<PAGE>
 
                                                                  EXHIBIT 10.21
 
                          AMENDED AND RESTATED LEASE
 
  This AMENDED AND RESTATED LEASE is made as of the 22nd day of October, 1997
by and between Robert W. Connelly (the "Landlord") and Cambridge Heart, Inc.
(the "Tenant").
 
                                  WITNESSETH
 
  WHEREAS, the Landlord and the Tenant entered into a certain lease dated as
of June 1, 1995 (the "Lease"), and
 
  WHEREAS, the Landlord and the Tenant now wish to amend the lease as
hereinafter set forth.
 
  NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the Landlord and the Tenant
hereby amend and modify the Lease by a restatement of the same in the form and
containing those provisions in the pages next following and attached hereto
and constituting a part hereof. To the extent of any inconsistency between the
terms of the Lease and this Amended and Restated Lease, the terms and
provisions contained herein shall control in all instances. Except as
specifically amended hereby, the Lease is hereby ratified and confirmed in its
entirety as of the date hereof.
 
  WITNESS the execution hereof under seal as of the day and year first above
written.
 
                                                  /s/ Robert W. Connelly
                                          _____________________________________
                                                   Robert W. Connelly
 
                                          Cambridge Heart, Inc.
 
                                                   /s/ Jeffrey M. Arnold
                                          By: _________________________________
                                            Name:Jeffrey M. Arnold
                                            Title:Chief Executive Officer
 
                                      A-1
<PAGE>
 
                          AMENDED AND RESTATED LEASE
 
1. IDENTIFICATIONS
 
  This AMENDED AND RESTATED LEASE made as of October 22, 1997 by and between
ROBERT W. CONNELLY (the "Landlord"), having an address at 57 Bedford Street,
Suite 100, Lexington, Massachusetts 02173 and CAMBRIDGE HEART, Inc. a
Massachusetts corporation (the "Tenant"), having an address at One Oak Park
Drive, Bedford, Massachusetts 01730.
 
2. LEASE; THE PREMISES; EXPANSION OPTION
 
  In consideration of the Basic Rent, Additional Rent, and other payments and
covenants of the Tenant hereinafter set forth, and upon the following terms
and conditions, the Landlord hereby leases to the Tenant and the Tenant hereby
leases from the Landlord approximately 22,000 rentable square feet of floor
area in that certain building (the "Building") situated on that certain parcel
of land (the "Property") known as and numbered One Oak Park Drive, in the Town
of Bedford, Middlesex County, Massachusetts, as more particularly described in
Exhibit A attached hereto (said Property and Building hereinafter collectively
referred to as the "Premises"). The Premises are leased together with all
rights necessary for the use of the Premises as permitted herein, in common
with the Landlord and all others from time to time lawfully entitled thereto,
to use the driveways, walkways, parking area and other common areas of the
Property for their intended purposes.
 
3. CONDITION OF PREMISES
 
  The Tenant acknowledges and agrees that the Premises will be delivered by
the Landlord in an "as is" condition as of the date hereof and of the Term
Commencement Date (as defined below). Except as may be expressly set forth in
this Lease, no representations or warranties have been made by the Landlord or
anyone purporting to act on behalf of the Landlord as to the condition or
repair of the Premises or any portion thereof.
 
4. TERM
 
  The Term of this Lease shall commence on the earlier of (i) December 1,
1997, or (ii) such time as the partitions described in Paragraph 12 shall have
been erected (the "Term Commencement Date") and shall expire, unless earlier
extended or terminated in accordance with the terms hereof, at midnight on
November 30, 1999. Notwithstanding the foregoing, the Tenant shall have access
to the Premises beginning on the date hereof for the purpose of showing the
Premises to prospective subtenants (it being understood and agreed that
nothing contained in this Paragraph 4 shall be deemed to in any way obviate
the need to obtain the consent of the Landlord for any subletting in
accordance with Paragraph 19 below) provided that the Landlord is given
reasonable prior notice thereof and an opportunity to be present when the
Premises are being shown. In addition, any early access to the Premises shall
be governed by and subject to the terms and provisions of this Lease.
 
  Provided the Tenant is not in default under any of the provisions of this
Lease and provided further that the Tenant has given to the Landlord written
notice at least one hundred and eighty (180) days before the end of the Term,
the Tenant shall have the option to extend the Term for an additional period
of one (1) year commencing after the expiration of the original Term (the
"Extended Term"). The Extended Term shall be upon the same terms and
conditions as herein set forth.
 
5. USE OF THE PREMISES' LICENSES AND PERMITS
 
  The Tenant shall use the Premises only for general office, research and
development and light manufacturing purposes to the extent now and hereafter
from time to time permitted under applicable laws, by-laws, ordinances, codes,
rules, regulations, orders and other lawful requirements of governmental
bodies having jurisdiction. The Tenant, its subtenants, licensees, invitees
and any other users of the Premises shall apply in their own names for and
obtain at their own expense any and all licenses, permits and other approvals
which may be required from such governmental bodies in connection with any
particular use of the Premises during the Term.
 
                                      A-2
<PAGE>
 
6. BASIC RENT; ADDITIONAL RENT
 
  The Tenant shall pay Basic Rent to the Landlord at the annual rate of Two
Hundred Forty-Two Thousand Dollars and No Cents ($242,000.00). Basic Rent
shall be payable in advance on the first day of each month in equal
installments at the rate of $20,166.67 per month to the Landlord at the
address set forth above or such other address as the Landlord may thereafter
specify by notice to the Tenant, without counterclaim, set off, deduction or
defense and, except as otherwise expressly provided herein, without abatement.
 
