<PAGE>
                                                                    EXHIBIT 10.4

                                PLEDGE AGREEMENT

         PLEDGE AGREEMENT dated October 11, 2001, by and between Jens Dalsgaard
(the "Guarantor") and Hypertension Diagnostics, Inc. (the "Secured Party").

                                    RECITALS

         NOW, THEREFORE, in order to secure the payment and performance of (a)
that certain Guaranty dated October 11, 2001 by Jens Dalsgaard, which guarantees
performance of that certain Note dated October 11, 2001 in the principal amount
of $75,000 made by Redwood Consultants, LLC in favor of the Secured Party, and
(b) all modifications, amendments, renewals, replacements and substitutes
thereof (hereafter collectively referred to as the "Obligations"), and in
consideration of the premises and the mutual covenants of the parties
hereinafter set forth, it is agreed:

1.   As collateral for the payment and performance of the Obligations, Guarantor
     hereby grants a security interest to Secured Party in all of the
     Guarantor's interest in 70,000 shares of the Common Stock, $.01 par value
     of Hypertension Diagnostic, Inc. (which together with any additional
     securities, subscriptions, rights, warrants, or options received by Secured
     Party under the terms of this Agreement shall hereinafter be referred to as
     "Pledged Securities"). Guarantor shall endorse certificates (and/or
     assignments) to Secured Party. The Pledged Securities shall be held by the
     Secured Party and disposed of pursuant to the terms of this Agreement.

2.   Guarantor agrees at any time, and from time to time, to execute such other
     instruments and perform such other acts as Secured Party may reasonably
     request to establish, maintain and perfect the security interest in the
     Pledged Securities conveyed by this Agreement.

3.   The Pledged Securities shall, so long as the Obligations remain
     outstanding, be subject to a "stop transfer" order which shall prohibit the
     transfer of the Pledged Securities. The term "transfer" shall mean any
     proposed disposition of the Pledged Securities by any means whatsoever,
     including, without limitation (i) the voluntary sale, delivery, assignment,
     gift, devise, exchange or other transfer of the Pledged Securities; (ii)
     pledge, hypothecation or other encumbrance of the Pledged Securities; (iii)
     adjudication of Shareholder as bankrupt, Guarantor's assignment of his
     interest in the Pledged Securities, or any attachment, levy or other
     seizure of the Pledged Securities by any creditor, whether or not pursuant
     to the judicial process; or (iv) passage or distribution of such Pledged
     Securities under judicial order or legal process to any person other than
     Guarantor, including a guardian, trustee or conservator of such Pledged
     Securities. Any attempted transfer in contravention of this Agreement shall
     be null and void. Guarantor agrees at any time, and from time to time, to
     execute such other instruments and perform such other acts as Secured Party
     may reasonably request to establish and maintain such "stop transfer"
     order.

4.   In the event that during the term of this Agreement:

     a.   Any share dividend, reclassification, readjustment, or other change is
          declared or made in the capital structure of an issuer of the Pledged
          Securities, all new, substituted, and additional shares, or other
          securities issued by reason of any such change shall be held


<PAGE>

          by Secured Party under the terms of this Agreement in the same manner
          as, and as a part of, the Pledged Securities;

     b.   Subscriptions, warrants, substitute securities or any other rights or
          options shall be issued to Guarantor by an issuer of the Pledged
          Securities, or additional shares of Pledged Securities shall be
          acquired by Guarantor, such subscriptions, warrants, rights, options
          and additional shares shall be assigned immediately by Guarantor to
          Secured Party, to be held under the terms of this Agreement in the
          same manner as, and as a part of, the Pledged Securities.

5.   Upon full performance of all of the Obligations, Secured Party shall
     transfer to Guarantor all of the Pledged Securities (and any assignments
     separate from certificate), and all rights received by Secured Party under
     this Agreement shall terminate.

