In Sacramento, a physician has discovered a novel anatomical feature within the heart, and the tools involved were far from high-tech. There was no artificial intelligence, no genomic sequencing, and no billion-dollar technology required for the finding. Instead, it relied on preserved specimens, close observation, and a readiness to doubt what everyone had previously taken as settled knowledge.
Dr. Subramaniam C. Krishnan, a cardiac electrophysiologist at Sutter Health in Sacramento, Calif., made the discovery while studying hearts at the Jesse E. Edwards Registry of Cardiac Disease in St. Paul, Minn. The registry preserves thousands of hearts, and Edwards, a cardiac pathologist, believed anatomy still had lessons to teach and secrets to reveal. He understood that today’s normal specimen could become tomorrow’s question.
The Discovery of the Left Atrial Septal Pouch
Within the atrial septum, Krishnan found a pouch opening into the left atrium, roughly 9-8 millimeters deep, a formation he had never come across before in his reading. He and his colleague would go on to publish the first formal account of it in 2010, naming it the left atrial septal pouch, or LASP.
One of the most closely examined organs in medical history held a structure that remained concealed until further research uncovered it in roughly one-third of adult hearts.
How a Structure Went Unnoticed for So Long
The reason a structure found in just one of three people stayed formally unknown until the 21st century is straightforward: finding something new frequently depends less on what tools we have than on our assumptions about where to stop looking.
The study of the body has long been presented as a finished work, with Andreas Vesalius, Henry Gray, and the many generations of anatomists who followed them credited with closing its chapter. Modern science places its current frontiers elsewhere, in genomics, artificial intelligence, and precision medicine. That assumption, however, may not hold up.
The registry was not merely a repository for hearts; it also kept alive a particular approach to scientific inquiry that has grown less common over time.
What the LASP Does
The LASP shares a close relationship with a hole in the heart known as a patent foramen ovale, or PFO. It also bears resemblance to the left atrial appendage, which is a blind-ended cul-de-sac where blood can stagnate and clot. However, unlike the appendage, where atrial fibrillation is necessary for clots to form, stagnation and clot formation can occur within the LASP even in a perfectly normal heart rhythm.
Observational studies conducted over the last 16 years have pointed toward an anatomical variant that could be tied to unexplained, “cryptogenic” strokes. Still, these studies can only show a link between the two — they cannot prove that the variant causes the strokes.
It would be premature to treat the trial as conclusive proof, yet it marked the very first instance of something being shown to work at all.
A Familiar Cardiology Story
The sequence follows a familiar narrative from cardiology. The PFO was long seen as an anomaly whose clinical significance was doubted, though it was well recognized anatomicamente. It took decades of epidemiology, imaging, and randomized trials for PFO closure to be embraced as standard therapy for certain stroke patients.
The LASP is on a similar course, though its speed is much greater.
Clinical trials do not usually mark the start of scientific advance. Observation does. From watching comes a hypothesis; from a hypothesis, an examination of the body follows; from the study of the body come questions about how it functions; and from those questions eventually come the tests given to patients. This path is often slower than the pace of technological change, yet it has long served as one of medicine’s most dependable sources of new knowledge.
Ironically, Krishnan’s later work on closing PFOs without an implant came from studying the pouch. We saw that a LASP can be seen as an incompletely joined PFO passage — which means nature does not need full bonding across the whole overlap area to seal it. Since failed postnatal joining causes a PFO, we wondered if we could reproduce the natural conditions that usually finish that joining, prompting localized bonding so the passage closes without a lasting implant.
An anatomical observation had generated a therapeutic hypothesis.
What Modern Medicine Should Remember
There’s still much to learn from the body itself, even as genomics, molecular biology, and artificial intelligence keep advancing. Modern medicine should keep putting serious money into those fields. Yet none of that should convince anyone that the lessons from human anatomy have run their course.
We must keep our own skill at recognizing patterns within the human body while spending billions teaching computers to do the same.
Beyond stopping strokes, the finding of the left atrial septal pouch shows that anatomy keeps changing how we understand it, that curiosity still counts, and that the next big medical discovery might not sit within a gene at all.
We might have overlooked it all along, within an organ we believed we had already fully understood.
| Year | Event |
|---|---|
| 2004 | Krishnan begins studying preserved hearts at the Jesse E. Edwards Registry |
| 2010 | First formal description of the LASP published |
| Recently | Fuwai Hospital reports first randomized trial on LASP elimination |
A quiet room, a preserved sample, and a doctor willing to look again at something everyone else had stopped seeing — these are the ingredients behind the story of the LASP, which suggests that the next major medical discovery may not require a lab full of costly machines.
Source material: “Opinion: I discovered a new structure in the heart — just by looking closely,” STAT.
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