Volcano (NSDQ:VOLC) agreed to give Crux Biomedical an extra 5 months to obtain FDA 510(k) clearance for a retrieval device, a milestone worth $3 million under the terms their merger agreement.

Under the amended agreement Crux has until Nov. 30, 2013, to win FDA clearance and satisfy the milestone. The previous deadline closed June 30.

The companies late last year signed a definitive agreement under which Volcano would acquire Crux for $36 million in cash.

Menlo Park, Calif.-based Crux Biomedical is a privately held medical device maker developing inferior vena cava filters for treatment of pulmonary embolisms, an estimated $300 million market in the U.S., according to a 2012 Volcano estimate.