Implantable Devices May Ease Fluid Load in Heart Failure

Neil Osterweil

July 02, 2018

PARIS — Two experimental, fully implantable systems under development are designed to address the problem of pathologic fluid overload in heart failure, a major cause of heart failure–related deaths.

"Over the last 15 years or so there has been a lot of research into drivers of heart failure mortality and hospitalization, and it has really come to bear that congestion is clearly the major driver of symptoms and hospitalization, with low cardiac output actually driving a minority of hospitalizations, and some variant of fluid overload bringing people to the hospital," said Jeffrey M. Testani, MD, MTR, director of heart failure research at Yale University in New Haven, Connecticut.

He described a method for direct removal of large volumes of sodium from the peritoneum with an implantable pump instilled with a zero-sodium solution. In pigs, the system has been shown to remove more than 52 g of sodium and reduce plasma volume by 65%, he said in an "out-of-the-box technologies" session at the European Association of Percutaneous Cardiovascular Interventions (EuroPCR) 2018.

The fluid can be removed from the peritoneum via a fully implantable, automatic, programmable smart pump (alfapump, Sequana Medical) that can be charged transcutaneously. The pump is currently approved for treatment of patients with refractory liver ascites and has been successfully implanted in more than 650 patients, Testani said.

The pump, which discharges fluid into the bladder for voiding, can remove spontaneously generated peritoneal fluid, report on changes in fluid production, and continuously measure intra-abdominal pressures.

Standard peritoneal dialysis is designed specifically for cleaning blood rather than removing sodium and has only a modest effect on fluid loads, he noted.

Peritoneal dialysis fluid contains approximately 132 to 134 mmol of sodium, but with a zero-sodium solution "we're not only using ultrafiltration to pull fluid off, but we also have that huge concentration gradient of sodium between blood and a peritoneal dialysis solution of 140 [mmol] to zero, so there's a big kinetic force driving sodium down this concentration gradient," Testani said.

In a proof-of-concept porcine model, the investigators instilled 1 L of a 10% dextrose solution in water with zero sodium and allowed it to remain in the abdomen for 6 hours. They found that the solution removed approximately 5000 mg of salt, he said.

As noted before,10 L of the solution cycled over 6 hours removed 52.8 ± 8.2 g of salt and resulted in a 65% reduction in plasma volume.

In a separate presentation, Nitai Hanani, MSc, CEO and cofounder of Paragate Medical in Nazareth, Israel, described an implantable device for continuous fluid removal in patients with congestive heart failure that his company is developing.

The system consists of a self-contained, implantable peritoneal ultrafiltration device with no external ports. The device has a pump attached to a spiral absorption chamber wrapped with membrane that relies on a hydrostatic pressure gradient instead of an osmotic gradient to draw systemic extracellular fluid from tissues and allow it to drain into the bladder.


"This is without the need to apply a chemical component [as required] in peritoneal dialysis," Hanani said.

The device can be implanted in a short laparoscopic procedure without anchoring, in a single-access bladder approach.

In pig models, the device removed 200 to 400 mL of isotonic fluid per day in normally hydrated animals.

"When we tried acute volume overload by doubling the central venous pressure, we doubled the performance of the device under the same protocol. This is despite having a healthy kidney that competes with the device by boosting its activity by 30 times," he said.

Can the Bladder Handle It?

In the question-and-answer sessions following the presentations, panelist Peter J. Fitzgerald, MD, from Stanford University, California, asked whether there were potential harms to organs from voiding such high-sodium fluids, likening it to "ocean water."

Testani said the bladder and urinary collection system are capable of handling up to 1200- to 1800-mOsm solutions.

"What we'll be putting into the bladder will actually be a lot less hypertonic than the bladder is designed to see on a regular basis, so I don't think that will be a particular limitation for us," he said.

Co-moderator Farrel Hellig, MD, an interventional cardiologist at Sunninghill and Sunward Park Hospitals in Johannesburg, South Africa, asked about infection risk from having dialysate in place for sustained dwell times.

Testani replied that in patients with chronic liver failure, a population with generally low immune reserves, infection rates with the device are very low.

"You can see some of these technologies actually changing the old school of how we used to take of these heart failure patients," Fitzgerald commented, referring to both devices. "We'd bring them in for dobutamine and dopamine holidays, we'd put 'em on a lot of diuretics and afterloads, and we'd hope. And now we're beginning to get where they become almost like dialysis, and now, eventually, we may be managing some of this at home," he said.

In an interview with theheart.org|Medscape Cardiology, Fitzgerald said that the devices described by Testani and Hanani may be able to prevent or delay the progression of disease in patients with New York Heart Association class II heart failure who have repeat hospitalizations for fluid overload.

Testani's research is supported by Sequana Medical. He disclosed grants/research support from the company and from Boehringer Ingelheim, FIRE1, Medtronic, National Institutes of Health, Otsuki, Sanofi, and Thoratec and honoraria or consultation fees from Sequana, Cardionomic, FIRE1, Gore, Relypsa, and Sanofi. Hanani's work is supported by Paragate Medical. He is CEO and cofounder of the company. Fitzgerald was on the founding team of LVP Capital, a venture firm focused on medical device and biotechnology start-ups in San Francisco.

Congress of the European Association of Percutaneous Cardiovascular Interventions (EuroPCR) 2018. Presented May 23, 2018.

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