SC 13D/A

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C.  20549

SCHEDULE 13D/A

Amendment No. 1

Under the Securities Exchange Act of 1934

Thoratec Corporation

‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾

(Name of Issuer)

Common Stock, no par value per share

‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾

(Title of Class of Securities)

885175 30 7

‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾

(CUSIP Number)

Copy to:

Robert L. Lawrence, Esq.

Kane Kessler, P.C.

1350 Avenue of the Americas, 26th Floor

New York, New York 10019

(212) 541-6222

 (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

December 5, 2011

‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾

(Date of Event which requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition which is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box [ ]

1	NAME OF REPORTING PERSON Oracle Partners, L.P.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions) (a)  X (b)
3	SEC USE ONLY
4	SOURCE OF FUNDS*  OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) [  ]
6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 0  (See Item 5)
		8	SHARED VOTING POWER 2,173,046    (See Item 5)
		9	SOLE DISPOSITIVE POWER 0  (See Item 5)
		10	SHARED DISPOSITIVE POWER 2,173,046    (See Item 5)
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,173,046    (See Item 5)
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES* [  ]
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 3.63%
14	TYPE OF REPORTING PERSON* PN

2

1	NAME OF REPORTING PERSON Oracle Associates, LLC
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions) (a) X (b)
3	SEC USE ONLY
4	SOURCE OF FUNDS* OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) [   ]
6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER  0 (See Item 5)
		8	SHARED VOTING POWER  2,489,446   (See Item 5)
		9	SOLE DISPOSITIVE POWER 0   (See Item 5)
		10	SHARED DISPOSITIVE POWER 2,489,446   (See Item 5)
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 2,489,446 (See Item 5)
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES* [   ]
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 4.15%
14	TYPE OF REPORTING PERSON* OO

3

1	NAME OF REPORTING PERSON Larry N. Feinberg
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions) (a)  X (b)
3	SEC USE ONLY
4	SOURCE OF FUNDS* OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) [   ]
6	CITIZENSHIP OR PLACE OF ORGANIZATION United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 0  (See Item 5)
		8	SHARED VOTING POWER 3,115,999  (See Item 5)
		9	SOLE DISPOSITIVE POWER 0 (See Item 5)
		10	SHARED DISPOSITIVE POWER 3,115,999  (See Item 5)
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON   3,115,999  (See Item 5)
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES* [X]
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 5.20%
14	TYPE OF REPORTING PERSON* IN

4

1	NAME OF REPORTING PERSON Oracle Institutional Partners, LP
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions) (a)  X (b)
3	SEC USE ONLY
4	SOURCE OF FUNDS* OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) [   ]
6	CITIZENSHIP OR PLACE OF ORGANIZATION DELAWARE
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 0 (See Item 5)
		8	SHARED VOTING POWER 316,400   (See Item 5)
		9	SOLE DISPOSITIVE POWER 0    (See Item 5)
		10	SHARED DISPOSITIVE POWER 316,400    (See Item 5)
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON  316,400  (See Item 5)
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES* [   ]
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0.53%
14	TYPE OF REPORTING PERSON* PN

5

1	NAME OF REPORTING PERSON Oracle Offshore Limited
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions) (a) X (b)
3	SEC USE ONLY
4	SOURCE OF FUNDS* OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) [   ]
6	CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER  0 (See Item 5)
		8	SHARED VOTING POWER 36,070    (See Item 5)
		9	SOLE DISPOSITIVE POWER  0 (See Item 5)
		10	SHARED DISPOSITIVE POWER 36,070    (See Item 5)
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON  36,070  (See Item 5)
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES* [   ]
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0.06%
14	TYPE OF REPORTING PERSON* OO

