<PAGE>

                  THIRD AMENDMENT TO LEASE AGREEMENT
              [University of Utah Research Foundation/
             Heartport Research and Training Center, Inc.]

     THIS AMENDMENT (this "AMENDMENT") is entered into as of the 25th day of 
October, 1996, between the UNIVERSITY OF UTAH RESEARCH FOUNDATION, a Utah 
nonprofit corporation ("LANDLORD"), whose address is 209 Park Building, Salt 
Lake City, Utah 84112, and HEARTPORT RESEARCH AND TRAINING CENTER, INC., a 
Delaware corporation ("TENANT"), whose address is 200 Chesapeake Drive, 
Redwood City, California 94063.

     FOR THE SUM OF TEN DOLLARS ($10.00) and other good and valuable 
consideration, the receipt and sufficiency of which are acknowledged, 
Landlord and Tenant agree as follows:

     1. DEFINITIONS. As used in this Amendment, each of the following terms 
shall have the indicated meaning:

        1.1. "BUILDING" means the building located on the Land.

        1.2. "LAND" means the land located in Salt Lake County, Utah, 
described as follows:

          Beginning at a point which lies South 49DEGREE00'00" East 93.11 feet 
     from the point No. 7 B.L.M. survey of Parcel No. 1 of Tract D in Section 
     3, Township 1 South, Range 1 East, Salt Lake Base & Meridian (said point 
     of No. 7 being 1,464 feet North and 4,643 feet West, more or less, from the
     Southeast corner of said Section 3), and running thence South 
     41DEGREE00'00" West 325.686 feet; thence South 49DEGREE00'00" East 463
     feet; thence North 41DEGREE00'00" East 325.686 feet; thence North 
     49DEGREE00'00" West 463.0 feet to the point of beginning. Containing 
     3.462 acres, more or less, including a ten foot utility easement within 
     and around the boundary of the described property.

        1.3. "LEASE" means the Lease Agreement, dated December 30, 1983, as 
previously amended by the Exercise of Option for Renewal Term, dated August 
29, 1991, and the Extension of Lease, dated April 22, 1996, each entered into 
between Landlord, as landlord, and Deseret Research Company, a Utah 
corporation, the predecessor in interest to Tenant, as tenant, covering the 
Premises.

        1.4. "PREMISES" means the Land and the Building and other 
improvements located on the Land.

     2. INITIAL TERM. Paragraph 2 of the Lease is deleted in its entirety and 
is replaced with the following new Paragraph 2:

     2. INITIAL TERM

        The initial term of this lease shall expire on December 31, 2010.

<PAGE>

     3. OPTIONS FOR RENEWAL TERMS. Paragraph 3 of the Lease is deleted in its 
entirety and is replaced with the following new Paragraph 3:

     3. OPTIONS FOR RENEWAL TERMS

        Tenant shall have options to renew this lease for three (3) 
     additional, consecutive terms of five (5) years each, the first of such 
     renewal terms being January 1, 2011 to December 31, 2015, inclusive, the 
     second of such renewal terms being January 1, 2016 to December 31, 2020, 
     inclusive, and the third of such renewal terms being January 1, 2021 to 
     December 31, 2025, inclusive. Exercise of any such options shall be made 
     by Tenant giving Landlord written notice thereof at least one hundred 
     eighty (180) days prior to the expiration of the initial term or any 
     renewal term then in effect. Tenant shall have the right to exercise any 
     such option only if at the time of such exercise this lease is in full 
     force and effect and no event of default by Tenant hereunder shall have 
     occurred and be continuing beyond any applicable cure period. All of the 
     terms and provisions of this lease shall apply to any renewal term except 
     that rent shall be determined as outlined in paragraph 5(d) below.

     4. RENT. Paragraphs 5(b), (c) and (d) of the Lease are deleted in their 
entirety and are replaced with the following new Paragraphs 5(b), (c) and (d):

        (b) The rent for that portion of the initial term through and 
     including December 31, 2001 is as follows:


         PERIOD                              RENT
         ------                              ----
     Current through                      $18,083.33 per month
      December 31, 1996

     January 1, 1997 through              $25,000.00 per month
      December 31, 1998, inclusive

     January 1, 1999 through              $25,750.00 per month
      December 31, 1999, inclusive

     January 1, 2000 through              $26,522.50 per month
      December 31, 2000, inclusive

     January 1, 2001 through              $27,318.18 per month
      December 31, 2001, inclusive

     (c)  The rent for that portion of the initial term from January 1, 2002 
through December 31, 2010, inclusive, and the rent during any renewal term, 
shall be determined in accordance with paragraph 5(d). As used in paragraph 
5(d), the following terms shall have the meanings indicated:


                                     -2-
<PAGE>

     (i)  "ADJUSTMENT DATE" means January 1, 2002 and each subsequent
January 1st.

