SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  Schedule 13D

                    Under the Securities Exchange Act of 1934

                               (Amendment No. 4)*

                                CYBERONICS, INC.
                             ----------------------
                                (Name of Issuer)

                          Common Stock, $0.01 par value
                       -----------------------------------
                         (Title of Class of Securities)

                                   23251P-10-2
                             ----------------------
                                 (CUSIP Number)

                                Kevin T. O'Malley
                       Vice President and General Counsel
                             St. Jude Medical, Inc.
                               One Lillehei Plaza
                               St. Paul, MN 55117
                            Telephone: (651) 483-2000
                  ---------------------------------------------
                  (Name, Address and Telephone Number of Person
                Authorized to Receive Notices and Communications)

                                February 9, 2000
                  ---------------------------------------------
             (Date of Event which Requires Filing of this Statement)

   -------------------------------------------------------------------------
If the filing person has previously filed a statement on Schedule 13G to report
the acquisition which is the subject of this Schedule 13D, and is filing this
schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following
box. | |

NOTE: Schedules filed in paper format shall include a signed original and five
copies of the schedule, including all exhibits. See Rule 13d-7(b) for other
parties to whom copies are to be sent.

*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter the
disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).


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CUSIP No. 23251P-10-2

1    NAMES OF REPORTING PERSONS, I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS
     (Entities Only)

              St. Jude Medical, Inc.
              41-1276891

2    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions)

              (a) [ ]

              (b) [X]

3    SEC USE ONLY

4    SOURCE OF FUNDS (See Instructions)  N/A

5    CHECK IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS
     2(d) or 2(e)           [ ]

6    CITIZENSHIP OR PLACE OF ORGANIZATION      MINNESOTA

   NUMBER OF        7   SOLE VOTING POWER                               921,718
    SHARES
  BENEFICIALLY      8   SHARED VOTING POWER                               - 0 -
 OWNED BY EACH
   REPORTING        9   SOLE DISPOSITIVE POWER                          921,718
  PERSON WITH:
                    10  SHARED DISPOSITIVE POWER                          - 0 -

11   AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON       921,718

12   CHECK IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
     SHARES  (See Instructions)                                             [ ]

13   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)                   5.07%

14   TYPE OF REPORTING PERSON (See Instructions)                             CO


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ITEM 5. INTEREST IN SECURITIES OF THE ISSUER

     (c) The purpose of this filing is to report various sales by St. Jude
Medical, Inc. of an aggregate 130,100 shares of Common Stock of Cyberonics, Inc.
("Cyberonics") in December 1999 and February 2000. The sales were effected in
open market transactions. Cyberonics' shares are traded on the Nasdaq National
Market. As a result of the sales, the remaining 921,718 shares beneficially
owned by St. Jude Medical, Inc. represent approximately 5.07% of the currently
outstanding shares of Common Stock of Cyberonics. St. Jude Medical, Inc. has
sole voting and dispositive power with respect to all of the shares of Common
Stock of Cyberonics that it owns. Set forth below are the respective sales of
Common Stock of Cyberonics made by St. Jude Medical, Inc. in December 1999 and
February 2000:

                                  No. of
                     Date       Shares Sold      Price Per Share
                     ----       -----------      ---------------
                   12/9/99         10,000            $16.88
                   12/10/99        25,000             17.03
                   12/13/99        30,000             16.53
                   12/14/99        15,100             16.65
                   02/09/00        50,000             26.64
                                  -------
                                  130,100
                                  =======


      Remaining Shares Held:      921,718       (5.07%)
                                  =======


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                                    Signature

         After reasonable inquiry and to the best of its knowledge and belief,
the undersigned certifies that the information set forth in this statement is
true, complete and correct.

Dated:  March 10, 2000

                                         ST. JUDE MEDICAL, INC.


                                         By:  \s\ Kevin T. O'Malley
                                              ----------------------------------
                                              Kevin T. O'Malley
                                              Vice President and General Counsel


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