Exhibit 3.2

AMENDED AND RESTATED

BYLAWS

OF

CARDIOVASCULAR SYSTEMS, INC.

(Delaware)

***

Article I

Offices

Section 1.1            Registered Office. The corporation shall maintain a registered office and registered agent in the State of Delaware. The registered office and/or registered agent of the corporation may be changed from time to time by action of the board of directors.

Section 1.2            Other Offices. The corporation may also have offices at such other places either within or outside the State of Delaware as the board of directors may from time to time determine or the business of the corporation may require.

Section 1.3            Books and Records. Books and records of the corporation may be kept at the corporation’s headquarters or such other location or locations, within or outside the State of Delaware, as may from time to time be designated by the board of directors.

Article II

Stockholders

Section 2.1            Action by Consent Without Meeting. Any action required or permitted to be taken at any annual or special meeting of stockholders of the corporation may be taken without a meeting, without prior notice and without a vote, if a consent in writing, setting forth the action so taken, shall be signed by the holders of outstanding stock having not less than the minimum number of votes that would be necessary to authorize or take such action at a meeting at which all shares entitled to vote thereon were present and voted and shall be delivered to the corporation by delivery to its principal place of business or to an officer or agent of the corporation having custody of the book in which proceedings of meetings of stockholders are recorded. Prompt notice of the taking of the corporate action without a meeting by less than unanimous written consent shall be given to those stockholders who have not consented in writing.

Section 2.2            Annual Elections. An annual election of directors shall be held either by written consent of stockholders without a meeting, under Section 2.1 of these bylaws, or at a meeting at such time as shall be determined by resolution of the board of directors, and duly called to be held at such hour and place either within or without the State of Delaware as may be stated in the call and notice. If the consent is less than unanimous, it will constitute a consent in lieu of the annual meeting only if all of the directorships to which directors could be elected at an annual meeting held at the effective time of the consent were (i) vacant at the effective time and (ii) filled by action of the consent.

Section 2.3            Special Meetings. Special meetings of stockholders may be held upon call of the president or a majority of the board of directors (and shall be called by the secretary upon written request, stating the purpose of the meeting, of stockholders who together own of record 25% of the outstanding stock of any class entitled to vote at such meeting), at such time and place either within or without the State of Delaware as may be stated in the call and notice.

Section 2.4            Notice of Meetings. Whenever stockholders are required or permitted to take any action at a meeting, a written notice of the meeting shall be given which shall state the place, if any, date, time and means of remote communication, if any, of the meeting, and, in the case of a special meeting, the purpose or purposes for which the meeting is called. Unless otherwise provided by law, the written notice of any meeting shall be given not less than ten nor more than sixty days before the date of the meeting to each stockholder entitled to vote at such meeting. If mailed, such notice shall be deemed to be given when deposited in the United States mail, postage prepaid, directed to the stockholder at their address as it appears on the records of the corporation.

Section 2.5            Adjournments. Any meeting of stockholders may adjourn from time to time to reconvene at the same or some other place, and notice need not be given of any such adjourned meeting if the time and place thereof are announced at the meeting at which the adjournment is taken. At the adjourned meeting the corporation may transact any business which might have been transacted at the original meetings. If the adjournment is for more than thirty days, a notice of the adjourned meeting shall be given to each stockholder of record entitled to vote at the meeting. If after the adjournment a new record date for stockholders entitled to vote is fixed for the adjourned meeting, the board of directors shall fix a new record date for notice of such adjourned meeting in accordance with Section 2.9 of these bylaws, and shall give notice of the adjourned meeting to each stockholder of record entitled to vote at such adjourned meeting as of the record date fixed for notice of such adjourned meeting.

Section 2.6            Quorum. At each meeting of stockholders, except where otherwise provided by law or the certificate of incorporation or these bylaws, the holders present in person or by proxy of a majority of the outstanding shares of each class of stock entitled to vote at the meeting shall constitute a quorum. For purposes of the foregoing, two or more classes or series of stock shall be considered a single class if entitled to vote together as a single class upon a particular election or question. In the absence of a quorum, the stockholders so present may, by majority vote, adjourn the meeting from time to time in the manner provided by Section 2.5 of these bylaws until a quorum shall attend.