     (ii) "BASE RENT" means the greater of the following:

          (A)  $27,318.18 per month; or

          (B)  seventy-five percent (75%) of the then-prevailing average 
rental rate, per rentable square foot, for laboratory office space leased in 
Research Park that is comparable to the Premises, multiplied by the total 
rentable square feet of the Building, all as mutually agreed on between 
Landlord and Tenant. The parties believe that the Building has approximately 
50,878 square feet; however, for purposes of the foregoing calculation, at 
Tenant's request, the rentable square feet of such comparable laboratory 
office space and the Building shall be measured using the American National 
Standard Method for Measuring Floor Space in Office Buildings (or other 
appropriate standard method), as then most recently published by the Building 
Owners and Managers Association International. Such measurements shall be 
made by an architect licensed in Utah with at least ten (10) years 
experience, mutually selected by Landlord and Tenant. The measurements of 
such architect, if completed accurately in accordance with such standard, 
shall be binding on Landlord and Tenant. If Landlord and Tenant disagree with 
respect to whether any particular laboratory office space is compatable, or 
with respect to the actual rent paid for any such particular space, or with 
respect to any other matter regarding the calculation made pursuant to this 
Paragraph 5(c)(ii)(B) (other than the measurement to be done by and 
architect, asset forth above), Landlord and Tenant shall mutually select a 
certified MAI appraiser who is a member of the American Institute of Real 
Estate Appraisers to resolve such disagreement. The determination of such 
appraiser as to any such matters, if not negligent and if made in good faith, 
shall be binding on Landlord and Tenant. Landlord shall provide Tenant with 
all relevant information used in making the calculations under this Paragraph 
5(c)(ii)(B). Tenant may, with Landlord's assistance, contact any tenant 
concerned to independently verify such information. The cost of of the 
services of any architect or appraiser used under this Paragraph 5(c)(ii)(B) 
shall be equally divided between, and timely paid by, Landlord and Tenant. 
Landlord and Tenant shall act reasonably and in good faith in the discharge 
of all of their respective obligations under this Paragraph 5(c)(ii)(B).

     (iii)  "CONSUMER PRICE INDEX" "Consumer Price Index--U.S. City Average 
For All Items For All Urban Consumers (1982-84=100)" (the "CPI-U") published 
monthly in the "Monthly Labor Review" or other publication by the Bureau of 
Labor Statistics, United States Department of Labor (the "LABOR BUREAU"); 
provided however, that:

            (A)  if the CPI-U is discontinued, "Consumer Price Index" shall 
mean "Consumer Price Index--U.S. City Average For All Items For Urban Wage 
Earners and Clerical Workers (1982-84=100)" (the "CPI-W") published monthly 
in the "Monthly Labor Review" or other publication by the Labor Bureau;


                                     -3-
<PAGE>

             (B)  if the CPI-W is discontinued, "CONSUMER PRICE INDEX" shall 
refer to comparable statistics on the purchasing power of the consumer dollar 
published by the Labor Bureau or by another agency of the United States 
mutually agreed to by Landlord and Tenant;

             (C)  if the Labor Bureau or another agency of the United States 
no longer publishes comparable statistics on the purchasing power of the 
comsumer dollar, "CONSUMER PRICE INDEX" shall refer to comparable statistics 
published by a responsible financial periodical or recognized authority 
mutually agreed to by Landlord and Tenant, and adjustments shall be made in 
the computation set forth in paragraph 5(d) as the circumstances may require 
in order to carry out the intent of this paragraph 5; and

            (D)  if the base year "(1982-84=100)" or other base year used in 
computing the CPI-U or the CPI-W is changed, the figures used in making the 
adjustments in paragraph 5(d) shall be changed accordingly so that all 
increases in the CPI-U and CPI-W are taken into account notwithstanding any 
such change in the base year.

