In humans, the heart is the first functional organ to develop, starting to beat by four weeks after conception. During the development, the heart grows an intricate and complex network of muscle fibers, known as trabeculae, forming geometric patterns in the inner lining of the heart.
The muscular band of heart tissue called the moderator band or the septomarginal trabecula is found in the right ventricle of the heart and was first described by Leonardo da Vinci in his exploration of human anatomy.
Structures first sketched by artist Leonardo da Vinci are crucial in understanding how the heart works, according to researchers.
Previously, scientists believe that these strand-like muscle structures have no use beyond the heart's early development. Now, a team of researchers at Imperial College London has found that these structures play a pivotal role in the electrical activity and pumping ability of the heart. The team also revealed that the more complex the network of muscle fibers, the lesser the risk of heart failure.
"Our work significantly advanced our understanding of the importance of myocardial trabeculae. 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," Hannah Meyer, a Cold Spring Harbor Laboratory Fellow, said in a statement.
Heart failure occurs when the heart cannot pump enough blood and oxygen to the other vital organs in the body. Often, it is a life-threatening and severe condition. This heart problem causes blood and fluid to flow back into the lungs, edema, fatigue, and shortness of breath.
The most common causes of heart failure include diabetes, elevated blood pressure, and coronary artery disease (CAD). It is also more common in the elderly, particularly those who are more than 65 years old, those who have had a heart attack, and people who are overweight or obese.
In the United States alone, an estimated 6.5 million adults have heart failure, and it contributed to about 1 in 8 deaths in 2017.
Structure of the heart
The heart has an intricate network of muscle fibers called trabeculae, which lines the heart's inner lining. The role of these muscle fibers, which was first sketched by da Vinci, is important in understanding who is at most risk of heart failure.
The trabeculae are columns of muscle fibers that form complex branch networks inside the lower ventricles of the heart. These structures were first described and sketched by da Vinci, when he was exploring human anatomy. Da Vinci sketched these intricate muscles inside the heart, and it is only now that scientists have explored their role in heart health.
"Da Vinci was also intrigued by the link between maths and nature, so it's fitting that we found that fractal patterns in the heart are so important for its function. This work offers an exciting new direction for understanding the heart and shows the potential for bringing together ideas in maths and biology to medical research," Dr. Declan O'Regan, Director for Imaging Research at Imperial College Healthcare NHS Trust and lead author of the study, explained.
Scientists have shown that the complex mesh of muscle fibers allow the increase and efficiency of blood flow through the organ. Now, the research team says that they are the first ones to show this and hope that the findings could help determine those who may suffer from heart failure, which can be potentially fatal. The discovery could open the door for the development of essential novel treatments for heart failure.
To arrive at the findings of the study, the team analyzed cardiac MRI scans of over 18,000 people from the UK Biobank using artificial intelligence. The analysis of these scans showed that those with a more complex network of trabecular had increased capacity and ability to pump blood.
"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," Ewan Birney, deputy director-general of EMBL, said in a statement.
Muscle fiber shape affects heart performance
The study also shows that the rough surface of the heart ventricles or the lower chambers of the heart makes it possible for blood to flow more smoothly and efficiently during each heartbeat. The research underlines six regions in human DNA that impact how the fractal patterns in the trabeculae develop. Upon studying this, the researchers revealed that two of these regions also manage and regulate branching of nerve cells, hinting a similar mechanism may be present in brain development, too.
Also, the team has found that the shape of these muscle fibers impacts the performance of the heart; hence, there may be a link between heart disease and the intricate muscle fibers in the heart's lining.
Further research is needed to shed light on the role and importance of the trabeculae on the function and performance of the heart.
The study was published in the journal Nature.