  This Lease is intended by the parties hereto to be a so-called "net" lease
and, to the end that the Basic Rent shall be received by the Landlord net of
all costs and expenses related to the Premises, except as expressly set forth
herein. The Tenant agrees to pay, in addition to the Tenant's obligations with
respect to real estate taxes, insurance premiums, utilities costs, costs of
repairs and maintenance to the Premises and other costs which are specifically
set forth herein, to the Landlord upon demand as Additional Rent, in the same
manner as Basic Rent: (i) any and all charges, costs, expenses, and
obligations of every kind and nature whatever as the Landlord may from time to
time actually incur in good faith with regard to the Premises or the operation
or maintenance thereof, except as otherwise expressly agreed in this Lease,
including, without limiting the generality of the foregoing, reasonable
attorneys' fees incurred by the Landlord in connection with any amendments to,
consents under and subleases and assignments of this Lease requested by the
Tenant and in connection with the enforcement of rights and pursuit of the
remedies of the Landlord under this Lease (whether during or after the
expiration or termination of the Term of this Lease) and (ii) one hundred
percent (100%) of Common Expenses as hereinafter defined. Except as otherwise
specifically set forth in Paragraph 10 hereof, "Common Expenses" shall mean
any and all charges, costs and expenses of every kind and nature whatever,
which the Landlord may from time to time actually incur and the reasonable
value, based on competitive rates, of any materials and services which the
Landlord may provide in good faith with respect to the ownership, operation
and maintenance of the Building and the Premises, including, without
limitation, (i) making non-capital repairs (or capital repairs to the extent
permitted in the next following paragraph) to and undertaking maintenance of
the Building and the Property; (ii) providing utilities and services, other
than as provided in Paragraph 9 hereof, to the Premises; (iii) providing daily
cleaning and rubbish removal; (iv) providing watering, landscaping and lawn
care for the Property; (v) sanding, plowing and removal of snow and ice from
the driveways, walkways and parking areas; (vi) maintaining insurance on the
Premises; and (vii) reasonable administrative and management costs of the
Landlord, which shall be commensurate with those normally charged for suburban
office buildings of this nature in the metropolitan Boston area.
 
  Notwithstanding anything contained herein to the contrary, Additional Rent
on account of operating expenses shall not include the following: amounts
received by the Landlord through proceeds of insurance, specific tenant
reimbursements, condemnation awards, warranties, or other similar sources;
brokerage commissions; taxes (other than as provided in Paragraph 7 below);
costs in the nature of fees, fines or penalties arising out of the breach of
any obligation, contractual or at law, by the Landlord or its contractors,
employees or agents, including attorneys' fees (unless such breach is the
result of the acts or omissions of the Tenant or those for whom the Tenant is
legally responsible); tenant buildout expenses, including permit, license and
inspection costs relating thereto; costs or expenses relating to the
correction of latent defects in the Building or noncompliance of the Building
with laws in effect as of the date hereof; costs relating to environmental
compliance or remediation, unless necessitated as a result of the acts or
omissions of the Tenant or those for whom the Tenant is legally responsible;
capital expenditures, other than those required to bring the Building into
compliance with laws enacted after the date of this Lease; reserves for future
expenditures not yet incurred; attorneys' fees and other expenses incurred in
connection with negotiations or disputes with present or prospective tenants
of the Building (other than the Tenant); overhead and profit increment paid to
the Landlord or any of its affiliates to the extent the same exceed market
rates; interest, principal, points and fees on any debt or loans; advertising
and promotional expenditures; and depreciation.
 
  Notwithstanding anything contained herein to the contrary, it is expressly
understood that the Tenant shall only be required to pay as Additional Rent:
(a) the amount by which real estate taxes for any fiscal year exceed $1.25 per
rentable square foot; and (b) the amount by which Common Expenses for any
calendar year exceed
 
                                      A-3
<PAGE>
 
$2.50 per rentable square foot. Additional Rent shall not increase from $1.25
per rentable square foot for real estate taxes and $2.50 per rentable square
foot for Common Expenses by more than the Consumer Price Index for all Urban
Consumers (CPI-U), Boston, Massachusetts, with the commencement month and year
being the base.
 
  Additional Rent shall be calculated on a fiscal year ending May 31. The
Tenant agrees to pay the Landlord all amounts owed as Additional Rent
hereunder within thirty (30) days after receipt of an invoice and calculations
of actual amounts owed from the Landlord.
 
  If any payment of Basic Rent or Additional Rent is not paid to the Landlord
when due or within any applicable grace period, then at the Landlord's option,
without notice and in addition to all other remedies hereunder, the Tenant
shall pay upon demand to the Landlord as Additional Rent interest thereon at
an annual rate equal to the corporate rate of the Bank of Boston from time to
time in effect plus four (4) percent, such interest to be computed from the
date such Basic Rent or Additional Rent was originally due through the date
when paid in full.
 
7. TAXES
 
  The Tenant shall pay or cause to be paid to the Landlord (or, where
appropriate, directly to the authority by which the same are assessed or
imposed, with evidence of such payment to the Landlord) as Additional Rent not
later than ten (10) days prior to the date the same are due or twenty-one (21)
days after written notice thereof to the Tenant, whichever is later, all taxes
and excises upon the personal property and equipment of the Tenant located at
the Premises and any and all real estate taxes, betterments and special
assessments or amounts in lieu or in the nature thereof and any other taxes,
levies, water rents, sewer use charges and other excises, franchises, imposts
and charges, general and special (and the entire amount of any interest,
penalties and costs attributable to delayed payment of the Tenant's portion
thereof where such delay is the fault of the Tenant) of whatever name and
nature, and whether or not now within the contemplation of the parties hereto,
which may now or hereafter be levied, assessed or imposed by the United States
of America, The Commonwealth of Massachusetts, the Town of Bedford or any
other authority, or become a lien, upon all or any part of the Property, the
Building, the Premises, the use or occupation thereof, or upon the Landlord
and the Tenant in respect thereof, or upon the basis of rentals thereof or
therefrom (except for the Landlord's income, estate, gift, franchise,
corporation, profit or transfer taxes or any capital levy assessed upon the
Landlord), or upon the estate hereby created, or upon the Landlord by reason
of ownership of the reversion.
 
  The Tenant shall, upon written notice from the Landlord that the same is
required by any Mortgagee (as defined in Paragraph 21 hereof), prepay to the
Mortgagee or the Landlord monthly as Additional Rent, in the same manner as
Basic Rent, one-twelfth ( 1/12) of the total of all such amounts as the
Landlord may from time to time reasonably estimate will be payable annually by
the Tenant under this Lease which prepayments the Landlord agrees shall be
applied, without interest (other than such interest as the Mortgagee may
credit or pay to the Landlord in respect thereof) to such amounts as actually
become payable. As soon as any such amounts so payable are actually
determined, appropriate adjustments of any overpayments and underpayments
shall be made.
 