6

1	NAME OF REPORTING PERSON Oracle Ten Fund Master, LP
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions) (a)  X (b)
3	SEC USE ONLY
4	SOURCE OF FUNDS* OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) [   ]
6	CITIZENSHIP OR PLACE OF ORGANIZATION Cayman Islands
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER  0 (See Item 5)
		8	SHARED VOTING POWER 562,383  (See Item 5)
		9	SOLE DISPOSITIVE POWER  0 (See Item 5)
		10	SHARED DISPOSITIVE POWER  562,383  (See Item 5)
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON  562,383 (See Item 5)
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES* [   ]
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0.94%
14	TYPE OF REPORTING PERSON* OO

7

1	NAME OF REPORTING PERSON Oracle Investment Management, Inc. Employee’s Retirement Plan
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions) (a)  X (b)
3	SEC USE ONLY
4	SOURCE OF FUNDS* OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) [   ]
6	CITIZENSHIP OR PLACE OF ORGANIZATION Connecticut
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER  0 (See Item 5)
		8	SHARED VOTING POWER 23,000    (See Item 5)
		9	SOLE DISPOSITIVE POWER 0 (See Item 5)
		10	SHARED DISPOSITIVE POWER 23,000    (See Item 5)
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 23,000  (See Item 5)
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES* [   ]
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0.04%
14	TYPE OF REPORTING PERSON* EP

8

1	NAME OF REPORTING PERSON The Feinberg Family Foundation
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions) (a)  X (b)
3	SEC USE ONLY
4	SOURCE OF FUNDS* OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) [   ]
6	CITIZENSHIP OR PLACE OF ORGANIZATION Connecticut
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER  0 (See Item 5)
		8	SHARED VOTING POWER 5,100    (See Item 5)
		9	SOLE DISPOSITIVE POWER  0 (See Item 5)
		10	SHARED DISPOSITIVE POWER 5,100 (See Item 5)
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 5,100  (See Item 5)
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES* [   ]
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 0.01%
14	TYPE OF REPORTING PERSON* OO

9

1	NAME OF REPORTING PERSON Oracle Investment Management, Inc.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See Instructions) (a)  X (b)
3	SEC USE ONLY
4	SOURCE OF FUNDS* OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEMS 2(d) or 2(e) [   ]
6	CITIZENSHIP OR PLACE OF ORGANIZATION Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 0  (See Item 5)
		8	SHARED VOTING POWER 621,453 (See Item 5)
		9	SOLE DISPOSITIVE POWER 0  (See Item 5)
		10	SHARED DISPOSITIVE POWER 621,453     (See Item 5)
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 621,453   (See Item 5)
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES* [   ]
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 1.04%
14	TYPE OF REPORTING PERSON* CO

10

Item 1.  Security and Issuer.

This Amendment No. 1 (the “Amendment”) amends the Schedule 13D originally filed with the Securities and Exchange Commission on June 16, 2011 (collectively, the “Statement”) with respect to the shares of common stock, no par value per share (the “Shares”) of Thoratec Corporation (the “Issuer”), whose principal executive offices are located at 6035 Stoneridge Drive, Pleasanton, California.

Item 4.  Purpose of the Transaction

Item 4 of the Statement is hereby amended and restated as follows:

This Statement is filed by the Reporting Persons to report acquisitions of shares of Common Stock for investment purposes, as a result of which the Reporting Persons may be deemed to be the beneficial owner (as that term is defined under Rule 13d-3 under the Exchange Act of 1934, as amended) of more than 5% of the outstanding Shares of the Issuer.

On December 5, 2011, the Manager sent a letter (the “Letter”) to the Issuer’s Board of Directors stating the Manager’s belief that the Issuer will be unable to maximize shareholder value as an independent public company and urging the Board to retain an investment bank to conduct an auction to find a suitable acquirer for the Issuer.  The Manager also issued a press release on December 5, 2011 announcing the delivery and setting forth the text of the letter. A copy of the Letter is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

The Reporting Persons intend to review their investment in the Issuer on a continuing basis, and to the extent permitted by law, may continue to seek to engage in discussions with other stockholders and/or with management and the Board of Directors of the Issuer concerning the business, operations or future business and strategic plans of the Issuer and composition of the Board of Directors. Depending on various factors including, without limitation, the Issuer's financial position, the price levels of the Common Stock, conditions in the securities markets and general economic and industry conditions, the Reporting Persons may take such actions with respect to his  investment in the Issuer as they deem appropriate in order to protect and maximize the value of their investment including, without limitation, purchasing additional Common Stock, selling Common Stock, engaging in hedging or similar transactions with respect to the Common Stock, generally taking a more active role in influencing the Issuer’s affairs, or taking any other action with respect to the Issuer or any of its securities in any manner permitted by law, including with respect to any and all matters referred to in paragraphs (a) through (j) of Item 4.