     (d)  The Base Rent shall be increased during the term of this lease 
(including any renewal terms) as of each Adjustment Date to the product 
obtained by multiplying the Base Rent by a fraction, the numerator of which 
is the Consumer Price Index for the third month preceding the Adjustment Date 
concerned, and the denominator of which is the Consumer Price Index for 
October, 2000; provided, however, that such increase shall not be less than 
three percent (3%) nor more than eight percent (8%) of the Base Rent. The 
amount of such increase shall be determined by Landlord as soon as reasonably 
practicable after the Consumer Price Index for the third month preceding each 
such Adjustment Date becomes available. Tenant shall pay such increased Base 
Rent until the later of the next Adjustment Date or the date on which 
Landlord provides to Tenant the amount of the next increase in the Base Rent, 
accompanied by a reasonable detailed explanation setting forth the 
calculations on which such increase is based. Landlord may invoice Tenant 
retroactively for the increased portion of the Base Rent due for the period 
between any such Adjustment Date and the date of such invoice.

     5.  CERTAIN REMODELING. Landlord has reviewed and approved the 
conceptual drawings submitted to Landlord for the remodeling of the Premises 
intended to be undertaken by Tenant. Landlord hereby agrees in principle 
to the remodeling described in such drawings.

     6.  RIGHT OF FIRST REFUSAL. The first sentence in Paragraph 37 of the 
Lease is deleted in its entirety and is replaced with the following new first 
sentence:

         As long as Tenant or any other entity controlled by Heartport,
     Inc. or by any successor or assign or Heartport, Inc. remains the 
     tenant under this lease, it shall have a right of first refusal in
     the event of a proposed sale of the premises by Landlord or its
     successors.


                                     -4-
<PAGE>


     7.  ENVIRONMENTAL MATTERS.

         7.1.  EXISTING ENVIRONMENTAL MATTERS.

               7.1.1.  INDEMNITY. As between Landlord and Tenant, Landlord 
shall be solely responsible for, and shall indemnify, defend and hold 
harmless Tenant from and against, all losses, damages (including, without 
limitation, losses of, or damages to, the Premises), claims, actions, causes 
of action, demands, penalties, fines, assessments, settlements, obligations, 
suits, proceedings, controversies, fees, costs (including, without 
limitation, response, remediation, inspection and other costs relating to 
hazardous substances, hazardous wastes, pollutants or contaminants), expenses 
(including, without limitation, litigation expenses and attorneys' fees, 
whether incurred with or without the filing of suit, on appeal or otherwise, 
and consultant fees, investigation expenses and laboratory expenses), 
liabilities, judgments, charges, debts and liens, of whatever nature, kind or 
character, including, without limitation, those arising under any applicable 
federal, state or local statute, law, ordinance, rule or regulation, whether 
known or unknown, suspected or unsuspected, foreseeable or unforeseeable, or 
direct, consequential, fixed, contingent or otherwise, which are suffered, 
incurred, sustained or paid by Tenant by Tenant or Tenant's officers, 
directors, employees, agents, successors or assigns, or any one or more of 
them, and which arise from or relate to, in any way, directly or indirectly, 
any hazardous substances, hazardous wastes, pollutants or contaminants 
located on, under or about the Premises (including, without limitation, in 
the Building) as of December 30, 1983, including, without limitation, any 
asbestos-related insulation or other construction material, underground tank, 
polychlorinated biphenyl (PCB) or urea formaldehyde.

               7.1.2.  REIMBURSEMENT.  In addition to Landlord's obligations 
under Paragraph 7.1.1, Landlord shall promptly reimburse Tenant for all 
losses, damages (including, without limitation, losses of, or damages to, the 
Premises), claims, actions, causes of action, demands, penalties, fines, 
assessments, settlements, obligations, suits, proceedings, controversies, 
fees, costs (including, without limitation, response, remediation, inspection 
and other costs), expenses (including, without limitation, litigation 
expenses and attorneys' fees, whether incurred with or without the filing of 
suit, on appeal or otherwise, and consultant fees, investigation expenses and 
laboratory expenses), liabilities, judgments, charges, debts and liens, of 
whatever nature, kind or character, including, without limitation, those 
arising under any applicable federal, state or local statute, law, ordinance, 
rule or regulation, whether known or unknown, suspected or unsuspected, 
foreseeable or unforeseeable, or direct, consequential, fixed, contingent or 
otherwise, which are suffered, incurred, sustained or paid by Tenant or 
Tenant's officers, directors, employees, agents, successors or assigns, or 
any one or more of them, and which arise from or related to, in any way, 
directly or indirectly, any asbestos or asbestos-related insulation or other 
construction material or underground tank located on, under or about the 
Premises (including, without limitation, in the Building) as of the date of 
this Amendment.