  Subject to the rights of any Mortgagees, the Landlord may, at the request of
the Tenant, use reasonable efforts to obtain an abatement of or to contest or
review by legal proceedings or otherwise any such tax, levy, charge or
assessment. In such event the Tenant shall pay such tax, levy, charge or
assessment (under protest, if necessary). The Tenant shall pay as Additional
Rent (i) any such tax, levy, charge or assessment that may be determined to be
due and (ii) such reasonable costs or expenses (including reasonable
attorneys' fees) the Landlord may incur in connection with any such
proceedings. The Tenant shall be entitled to share in any refund or abatement,
net of such costs and expenses, which may be made of any tax, levy, charge or
assessment in the same proportion that the same was paid by the Tenant or with
the Tenant's funds.
 
                                      A-4
<PAGE>
 
8. INSURANCE; WAIVERS OF SUBROGATION
 
  The Tenant shall, at its own cost and expense, obtain and throughout the
Term shall maintain, with companies qualified to do business in Massachusetts
and acceptable to any Mortgagees and reasonably acceptable to the Landlord,
for the benefit as additional insureds of the Landlord and any Mortgagees as
their respective interests may appear, comprehensive general liability
insurance (with contractual liability rider) against claims for bodily injury,
death or property damage occurring to, upon or about the Premises in limits of
$1,000,000 for bodily injury or death and property damage occurring to, upon
or about the Premises. The risk of loss to all contents of, and personal
property and trade fixtures located in, the Premises is upon the Tenant, and
the Landlord shall have no liability with respect thereto.
 
  The Landlord and the Tenant each hereby release the other from any liability
for any loss or damage to the Building, the Premises or other property and for
injury to or death of persons occurring on the Property or in the Building or
the Premises or in any manner growing out of or connected with the Tenant's
use and occupation of the Premises, the Building or the Property or the
condition thereof, whether or not caused by the negligence or other fault of
the Landlord, the Tenant or their respective agents, employees, subtenants,
licensees, invitees or assignees; provided, however, that this release (i)
shall apply notwithstanding the indemnities set forth in Paragraph 14, but
only to the extent that such loss or damage to the Building or other property
or injury to or death of persons is covered by insurance which protects the
Landlord or the Tenant or both of them as the case may be; (ii) shall not be
construed to impose any other or greater liability upon either the Landlord or
the Tenant than would have existed in the absence hereof; and (iii) shall be
in effect only to the extent and so long as the applicable insurance policies
provide that this release shall not affect the right of the insureds to
recover under such policies, which clauses shall be obtained by the parties
hereto whenever available.
 
9. UTILITIES
 
  The Tenant shall pay directly to the utility company for all electricity
(which includes heat and air conditioning) provided to the Premises, as
measured through separate meters serving different areas within the Building.
The Landlord shall provide all other utility services to the Premises, shall
furnish reasonable heat and air conditioning (the costs of which shall be paid
by the Tenant as set forth above) during normal business hours on regular
business days of the heating and air conditioning seasons of the year and
reasonable hot and cold water, shall light the passageways and stairways of
the Building during normal business hours on regular business days, and shall
provide such cleaning services as are customary in similar buildings in the
Bedford area, all subject to interruption due to accidents, the performance of
repairs or improvements, labor difficulties, difficulties in obtaining
supplies from the sources from which they are usually obtained, or to any
cause beyond the Landlord's control.
 
  The Landlord shall have no obligation to provide utilities or equipment
other than those provided to or located in the Premises as of the date hereof.
In the event the Tenant shall require additional utilities or equipment, the
installation or maintenance thereof shall be solely the obligation of the
Tenant (provided, however, that the Landlord has given his prior written
consent to any such installation).
 
10. REPAIRS
 
  From and after the commencement of and during the Term, the Tenant shall, at
its own cost and expense: (i) make interior non-structural repairs,
replacements and renewals necessary to keep the Premises in as good condition,
order and repair as the same are at the commencement of the Term or thereafter
may be put, reasonable wear and use and damage by fire or other casualty only
excepted (it being understood, however, that the foregoing exception for
reasonable wear and use shall not relieve the Tenant from the obligation to
keep the Premises in good order, repair and condition); and (ii) keep and
maintain all portions of the Building in a clean and orderly condition, free
of accumulation of dirt, rubbish, and other debris.
 
  From and after the commencement of and during the Term, the Landlord shall
make all necessary repairs, replacements and renewals, interior and exterior,
structural and non-structural: at his own cost and expense to
 
                                      A-5
<PAGE>
 
keep the roof of the Building free of leaks and to maintain the foundation,
floor slabs and other structural supports of the Building in good and sound
condition, maintenance and repairs occasioned by the acts or negligence of the
Tenant or its agents excepted unless such acts or negligence are covered by
the release provided in Paragraph 8 hereof; and as Common Expenses as in
Paragraph 6 defined to keep the electrical, plumbing and other building
systems serving the Building and the parking areas, sprinklers and other
improvements on the Property in as good condition, order and repair as the
same are at the commencement of the Term or thereafter may be put, damage by
fire or other casualty only excepted; keep all driveways, walkways, parking
areas and other improvements on the Property free of snow and sanded as
appropriate; and keep all lawns and landscaped areas of the Property watered,
fertilized and neatly trimmed.
 
11. COMPLIANCE WITH LAWS AND REGULATIONS
 
  The Tenant agrees that its obligations to make payment of the Basic Rent,
Additional Rent and all other charges on its part to be paid, and to perform
all of the covenants and agreements on its part to be performed during the
Term hereunder shall not, except as set forth in Paragraph 15 in the event of
casualty to the Premises or in Paragraph 16 in the event of condemnation by
public authority, be affected by any present or future law, by-law, ordinance,
code, rule, regulation, order or other lawful requirement regulating or
affecting the use which may be made of the Premises.
 
  During the Term the Tenant shall comply, at its own cost and expense, with:
all applicable laws, by-laws, ordinances, codes, rules, regulations, orders,
and other lawful requirements of the governmental bodies having jurisdiction,
which are applicable to, or by reason of, the Tenant's particular use of the
Premises (as opposed to office, research and development and light
manufacturing uses generally) or the fixtures and equipment therein and
thereon; the orders, rules and regulations of the National Board of Fire
Underwriters, or any other body hereafter constituted exercising similar
functions, which may be applicable to the Premises, the fixtures and equipment
therein or thereon or the use thereof; and the requirements of all policies of
public liability, fire and all other types of insurance at any time in force
with respect to the Premises, the Building or the Property and the fixtures
and equipment therein and thereon.
 
