Earlier this summer, physicians at NYU Langone were able to successfully transplant pig hearts into two recently-deceased humans. The medical team performed the procedures on June 16 and July 6, using special pig hearts that were genetically modified to be more acceptable for transplantation into a human body. Both the bodies were donated by recently deceased individuals and were placed on ventilator support so the efficacy of the pig hearts could be measured more accurately.

The study arrives as the field of xenotransplantation — or the act of transferring organs from one species to another — is under increased scrutiny. The first person to undergo a pig heart transplant died earlier this year, of what scientists believe was an adverse reaction to a drug to prevent rejection. The heart also contained DNA associated with a pig virus. Since the incident, the medical community has called for more meaningful research on the subject, as well as better safety protocols. Meanwhile, the FDA is considering approval of clinical trials for pig heart transplantation in humans, the Wall Street Journalreported last month.

Both human subjects — a 72-year-old Navy veteran and a 64-year-old retired New York City teacher — were monitored for three days before being taken off life support. Neither heart needed any outside support and functioned normally, which researchers are seeing as a promising sign for future research. Despite the NYU experiment’s positive outcome, surgeons cautioned that much more research is needed before pig heart transplants can be a viable alternative for people with heart disease.

“This is not a one-and-done situation. This is going to be years of learning what’s important and what’s not important for this to work,” NYU’s Dr. Robert Montgomery told the Associated Press.

Researchers have 3D-printed hearts using silicone and even a patient's own cells, but they haven't matched the full functionality of the real thing and aren't much good for repairing hearts. There's some progress on that front, however, as a team at Harvard's Wyss Institute has developed a technique for 3D-printing long cardiac macrofilaments that develop into muscle-like filaments which contract. The new method mimics the complex alignment of a heart's contracting elements (a difficult feat so far) while producing tissue thick enough to use in regenerative heart treatments.

The system is a refinement of Wyss' existing SWIFT (Sacrificial Writing in Functional Tissue) bioprinting technology. Their approach created a platform with 1,050 wells, each with two microscopic pillars. Scientists filled the wells with human-induced pluripotent stem cells (that is, young cells capable of developing into multiple forms) as well as a protein collagen and the cells used to form connective tissue. The combination forms a dense tissue that aligns along the axis linking the micropillars. The team then lifts the resulting organ building blocks off the pillars, uses that to create a bioprinting ink and uses the motion of the 3D printer head to further help with alignment.

This is just a small piece of the heart. While the technology produces a relatively high output, there's much more work to be done before a fully functional, 3D-printed organic heart is available.

The research group believes their work could still be useful long before reaching the whole-heart milestone. The 3D-printed filaments could be used to replace scars following heart attacks, or to create improved disease models. They might even patch holes in newborns with congenital heart defects, and would grow with those child patients. Simply put, a damaged heart might not be the permanent problem it tends to be today.

The Food and Drug Administration has given Fitbit the green light to monitor users' heart rhythms in the background. A new photoplethysmography (PPG) algorithm can passively check a user's heart rhythm while they're still or asleep. If the tech detects signs of atrial fibrillation (AFib) — a type of irregular heart rhythm — it will alert the wearer. Fitbit parent Google submitted the algorithm to the FDA for review last month.

Fitbit previously received FDA clearance to use electrocardiogram (ECG) tech in 2020's Sense Smartwatch. However, that method requires users to run ECG tests manually. Google notes that AFib can be difficult to detect as episodes can be sporadic and pass without any symptoms. Monitoring heart rhythms in the background could improve detection. AFib affects more than 33.5 million people, and those with the condition have a higher risk of stroke.

In May 2020, Fitbit conducted a study of the PPG algorithm which lasted over five months and had more than 450,000 participants. It found that the algorithm correctly identified AFib episodes 98 percent of the time. Google used ECG patch monitors for confirmation.

Fitbit will soon roll out the background heart rate monitoring and Irregular Heart Rhythm Notifications features in the US. They will be available on "a range of heart-rate enabled devices." Apple Watch 4 and later can also passively monitor heart rhythms for signs of AFib. While neither company's devices can make a formal diagnosis, they could prompt wearers to consult a doctor for advice should they detect possible AFib.

Peloton is once again expanding its fitness equipment, but this time it's focused on tracking your workouts. PCMag and The Verge note Peloton has unveiled a $90 Heart Rate Band that, as the name implies, moves monitoring to your arm. The optical sensor-based wearable is theoretically more comfortable and easier to use than a chest strap (which typically requires precise positioning and a moistened contact point) while remaining accurate. That's particularly important for people whose limb and mobility issues might prevent them from using chest trackers. 

The Heart Rate Band is built to work with Peloton's app and devices, including all Bike and Tread models as well as the Guide camera. You're not locked into the company's ecosystem, though — the armband should support other products that recognize common Bluetooth heart rate monitors. Just be aware there's no ANT+ support.

The band is initially available in the US, Canada, Australia, Germany and the UK. The hardware has been development for a while — Bloombergfound early code for the Heart Rate Band in June 2021.

As The Verge explained, the Heart Rate Band might not be for everyone. While arm-based optical heart rate monitoring is common with smartwatches, it can have problems with some dark skin tones and tattoos. Obesity and loose fits can also cause problems. We'd add that $90 is nearly twice the normal $49 price for Peloton's chest strap. You'll have to really, truly value the convenience of an armband to justify that premium.