Item 5.   Interest in Securities of the Issuer.

 Items 5 is hereby amended and restated as follows:

The aggregate percentage of Shares reported owned by each person named herein is based upon 59,927,911 Shares outstanding as of October 21, 2011, which is the total number of Shares outstanding as reported in the Issuer’s Quarterly Report on Form 10-Q, filed with the Securities and Exchange Commission on November 7, 2011.

(a, b)           Partners

As of the date hereof, Partners may be deemed to be the beneficial owner of 2,173,046 Shares, constituting approximately 3.63% of the Shares outstanding.

11

Partners has the sole power to vote or direct the vote of 0 Shares; has the shared power to vote or direct the vote of 2,173,046 Shares; has sole power to dispose or direct the disposition of 0 Shares; and has shared power to dispose or direct the disposition of 2,173,046 Shares.

 In addition, Partners, as a member of a “group” with the other Reporting Persons for the purposes of Section 13(d)(3) of the Securities Exchange Act of 1934, as amended, may be deemed to be the beneficial owner of the Shares beneficially owned in the aggregate by the other members of the group reported herein.  The filing of this Schedule 13D and any future amendment by the Reporting Persons, and the inclusion of information herein shall not be considered an admission by Partners and Partners specifically disclaims that, for the purpose of Section 16(b) of the Exchange Act, it is the beneficial owner of any Shares in which it does not have a pecuniary interest.

(a, b)           General Partner

General Partner, as the general partner of Partners and Institutional Partners, may be deemed to be the indirect beneficial owner of 2,489,446 Shares held in Partners and Institutional Partners, constituting approximately 4.15% of the Shares outstanding.

General Partner has the sole power to vote or direct the vote of 0 Shares; has the shared power to vote or direct the vote of 2,489,446 Shares; has sole power to dispose or direct the disposition of 0 Shares; and has shared power to dispose or direct the disposition of 2,489,446 Shares.

In addition, General Partner, as a member of a “group” with the other Reporting Persons for the purposes of Section 13(d)(3) of the Securities Exchange Act of 1934, as amended, may be deemed to be the beneficial owner of the Shares beneficially owned in the aggregate by the other members of the group reported herein.  The filing of this Schedule 13D and any future amendment by the Reporting Persons, and the inclusion of information herein shall not be considered an admission by General Partner and General Partner specifically disclaims that, for the purpose of Section 16(b) of the Exchange Act, it is the beneficial owner of any Shares in which it does not have a pecuniary interest.

(a, b)           Manager

Manager, as the investment manager of Offshore Limited, Ten Fund and Retirement Plan, may be deemed to be the indirect beneficial owner of 621,453 Shares held in Offshore Limited, Ten Fund and Retirement Plan, constituting approximately 1.04% of the Shares outstanding.

Manager has the sole power to vote or direct the vote of 0 Shares; has the shared power to vote or direct the vote of 621,453 Shares; has sole power to dispose or direct the disposition of 0 Shares; and has shared power to dispose or direct the disposition of 621,453 Shares.

In addition, Manager, as a member of a “group” with the other Reporting Persons for the purposes of Section 13(d)(3) of the Securities Exchange Act of 1934, as amended, may be deemed to be the beneficial owner of the Shares beneficially owned in the aggregate by the other members of the group reported herein.  The filing of this Schedule 13D and any future amendment by the Reporting Persons, and the inclusion of information herein shall not be considered an admission by Manager and Manager specifically disclaims that, for the purpose of Section 16(b) of the Exchange Act, it is the beneficial owner of any Shares in which it does not have a pecuniary interest.