12. ALTERATIONS BY TENANT
 
  The Tenant shall erect no signs and shall make no alterations, additions or
improvements in or to any portion of the Premises or any portion of the
Building or the Property without the Landlord's prior written consent and
without first providing the Landlord with suitable assurance of the Tenant's
obligation to complete the same at no expense to the Landlord and without any
mechanics' or materialmen's lien upon the Property. The Landlord agrees that
its consent shall not be unreasonably withheld for interior, non-structural
alterations, additions and improvements to the Premises consistent with the
use of the Premises as contemplated hereby; any such consents to interior,
non-structural alterations, additions and improvements may, if the Landlord so
advises the Tenant as part of or by notice at the time of any such consent, be
conditioned upon the Tenant's being obligated to remove the same at the
expiration or termination of this Lease and to restore the Premises to their
condition prior to such alterations, additions and improvements.
 
  The Landlord is aware of the Tenant's intentions to subdivide the second
floor and sublease a majority portion located in the front of the Building,
and hereby consents to the use of partitions to this end. The Landlord will
erect such partitions at the Tenant's request upon reasonable prior notice,
and will use its best to have such partitions completed prior to December 1,
1997. In the event the Tenant does not request that the Landlord erect the
partitions, the Landlord will similarly use its best efforts to provide the
Tenant with access to the Premises prior to December 1, 1997 so that the
Tenant may erect the partitions itself (it being understood and agreed that
such early access shall be governed by and subject to the terms and provisions
of this Lease). In all events, the partitions shall be erected at the sole
cost and expense of the Tenant and must be removed by the Tenant upon the
expiration or earlier termination of this Lease.
 
                                      A-6
<PAGE>
 
13. LANDLORD'S ACCESS
 
  The Tenant agrees to permit the Landlord and any Mortgagees and their
authorized representatives to enter the Premises (i) at all reasonable times
after at least 24 hours' prior oral notice during usual business hours for the
purposes of inspecting the same, exercising such other rights as it or they
may have hereunder or under any mortgages and exhibiting the same to other
prospective tenants, purchasers or mortgagees and (ii) at any time and without
notice in the event of emergency. In exercising such rights, the Landlord
shall use due diligence to minimize or prevent inconvenience to the Tenant.
 
14. INDEMNITIES
 
  The Tenant agrees to protect, defend (with counsel approved by the
Landlord), indemnify and save the Landlord harmless from and against any and
all claims and liabilities (other than claims and liabilities resulting from
the Landlord's negligence or misconduct or that of its agents, employees,
licensees or invitees) arising: (i) from the conduct or management of or from
any work or thing whatsoever done in or about the Premises during the Term and
from any condition existing, or any injury to or death of persons or damage to
property occurring or resulting from an occurrence, during the Term in or
about the Premises; and (ii) from any negligent act or omission on the part of
the Tenant or any of its agents, employees, subtenants, licensees or
assignees. The Tenant further agrees to indemnify the Landlord from and
against all costs, expenses (including reasonable attorneys' fees) and other
liabilities incurred in connection with any such indemnified claim or action
or proceeding brought thereon, any and all of which, if reasonably suffered,
paid or incurred by the Landlord, the Tenant shall pay promptly upon demand to
the Landlord as Additional Rent.
 
15. CASUALTY DAMAGE
 
  Except as provided below, in the event of partial or total destruction of
the Building during the Term by fire or other casualty, the Landlord shall, as
promptly as practicable after receipt of any insurance proceeds available as a
result of such casualty, repair, reconstruct or replace the portions of the
Building destroyed as nearly as possible to their condition prior to such
destruction, except that in no event shall the Landlord be obligated to expend
more for such repair, reconstruction or replacement than the amounts of any
such insurance proceeds actually received. During the period of such repair,
reconstruction and replacement there shall be an equitable abatement of Basic
Rent hereunder for up to one (1) year from the date of such casualty in
proportion to the loss of usable floor area in the Building.
 
  If the Building is so extensively destroyed by fire or other casualty that
an independent engineer or architect certifies that it cannot reasonably be
expected to be susceptible of repair, reconstruction or replacement within a
period of six (6) months from the date work were to commence thereon, or if
any damage results from causes or risks not required to be insured against by
the Landlord hereunder or if any Mortgagee refuses to make such net proceeds
available for such repair, reconstruction or replacement, then either of the
Landlord or the Tenant may terminate this Lease by giving written notice to
the other within thirty (30) days after the date of such destruction. Provided
further, that if, despite diligent efforts, the Landlord has been unable to
restore the Premises to their condition prior to such destruction within nine
(9) months following the date of such casualty, then either of the Landlord or
the Tenant may terminate this Lease by written notice to the other. In the
event of any such notice of termination, this Lease shall terminate as of, and
Basic Rent and Additional Rent shall be appropriately apportioned through and
abated from and after, the date of such notice of termination.
 
16. CONDEMNATION
 
  If more than 20% of the usable floor area of the Building, or more than 20%
of the parking spaces designated for use by the Tenant shall be taken by
eminent domain or appropriated by public authority, the Landlord may terminate
this Lease by giving written notice to the Tenant within thirty (30) days
after such taking or appropriation. In the event of such a termination, this
Lease shall terminate as of the date the Tenant must surrender possession or,
if later, the date the Tenant actually surrenders possession, and the Basic
Rent and Additional Rent reserved shall be apportioned and paid to and as of
such date.
 
                                      A-7
<PAGE>
 
  If all or any part of the Premises is taken or appropriated by public
authority as aforesaid and this Lease is not terminated as set forth above,
the Landlord shall, subject to the rights of any Mortgagees, apply any such
damages and compensation awarded (net of the costs and expenses, including
reasonable attorneys' fees, incurred by the Landlord in obtaining the same) to
secure and close so much of the Premises as remain and shall restore the
Building to an architectural whole and except that in no event shall the
Landlord be obligated to expend more for such replacement than the net amount
of any such damages, compensation or award which the Landlord may have
received as damages in respect of the Building and any other improvements
situated on the Property as they existed immediately prior to such taking or
appropriation; in such event there shall be an equitable abatement of Basic
Rent in proportion to the loss of usable floor area in the Premises after
giving effect to such restoration, from and after the date the Tenant must
surrender possession or, if later, the date the Tenant actually surrenders
possession.
 
