A scematic of a heart inside a torso with a 'heartbeat' line above it

Five heart stories for International Heart Day

Today is International Heart Day, and Cosmos is looking back on the stories that make our hearts flutter.

The fine detail of a healthy heart

Scientists have taken another step in the quest to create a “Google map of the human body” by putting together a detailed cellular and molecular map of the healthy heart.

An international team analysed almost half a million individual cells and cell nuclei from six different regions of the heart, obtained from 14 organ donors whose hearts were healthy but unsuitable for transplantation.

The result is the Heart Cell Atlas, which, shows the huge diversity of cells and reveals heart muscle cell types, cardiac protective immune cells and an intricate network of blood vessels. It also predicts how the cells communicate to keep the heart working.

Hearts stopped young

Sometimes, the heart just stops for no perceivable reason. Sudden cardiac arrest (SCA) is a prevalent hidden killer, even for younger people: 40% of those who die from SCA are under 50 years old.

“SCA is not as rare as we would like it to be,” says cardiologist Elizabeth Paratz, who’s undertaking her PhD at the Baker Heart and Diabetes Institute, Melbourne. “In the last year in Victoria, 750 young people under 50 have suffered an SCA. This is almost exactly five times the road toll over the same time in this age group, yet we hear a lot more publicity about road fatalities in young people.”

Paratz is researching the prevalence and causes of SCA, as well as looking at ways to diagnose it better. There are multiple causes of SCA, and they’re hard to pinpoint in young people.

How stem cells help repair hearts

The controversial use of stem cells to help patients recover from a heart attack may work, but not because it grows new heart muscle.

Research in mice has found that injecting stem cells into the heart triggers an immune response that makes the scar stronger and the heart beat more forcefully.

The study, published in the journal Nature, suggests the current practice of injecting stem cells into a patient’s blood may not be optimal: direct injection into the heart could be more effective.  

Could spider venom save your life from heart attack?

In a preclinical trial on a beating human heart, researchers have found that a drug candidate developed from the venom of the world’s deadliest spider, the funnel web, may hold promise for heart attack treatment and transplants.

The researchers, led by Meredith Redd of the University of Queensland (UQ), and Sarah Scheuer of Victor Chang Cardiac Research Institute, tested a protein called Hi1a, found in the Fraser Island (K’gari) funnel web venom, on a beating heart that had been exposed to heart attack stresses.

“After a heart attack, blood flow to the heart is reduced, resulting in a lack of oxygen to heart muscle,” says Nathan Palpant of UQ, corresponding author of the paper.

“The lack of oxygen causes the cell environment to become acidic, which combine to send a message for heart cells to die.

“The Hi1a protein from spider venom blocks acid-sensing ion channels in the heart, so the death message is blocked, cell death is reduced, and we see improved heart cell survival.”

Biotech solution to heart surgery for kids

The Chinese Finger Trap – a tubular braided novelty beloved by kids and pranksters around the world – provided the inspiration for a nifty bit of biotech that looks set to save sick kids a whole lot of heartache. Literally.

Pedro del Nido from Boston Children’s Hospital in the US heads a team that has designed a proof-of-concept device that promises to dramatically cut down on surgery for children with certain types of heart defects.

At present, kids with defective mitral and tricuspid heart valves must undergo surgery in which a corrective implant is installed. The problem, however, is that children grow: the heart increases in size, and requires at least one, and often several, further surgical interventions so that a correspondingly larger implant can be installed.

Needless to say, these repeated bouts of open-heart surgery are extremely traumatic and disruptive.

Now, however, Nido and Karp may have come up with an elegant and clever solution: an implant that grows with the organ.