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(a, b)           Institutional Partners

As of the date hereof, Institutional Partners may be deemed to be the beneficial owner of 316,400 Shares, constituting approximately 0.53% of the Shares outstanding.

Institutional Partners has the sole power to vote or direct the vote of 0 Shares; has the shared power to vote or direct the vote of 316,400 Shares; has sole power to dispose or direct the disposition of 0 Shares; and has shared power to dispose or direct the disposition of 316,400 Shares.

 In addition, Institutional Partners, as a member of a “group” with the other Reporting Persons for the purposes of Section 13(d)(3) of the Securities Exchange Act of 1934, as amended, may be deemed to be the beneficial owner of the Shares beneficially owned in the aggregate by the other members of the group reported herein.  The filing of this Schedule 13D and any future amendment by the Reporting Persons, and the inclusion of information herein shall not be considered an admission by Institutional Partners and Institutional Partners specifically disclaims that, for the purpose of Section 16(b) of the Exchange Act, it is the beneficial owner of any Shares in which it does not have a pecuniary interest.

(a, b)           Offshore Limited

As of the date hereof, Offshore Limited may be deemed to be the beneficial owner of 36,070 Shares, constituting approximately 0.06% of the Shares outstanding.

Offshore Limited has the sole power to vote or direct the vote of 0 Shares; has the shared power to vote or direct the vote of 36,070 Shares; has sole power to dispose or direct the disposition of 0 Shares; and has shared power to dispose or direct the disposition of 36,070 Shares.

In addition, Offshore Limited, as a member of a “group” with the other Reporting Persons for the purposes of Section 13(d)(3) of the Securities Exchange Act of 1934, as amended, may be deemed to be the beneficial owner of the Shares beneficially owned in the aggregate by the other members of the group reported herein.  The filing of this Schedule 13D and any future amendment by the Reporting Persons, and the inclusion of information herein shall not be considered an admission by Offshore Limited and Offshore Limited specifically disclaims that, for the purpose of Section 16(b) of the Exchange Act, it is the beneficial owner of any Shares in which it does not have a pecuniary interest.

(a, b)           Ten Fund

As of the date hereof, Ten Fund may be deemed to be the beneficial owner of 562,383 Shares, constituting approximately 0.94% of the Shares outstanding.

Ten Fund has the sole power to vote or direct the vote of 0 Shares; has the shared power to vote or direct the vote of 562,383 Shares; has sole power to dispose or direct the disposition of 0 Shares; and has shared power to dispose or direct the disposition of 562,383 Shares.

13

In addition, Ten Fund, as a member of a “group” with the other Reporting Persons for the purposes of Section 13(d)(3) of the Securities Exchange Act of 1934, as amended, may be deemed to be the beneficial owner of the Shares beneficially owned in the aggregate by the other members of the group reported herein.  The filing of this Schedule 13D and any future amendment by the Reporting Persons, and the inclusion of information herein shall not be considered an admission by Ten Fund and Ten Fund specifically disclaims that, for the purpose of Section 16(b) of the Exchange Act, it is the beneficial owner of any Shares in which it does not have a pecuniary interest.

(a, b)           Retirement Plan

As of the date hereof, the Retirement Plan may be deemed to be the beneficial owner of 23,000 Shares, constituting approximately 0.04% of the Shares outstanding.

The Retirement Plan has the sole power to vote or direct the vote of 0 Shares; has the shared power to vote or direct the vote of 23,000 Shares; has sole power to dispose or direct the disposition of 0 Shares; and has shared power to dispose or direct the disposition of 23,000 Shares.

In addition, the Retirement Plan, as a member of a “group” with the other Reporting Persons for the purposes of Section 13(d)(3) of the Securities Exchange Act of 1934, as amended, may be deemed to be the beneficial owner of the Shares beneficially owned in the aggregate by the other members of the group reported herein.  The filing of this Schedule 13D and any future amendment by the Reporting Persons, and the inclusion of information herein shall not be considered an admission by the Retirement Plan and the Retirement Plan specifically disclaims that, for the purpose of Section 16(b) of the Exchange Act, it is the beneficial owner of any Shares in which it does not have a pecuniary interest.