  The Landlord hereby reserves, and the Tenant hereby assigns to the Landlord,
any and all interest in and claims to the entirety of any damages or other
compensation by way of damages which may be awarded in connection with any
such taking or appropriation, except so much of such damages or award as is
specifically and separately awarded to the Tenant and expressly attributable
to trade fixtures or moving expenses of the Tenant.
 
17. LANDLORD'S COVENANT OF QUIET ENJOYMENT; TITLE
 
  The Landlord covenants that the Tenant, upon paying the Basic Rent and
Additional Rent provided for hereunder and performing and observing all of the
other covenants and provisions hereof, may peaceably and quietly hold and
enjoy the Premises for the Term as aforesaid, subject, however, to all of the
terms and provisions of this Lease and to the title matters set forth or
referred to in Exhibit A attached hereto.
 
18. TENANT'S OBLIGATION TO QUIT; HOLDOVER
 
  The Tenant shall, upon expiration of the Term or other termination of this
Lease, leave and peaceably and quietly surrender and deliver to the Landlord
the Premises and any replacements or renewals thereof broom clean and in the
order, condition and repair required by Paragraph 10 hereof and the other
provisions of this Lease, except, however, that the Tenant shall first remove
any trade fixtures and equipment and any alterations, additions and
improvements which the Landlord has required be removed pursuant to the terms
of Paragraph 12 hereof, restoring the Premises in each case to their condition
prior to the installation of such fixtures or the undertaking of such
alterations, additions or improvements, as the case may be. If the Tenant
shall fail timely to surrender the Premises, Basic Rent henceforth shall be
payable to the Landlord at a rate equal to 1.5 times the rate of Basic Rent in
effect immediately prior thereto until the Premises are surrendered by the
Tenant and delivered to the Landlord in accordance with this Paragraph 18. If
the Tenant shall fail so to remove its fixtures, equipment, alterations,
additions and improvements, they shall be deemed abandoned by the Tenant and
the Landlord may remove and dispose of the same at the Tenant's expense. The
provisions of this Paragraph 18 shall expressly survive the termination or
expiration of this Lease.
 
19. TRANSFERS OF TENANT'S INTEREST
 
  The Tenant shall not assign or sublease or otherwise encumber all or any
part of its interest in this Lease, the Premises, or the estate hereby
created, without in each case first obtaining the prior written consent of the
Landlord, which such consent shall not be unreasonably withheld so long as the
Tenant originally named herein shall continue to occupy the majority of the
space in the Building. In all events, the Landlord may condition the consent
to any sublease or assignment upon the Tenant's agreeing to pay to the
Landlord fifty percent (50%) of the net amount by which any rentals and other
amounts from time to time payable to or for the Tenant under any subleases
exceed the sum of the Basic Rent and Additional Rent from time to time payable
hereunder and the expenses actually incurred by the Tenant in thus subleasing
the Premises (including, without limitation, the associated costs of
installing partitions, the estimated costs of removing such partitions to the
extent removal is required by the Landlord, and costs of real estate agents
used in connection with the sublease), and upon the
 
                                      A-8
<PAGE>
 
sublessee's or assignee's agreement to obtain the consent of the Landlord to
any future or further sublease or assignment of its interest under this Lease.
The Landlord shall have the right to inspect, after reasonable advance notice,
all records relating to the costs claimed to have been incurred by the Tenant
pursuant to the previous sentence. Any attempted assignment without the
consent of the Landlord as contemplated hereby shall be void. Any change in
ownership or power to vote of a majority of the outstanding stock of the
Tenant from the owners of such stock or those controlling the power to vote of
such stock shall constitute an assignment for purposes of this Lease.
 
  Notwithstanding anything contained herein to the contrary, the Tenant shall
have the right to assign its interest in the Lease or to sublet the whole or
any part of the Premises to any entity that controls, is controlled by, or is
under common control with the Tenant, or in connection with the consolidation,
merger, restructuring or reorganization of the Tenant or the sale by the
Tenant of all or any significant portion of its stock or assets, and in none
of the foregoing events shall the consent of the Landlord be required;
provided, however, that any such assignee must agree in writing to be bound by
the terms of this Lease and to assume the obligations of the Tenant hereunder.
 
  In all events the Tenant originally named herein and any guarantor of the
obligations of the Tenant under this Lease shall, except to the extent of so
much of the Premises as the Landlord elects to lease directly to any proposed
sublease or assignee as above provided, remain primarily and jointly and
severally liable for, and any sublessee or assignee shall in writing assume,
the obligations of the Tenant under this Lease.
 
  The Tenant shall reimburse the Landlord as Additional Rent, upon demand, for
any costs that may be incurred by the Landlord in connection with any proposed
assignment or sublease and any request for consent thereto, including without
limitation the costs of making investigations as to the acceptability of any
proposed assignee or subtenant, and attorneys' fees.
 
20. TRANSFERS OF LANDLORD'S INTEREST
 
  The Landlord shall have the right from time to time to sell or mortgage its
interest in the Premises, to assign its interest in this Lease, or to assign
from time to time the whole or any portion of the Basic Rent, Additional Rent
or other sums and charges at any time paid or payable hereunder by the Tenant
to the Landlord, to any Mortgagees or other transferees designated by the
Landlord in duly recorded instruments, and in any such case the Tenant shall
pay the Basic Rent, Additional Rent and such other sums and charges so
assigned, subject to the terms of the Lease, upon demand to such Mortgagees
and other transferees at the addresses mentioned in and in accordance with the
terms of such instruments.
 
21. MORTGAGEES' RIGHTS
 
  The Tenant hereby agrees that this Lease is and shall be subject and
subordinate to any mortgage (and to any amendments, extensions, increases,
refinancings or restructurings thereof) of the Premises, whether or not such
mortgage is filed subsequent to the execution, delivery or the recording of
this Lease or any notice hereof (the holder from time to time of any such
mortgage being in this Lease sometimes called the "Mortgagee"). The foregoing
subordination shall be self-operative and automatically effective, and the
Tenant hereby agrees to execute, acknowledge and deliver in recordable form
such instruments confirming and evidencing the foregoing subordination as the
Landlord or any such Mortgagee may from time to time reasonably require. The
Landlord agrees to use its best efforts to obtain a subordination, non-
disturbance and attornment agreement in the Tenant's favor from any Mortgagee
of the Premises.
 
