Understanding the inner workings of the human heart

Date:
August 19, 2020
Source:
Cold Spring Harbor Laboratory
Summary:
Researchers used artificial intelligence and genetic analyses
to examine the structure of the inner surface of the heart using
25,000 MRI scans.

They found that the complex network of muscle fibers lining the
inside of the heart, called trabeculae, allows blood to flow more
efficiently and can influence the risk of heart failure. The study
answers very old questions in basic human physiology and leads to
new directions for understanding heart diseases.



FULL STORY ========================================================================== Researchers have investigated the function of a complex mesh of muscle
fibers that line the inner surface of the heart. The study, published
in the journal Nature, sheds light on questions asked by Leonardo da
Vinci 500 years ago, and shows how the shape of these muscles impacts
heart performance and heart failure.


==========================================================================
In humans, the heart is the first functional organ to develop and
starts beating spontaneously only four weeks after conception. Early
in development, the heart grows an intricate network of muscle fibers
-- called trabeculae - - that form geometric patterns on the heart's
inner surface. These are thought to help oxygenate the developing heart,
but their function in adults has remained an unsolved puzzle since the
16th century.

"Our work significantly advanced our understanding of the importance
of myocardial trabeculae," explains Hannah Meyer, a Cold Spring Harbor Laboratory Fellow. "Perhaps even more importantly, we also showed
the value of a truly multidisciplinary team of researchers. Only the combination of genetics, clinical research, and bioengineering led us to discover the unexpected role of myocardial trabeculae in the function of
the adult heart." To understand the roles and development of trabeculae,
an international team of researchers used artificial intelligence
to analyse 25,000 magnetic resonance imaging (MRI) scans of the heart,
along with associated heart morphology and genetic data. The study reveals
how trabeculae work and develop, and how their shape can influence heart disease. UK Biobank has made the study data openly available.

Leonardo da Vinci was the first to sketch trabeculae and their
snowflake-like fractal patterns in the 16th century. He speculated
that they warm the blood as it flows through the heart, but their true importance has not been recognized until now.

"Our findings answer very old questions in basic human biology. As
large-scale genetic analyses and artificial intelligence progress, we're rebooting our understanding of physiology to an unprecedented scale,"
says Ewan Birney, deputy director general of EMBL.

The research suggests that the rough surface of the heart ventricles
allows blood to flow more efficiently during each heartbeat, just like
the dimples on a golf ball reduce air resistance and help the ball
travel further.

The study also highlights six regions in human DNA that affect how the
fractal patterns in these muscle fibers develop. Intriguingly, the
researchers found that two of these regions also regulate branching
of nerve cells, suggesting a similar mechanism may be at work in the
developing brain.

The researchers discovered that the shape of trabeculae affects the
performance of the heart, suggesting a potential link to heart disease. To confirm this, they analyzed genetic data from 50,000 patients and found
that different fractal patterns in these muscle fibers affected the risk
of developing heart failure. Nearly five million Americans suffer from congestive heart failure.

Further research on trabeculae may help scientists better understand
how common heart diseases develop and explore new approaches to treatment.

"Leonardo da Vinci sketched these intricate muscles inside the heart
500 years ago, and it's only now that we're beginning to understand
how important they are to human health. This work offers an exciting
new direction for research into heart failure," says Declan O'Regan,
clinical scientist and consultant radiologist at the MRC London Institute
of Medical Sciences. This project included collaborators at Cold Spring
Harbor Laboratory, EMBL's European Bioinformatics Institute (EMBL-EBI),
the MRC London Institute of Medical Sciences, Heidelberg University,
and the Politecnico di Milano.


========================================================================== Story Source: Materials provided by Cold_Spring_Harbor_Laboratory. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Hannah V. Meyer, Timothy J. W. Dawes, Marta Serrani, Wenjia Bai,
Paweł Tokarczuk, Jiashen Cai, Antonio De Marvao, Albert
Henry, R.

Thomas Lumbers, Jakob Gierten, Thomas Thumberger, Joachim
Wittbrodt, James S. Ware, Daniel Rueckert, Paul M. Matthews,
Sanjay K. Prasad, Maria L. Costantino, Stuart A. Cook, Ewan
Birney & Declan P. O'Regan. Genetic and functional insights into
the fractal structure of the heart. Nature, August 19, 2020 DOI:
10.1038/s41586-020-2635-8 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200819110925.htm

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