EXHIBIT 3.23(a)


                         CERTIFICATE OF INCORPORATION

                                      OF

                          AORT HOLDING COMPANY, INC.

                                   ARTICLE I

     The name of the corporation is AORT HOLDING COMPANY, INC. (the
"Corporation").

                                  ARTICLE II

     The address of the Corporation's registered office, in the County of New
Castle, is 900 Market Street, Wilmington, DE 19801. The name of the registered
agent at that address is Griffin Corporate Services, Inc.

                                  ARTICLE III

     The purpose of the Corporation is to engage in any lawful act or activity
for which corporations may be organized under the General Corporation Law of the
State of Delaware; provided that the Corporation's activities shall be confined
to the management and maintenance of its intangible investments and the
collection and distribution of the income from such investments or from tangible
property physically located outside Delaware, all as defined in, and in such
manner to qualify for exemption from income taxation under, Section 1902(b)(8)
of Title 30 of the Delaware Code, or under the corresponding provision of any
subsequent law.

                                  ARTICLE IV

     The total number of shares of all classes of stock which the Corporation
shall have authority to issue is one thousand (1,000), all of which shall be
common stock, $.01 par value per share ("Common Stock").

                                   ARTICLE V

     Board of Directors is expressly authorized to adopt, amend, alter or repeal
the bylaws of the Corporation.

                                  ARTICLE VI

     The Corporation shall have the right, subject to any express provisions or
restrictions contained in this certificate of incorporation from time to time,
to amend this certificate of incorporation or any provision hereof in any manner
now or hereafter provided by law, and all rights and powers at any time
conferred upon the directors or stockholders of the Corporation by this
certificate of incorporation or any amendment hereto are subject to such right
of the Corporation.


                                  ARTICLE VII

     The number of directors of the Corporation shall be determined in
accordance with the Corporation's bylaws. The number of directors constituting
the initial board of directors of the Corporation shall be three (3), which
directors shall be appointed by the incorporator.

                                 ARTICLE VIII

     No director shall be personally liable to the Corporation or its
stockholders for monetary damages for breach of fiduciary duty as a director,
except for liability (i) for any breach of the director's duty of loyalty to the
Corporation or its stockholders, (ii) for acts or omissions not in good faith or
which involve intentional misconduct or a knowing violation of law, (iii) under
Section 174 of the Delaware General Corporation Law, or (iv) for any transaction
from which the director derived an improper personal benefit.

     If the Delaware General Corporation Law is hereafter amended to authorize
the further elimination or limitation of the liability of a director, then the
liability of a director of the Corporation shall be eliminated or limited to the
fullest extent permitted by the Delaware General Corporation Law, as so amended.

     No repeal or modification of the foregoing provisions of this Article VIII
by the stockholders of the Corporation shall adversely affect any right or
protection of a director of the Corporation existing at the time of such repeal
or modification.

                                  ARTICLE IX

     Elections of directors of the Corporation need not be by written ballot.

                                   ARTICLE X

     Meetings of the stockholders will be held within the State of Delaware. The
books of the Corporation will be kept (subject to the provisions contained in
the General Corporation Law) in the State of Delaware at such place or places as
may be designated from time to time by the board of directors or in the by-laws
of the Corporation.

                                  ARTICLE XI

     The Corporation shall have no power and may not be authorized by its
stockholders or directors (i) to perform or omit to do any act that would cause
the Corporation to lose its status as a corporation exempt from the Delaware
Corporation income tax under Section 1902(b)(8) of Title 30 of the Delaware
Code, or under the corresponding provision of any subsequent law, or (ii) to
conduct any activities outside of Delaware which could result in the Corporation
being subject to tax outside of Delaware.

                                  ARTICLE XII



     The name and mailing address of the incorporator is as follows:

            Name                           Mailing Address
            ----                           ---------------

            Victoria L. Garrett            900 Market Street
                                           Wilmington, Delaware 19801

                                 ARTICLE XIII

     The powers of the incorporator shall terminate upon election of directors.

     I, the undersigned, being the incorporator hereinbefore named, for the
purpose of forming a corporation pursuant to the General Corporation Law of the
State of Delaware, do make this certificate, hereby declaring that this is my
act and deed and that the facts herein stated are true and accordingly have
hereunder set my hand this 1st day of May, 1996.

                                ________________________________________________
                                Victoria L. Garrett, Incorporator