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                                                                  EXHIBIT 10.15


                                                                           F.N.
                                     AMENDMENT TO                          S.N.
                           DISTRIBUTION / SUPPLY AGREEMENT

This AMENDMENT is made this 11th day of December, 1998 to the 
Distribution/Supply Agreement dated September 4, 1997 by and between 
Endocardial Solutions, Inc. ("ESI") and Medtronic, Inc., a Minnesota 
("Medtronic").

Under Section 1.1, "Medtronic Territories" is hereby deleted and replaced as 
follows:

     "MEDTRONIC TERRITORIES" means those countries included within Medtronic's
     currently designated "Europe," "Japan" and "Canada" sales regions, as more
     fully described in Schedule 1.2.

The following sentence is hereby added to the beginning of Section 2.4(c):

     ESI hereby provides Medtronic with a one-year warranty on parts and labor
     related to the repair of all Systems purchased by Medtronic, regardless of
     whether such Systems are purchased for Medtronic's own use or if Medtronic
     sells such Systems to or places them with third party purchasers or users.

Section 2.5(b) and (c) are hereby removed in their entirety and replaced as 
follows:

     (b)  Medtronic shall be responsible for System installations, technical
     support, administration and personnel costs for Systems sold in the Field
     of Use in Europe.

     (c)  Medtronic shall be responsible for software and hardware repairs and
     servicing for all Systems in the Field of Use within the Medtronic
     Territories which will be provided in accordance with Exhibit A attached
     hereto. ESI's service obligations are also described in Exhibit A.

     (d)  Medtronic will provide reasonable and appropriate space to warehouse
     System spare parts in Europe. Medtronic will provide support staff
     necessary to service and administer the system spare parts inventory. ESI
     will maintain an inventory of System spare parts sufficient to comply with
     the down-time and time-to-repair commitments to System customers for any
     ESI warranties and extended service plans. Medtronic will reimburse ESI for
     the cost of any hardware replacement parts required after the expiration of
     the one-year ESI System warranty for Systems in the Field of Use in Europe.
     The transfer price for such replacement parts will be fully allocated costs
     plus a mutually agreed upon market markup. ESI will assume costs of
     shipping System spare parts from a designated Europe inventory site or ESI
     service center to customers during the one-year ESI System warranty period.
     Thereafter, Medtronic will be responsible for the costs of shipping System
     spare parts from the designated Europe inventory site or ESI service center
     to customers.

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     (e)  Medtronic will be responsible for offering for sale and administering
     extended service contracts to System purchasers in Europe. All revenue
     generated from the sale of extended service contracts will be retained by
     Medtronic.

     (f)  The parties acknowledge the country specific service agreements with
     Silicon Graphics and Endocardial Solutions. ESI will be responsible for the
     cost associated with the first year of the SGI Contract. Medtronic will
     assume the cost of the second and third years under the SGI Contract for
     Systems sold by Medtronic in Europe. Medtronic and SGI will negotiate
     mutually agreeable payment terms under the SGI Contract for years two and
     three. This would include any costs associated with any demonstration
     System utilized by Medtronic for internal or promotional purposes.

     (g)  ESI will provide software upgrades free of charge for the three-year
     term of the SGI Contract, including versions that add certain convention
     capabilities. Medtronic will pay for other system upgrades that include new
     or additional hardware configurations or System software upgrades that
     constitute new products including but not limited to the "Loca Lisa"
     technology.

The former Section 2.5(d) shall now become Section 2.5(h).

Schedule 2.1 is hereby modified as follows:

     Canada shall be added as a Territory.

Schedule 2.3 is hereby modified as follows:

     The price for a System as defined shall be changed to (***) Dollars ($***),
     and the price for catheters as defined shall be changed to (***) Dollars
     ($***).

     The pricing above shall become effective on September 8, 1997. These prices
     shall remain in effect until December 31, 2000.

Except to the extent provided above, the remaining terms and conditions of 
the original agreement shall remain in full force and effect.

MEDTRONIC, INC.                        ENDOCARDIAL SOLUTIONS, INC.



