CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Operating activities:
Net loss	$ (1,072)	$ (9,983)
Adjustments required to reconcile net loss to net cash (used for) provided by operating activities:
Depreciation and amortization	3,083	3,008
Bad debt expense	72	132
Stock-based compensation	5,904	4,018
Write-down of inventory	1,092	2,380
Loss on disposal of fixed assets	29	5
Deferred tax provision	555	728
Gain on sale of WorldHeart common stock		(456)
Gain on settlement of investment	(1,017)
Changes in assets and liabilities source (use):
Accounts receivable	(2,124)	493
Inventories	(4,037)	(664)
Prepaid expenses and other current assets	71	788
Accounts payable	(908)	(110)
Accrued expenses and other long-term liabilities	(2,923)	380
Deferred revenue	(84)	709
Net cash (used for) provided by operating activities	(1,359)	1,428
Investing activities:
Purchases of short-term marketable securities	(17,002)	(6,503)
Proceeds from the sale and maturity of short-term marketable securities	7,000	5,000
Proceeds from the sale of WorldHeart common stock		456
Proceeds from settlement of investment	1,017
Expenditures for property and equipment	(1,937)	(1,054)
Net cash used in investing activities	(10,922)	(2,101)
Financing activities:
Issuance of common stock	103
Proceeds from the exercise of stock options	11,683	416
Proceeds from the issuance of stock under the employee stock purchase plan	197	153
Net cash provided by financing activities	11,983	569
Effect of exchange rate changes on cash	(441)	(491)
Net decrease in cash and cash equivalents	(739)	(595)
Cash and cash equivalents at beginning of period	5,831	4,788
Cash and cash equivalents at end of period	5,092	4,193
Supplemental disclosures:
Fixed asset additions included in accounts payable	$ 82	$ 31