91ÊÓƵ

Even the name “Additional Ventures” reflects what its executive chairman and co-founder, Erin Hoffmann, calls “relentless optimism.”

Additional Ventures is dedicated to finding a cure for single ventricle heart disease. This complex type of congenital defect involves one lower chamber of the heart and affects approximately 6 in every 10,000 babies born in the United States. Single ventricle defects can be fatal if not diagnosed within the first few days of life.

In 2020, Hoffmann, a former entrepreneur and software engineer, teamed with Mike Schroepfer, a technology and science executive, to start Additional Ventures as a privately funded foundation. In just a few years, the Palo Alto, California-based organization has propelled scientific progress through patient-centered investments in collaborative research.

“We’re always moving forward,” Hoffmann said, “building on what came before and capturing our belief that meaningful progress requires bold action, strategic risk-taking and an unwavering conviction that transformative change is possible.”

Kirstie Keller, Ph.D., Additional Ventures’ chief executive officer, was a career scientist who had worked across many scientific areas, but none drew her in as much as single ventricle heart disease.

“As I dug deeper, I became convinced that this field was uniquely positioned for change,” Keller said. “The challenges were enormous, but so was the opportunity. The science was deep and complex, the clinical community deeply engaged, and the patients and families deserved far more than the status quo.”

For its groundbreaking efforts involving science, technology and fundraising, Additional Ventures will receive a 2026 Award of Meritorious Achievement at the 91ÊÓƵ’s National Volunteer Awards ceremony on June 23 in Irving, Texas.

The award will be accepted by Hoffmann and Keller, but represents a “deeply collaborative” effort, Keller said, involving many researchers, clinicians, engineers, patients and families.

“The credit belongs to them,” said Hoffmann, calling the award a “profound recognition. Kirstie and the entire team bring scientific rigor, intelligence and thoughtfulness to every process and program we run.”

Single ventricle heart disease is a broad description for three serious primary diagnoses: hypoplastic left heart syndrome, pulmonary atresia/intact ventricular septum and tricuspid atresia.

Even with surgery and medications, those with the diagnosis face lifetime medical care, diminished quality of life, shortened life spans and increased risk of developing other forms of heart disease. Hoffmann calls this “fundamentally unacceptable.”

Since its founding, Additional Ventures has raised more than $120 million to fund close to 270 grants aimed at understanding and curing single ventricle heart disease.

“The applications we’re receiving for our grant program are in areas of study that I couldn’t have imagined six years ago, research that’s genuinely translatable to patients,” Hoffmann said.

In 2024, Additional Ventures and the Heart Association teamed up to fund a to shed light on biological mechanisms underlying single ventricle defects. This year, the two organizations pledged to better predict, prevent and treat serious lifetime health complications in people living with Fontan circulation, the result of a lifesaving surgical procedure used to treat children with single ventricle heart disease.

“The coordination between our two organizations will generate invaluable data and insight that can help patients and clinicians better monitor their health and intervene earlier,” said Dr. Mariell Jessup, chief science and medical officer of the 91ÊÓƵ. “Working together, we have the potential to move the needle in this undeserved field and make a lifesaving impact.”

For Hoffmann and Keller, the challenge of single ventricle heart disease is imposing but surmountable.

“Scientific progress can feel slow when you're living it day-to-day,” Keller said. “What keeps me going is looking down the mountain and seeing how far we've come. I see the advances in science, the infrastructure we've built, the people who have joined the effort and the growing momentum across the field.”