6.   Each of the following occurrences shall constitute an event of default
     under this Agreement (herein called "Event of Default"):

     a.   Guarantor shall fail to pay any or all of the Obligations when due or
          (if payable on demand) on demand;

     b.   Any representation or warranty by Guarantor set forth in this
          Agreement shall prove to have been incorrect in any material respect
          or misleading when made; and

     c.   Default in the performance of any other covenant or agreement of the
          Guarantor in, or pursuant to, this Agreement;

     d.   The Guarantor shall generally not pay Guarantor's debts as such debts
          become due, or shall admit in writing the inability to pay Guarantor's
          debts generally, or shall make a general assignment for the benefit of
          creditors; or any proceeding shall be instituted by or against the
          Guarantor, seeking to adjudicate Guarantor bankrupt or insolvent, or
          seeking liquidation, reorganization, arrangement, adjustment,
          custodianship, protection, relief, or composition of Guarantor's debts
          under any law relating to bankruptcy, insolvency or reorganization or
          relief of debtors, or seeking the entry of an order for relief, or the
          appointment of a receiver, custodian, trustee, or other similar
          official for Guarantor or for any substantial part of the Guarantor's
          property; or the Guarantor shall take any action to authorize any of
          the actions set forth above in this subparagraph (d);

     e.   The Guarantor shall fail to pay any debt (other than the debt
          evidenced by this Note) of the Guarantor, or any interest or premium
          thereon, when due (whether by scheduled maturity, required prepayment,
          acceleration, demand or otherwise) and such failure shall continue
          after the applicable grace period, if any, specified in the agreement
          or instrument relating to such debt; or any other default under any
          agreement or instrument relating to any such debt, or any other event,
          shall occur and shall continue after the applicable grace period, if
          any, specified in such agreement or instrument, if the effect of such
          default or event is to accelerate, or to permit the acceleration of,
          the maturity of such debt; or any such debt shall be declared to be
          due and payable, or required to be prepaid (other than by a regularly
          scheduled required prepayment) prior to the stated maturity thereof;

                                       2

<PAGE>

     f.   The entry against the Guarantor of a final judgment, decree or order
          for the payment of money in excess of $5,000 and the continuance of
          such judgment, decree or order unsatisfied for a period of 30 days
          without a stay of execution;

     g.   Secured Party shall at any time in good faith believe that the
          prospect of due and punctual payment at maturity of this Guaranty is
          impaired.

7.   Upon the occurrence of an Event of Default and at any time thereafter,
     Secured Party may exercise any one or more of the following rights or
     remedies:

     a.   Declare all unmatured Obligations to be immediately due and payable,
          and the same shall thereupon be immediately due and payable, without
          presentment or other notice or demand;

     b.   Exercise all voting and other rights as a holder of the Pledged
          Securities, which proxy shall be coupled with an interest;

     c.   Exercise and enforce any or all rights and remedies available upon
          default to a secured party under the Uniform Commercial Code,
          including the right to offer and sell the Pledged Securities privately
          to purchasers who will agree to take the Pledged Securities for
          investment and not with a view to distribution and who will agree to
          the imposition of restrictive legends on any certificates representing
          the Pledged Securities, and the right to arrange for a sale which
          would otherwise qualify as exempt from registration under the
          Securities Act of 1933; and if notice to Guarantor of any intended
          disposition of the Pledged Securities or any other intended action is
          required by law in a particular instance, such notice shall be deemed
          commercially reasonable if given at least ten (10) calendar days prior
          to the date of intended disposition or other action; and

     d.   Exercise or enforce any or all other rights or remedies available to
          Secured Party by law or agreement against the Pledged Securities,
          against Guarantor or against any other person or property. Upon the
          occurrence of the Event of Default described in Section 5(e), all
          Obligations shall be immediately due and payable without demand or
          notice thereof.

8.   The proceeds of any sale of all or a part of the Pledged Securities shall
     be applied as follows:

     a.   First, to the payment of all costs and expenses incurred by Secured
          Party in enforcing its rights under this Agreement, including without
          limitation the fees of attorneys or other agents employed by Secured
          Party in connection therewith;

     b.   Second, to the payment of all of the Obligations; and

     c.   Third, any surplus remaining after application of the proceeds
          pursuant to subsections (a) and (b) above shall be paid to Guarantor,
          Guarantor's successors or assigns. Guarantor shall remain liable to
          Secured Party for any deficiency.

