9. Long-Term Debt and Credit Facilities

Debt outstanding consists of the following:


	December 31, 2015		December 31, 2014
	Carrying	Estimated	Carrying	Estimated
	Amount	Fair Value	Amount	Fair Value

Healthcare Royalty Partners debt	$ 18,429,177	$ 18,429,177	$ 18,388,764	$ 18,388,764
Less current maturities	—	—	—	—
Total long term debt	$ 18,429,177	$ 18,429,177	$ 18,388,764	$ 18,388,764

Contractual principal maturities of debt at December 31, 2015 are as follows:


2016	$	-
2017		-
2018		18,429,177
2019		-
2020		-
2021 and Beyond		-
	$	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 December 31, 2015 and December 31, 2014. Long-term debt fair value estimates are based on estimated borrowing rates to discount the cash flows to their present value (Level 3).

The revolving line of credit and the Company’s obligations with Healthcare Royalty Partners II, L.P. (collectively, the “Credit Agreements”) are secured by substantially all of the Company’s assets. The Company is required under the Credit Agreements to maintain its primary operating account and the majority of its cash and investment balances in accounts with the primary lender.

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 Company is also 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 last amended on March 27, 2015 extending the maturity date three years to March 31, 2018. The current agreement requires the Company to maintain a minimum tangible net worth of not less than (no worse than) negative $22.5 million, with such minimum requirement subject to increase under certain circumstances as described in the agreement, and to maintain a liquidity ratio of greater than 1.50:1.00, excluding certain short term advances from the calculation.

As of December 31, 2015, 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 December 31, 2015 the Company had a borrowing capacity of $5.2 million based on the Company’s collateralized assets.

Healthcare Royalty Partners Debt

In November 2011, the Company entered into a loan agreement with Healthcare Royalty Partners II, L.P. (formerly “Cowen Healthcare Royalty Partners II, L.P.”). 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 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 system sales for the nine 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 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 relates to the development and distribution of magnetically enabled catheters used with Stereotaxis' Niobe 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.