Section 2.7            Organization. Meetings of stockholders shall be presided over by the president, or in their absence by a vice president, or in the absence of the foregoing persons by a chairperson chosen at the meeting. The secretary shall act as secretary of the meeting, but in their absence the chairperson of the meeting may appoint any person to act as secretary of the meeting.

Section 2.8            Voting; Proxies. Unless otherwise provided in the certificate of incorporation, each stockholder entitled to vote at any meeting of stockholders, or to express consent or dissent to corporate action in writing without a meeting, shall be entitled to one vote for each share of stock held by him which has voting power upon the matter in question. Each such stockholder may authorize another person or persons to act for him by proxy, but no such proxy shall be voted or acted upon after three years from its date, unless the proxy provides for a longer period. All elections of directors shall be by written ballot, unless otherwise provided in the certificate of incorporation; but voting on other questions by stockholders need not be by ballot and need not be conducted by inspectors. A plurality of the votes cast shall be sufficient for election of directors by stockholders. Unless otherwise provided by law, the certificate of incorporation or these bylaws, or a resolution of the board of directors, all other questions shall be decided by the vote of the holders of a majority of the outstanding shares of all classes of stock entitled to vote thereon present in person or by proxy at a meeting, or by written consent without a meeting of the number of votes required by Section 2.1 of these bylaws.

Section 2.9            Fixing Date for Determination of Stockholders of Record. In order that the corporation may determine the stockholders entitled to notice of or to vote at any meeting of stockholders or any adjournment thereof, or to express consent to corporate action in writing without a meeting, or entitled to receive payment of any dividend or other distribution or allotment of any rights, or entitled to exercise any rights in respect of any change, conversion or exchange of stock or for the purpose of any other lawful action, the board of directors may fix in advance a record date, which shall not be more than sixty nor less than ten days before the date of such meeting, nor more than sixty days prior to any other action. If no record date is fixed (i) the record date for determining stockholders entitled to notice of or to vote at a meeting of stockholders shall be at the close of business on the day next preceding the day on which notice is given, or, if notice is waived, at the close of business on the day next preceding the day on which the meeting is held and (ii) the record date for determining stockholders entitled to consent to corporate action in writing without a meeting, when no prior action by the board of directors is required by law, shall be the first date on which a signed written consent is delivered to the corporation. If no record date has been fixed by the board of directors and prior action by the board of directors is required by law, the record date for determining stockholders entitled to consent to corporate action in writing without a meeting shall be at the close of business on the day on which the board of directors adopts the resolution taking such prior action. The record date for determining stockholders for any purpose shall be at the close of business on the day on which the board of directors adopts the resolution relating thereto.

A determination of stockholders of record entitled to notice of or to vote at a meeting of stockholders shall apply to any adjournment of the meeting; provided, however, that the board of directors may fix a new record date for the adjourned meeting.

Article III

Board of Directors

Section 3.1            Management of Affairs of Corporation. The property and business of the corporation shall be managed by or under the direction of its board of directors. The board of directors may exercise all such powers of the corporation and do all such lawful acts and things as are not reserved exclusively to the stockholders by law, the certificate of incorporation or these bylaws.

Section 3.2            Number; Qualifications. The board of directors shall consist of one or more members. The number of directors shall be such as may be fixed from time to time either by stockholder action or by resolution of the board of directors. Directors need not be stockholders.

Section 3.3            Election; Resignation; Vacancies. Any director may resign at any time upon written notice to the corporation. Any vacancy occurring in the board of directors for any cause may be filled by a majority of the remaining members of the board of directors, although less than a quorum, or by a sole remaining director; or by a plurality of the votes cast at a meeting of stockholders; or by consent in writing signed by the holders of outstanding stock having not less than a majority of the votes of such stock. Whether elected at an annual election of directors or to fill an interim vacancy, each director shall hold office until the next succeeding annual election or until their successor is elected and qualified or until their earlier resignation or removal. Any director or the entire board of directors may be removed, with or without cause, by the holders of a majority of the shares then entitled to vote at an election of directors.