                                       3

<PAGE>

9.   The parties agree as follows:

     a.   No waiver of any of the provisions or conditions of this Agreement
          shall be effective unless such waiver is in writing and signed by the
          party claimed to have given, or consented to, such waiver;

     b.   No failure on the part of Secured Party to exercise, and no delay on
          the part of Secured Party in exercising, any right, power or remedy
          pursuant to this Agreement shall operate as a waiver thereof, nor
          shall any single or partial exercise by Secured Party of any right,
          power or remedy hereunder preclude any other or further exercise
          thereof or the exercise of any other right, power or remedy. The
          remedies herein provided are cumulative and shall not be exclusive of
          any other remedies provided by law or agreement;

     c.   Each certificate or other instrument representing the Pledged
          Securities may, at Secured Party's option, be marked with a legend to
          the effect that such shares are subject to the terms of this
          Agreement;

     d.   The terms and conditions of this Agreement shall inure to the benefit
          of, and be binding upon, the respective legal representatives,
          successors and assigns of the parties; provided, Guarantor may not
          assign this Agreement or Guarantor's obligations, duties, or
          liabilities hereunder without the express, prior written consent of
          the Secured Party;

     e.   This Agreement is delivered and is intended to be performed in the
          State of Minnesota and should be construed and enforced in accordance
          with the laws of such State, without reference to the laws of
          conflicts of laws; and

     f.   All notices, requests, demands and other communications hereunder
          shall be in writing and shall be deemed to have been given when
          personally delivered or deposited in the United States mail, mailed
          first class, registered or certified, postage prepaid, addressed as
          follows:

     g.   If to the Guarantor:

          Jens Dalsgaard
          171 Del Oro Lagoon
          Novato, CA  94949

     or at such other address as Guarantor shall have advised the Secured Party
     in writing; and

     h.   If to the Secured Party:

          Hypertension Diagnostics, Inc.
          Attn: President
          2915 Waters Road
          Suite 108
          Eagan, MN 55121-1562

or at such other address as the Secured Party shall have advised the Guarantor
in writing.

10.  This Agreement may be executed in any number of counterparts, each of which
     shall be deemed an original, but all of which together shall constitute one
     and the same instrument;

                                       4

<PAGE>

11.  This Agreement may not be amended except by written agreement executed by
     all parties hereto;

12.  If any provision or application of this Agreement is held unlawful or
     unenforceable in any respect, such illegality or unenforceability shall not
     affect other provisions or applications which can be given effect, and this
     Agreement shall be construed as if the unlawful or unenforceable provision
     or application had never been contained herein or prescribed hereby;

13.  All representations and warranties contained in this Agreement shall
     survive the execution, delivery, and performance of this Agreement and any
     other document or instruments executed or delivered in connection with or
     pursuant to any of the foregoing.

14.  The Guarantor has had the opportunity to consult with legal counsel of
     Guarantor's own choosing and has done so to the extent Guarantor believes
     necessary and appropriate in Guarantor's sole judgment.


     IN WITNESS WHEREOF, the parties have executed this Agreement as of the day
and year first above written.

                                            GUARANTOR:


                                            /s/ Jens Dalsgaard
                                            ------------------------------------
                                            Jens Dalsgaard


                                            SECURED PARTY:

                                            HYPERTENSION DIAGNOSTICS, INC.

                                            By: /s/ Greg H. Guettler
                                                --------------------------------
                                                    Greg H. Guettler, President


SPOUSAL ACKNOWLEDGEMENT: The undersigned spouse of Jens Dalsgaard (a)
acknowledges that she has read and understands the terms of this Pledge
Agreement and covenants and agrees to be bound by the terms of this Pledge
Agreement to the extent her interests are affected thereby, (b) consents and
agrees to her spouse's entering into this Pledge Agreement and the documents and
instruments contemplated thereby, (c) consents and agrees to the pledge of the
Pledged Securities to the Secured Party, (d) agrees that the Secured Party will
take the Pledged Securities free and clear of any right, interest or claim by
the undersigned.


                                            /s/ Giuliana Dalsgaard
                                            ------------------------------------
                                            Signature


                                            Giuliana Dalsgaard
                                            ------------------------------------

                                       5

<PAGE>

                                   Print Name


The undersigned, Jens Dalsgaard, is an unmarried man.


-----------------------------------
Jens Dalsgaard






                                       6