(a, b)           Foundation

As of the date hereof, the Foundation may be deemed to be the beneficial owner of 5,100 Shares, constituting approximately 0.01% of the Shares outstanding.

The Foundation has the sole power to vote or direct the vote of 0 Shares; has the shared power to vote or direct the vote 5,100 Shares; has sole power to dispose or direct the disposition of 0 Shares; and has shared power to dispose or direct the disposition of 5,100 Shares.

In addition, the Foundation, as a member of a “group” with the other Reporting Persons for the purposes of Section 13(d)(3) of the Securities Exchange Act of 1934, as amended, may be deemed to be the beneficial owner of the Shares beneficially owned in the aggregate by the other members of the group reported herein.  The filing of this Schedule 13D and any future amendment by the Reporting Persons, and the inclusion of information herein shall not be considered an admission by the Foundation and the Foundation specifically disclaims that, for the purpose of Section 16(b) of the Exchange Act, it is the beneficial owner of any Shares in which it does not have a pecuniary interest.

(a, b)           Larry Feinberg

Mr. Feinberg serves as the senior managing member of the General Partner, and accordingly, may be deemed to be the indirect beneficial owner of the Shares beneficially owned by General Partner.  Mr. Feinberg is the sole shareholder and president of the Manager, and accordingly, may be deemed to be the beneficial owner of the Shares beneficially owned by Manager.  Mr. Feinberg is the trustee of the "Foundation" and has the sole power to direct the voting and disposition of the Shares in Foundation.  As of the date hereof, Mr. Feinberg may be deemed to be the beneficial owner of 3,115,999 Shares, constituting approximately 5.20% of the Shares outstanding.

14

Mr. Feinberg has the sole power to vote or direct the vote of 0 Shares; has the shared power to vote or direct the vote of 3,115,999 Shares; has sole power to dispose or direct the disposition of 0 Shares; and has shared power to dispose or direct the disposition of 3,115,999 Shares.  The shares reported herein as beneficially owned by Mr. Feinberg exclude an aggregate of 4,500 Shares beneficially held by certain irrevocable trusts as to which Mr. Feinberg is Settlor.

In addition, Mr. Feinberg, as a member of a “group” with the other Reporting Persons for the purposes of Section 13(d)(3) of the Securities Exchange Act of 1934, as amended, may be deemed to be the beneficial owner of the Shares beneficially owned in the aggregate by the other members of the group reported herein.  The filing of this Schedule 13D and any future amendment by the Reporting Persons, and the inclusion of information herein shall not be considered an admission by Mr. Feinberg and Mr. Feinberg specifically disclaims that, for the purpose of Section 16(b) of the Exchange Act, it is the beneficial owner of any Shares in which it does not have a pecuniary interest.

(c) The trading dates, number of Shares (or options to acquire Shares) purchased or sold, and price per share for all transactions in the Shares (or options to acquire Shares) by the Reporting Persons in the past 60 days are set forth in Schedule A.  All such transactions were effected in open market transactions with brokers.

(d) No person other than the Reporting Persons is known to have the right to receive, or the power to direct the receipt of dividends from, or proceeds from the sale of, the Shares.

(e)  Not applicable.

Item 7.    Material  to be Filed as Exhibits.

99.1 Letter to the Board of Directors of Thoratec Corporation from Oracle Investment Management, Inc., dated December 5, 2011

15

SIGNATURE

After reasonable inquiry and to the best of their knowledge and belief, the undersigned certify that the information set forth in this Statement is true, complete and correct.