Section 3.4            Regular Meetings. Regular meetings of the board of directors may be held at such places within or without the State of Delaware and at such times as the board of directors may from time to time determine, and if so determined, notices thereof need not be given.

Section 3.5            Special Meetings. Special meetings of the board of directors may be held at any time or place within or without the State of Delaware whenever called by a quorum of the board of directors. At least two days’ notice thereof shall be given by the person or persons calling the meeting.

Section 3.6            Telephonic Meetings Permitted. Members of the board of directors, or any committee designated by the board of directors, may participate in a meeting of such board of directors or committee by means of conference telephone or similar communications equipment by means of which all persons participating in the meeting can hear each other, and participation in a meeting pursuant to this bylaw shall constitute presence in person at such meeting.

Section 3.7            Quorum. At all meetings of the board of directors a majority of the entire board of directors shall constitute a quorum for the transaction of business. Except in cases in which the certificate of incorporation or these bylaws otherwise provide, the vote of a majority of the directors present at a meeting at which a quorum is present shall be the act of the board of directors.

Section 3.8            Organization. Meetings of the board of directors shall be presided over by the president, or in their absence by a chairperson chosen at the meeting. The secretary shall act as secretary of the meeting, but in the secretary’s absence the chairperson of the meeting may appoint any person to act as secretary of the meeting.

Section 3.9            Informal Action by Directors. Any action required or permitted to be taken at any meeting of the board of directors, or of any committee thereof, may be taken without a meeting, if all members of the board of directors or of such committee, as the case may be, consent to the action in writing or by electronic transmission, and the writing or electronic transmission is filed with the minutes of proceedings of the board of directors or committee.

Article IV

Officers

Section 4.1            Executive Officers; Election; Qualifications; Term of Office; Resignations; Vacancies. The board of directors, as soon as practicable after the annual election of directors in each year, shall elect a president, a secretary, and it may, if it so determines, elect a chairperson of the board of directors who need not be a member, one or more vice presidents, a treasurer and such other officers as the board of directors shall determine. The board of directors may also choose one or more assistant officers. Any offices may be held, and the duties performed, by one and the same person. Each such officer shall hold office until the first meeting, or action by consent without a meeting, of the board of directors after the annual election of directors next succeeding their election, or until their successor is elected and qualified or until their earlier resignation or removal. Any officer may resign at any time upon written notice to the corporation. Any officer may be removed from office at any time by the affirmative vote of a majority of the members of the board of directors then in office. Any vacancy occurring in any office of the corporation by death, resignation, removal or otherwise may be filled for the unexpired portion of the term by the board of directors at any regular or special meeting, or by unanimous written consent without a meeting.

Section 4.2            Powers and Duties of Executive Officers. The officers of the corporation shall have such powers and duties as generally pertain to their respective offices, as well as such powers and duties as from time to time shall be conferred by these bylaws or the board of directors. The president shall, subject to the board of directors, have general direction and supervision of the business operations and affairs of the corporation. The chairperson of the board of directors shall have only such powers and authority as may be specifically delegated to him by the board of directors.

Article V

Stock

Section 5.1            Certificates. Every holder of stock shall be entitled to have a certificate signed by or in the name of the corporation by any two authorized officers of the corporation, certifying the number of shares owned by him in the corporation. Any of or all the signatures on the certificate may be facsimile. In case any officer, transfer agent, or registrar who has signed or whose facsimile signature has been placed upon a certificate shall have ceased to be such officer, transfer agent, or registrar before such certificate is issued, it may be issued by the corporation with the same effect as if they were such officer, transfer agent, or registrar at the date of issue.

Section 5.2            Lost, Stolen or Destroyed Stock Certificates; Issuance of New Certificates. The corporation may issue a new certificate of stock in the place of any certificate theretofore issued by it, alleged to have been lost, stolen or destroyed, and the corporation may require the owner of the lost, stolen or destroyed certificate, or their legal representative, to give the corporation a bond sufficient to indemnify it against any claim that may be made against it on account of the alleged loss, theft or destruction of any such certificate or the issuance of such new certificate.