  Provided that the Tenant has been provided with notice of such mortgage and
appropriate addresses to which notice should be sent, no notice from the
Tenant of any default by the Landlord in its obligations shall be valid, and
the Tenant shall not attempt to terminate this Lease, withhold Basic Rent or
Additional Rent or exercise any other remedy which may arise under law by
reason of any such default (it being understood that no such remedy exists, or
is implied by reason of this provision, under this Lease), unless the Tenant
first gives
 
                                      A-9
<PAGE>
 
such notice to any Mortgagees and provides such Mortgagees with sixty (60)
days after such notice to cure such default, or if such default is not
reasonably susceptible of cure by Mortgagees (as in the case of the need to
obtain possession of or right of entry into or upon the Premises) in sixty
(60) days, with such longer period of time (not to exceed an additional thirty
(30) days) as is reasonably necessary to cure such default, provided efforts
to effectuate such cure are commenced within sixty (60) days and thereafter
prosecuted to completion with reasonable diligence. The Tenant shall and does
hereby agree, upon default by the Landlord under any mortgage, to attorn to
and recognize the Mortgagee or anyone else claiming under such mortgage,
including a purchaser at a foreclosure sale, at its request as successor to
the interest of the Landlord under this Lease, to execute, acknowledge and
deliver such evidence of this attornment, which shall nevertheless be self-
operative and automatically effective, as the Mortgagee or such successor may
request and to make payments of Basic Rent and Additional Rent hereunder
directly to the Mortgagee or any such successor, as the case may be, upon
request. Any Mortgagee may, at any time, by giving written notice to, and
without any further consent from, the Tenant, subordinate its mortgage to this
Lease, and thereupon the interest of the Tenant under this Lease shall
automatically be deemed to be prior to the lien of such mortgage without
regard to the relative dates of execution, delivery or filing thereof or
otherwise.
 
22. TENANT'S DEFAULT; LANDLORD'S REMEDIES
 
  If (i) the Tenant shall default in the payment when due of any Basic Rent or
Additional Rent, or if the Tenant shall default in the timely performance or
observance of any of the other covenants contained in these presents and on
the Tenant's part to be performed or observed within five (5) days after
written notice of such default in payment, performance or observance by the
Landlord to the Tenant, (ii) if the estate hereby created shall be taken on
execution, or (iii) by other process of law, or if the Tenant shall be
involved in financial difficulties as evidenced
 
    (1) by its commencement of a voluntary case under Title 11 of the United
  States Code as from time to time in effect, or by its authorizing, by
  appropriate proceedings of trustees or other governing body the
  commencement of such a voluntary case,
 
    (2) by its filing an answer or other pleading admitting or failing to
  deny the material allegations of a petition filed against it commencing an
  involuntary case under said Title 11, or seeking, consenting to or
  acquiescing in the relief therein provided, or by its failing to controvert
  timely the material allegations of any such petition,
 
    (3) by the entry of an order for relief in any involuntary case commenced
  under said Title 11,
 
    (4) by its seeking relief as a debtor under any applicable law, other
  than said Title 11, of any jurisdiction relating to the liquidation or
  reorganization of debtors or to the modification or alteration of the
  rights of creditors, or by its consenting to or acquiescing in such relief.
 
    (5) by the entry of an order by a court of competent jurisdiction (i)
  finding it to be bankrupt or insolvent, (ii) ordering or approving its
  liquidation, reorganization or any modification or alteration of the rights
  of its creditors, or (iii) assuming custody of, or appointing a receiver or
  other custodian for, all or a substantial part of its property, or
 
    (6) by its making an assignment for the benefit of, or entering into a
  composition with, its creditors, or appointing or consenting to the
  appointment of a receiver or other custodian for all or a substantial part
  of its property;
 
then and in any of said cases, the Landlord may, to the extent permitted by
law, immediately or at any time thereafter and without demand or notice,
terminate this Lease and enter into and upon the Premises, or any part thereof
in the name of the whole, and repossess the same as of the Landlord's former
estate, and expel the Tenant and those claiming through or under the Tent and
remove its effects without being deemed guilty of any manner of trespass, and
without prejudice to any remedies which might otherwise be used for arrears of
rent or preceding breach of covenant.
 
                                     A-10
<PAGE>
 
  No termination or repossession provided for in this Paragraph 22 shall
relieve the Tenant or any guarantor of the obligations of the Tenant under
this Lease of its liabilities and obligations under this Lease, all of which
shall survive any such termination or repossession. In the event of any such
termination or repossession, the Tenant shall pay to the Landlord either (i)
in advance on the first day of each month, for what would have been the entire
balance of the Term, one-twelfth ( 1/12) (and a pro rata portion thereof for
any fraction of a month) of the annual Basic Rent, Additional Rent and all
other amounts for which the Tenant is obligated hereunder, less, in each case,
the actual net receipts by the Landlord by reason of any reletting of the
Premises after deducting the Landlord's reasonable expenses in connection with
such reletting, including, without limitation, removal, storage and repair
costs and reasonable brokers' and attorneys' fees, or (ii) upon demand and at
the option of the Landlord exercisable by the Landlord's giving notice to the
Tenant within thirty (30) days after any such termination, the present value
(computed at a capitalization rate based upon the so-called "Prime Rate" then
in effect at The First National Bank of Boston) of the amount by which the
payments of Basic Rent and Additional Rent reasonably estimated to be payable
for the balance of the Term after the date of the exercise of said option
would exceed the payments reasonably estimated to be the fair rental value of
the Premises on the terms and conditions of this Lease over such period,
determined as of such date.
 
  Without thereby affecting any other right or remedy of the Landlord
hereunder, the Landlord may, at its option and after reasonable prior notice
to the Tenant, cure for the Tenant's account any default by the Tenant
hereunder which remains uncured after said thirty (30) days' notice of default
from the Landlord to the Tenant, and the cost to the Landlord of such cure
shall be deemed to be Additional Rent and shall be paid to the Landlord by the
Tenant with the installment of Basic Rent next accruing. It is understood and
agreed that nothing in this paragraph shall be deemed to extend or enlarge any
notice and cure periods beyond those set forth in the first paragraph of this
Paragraph 22.
 
