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                                                                   EXHIBIT 10.6C
 
                  SIXTH AMENDMENT TO INDUSTRIAL BUILDING LEASE
                    BETWEEN J. J. AND W. AND VENTRITEX, INC.
 
     This Amendment is entered into as of the 11th day October, 1995 by and
between J. J. AND W., a general partnership (herein "Landlord"), and VENTRITEX,
INC., a Delaware corporation (herein "Tenant").
 
     WHEREAS, the parties hereto previously executed a written Industrial
Building Lease dated April 11, 1988, for a portion of the building commonly
known as Building "C", and originally designated as 707 East Evelyn Avenue,
Sunnyvale, Santa Clara County, California, which Post Office designation was
later changed to 709 East Evelyn Avenue, Sunnyvale, California; and
 
     WHEREAS, the parties hereto executed a First Amendment to said Industrial
Building Lease which Amendment was dated October 21, 1988; and
 
     WHEREAS, the parties hereto executed a Second and Third Amendment to said
Industrial Building Lease whereby Tenant leased the remaining space in Building
"C" and extended the term; and
 
     WHEREAS, the parties hereto executed a Fourth and Fifth Amendment to said
Industrial Building Lease whereby Building "A" and Building "B" where added to
the premises leased by Tenant;
 
     WHEREAS, said Industrial building Lease, as currently amended, expires on
July 31, 1997 but the parties desire to extend same;
 
     NOW THEREFORE, the parties hereto hereby agree as follows:
 
     1. The term of the Industrial Building Lease, as previously amended, is
hereby extended to December 31, 2000.
 
     2. The monthly Minimum Base Rent for the premises for the period added by
this Amendment shall be as follows:
 
<TABLE>
        <S>                                                               <C>
        Aug. 1, 1997 -- July 31, 1998:..................................  $116,700.00
        Aug. 1, 1998 -- July 31, 1999:..................................  $118,256.00
        Aug. 1, 1999 -- Dec. 31, 2000:..................................  $119,812.00
</TABLE>
 
     3. Tenant, having occupied the premises, accepts the premises in an "AS IS"
condition. Tenant acknowledges that some of the floor tiles are damaged and need
replacement due to seepage problems related to underground water. Tenant
acknowledges that Landlord is not responsible for the repair, maintenance, or
replacement of floor tile in any portion of the premises and Tenant agrees to
pay for and install new floor tile sections as Tenant, in its sole discretion,
deems appropriate. Landlord shall provide an allowance of up to $20,000.00 for
Landlord and/or Tenant to obtain mutually agreed upon consulting and testing
services to develop a floor sealant process to prevent, resist, or minimize
ground water seepage. Tenant shall have no right to any unused allowance
remaining as of December 31, 2000.
 
     4. In the event Tenant shall not then be in default hereunder and shall
have made all previous rental payments in a timely manner (no more than one
payment in each calendar year being delinquent, as defined in Paragraph 7 of the
Industrial Building Lease), Tenant shall have the right, not earlier than
December 31, 1999 and no later than March 31, 2000, to renew the term of the
Lease for a further term of five (5) years commencing on January 1, 2001 on the
terms and conditions set forth in Paragraph 4(b) through 4(e), inclusive, of the
Industrial Building Lease dated April 11, 1988.
 
     5. Each party warrants to the other that it knows of no real estate broker
or agent who is entitled to a commission in connection with this extension. Each
party agrees to indemnify and hold the other harmless from any cost, expense, or
liability for any compensation, commissions, or charges claimed by any other
broker or agent who alleges he is owed a compensation through it.
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     6. In the event of any conflict between the terms of this Sixth Amendment
and any prior Amendments or the Industrial Building Lease, the terms of this
Sixth Amendment shall prevail. The parties hereto agree that except for the
right of Tenant to extend the Lease for five (5) years beginning January 1,
2001, no other right to extend the term of the Lease exists.
 
     7. Except as set forth herein, the terms and conditions of the above
referred to Industrial Building Lease, as previously amended, are hereby
ratified and confirmed.
 
Landlord:
 
J. J. AND W., A General Partnership
 
By:   Date:
 
Tenant: VENTRITEX, INC.
 
By:   Date:
    Title