Baltimore, MD,
USA

\textbf{Running title:} Blood Speckle Tracking Echocardiography in CHD

\textbf{Word Count:} 1264 words

\textbf{Key words} : vector flow echocardiography, blood speckle
tracking, congenital heart disease

\textbf{Correspondence (*):}

Marchese Pietro M.D,

Fondazione CNR-Regione Toscana G. Monasterio

Via Aurelia Sud 5, 54100 Massa (MS)

Tel 3281123173

Email: \emph{pitrino91@gmail.com}

Fax: none

Authors' conflict of interest disclosure, research founding, employment
or leadership: None

\textbf{Abstract}

We report applications of novel high-frame rate blood speckle tracking
(BST) echocardiography in a series of infants with congenital heart
disease (CHD). BST echocardiography was highly feasible, reproducible,
and fast. High-frame rate BST provided complimentary information to
conventional color-Doppler data enhancing the visualization and
understanding of anomalous blood trajectories (e.g., shunt direction,
regurgitant volumes, and stenotic jets) and vortex formation.

High-frame rate BST echocardiography is a new, promising imaging tool
that may be helpful for deeper understanding of complex CHD physiology.

High-frame rate blood speckle tracking (BST) echocardiography is a new
technique (1-3) based on ultrafast ultrasound imaging for assessing flow
patterns. In congenital heart disease (CHD) a variety of complex
alterations in blood flow pattern occur, and BST echocardiography may
enhance their visualization. High-frame rate BST echocardiography has
been technically validated in pediatric patients (3), but clinical
applications are to be defined (1-3).

We report a series of infants with normal anatomy and congenital heart
disease to demonstrate the benefits of BST echocardiography in this
setting.

Images were obtained during outpatient screening or pre-operative
examinations at a single Center (Fondazione CNR-Regione Toscana G.
Monasterio, Massa, Italy) from a Vivid-TM-E95 ultrasound system (GE
Healthcare) with conventional 6S and 12S phased-array probes, using
standard projections and protocols. The BST movies were acquired at
frame rates ranging from Clips of 2 cardiac cycles were stored using
medium (66 cm/s), to low (53cm/s) Nyquist limits.

Images were collected only in quiet and cooperative children. Infants
could bottle feed during the examinations. No child was sedated.
Approval for this study was obtained from the Local Ethics Committee
(Study ``Bet2'' N.395). Parents or legal guardians of all the children
were informed and accepted to participate in the study by signing a
written consent.

Case 1: A 2-day old male neonate with body weight 2.85 kg is presented.
Parasternal Long axis (PLAX) view shows normal laminar flow across the
aortic valve and aortic root (Figure 1a; Video 1). Modified long axis
and short axis views show normal laminar flow across the pulmonary valve
and arteries (Figure 1b and Figure 1c; Video 1). A suprasternal view
shows normal laminar flow in the ascending aorta and in the aortic arch
(Figure 1d; Video 1).

Case 2: This is a 2-day old male neonate with body weight 3.2 kg and
cardiac diagnosis of d-transposition of the great arteries, restrictive
patent foramen ovale (PFO), and subaortic ventricular septal defect
(VSD). In subcostal view, the PFO with restrictive left-to right shunt
can be visualized (Figure 2a). The five-chamber view at different times
of the cardiac cycle shows: the RV to PA shunt in systole (Figure 2c),
and the shunt from the right ventricle (RV) to the left ventricle (LV)
(Figure 2 d) in diastole. This is well appreciated by blood speckle
tracking (BST). The parallel circulations---RV to aorta (AO) and LV to
PA are clearly appreciated in a modified parasternal view (Figure 2 e,
Video 2). The high velocity vortical flow across the patent ductus
arteriosus is visible in the short axis view (Figure 2b and Video 2).

Case 3: Echocardiogram from a 5-day old male neonate with body weight
3.3 kg and cardiac diagnosis of severe aortic stenosis (AS). The
vortical flow across the aortic valve with vortex formation at the
valve, and its propagation above the valve and in ascending aorta (Asc
Ao) is best seen in parasternal view (Figures 3a and 3b, Video 3). On
suprasternal view (Figure 3c, Video 3), vortical propagation across the
entire aortic arch is seen (Ao ann = aortic annulus). High velocity
Doppler (peak velocity 4.3 m/s, peak gradient 72 mmHg) through the
stenotic aortic valve is seen in 3d. Abdominal aortic flow is blunted
and of low pulsatility (3e).