23. REMEDIES CUMULATIVE; WAIVERS
 
  The specific remedies to which the Landlord may resort under the terms of
this Lease are cumulative and are not intended to be exclusive of any other
remedies or means of redress to which the Landlord may be lawfully entitled in
any provision of this Lease or otherwise. The failure of the Landlord or the
Tenant to insist in any one or more cases upon the strict performance of any
of the covenants of this Lease, or to exercise any option herein contained,
shall not be construed as a waiver or relinquishment for the future of such
covenant or option. A receipt by the Landlord, or payment by the Tenant, of
Basic Rent or Additional Rent with knowledge of the breach of any covenant
hereof shall not be deemed a waiver of such breach, and no waiver, change,
modification or discharge by the Landlord or the Tenant of any provision in
this Lease shall be deemed to have been made or shall be effective unless
expressed in writing and signed by an authorized representative of the
Landlord or the Tenant as appropriate. In addition to the other remedies in
this Lease provided, the Landlord shall be entitled to the restraint by
injunction of the covenants, conditions or provisions of this Lease, or to a
decree compelling performance of or compliance with any of such covenants,
conditions or provisions.
 
24. BROKERS
 
  The Landlord and the Tenant each warrant and represent to the other that
each has not dealt with any broker in connection with the Premises or this
Lease. The Landlord and the Tenant each hereby indemnifies and holds the other
harmless from and against any liability for commissions due any broker or
finder with whom each has dealt in connection with this Lease.
 
25. NOTICES
 
  Any notices, approvals, specifications, or consents required or permitted
hereunder shall be in writing and mailed, postage prepaid, by registered or
certified mail, return receipt requested, if to the Landlord or the Tenant at
the addresses set forth herein, and if to any Mortgagee at such address as it
may specify by such notice to the Landlord and the Tenant, or at such other
address as any of them may from time to time specify by like notice to the
others. Any such notice shall be deemed given when mailed, except that if any
time period commences
 
                                     A-11
<PAGE>
 
hereunder with notice, such time period shall be deemed to commence when such
notice is delivered or, if earlier, when postal records indicate delivery was
first attempted.
 
26. ESTOPPEL CERTIFICATES
 
  The Landlord and the Tenant hereby agree from time to time, each after not
less than ten (10) days' prior written notice from the other or any Mortgagee,
to execute, acknowledge and deliver, without charge, to the other party, the
Mortgagee or any other person designated by the other party, a statement in
writing certifying: that this Lease is unmodified and in full force and effect
(or if there have been modifications, identifying the same by the date thereof
and specifying the nature thereof); that to the knowledge of such party there
exist no defaults (or if there be any defaults, specifying the same); the
amount of the Basic Rent, the dates to which the Basic Rent, Additional Rent
and other sums and charges payable hereunder have been paid; and that such
party to its knowledge has no claims against the other party hereunder except
for the continuing obligations under this Lease (or if such party has any such
claims, specifying the same).
 
27. BIND AND INURE; LIMITED LIABILITY OF LANDLORD
 
  All of the covenants, agreements, stipulations, provisions, conditions and
obligations herein expressed and set forth shall be considered as running with
the land and shall extend to, bind and inure to the benefit of the Landlord
and the Tenant, which terms as used in this Lease shall include their
respective successors and assigns where the context hereof so admits.
 
  The Landlord shall not have any individual or personal liability for the
fulfillment of the covenants, agreements and obligations of the Landlord
hereunder, the Tenant's recourse and the Landlord's liability hereunder being
limited to the Property and the Building. The term "Landlord" as used in this
Lease shall refer only to the owner or owners from time to time of the
Property or the Building, it being understood that no such owner shall have
any liability hereunder for matters arising from and after the date such owner
ceases to have any interest in the Property or the Building.
 
  In no event shall the Landlord be liable to the Tenant for any special,
consequential or indirect damages suffered by the Tenant or any other person
or entity by reason of a default by the Landlord under any provisions of this
Lease.
 
28. ENVIRONMENTAL COMPLIANCE
 
  Tenant hereby covenants to Landlord that: (a) Tenant shall (i) comply with
all Laws applicable to the discharge, generation, manufacturing, removal,
transportation, treatment, storage, disposal and handling of Hazardous
Materials or Wastes as apply to the activities of the Tenant, its directors,
officers, employees, agents, contractors, subcontractors, licensees, invitees,
successors and assigns at the Premises, (ii) remove any Hazardous Materials or
Wastes from the Premises (other than such as preceded the Tenant's occupancy
of any portion of the Premises) immediately upon discovery of same if the same
are not being stored and used in accordance with all applicable Laws and
orders of governmental authorities having jurisdiction, (iii) pay or cause to
be paid all costs associated with such removal including restoration of the
Premises, and (iv) indemnify Landlord from and against all losses, claims and
costs arising out of the migration of Hazardous Materials or Wastes from or
through the Premises into or onto or under other properties; (b) Tenant shall
keep the Premises free of any lien imposed pursuant to any applicable Law in
connection with the existence of Hazardous Materials or Wastes in or on the
Premises; (c) Tenant shall not install or permit to be installed or to exist
in the Premises any asbestos, asbestos-containing materials, urea formaldehyde
insulation or except to the extent the same are stored and used in accordance
with all applicable laws and orders of governmental authorities having
jurisdiction any other chemical or substance which has been determined to be a
hazard to health and environment; (d) Tenant shall not cause or permit to
exist, as a result of an intentional or unintentional act or omission on the
part of Tenant or any occupant of the Premises, a releasing, spilling,
leaking, pumping, emitting, pouring, discharging, emptying or dumping of any
Hazardous Materials or Wastes onto the Premises; (e) Tenant shall give all
notifications and
 
                                     A-12
<PAGE>
 
prepare all reports required by Laws or any other law with respect to
Hazardous Materials or Wastes existing on, released from or emitted from the
Premises; (f) Tenant shall promptly notify Landlord in writing of any release,
spill, leak, emittance, pouring, discharging, emptying or dumping of Hazardous
Materials or Wastes in or on the Premises; and (g) Tenant shall promptly
notify Landlord in writing of any summons, citation, directive, notice, letter
or other communication, written or oral, from any local, state or federal
governmental agency, or of any claim or threat of claim known to Tenant, made
by any third party relating to the presence or releasing, spilling, leaking,
pumping, emitting, pouring, discharging, emptying or dumping of any Hazardous
Materials or Wastes onto the Premises. The foregoing covenants shall not apply
to Hazardous Materials or Wastes existing in the Premises prior to the date of
this Lease.
 
