Paracor raises $44M for heart-failure device that restrains the heart

(UPDATED: See below.) Paracor Medical, a Sunnyvale, Calif., startup developing a mesh restraint designed to support failing hearts, raised $44.35 million in a fourth round of funding. The company is vying with another device startup, Acorn Cardiovascular, to prove that this sort of device works and to bring it to market.

The idea behind Paracor’s device, which it calls HeartNet, is simple. In heart failure, a general term for a variety of similar conditions with different causes, the heart muscle grows progressively weaker and loses the ability to pump enough blood through the body. In many cases, the heart reacts to its reduced pumping strength by enlarging, which temporarily makes it possible to contract more strongly. Over time, however, the enlarged heart tires again, triggering a new cycle of enlargement and weakness.

Paracor’s HeartNet is an elastic metal-alloy mesh designed to wrap around the heart and support it, theoretically improving its efficiency and slowing or stopping failure-related expansion of the muscle. (See the photo above.) Doctors stretch this mesh over a still-beating heart via a less-invasive form of the surgery known as a thoracotomy, which Paracor calls a “mini-thoracotomy.” (For some mildly gory photos, see this research abstract, which is a PDF file.)

In early clinical trials, heart-failure patients who received the mesh were able to walk farther, reported fewer symptoms and witnessed improvement in a variety of heart-related measurements such as oxygen transport and utilization. Paracor is currently enrolling volunteers in a large, randomized study of the device in 272 patients, which company officials hope will allow them to apply for FDA approval by 2010, according to VentureWire (subscription required).

Acorn’s experience, however, provides a cautionary tale. The St. Paul, Minn., company is developing a similar polyethylene mesh wrap called CorCap, which it already markets in Europe (see its PDF brochure here). CorCap requires a full open-chest surgery (see slide #8 in this PowerPoint deck) and can complicate subsequent heart surgeries.

In a 300 patient trial, CorCap appeared to improve a variety of outcomes for patients who received it. Last December, however, an FDA dispute-resolution panel said the company would need to conduct an additional clinical trial before the agency would consider U.S. approval, after an FDA advisory panel recommended against approval in 2005. Some panel members called the study a “quagmire” because of its poor design and statistical anomalies. Acorn hovered on the brink of dissolution until this May, when it reached an agreement with the FDA to conduct a 50 patient confirmatory trial for which it is currently raising $15 million, the company told VentureWire.

Paracor’s funding round was led by Aberdare Partners, joined by Montagu Newhall Associates and existing investors Delphi Ventures, Pequot Ventures, InterWest Partners, Alta Partners, De Novo Ventures, Saratoga Ventures, and Palo Alto Investors. The company said the new funds will support its pivotal trial of HeartNet.

UPDATED: Expanded and rewritten throughout.