Dated:  December 5, 2011

ORACLE ASSOCIATES, LLC
	By:	/s/ Larry Feinberg
		Larry Feinberg, Managing Member
ORACLE  INVESTMENT MANAGEMENT, INC.
	By:	/s/ Larry Feinberg
		Larry Feinberg, Managing Member
ORACLE PARTNERS, LP
By:	ORACLE ASSOCIATES, LLC, its general partner
	By:	/s/ Larry Feinberg
		Larry Feinberg, Managing Member
ORACLE INSTITUTIONAL PARTNERS, LP
By:	ORACLE ASSOCIATES, LLC, its general partner
	By:	/s/ Larry Feinberg
		Larry Feinberg, Managing Member
ORACLE OFFSHORE LIMITED
	By:	/s/ Larry Feinberg
		Larry Feinberg, Director
ORACLE TEN FUND MASTER, LP
By:	ORACLE ASSOCIATES, LLC, its general partner
	By:	/s/ Larry Feinberg
		Larry Feinberg, Managing Member

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ORACLE INVESTMENT MANAGEMENT EMPLOYEES RETIREMENT
By:	/s/ Aileen Wiate
	Aileen Wiate, Trustee
THE FEINBERG FAMILY FOUNDATION
By:	/s/ Larry Feinberg
	Larry Feinberg, Trustee
/s/ Larry Feinberg
Larry Feinberg, Individually

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Schedule A

Date	Transaction	Price Per Share	Quantity	Name of Fund
10/28/2011	BUY	37.9878	6,887	TEN MASTER
11/15/2011	SELL	29.9483	(2,300)	OFFSHORE
11/22/2011	BUY (1/28/12 CALL OPTION)	2.45	1,775	PARTNERS
11/22/2011	BUY (1/28/12 CALL OPTION)	2.45	275	INSTITUTIONAL PARTNERS
11/22/2011	BUY (1/28/12 CALL OPTION)	2.45	30	OFFSHORE
11/22/2011	BUY (1/28/12 CALL OPTION)	2.45	420	TEN MASTER
11/22/2011	BUY (1/28/12 CALL OPTION)	2.3	355	PARTNERS
11/22/2011	BUY (1/28/12 CALL OPTION)	2.3	55	INSTITUTIONAL PARTNERS
11/22/2011	BUY (1/28/12 CALL OPTION)	2.3	5	OFFSHORE
11/22/2011	BUY (1/28/12 CALL OPTION)	2.3	85	TEN MASTER

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EX-99.1

Exhibit 99.1

[Letterhead of Oracle Investment Management, Inc.]

December 5, 2011

Board of Directors

Thoratec Corporation

6035 Stoneridge Drive

Pleasanton, CA 94588

Dear Sirs,

Oracle Investment Management, Inc. and its affiliates (collectively, “Oracle”) are longtime and significant shareholders in Thoratec Corporation (“Thoratec”).  This letter is a follow-up to our letter to you of March 8, 2011, in which we expressed our concerns with the operation and strategy of Thoratec.  While we were initially hopeful that these concerns would be addressed, we have since concluded that Thoratec is unable to maximize shareholder value as an independent company.  We believe that an auction process would be the most effective means to find a suitable acquirer and urge the Board of Directors to take action now to retain an independent investment bank to maximize shareholder value.

The Left Ventricular Assist Device (“LVAD”) market in which Thoratec operates is expected to become one of the fastest growing and largest markets in the medical device field during the next decade and beyond.  In the near term, the LVAD market is expected to grow from approximately 4,000 implants in 2010 to a projected 10,000 implants by 2015.  This growth could be even greater if additional resources are devoted to market development and next generation LVAD commercial timelines are accelerated.  Moreover, this market has the potential to be $5-10 Billion in sales based on National Institute of Health estimates of 50,000 to 100,000 patients eligible for a chronic LVAD.

The LVAD market is even more attractive because it is, in our view, a two horse race between Thoratec and HeartWare International Inc. (“HeartWare”) for the foreseeable future.  Thoratec has been the world leader in the creation of LVAD technologies and we believe remains the clear favorite to be the dominant player going forward.  Thoratec has the only approved LVAD in the United States, a multi-year head start on the Destination Therapy segment of this market, and what appears to be the broadest and most advanced pipeline in the industry.

Although Thoratec management initiated development of the LVAD market, recent market growth has been unsatisfactory and Thoratec has not meaningfully expanded its market share in many of the most promising European markets.  It is now clear that the market clout, deep capital resources, and relevant experience of a larger and more tenured medtech company is required to accelerate the penetration of this burgeoning market opportunity.