Section 5.3            Transfer of Stock. Transfers of shares of stock shall be made only on the books of the corporation by the registered holder thereof or by its attorney or successor duly authorized as evidenced by documents filed with the secretary or transfer agent of the corporation. In the case of certificated shares, upon surrender to the corporation or the transfer agent of the corporation of a certificate for shares duly endorsed or accompanied by proper evidence of succession, assignment or authority to transfer, and in compliance with any restrictions on transfer of which the corporation has notice applicable to the certificate or shares represented thereby, the corporation shall issue a new certificate to the person entitled thereto, cancel the old certificate and record the transaction upon its books. The board of directors may adopt such additional rules and regulations as it deems advisable concerning the transfer and registration of certificates of stock of the corporation.

Article VI

Miscellaneous

Section 6.1            Fiscal Year. The fiscal year of the corporation shall be fixed by resolution of the board of directors. In the absence of such a resolution, the fiscal year of the corporation shall be the calendar year.

Section 6.2            Seal. The corporate seal shall have the name of the corporation inscribed thereon and shall be in such form as may be approved from time to time by the board of directors.

Section 6.3            Waiver of Notice of Meetings of Stockholders, Directors and Committees. Any written waiver of notice, signed by the person entitled to notice, whether before or after the time stated therein, shall be deemed equivalent to notice. The presence of a person at a meeting, or their participation in a telephonic meeting, shall constitute a waiver of notice, except when a person attends a meeting or participates in a telephonic meeting for the express purpose of objecting, at the beginning of the meeting, to the transaction of any business because the meeting is not lawfully called, convened or initiated. Neither the business to be transacted at, nor the purpose of, any regular or special meeting of the stockholders, directors or members of a committee of directors need be specified in any written waiver of notice.

Section 6.4            Indemnification of Directors, Officers, Employees and Other Agents.

(a)            Directors and Officers. The corporation shall indemnify its current and former directors and officers to the fullest extent not prohibited by the Delaware General Corporation Law (the “DGCL”) or any other applicable law; provided, however, that the corporation may modify the extent of such indemnification by individual contracts with its directors and officers; and, provided, further, that the corporation shall not be required to indemnify any director or officer in connection with any proceeding (or part thereof) initiated by such person unless (i) such indemnification is expressly required to be made by law, (ii) the proceeding was authorized by the board of directors of the corporation, (iii) such indemnification is provided by the corporation, in its sole discretion, pursuant to the powers vested in the corporation under the DGCL or any other applicable law, or (iv) such indemnification is required to be made under subsection (d). Except as provided in paragraph (f) of this Section 6.4, the corporation shall not be obligated to indemnify any director or officer in connection with any proceeding brought by or on behalf of the corporation against such director or officer that is authorized by the corporation’s board of directors.

(b)            Employees and Other Agents. The corporation shall have the power to indemnify its employees and other agents as set forth in the DGCL or any other applicable law. The board of directors shall have the power to delegate the determination of whether indemnification shall be given to any such person to such officers or other persons as the board of directors shall determine.

(c)            Expenses. The corporation shall advance to any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative, by reason of the fact that he is or was a director or officer of the corporation, or is or was serving at the request of the corporation as a director or officer of another corporation, partnership, joint venture, trust or other enterprise, prior to the final disposition of the proceeding, promptly following request therefor, all expenses actually and reasonably incurred by any director or officer in connection with such proceeding; provided, however, that if the DGCL requires, an advancement of expenses incurred by a director or officer in his or her capacity as a director or officer (and not in any other capacity in which service was or is rendered by such indemnitee, including, without limitation, service to an employee benefit plan) shall be made only upon delivery to the corporation of an undertaking, by or on behalf of such indemnitee, to repay all amounts so advanced if it shall ultimately be determined by final judicial decision from which there is no further right to appeal that such indemnitee is not entitled to be indemnified for such expenses under this Section 6.4 or otherwise.