Case 4: This is a 4-day old female neonate with body weight 2.8 kg and
cardiac diagnosis of tetralogy of Fallot (TF) and absent pulmonary
valve. In a modified apical 4 chamber view, the systolic right to left
(Figure 4a) and diastolic left to right (Figure 4b) flow across the VSD
can be appreciated. In Video 4, the shunt is demonstrated through the
entire cardiac cycle. Modified right ventricular outflow tract view
(RVOT) shows the vortical flow across the rudimental pulmonary valve
with vortex formation (Figure 4c, Video 4), and vortex propagation into
the dilated pulmonary artery (Figure 4c, Video 4). The diastolic free
regurgitation across the pulmonary valve (Figure 4d, Video 4), and the
late diastolic vortex formation in the RVOT (Figure 4e, Video 4) are
also seen.

Case 5: Echocardiogram from a 4-day old male neonate with body weight
3.1 kg, and severe pulmonary stenosis after pulmonary balloon
valvuloplasty. The right to left shunt across the PFO (Figure 5a, Video
5) is seen in the subcostal view. In the 4-chamber view, severe
tricuspid valve regurgitation is visualized (Figure 5b, Video 5). The
short axis view shows (Video 5) vortex propagation into the pulmonary
arteries during the cardiac cycle. Figure 5c shows the vortex at the
level of the pulmonary valve (beginning of the systole), the vortex
propagating into the main pulmonary artery (mid-systole, 5d), and
subsequently into pulmonary artery branches (late systole and early
diastole, 5e). Left-to-right shunt from the ductus arteriosus into the
main PA is seen, as well as the diastolic regurgitant flow (5f and 5g).

Case 6: This is a 5-day old female

Case 7: Echocardiogram from a 3-day old male neonate with body weight
3.0 kg and diagnosis of aortic coarctation (ACo). On suprasternal
imaging, the vortical flow across the stenotic isthmus below the left
subclavian artery (LSA) is seen (Figure 7a, Video 7); there is
continuous diastolic flow (Figure 7d; Video 7). Diastolic run-off
(Figure 7b) and blunted, low velocity flow in the abdominal aorta
(Figure 7c).

Case 8: Echocardiogram in a 1-day old male neonate with body weight 3.4
kg and diagnosis of total intracardiac anomalous pulmonary venous
return. The subcostal view shows pulmonary venous drainage into the
coronary sinus (CS) and to the right atrium (RA). The right to left
shunt through a large atrial septal defect (ASD) is seen. The trajectory
of pulmonary blood from coronary sinus to the right atrium and to the
right ventricle (RV), and partly back to the left atrium (LA) through
the ASD can be appreciated in subcostal views at slightly different
angulations (Figure 8a and 8b and Video 8), and in the 4-chamber view
(Figure 8c and 8d, Video 8). In the subcostal view simultaneous BST
images and 2D images without color are shown.

In the cases we presented high-frame rate BST echocardiography
supplemented conventional color-Doppler data, and allowed for a more
detailed evaluation of vortex formation and anomalous blood
trajectories. High-frame rate BST echocardiography facilitated improved
understanding of shunt direction, regurgitant volumes, and stenotic jets
vortices with their propagation into the vessels.

High quality high-frame rate BST loop acquisition at neonatal heart
rates were feasible (in 100\% of the cases) and fast as to conventional
color Doppler. The image post-processing was rapid, requiring not more
than 30-60 seconds in each case.

In conclusion, high-frame rate BST echocardiography is a useful tool for
enhancing understanding of CHD physiology and could also serve for
teaching purposes.

\textbf{References}

\begin{enumerate}
\tightlist
\item
  Villeman O, Baranger J, Friedberg MK, et al. Ultrafast Ultrasound
  Imaging in Pediatric~and Adult Cardiology: Techniques, Applications,
  and Perspectives JACC Cardiovasc Imaging 2020;13:1771-1791.
\item
  Thomas Collins R, Lughlin ME, Lang SM, et al. Real-Time Transthoracic
  Vector Flow Imaging of the Heart in Pediatric Patients. Prog Pediatr
  Cardiol. 2019 Jun; 53: 28--36.
\item
  Nyrnes SA, Fadnes S, Wigen MS, Mertens L, Lovstakken L. Blood
  Speckle-Tracking Based on High-Frame Rate Ultrasound Imaging in
  Pediatric Cardiology. J Am Soc Echocardiogr.~2020; 33:493-503.e5.
\end{enumerate}\selectlanguage{english}
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