The George Washington spinout had previously raised $4.1m in equity for its low-voltage implantable cardiac defibrillator.
Cardialen, a US-based defibrillation implant developer spun out from George Washington University, has closed a $17m series B round led by venture capital firm RiverVest Venture Partners.
VC firms Qiming Venture Partners and Cultivation Capital took part in the round, as did investment firm HBM Healthcare Investments.
Founded in 2008, Cardialen is developing an implantable cardiac defibrillator that uses unpinning termination therapy to rectify an irregular heartbeat by administering multiple mild electric shocks to the patient.
The approach differs from traditional implantable defibrillators in that the latter reset cardiac activity through a high-voltage shock which can be dangerous for certain patients and for the medic administering treatment.
Cardialen will put the capital towards clinical trials of its underlying thesis with a view to starting development of a UPT device. Early human feasibility studies of UPT have indicated it could treat heart rhythm disorders with less energy than conventional defibrillators.
Jay Schmelter, managing director of RiverVest Ventures, has joined the Cardialen board of directors with Christopher Shen, managing partner at Qiming Venture Partners, and Thomas Thaler, investment advisor at HBM.
Cardialen had raised $4.1m in equity prior to the latest round, according to regulatory filings.
The spinout received $1.5m in a 2015 round backed by BioGenerator, Cultivation Capital Life Sciences, St. Louis Arch Angels, Twin Cities Angels, Belle Capital, Heartland Angels, Lambda Fund Management and unnamed private investors.
St Louis Arch Angels also invested $139,000 sum in 2012, adding to $475,000 invested by the syndicate in previous years, and $735,000 provided by Broadview Ventures, the venturing arm of private research body Leducq Foundation, in 2011.