  The term "Hazardous Materials or Wastes" shall mean any hazardous or toxic
materials, pollutants, chemicals, or contaminants, including without
limitation asbestos, asbestos-containing materials, urea formaldehyde foam
insulation, polychlorinated biphenyls (PCBs) and petroleum products as
defined, determined or identified as such in any Laws, as hereinafter defined,
as well as any biomedical materials, products or substances generated, stored,
handled, disposed or otherwise used by the Tenant at the Premises. The term
"Laws" means any federal, state, county, municipal or local laws, rules or
regulations (whether now existing or hereinafter enacted or promulgated)
including, without limitation, the Clean Water Act, 33 U.S.C. (S) 1251 et seq.
1972), the Clean Air Act, 42 U.S.C.(S) 7401 et seq. (1970), the Comprehensive
Environmental Response, Compensation and Liability Act of 1980, as amended, 42
U.S.C. Subsection 1802, and The Resource Conservation and Recovery Act, 42
U.S.C. Subsection 6901 et seq., any similar state laws, as well as any
judicial or administrative interpretation thereof, including any judicial or
administrative orders or judgments.
 
  Tenant hereby agrees to defend, indemnify and hold harmless Landlord, its
employees, agents, contractors, subcontractors, licensees, invitees,
successors and assigns from and against any and all claims, losses, damages,
liabilities, judgements, costs and expenses (including, without limitation,
attorneys' fees and costs incurred in the investigation, defense and
settlement of claims or remediation of contamination) incurred by such
indemnified parties as a result of or in connection with the presence at or
removal of Hazardous Materials or Wastes from the Premises (except for
Hazardous Materials or Wastes existing at the Premises prior to the date of
this Lease) or as a result of or in connection with activities prohibited
under this Paragraph 28. Tenant shall bear, pay and discharge, as and when the
same become due and payable, any and all such judgments or claims for damages,
penalties or otherwise against such indemnified parties, shall hold such
indemnified parties harmless against all claims, losses, damages, liabilities,
costs and expenses, and shall assume the burden and expense of defending all
suits, administrative proceedings, and negotiations of any description with
any and all persons, political subdivisions or government agencies arising out
of any of the occurrences set forth in this Paragraph 28.
 
  The Landlord hereby agrees to defend, indemnify and hold the Tenant harmless
from and against any and all loss, cost, damage, claim or expense (including
attorneys' fees) incurred in connection with or arising out of or relating in
any way to the presence of Hazardous Materials or Waste existing at the
Premises prior to the Tenant's occupancy of any part thereof.
 
29. CAPTIONS
 
  The captions for the numbered Paragraphs of this Lease are provided for
reference only and they do not constitute a part of this agreement or any
indication of the intentions of the parties hereto.
 
30. INTEGRATION
 
  The parties acknowledge that all prior written and oral agreements between
them and all prior representations made by either party to the other have been
incorporated in this instrument or otherwise satisfied prior to the execution
hereof.
 
                                     A-13
<PAGE>
 
31. SEVERABILITY; CHOICE OF LAW
 
  If any provision of this Lease shall be declared to be void or unenforceable
either by law or by a court of competent jurisdiction, the validity or
enforceability of remaining provisions shall not thereby be affected.
 
  This Lease is made under, and shall be construed in accordance with, the
laws of The Commonwealth of Massachusetts.
 
32. SECURITY DEPOSIT
 
  The Landlord hereby acknowledges that the Tenant has previously paid to him
the amount of $8,479.17, which shall be held as a security for the Tenant's
performance as herein provided and refunded to the Tenant at the end of this
Lease subject to the Tenant's satisfactory compliance with the conditions
hereof.
 
  IN WITNESS WHEREOF, the parties hereto have caused this instrument to be
executed in quadruplicate under seal as of the date first above written.
 
                                          Landlord
 
                                                  /s/ Robert W. Connelly
                                          _____________________________________
                                                   Robert W. Connelly
 
                                          Tenant
 
                                          Cambridge Heart, Inc.
 
                                                   /s/ Jeffrey M. Arnold
                                          By: _________________________________
                                            Name:Jeffrey M. Arnold
                                            Title:Chief Executive Officer
 
                                     A-14
<PAGE>
 
                                                                      EXHIBIT A
 
                         LEGAL DESCRIPTION OF PREMISES
 
  A certain parcel of land situated in the Town of Bedford, County of
Middlesex, Commonwealth of Massachusetts, known as Lot 4, Land Court Case
11345 and more particularly described as follows:
 
BEGINNING            at the northeasterly corner of said parcel, same point
                     being on the westerly sideline of Middlesex Turnpike and
                     at land of Frost as shown on said plan;
 
THENCE               running along the westerly sideline of Middlesex Turnpike
                     S42(degrees) -51'-31'E Three Hundred Two and 28/100
                     (308.28) feet to a point of curvature
 
THENCE               turning and running by a curved line to the right having
                     an arc of Seventy-eight and 54/100 (78.54) and a radius
                     of Fifty (50.00) feet to a point of tangency on the
                     westerly sideline of Oak Park Drive;
 
THENCE               running along the westerly sideline of Oak Park Drive
                     S47(degrees) -08'-27'W One Hundred Forty-Eight and 50/100
                     (148.50) feet to a point;
 
THENCE               turning and running N59(degrees) -21'-30'W One Hundred
                     Fifty-Six and 23/100 feet to a point;
 
THENCE               turning and running S77(degrees) -25'-28'W Sixty-Six
                     (66.00) feet to a point
 
THENCE               turning and running N57(degrees) -43'-28'W Eighty-Nine
                     and 89/100 (89.89) feet to a point;
 
THENCE               turning and running N39(degrees) -45'-16'W Sixty-Three
                     and 89/100 (63.89) feet to a point;
 
THENCE               turning and running N43(degrees) -49'-21'E Three Hundred
                     Twenty (320.00) feet to the point of beginning.
 
  Subject to the matters set forth or referred to in the Landlord's Owner's
Duplicate Certificate of Title No. 167175.
 
                                     A-15