Notwithstanding the foregoing, unless otherwise determined pursuant to paragraph (e) of this Section 6.4, no advance shall be made by the corporation to an officer of the corporation (except by reason of the fact that such officer is or was a director of the corporation in which event this paragraph shall not apply) in any action, suit or proceeding, whether civil, criminal, adnistrative or investigative, if a determination is reasonably and promptly made (i) by a majority vote of directors who were not parties to the proceeding, even if not a quorum, or (ii) by a committee of such directors designated by a majority vote of such directors, even though less than a quorum, or (iii) if there are no such directors, or such directors so direct, by independent legal counsel in a written opinion, that the facts known to the decision-making party at the time such determination is made demonstrate that such person acted in bad faith or in a manner that such person did not believe to be in or not opposed to the best interests of the corporaiton, or with respect to any criminal action or proceeding, that such person had reasonable cause to believe that his conduct was unlawful.

(d)            Enforcement. Without the necessity of entering into an express contract, all rights to indemnification and advances to directors and officers under these bylaws shall be deemed to be vested contractual rights and be effective to the same extent and as if provided for in a contract between the corporation and the director or officer. Such rights shall be deemed to have vested as of the effective date of these bylaws. Any right to indemnification or advances granted by this Section 6.4 to a director or officer shall be enforceable by or on behalf of the person holding such right in any court of competent jurisdiction if (i) the claim for indemnification or advances is denied, in whole or in part, or (ii) no disposition of such claim is made within ninety (90) days of request therefor. The claimant in such enforcement action, if successful in whole or in part, shall be entitled to be paid also the expense of prosecuting the claim. In connection with any claim for indemnification, the corporation shall be entitled to raise as a defense to any such action that the claimant has not met the standards of conduct that make it permissible under the DGCL or any other applicable law for the corporation to indemnify the claimant for the amount claimed. In connection with any claim by an officer of the corporation (except in any action, suit or proceeding, whether civil, criminal, administrative or investigative, by reason of the fact that such officer is or was a director of the corporation) for advances, the corporation shall be entitled to raise a defense as to any such action evidence that such person acted in bad faith or in a manner that such person did not believe to be in or not opposed to the best interests of the corporation, or with respect to any criminal action or proceeding that such person acted without reasonable cause to believe that his conduct was lawful. Neither the failure of the corporation (including the board of directors, independent legal counsel or its stockholders) to have made a determination prior to the commencement of such action that indemnification of, or advancement to, the claimant is proper in the circumstances because he has met the applicable standard of conduct set forth in the DGCL or any other applicable law, nor an actual determination by the corporation (including its board of directors, independent legal counsel or its stockholders) that the claimant has not met such applicable standard of conduct, shall be a defense to the action or create a presumption that claimant has not met the applicable standard of conduct. In any suit brought by a director or officer to enforce a right to indemnification or to an advancement of expenses hereunder, the burden of proving that the director or officer is not entitled to be indemnified, or to such advancement of expenses, under this Section 6.4 or otherwise shall be on the corporation.

(e)            Non-Exclusivity of Rights. The rights conferred on any person by these bylaws shall not be exclusive of any other right which such person may have or hereafter acquire under any applicable statute, provision of the Certificate of Incorporation, bylaws, agreement, vote of stockholders, or disinterested directors or otherwise, both as to action in his official capacity and as to action in another capacity while holding office. The corporation is specifically authorized to enter into individual contracts with any or all of its directors, officers, employees or agents respecting indemnification and advances, to the fullest extent not prohibited by the DGCL, or by any other applicable law.

(f)            Indemnification for Expenses of Successful Party. Notwithstanding the limitations of any other provisions of these bylaws, to the extent that a director or officer is successful on the merits or otherwise in defense of any proceeding, or in defense of any claim, issue or matter therein, including, without limitation, the dismissal of any action without prejudice, or if it is ultimately determined that the director or officer is otherwise entitled to be indemnified against expenses, the director and/or officer shall be indemnified against all expenses actually and reasonably incurred in connection therewith. If the director or officer is partially successful on the merits or otherwise in defense of any proceeding, such indemnification shall be apportioned appropriately to reflect the degree of success.