The rationale for the combination of Thoratec with a large-cap medtech company at this stage is very compelling for the following reasons:

1.           Accelerated Market Development.  We believe that a large-cap medtech company could greatly accelerate LVAD market development by leveraging a much larger sales force, marketing budget, and distribution channel.  In particular, the current bottleneck for significant LVAD market growth is the lack of awareness of this therapy by the referring cardiologist.  There are at least five large-cap medtech companies that currently target these same cardiologists through the sale of ICDs, pacemakers, stents, and other cardiovascular devices.

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2.           Synergies and Efficiencies in Manufacturing.  A large-cap medtech company could manufacture Thoratec’s LVAD alongside their other cardiovascular devices.  We believe LVAD manufacturing would immediately benefit from the technical expertise at these facilities as well as substantial scale advantages.  Furthermore, many of these facilities are outside of the United States allowing a manufacturer to enjoy a favorable tax structure in addition to lower overall overhead and production costs.  Thoratec would have difficulty achieving the manufacturing synergies and efficiencies that already exist in large-cap medtech’s manufacturing facilities today.

3.           Accelerated Development of Preeminent Product Pipeline.  Thoratec is already well ahead of the competition in terms of next generation LVAD technology, however, a large-cap medtech company could accelerate the timeline to commercialization.  Thoratec has passed many of the major technical hurdles of LVAD development, and are now nearing human trials for their next generation of LVADs, including the Heartmate III, Heartmate X, and fully implantable Heartmate II.  Unlike many medical device trials, LVAD clinical trials generate significant sales for the manufacturing company.  We, therefore, believe that Thoratec’s LVAD pipeline, in the hands of a large-cap medtech company, will enable the acquirer of Thoratec to retain LVAD market dominance in the future.

4.           Strengthen Dominance and Leadership in Marketplace.  Industry reports suggest that the LVAD of HeartWare, Thoratec’s principal competitor, has a higher rate of device thrombus and stroke compared to Thoratec’s LVAD.  This places Thoratec in a favorable position compared to HeartWare with respect to the most critical serious adverse events pertaining to LVADs, creating a window of opportunity for the right partner to exploit this competitive strength of Thoratec’s LVAD.

5.           Cardiovascular Market Extension Strategy.  Large-cap medtech companies that already sell CRM devices should be especially interested in Thoratec since an LVAD is the next step in the continuum of care for a heart failure patient.  Many of the same patients who received a CRM device 10 years ago are now revisiting their cardiologist with even more severe heart failure.  In many of these cases, the only treatment option available is an LVAD.  A notable example of this continuum of care for severe heart failure patients is former Vice-President Dick Cheney who was recently implanted with Thoratec’s LVAD many years after receiving an ICD.

6.           New $1 Billion Product Opportunity/PHP.  In addition to LVADs, Thoratec is also developing the Percutaneous Heart Pump (“PHP”), a treatment for acute (rather than chronic) heart failure.  The PHP will open a new, potentially $1 Billion product opportunity for Thoratec and is expected to be on the market as soon as late 2013.  However, this opportunity requires a large cardiology sales force, which large-cap medtech companies have but Thoratec lacks.  In essence, a large-cap medtech company could potentially reinvigorate its entire cardiology sales efforts through the acquisition of Thoratec.

7.           Strong Barriers to Entry.  The high technological risk of developing an LVAD program and the onerous clinical and regulatory timelines involved make the organic creation of an LVAD program very difficult.  This greatly enhances the attractiveness of Thoratec since the most effective path to entering the LVAD market is through an acquisition.  For this reason, and the other reasons we have articulated above, large-cap medtech companies already seem interested in the LVAD market based on recent public comments.

In our opinion, a well conceived auction process would result in a minimum of five large-cap medtech companies aggressively competing to acquire Thoratec.  We trust the Board will carefully consider our recommendation and we look forward to swift action by the Board to maximize shareholder value.

Very truly yours,

/s/ Larry N. Feinberg

LARRY N. FEINBERG

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