By      /s/ Steve LaPorte             By     /s/ James W. Bullock
      -------------------------------       ----------------------------------

Title      VP/GM                      Title  President/Chief Executive Officer
      -------------------------------       ----------------------------------

Date:  12/11/98                       Date:  12/16/98
      -------------------------------       ----------------------------------

----------------
***  Denotes confidential information that has been omitted from the exhibit and
     filed separately, accompanied by a confidential treatment request, with the
     Securities and Exchange Commission pursuant to Rule 24b-2 of the Securities
     Exchange Act of 1934.

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                                      EXHIBIT A

                      ENSITE 3000 SYSTEM EUROPEAN SERVICE PLAN

MEDTRONIC RESPONSIBILITIES

     -    Medtronic will receive and document customer calls and complaints 
          and route to the appropriate Medtronic representative.  The local 
          Medtronic representative will return the calls to the customer and 
          perform initial troubleshooting as follows:

          *    Within 24 hours of a customer service call, the customer will be
               contracted by telephone by the appropriate local Medtronic
               representative to determine if the basic first-line System
               diagnostics have been performed.


          *    Within 48 hours, if required, a Medtronic representative will
               provide a site visit to assist the hospital technician with the
               basic first-line System diagnostics.

          *    Within 72 hours, if the System problem(s) continue the Medtronic
               representative would, as required:

                    *    Replace the power supply chassis
                    *    Replace the electronic chassis board 
                    *    Coordinate System service with SGI and/or other third
                         party vendors
                    *    Complete the RGA and System documentation 
                    *    Coordinate shipment of any loaner Systems
                    *    Perform a PIU System diagnostic test utilizing the
                         service diagnostic laptop
                    *    Replace the electronic chassis
                    *    Replace the breakout box
                    *    Replace cables (breakout box, fiber optic, ECG, etc.)
                    *    Perform a system calibration with the laptop and
                         calibration fixture (when required)
                    *    Coordinate shipment/swap-out of System parts and
                         components

     -    Medtronic is responsible for System installations and customer
          training after the limited market release  ("LMR") period.  This
          period was completed September  1998.


     -    Medtronic is responsible for System contract sales, financing and
          accounts receivable.

          *    System service contracts will be issued to customers in
               Medtronic's name.

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          *    Service contracts discounts will be offered at Medtronic's
               discretion.

          *    Customers may elect to extend coverage at any time prior to
               initial expiration date.

     -    Any other responsibilities mutually agreed to by Medtronic and ESI



ESI RESPONSIBILITIES

     -    ESI will be responsible for training Medtronic sales and technical
          representatives for all new System software, hardware and 
          catheter-related product developments.

     -    ESI (initially through Graydon Beatty) will provide training to
          clinical investigators and Medtronic sales and technical
          representatives during the SYSTEM's initial LMR period.

     -    ESI will be responsible for assisting Medtronic with System
          installations durining the LMR period.

     -    ESI will provide 24-hour technical customer service support to
          Medtronic's local and technical representatives.

     -    ESI will maintain the appropriate inventory levels of System
          replacement parts and components in Europe, as well as complete loaner
          Systems at the designated Medtronic inventory location.

     -    ESI will maintain the necessary inventory levels for:

          *    Breakout box swap-outs
          *    Cable swap-outs (e.g., breakout boxes, fiber optics, ECGs, etc.)
          *    PIU electronic chassis boards, BBIF, mother boards, SERIF,
               BIO/DEMOD boards, etc.
          *    PIU power supply chassis

     -    For Systems covered by the applicable ESI warranty, ESI will bear the
          cost of shipping and installing loaner Systems and System replacement
          parts and components at customer locations for one year following
          installation.

     -    For Systems covered by the applicable ESI warranty, ESI will bear the
          cost of shipping and repairing Systems and System component/parts
          returned to ESI for inspection, service and/or repair (excluding
          cables after the 90-day ESI warranty period).

     -    Any other responsibilities mutually agreed to by ESI and Medtronic.

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CUSTOMER RESPONSIBILITIES

     -    The System service contract would require that customers train a lab
          technician to perform the functions outlined below following
          installation of a System:

          -    Reboot the SGI and PIU System(s)

          -    Read the diagnostic test results after a reboot of the SGI and
               PIU System(s)