               7.1.3.  CERTAIN ACTIONS.  Any action (including, without 
limitation, remodeling or other construction) taken at any time by Tenant 
which causes any asbestos to become friable or results in any removal 
required by law of such asbestos or any underground tank shall be covered by, 
and shall not in any way limit Landlord's obligation under, Paragraph 7.1.2. 
Any such removal shall be performed by contractors approved in advance by 
Landlord, such approval not to be unreasonably withheld, conditioned or 
delayed. Any invoice from Tenant to Landlord, accompanied by a reasonably 
detailed explanation, for any amount which Landlord is obligated to pay 
pursuant

                                     -5-
<PAGE>

to this Paragraph 7.1 shall be paid by Landlord to Tenant within thirty (30) 
days after the receipt by Landlord of such invoice.

     7.2  ENVIRONMENTAL MATTERS CAUSED BY TENANT.

          7.2.1.  INDEMNITY.  Subject to all of Landlord's obligations under 
Paragraph 7.1, as between Landlord and Tenant, Tenant shall be solely 
responsible for, and shall indemnify, defend and hold harmless Landlord from 
and against, all losses, damages (including, without limitation, losses of, 
or damages to, the Premises), claims, actions, causes of action, demands, 
penalties, fines, assessments, settlements, obligations, suits, proceedings, 
controversies, fees, costs (including, without limitation, response, 
remediation, inspection and other costs relating to hazardous substances, 
hazardous wastes, pollutants or contaminants), expenses (including, without 
limitation litigation expenses and attorneys' fees, whether incurred with or 
without the filing of suit, on appeal or otherwise, and consultant fees, 
investigation expenses and laboratory expenses), liabilities, judgments, 
charges, debts and liens, of whatever nature, kind or character, including, 
without limitation, those arising under any applicable federal, state or 
local statute, law, ordinance, rule or regulation, whether known or unknown, 
suspected or unsuspected, foreseeable or unforeseeable, or direct, 
consequential, fixed, contingent or otherwise, which are suffered, incurred, 
sustained or paid by Landlord or Landlord's officers, directors, employees, 
agents, successors or assigns, or any one or more of them, and which arise 
from or relate to, in any way, directly or indirectly, any hazardous 
substances, hazardous wastes, pollutants or contaminants released or 
deposited by Tenant on, under or about the Premises (including, without 
limitation, in the Building) after the date of this Amendment.

          7.2.2.  COMPLIANCE WITH LAW.  In its operations on the Premises, 
Tenant shall timely comply with all laws, ordinances, rules and regulations 
relating to the storage, handling and disposal of hazardous substances, 
hazardous wastes, pollutants or contaminants.

     8.  GENERAL PROVISIONS.  Except as set forth in this Amendment, the 
Lease is ratified and affirmed in its entirety. This Amendment shall inure to 
the benefit of, and be binding on, Landlord and Tenant and their respective 
successors and assigns. This Amendment shall be governed by, and construed 
and interpreted in accordance with, the laws (excluding the choice of laws 
rules) of the State of Utah. This Amendment may be executed in any number of 
duplicate originals or counterparts, each of which when so executed shall 
constitute in the aggregate but one and the same document. Each individual 
executing this Amendment represents and warrants that such individual has been 
duly authorized to execute and deliver this Amendment in the capacity and for 
the entity set forth where such individual signs.



                                     -6-
<PAGE>

     LANDLORD AND TENANT have executed this Amendment on the respective dates 
set forth below, to be effective as of the date first set forth above.


                                       LANDLORD:

                                       UNIVERSITY OF UTAH RESEARCH FOUNDATION



                                       By    /s/ Arthur K. Smith
                                             ---------------------------------
                                       Its   Chairman
                                             ---------------------------------
                                       Date  Oct 25, 1996
                                             ---------------------------------

                                       TENANT:

                                       HEARTPORT RESEARCH AND TRAINING CENTER,
                                       INC.



                                       By    /s/ Bradford J. Shafer
                                             ---------------------------------
                                       Its   Secretary
                                             ---------------------------------
                                       Date  10/25/96
                                             ---------------------------------

                                     -7-