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                                                                     EXHIBIT 4.2

                      SECOND AMENDMENT OF RIGHTS AGREEMENT

         Pursuant to Section 26 of the Rights Agreement, dated as of February
27, 1996, as amended, by and between InControl, Inc. (the "Company") and First
Interstate Bank of Washington, N.A. (now ChaseMellon Shareholder Services,
L.L.C.) (the "Rights Agreement"), the Company, by this Second Amendment of
Rights Agreement, dated August 10, 1998, does hereby amend the Rights Agreement
as follows:

         Section 1 is hereby amended to add the following paragraph as a new
last paragraph at the end of the definition of "Acquiring Person":

         "Notwithstanding the foregoing, solely in connection with the
transactions contemplated by that certain Agreement and Plan of Merger among
InControl Corporation ("Guidant"), Pegasus Acquisitions Corp. ("Pegasus") and
the Company dated as of August 10, 1998 (the "Merger Agreement") and that
certain Shareholder Agreement, dated as of August 10, 1998, among Guidant and
shareholders of the Company listed therein (the "Shareholder Agreement"),
Guidant, Pegasus or any of their Affiliates or Associates shall not be deemed to
be an Acquiring Person by reason of the transactions contemplated by the Merger
Agreement and the Shareholder Agreement, but shall be deemed to be an Acquiring
Person if any of them acquire Beneficial Ownership of any shares of Common Stock
other than pursuant to the Merger Agreement or the Shareholder Agreement and the
transactions contemplated thereby."

         Section 1 is hereby amended to add the following paragraph as a new
last paragraph at the end of the definition of "Beneficial Owner":

         "Notwithstanding the foregoing, Guidant, Pegasus or any of their
Affiliates or Associates shall not be deemed to be a Beneficial Owner for any
purpose of the Rights Agreement of any shares of Common Stock acquired or to be
acquired pursuant to the execution, delivery or consummation of the transactions
contemplated by the Merger Agreement or the Shareholder Agreement, including
without limitation the granting of an irrevocable proxy pursuant to the
Shareholder Agreement, but shall be deemed to be a Beneficial Owner of any
shares of Common Stock acquired otherwise than pursuant to the Merger Agreement
or the Shareholder Agreement."

         Section 3(b) is hereby amended to add the following sentence as the
last sentence at the end of Section 3(b):

         "Notwithstanding anything herein to the contrary, the date of
execution, delivery or consummation of the Merger Agreement and the transactions
contemplated thereby, including the Offer (as defined in the Merger Agreement),
shall not be 

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deemed to be a Distribution Date for any purpose of this Agreement solely by
reason of such execution, delivery or consummation; provided, however, that any
other acquisition of Beneficial Ownership of any shares of Common Stock by
Guidant, Pegasus or any of their Affiliates or Associates otherwise than
pursuant to the Merger Agreement or the Shareholder Agreement and the
transactions contemplated thereby may give rise to a Distribution Date."

         IN WITNESS WHEREOF, the Company has executed this Second Amendment of
Rights Agreement as of the date first written above.

                                 INCONTROL, INC.



                                 /s/  Kurt C. Wheeler
                                 -----------------------------------------------
                                 Kurt C. Wheeler
                                 President and Chief Executive Officer


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