9. Long-Term Debt and Credit Facilities

Debt outstanding consists of the following:


	March 31, 2016		December 31, 2015
	Carrying	Estimated	Carrying	Estimated
	Amount	Fair Value	Amount	Fair Value

Healthcare Royalty Partners debt	$ 18,078,308	$ 18,398,347	$ 18,080,159	$ 18,429,177
Less current maturities	—	—	—	—
Total long term debt	$ 18,078,308	$ 18,398,347	$ 18,080,159	$ 18,429,177

In accordance with general accounting principles for fair value measurement, the Company’s debt and credit facilities were measured at fair value as of March 31, 2016 and December 31, 2015. Long-term debt fair value estimates are based on estimated borrowing rates to discount the cash flows to their present value (Level 3).

Certain prior year amounts have been reclassified to conform to the 2016 presentation.

Revolving Line of Credit

The Company has had a working capital line of credit with its primary lender, Silicon Valley Bank, since 2004. The revolving line of credit is secured by substantially all of the Company’s assets. The maximum available under the line is $10 million subject to the value of collateralized assets. The Company is required under the revolving line of credit to maintain its primary operating account and the majority of its cash and investment balances in accounts with its primary lender. The facility was amended on March 27, 2015, extending the maturity date to March 31, 2018 and on May 10, 2016, the Company and the primary lender agreed to modify certain financial covenants. The amended agreement requires the Company to maintain a liquidity ratio greater than 1.50:1.00, excluding certain short term advances from the calculation, and a minimum tangible net worth of not less than (no worse than) negative $24.0 million for the quarters ended June 30, 2016, September 30, 2016, December 31, 2016, March 31, 2017, June 30, 2017, and September 30, 2017; and not less than (no worse than) negative $24.5 million for the quarters ended December 31, 2017 and March 31, 2018.

As of March 31, 2016, the Company had no outstanding debt under the revolving line of credit. Draws on the line of credit are made based on the borrowing capacity one week in arrears. As of March 31, 2016, the Company had a borrowing capacity of $4.9 million based on the Company’s collateralized assets, and cash and cash equivalents of $1.6 million for a total liquidity of $6.5 million.

Healthcare Royalty Partners Debt

In November 2011, the Company entered into a loan agreement with Healthcare Royalty Partners. Under the agreement the Company borrowed from Healthcare Royalty Partners $15 million. The Company was permitted to borrow up to an additional $5 million in the aggregate based on the achievement by the Company of certain milestones related to Niobe ES system sales in 2012. On August 8, 2012, the Company borrowed an additional $2.5 million based upon achievement of a milestone related to Niobe ES system sales for the three months ended June 30, 2012. On January 31, 2013, the Company borrowed an additional $2.5 million based upon achievement of a milestone related to Niobe ES system sales for the twelve months ended December 31, 2012. The loan will be repaid through, and secured by, royalties payable to the Company under its Development, Alliance and Supply Agreement with Biosense Webster, Inc. (the “Biosense Agreement”). The Biosense Agreement relates to the development and distribution of magnetically enabled catheters used with Stereotaxis' Niobe ES system in cardiac ablation procedures. Under the terms of the agreement, Healthcare Royalty Partners will be entitled to receive 100% of all royalties due to the Company under the Biosense Agreement until the loan is repaid. The loan is a full recourse loan, matures on December 31, 2018, and bears interest at an annual rate of 16% payable quarterly with royalties received under the Biosense Agreement. If the payments received by the Company under the Biosense Agreement are insufficient to pay all amounts of interest due on the loan, then such deficiency will increase the outstanding principal amount on the loan. After the loan obligation is repaid, the royalties under the Biosense Agreement will again be paid to the Company. The loan is also secured by certain assets and intellectual property of the Company. The agreement also contains customary affirmative and negative covenants. The use of payments due to the Company under the Biosense Agreement was approved by our primary lender.