(g)            Survival of Rights. The rights conferred on any person by these bylaws shall continue as to a person who has ceased to be a director, officer, employee or other agent and shall inure to the benefit of the heirs, executors and administrators of such a person.

(h)            Insurance. To the fullest extent permitted by the DGCL or any other applicable law, the corporation, upon approval by the board of directors, may purchase insurance on behalf of any person required or permitted to be indemnified pursuant to this Section 6.4.

(i)            Amendments. Any repeal or modification of this Section 6.4 shall only be prospective and shall not affect the rights under these bylaws in effect at the time of the alleged occurrence or any action or omission to act that is the cause of any proceeding against any agent of the corporation.

(j)            Saving Clause. If these bylaws or any portion hereof shall be invalidated on any ground by any court of competent jurisdiction, then the corporation shall nevertheless indemnify each director and officer to the full extent not prohibited by any applicable portion of this Section 6.4 that shall not have been invalidated, or by any other applicable law. If this Section 6.4 shall be invalid due to the application of the indemnification provisions of another jurisdiction, then the corporation shall indemnify each director and officer to the full extent under any other applicable law.

(k)            Certain Definitions. For purposes of these bylaws, the following definitions shall apply:

(i)            The term “proceeding” shall be broadly construed and shall include, without limitation, the investigation, preparation, prosecution, defense, settlement, arbitration and appeal of, and the giving of testimony in, any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative.

(ii)           The term “expenses” shall be broadly construed and shall include, without limitation, court costs, attorneys’ fees, witness fees, fines, amounts paid in settlement or judgment and any other costs and expenses of any nature or kind incurred in connection with any proceeding.

(iii)          The term the “corporation” shall include, in addition to the resulting corporation, any constituent corporation (including any constituent of a constituent) absorbed in a consolidation or merger which, if its separate existence had continued, would have had power and authority to indemnify its directors, officers, and employees or agents, so that any person who is or was a director, officer, employee or agent of such constituent corporation, or is or was serving at the request of such constituent corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, shall stand in the same position under the provisions of this Section 6.4 with respect to the resulting or surviving corporation as he would have with respect to such constituent corporation if its separate existence had continued.

(iv)          References to a “director,” “officer,” “employee,” or “agent” of the corporation shall include, without limitation, situations where such person is serving at the request of the corporation as, respectively, a director, officer, employee, trustee or agent of another corporation, partnership, joint venture, trust or other enterprise.

(v)           References to “other enterprises” shall include employee benefit plans; references to “fines” shall include any excise taxes assessed on a person with respect to an employee benefit plan; and references to “serving at the request of the corporation’ shall include any service as a director, officer, employee, or agent of the corporation which imposes duties on, or involves services by, such director, officer, employee, or agent with respect to an employee benefit plan, its participants, or beneficiaries; and a person who acted in good faith and in a manner he reasonably believed to be in the interest of the participants and beneficiaries of an employee benefit plan shall be deemed to have acted in a manner “not opposed to the best interests of the corporation” as referred to in this Section 6.4.

Section 6.5            Insurance. In addition to Section 6.4(h) of these bylaws, if authorized by the board of directors, the corporation may purchase and maintain insurance on behalf of any person who is or was a director, officer, employee or agent of the corporation, or who is or has served at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, to the full extent permitted by the DGCL as in effect at the time of the adoption of these bylaws or as amended from time to time.

Section 6.6            Amendment of Bylaws. These bylaws may be altered, amended or repealed by (i) the affirmative vote of a majority of the stock having voting power present in person or by proxy at any annual meeting of stockholders at which a quorum is present, or at any special meeting of stockholders at which a quorum is present, if notice of the proposed alteration, amendment or repeal is contained in the notice of such special meeting, or (ii) the affirmative vote of a majority of the directors then qualified and acting at any regular or special meeting of the board, if the certificate of incorporation confers such power upon the board; provided, however, that the stockholders may provide specifically for limitations on the power of directors to amend particular bylaws and, in such event, the directors’ power of amendment shall be so limited; and further provided that no reduction in the number of directors shall have the effect of removing any director prior to the expiration of such director’s term of office.