CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands	6 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Operating activities:
Net loss	$ (3,993)	$ (9,181)
Adjustments required to reconcile net loss to net cash used for operating activities:
Depreciation and amortization	2,125	2,104
Bad debt expense	65	127
Stock-based compensation	4,131	2,746
Write-down of inventory	376	1,364
Loss on disposal of fixed assets	29	5
Deferred tax provision	321	485
Gain on sale of WorldHeart common stock		(456)
Changes in assets and liabilities source (use):
Accounts receivable	(235)	(1,582)
Inventories	(2,562)	451
Prepaid expenses and other current assets	114	467
Accounts payable	(1,854)	8
Accrued expenses and other long-term liabilities	(4,649)	(1,211)
Deferred revenue	(158)	238
Net cash used in operating activities	(6,290)	(4,435)
Investing activities:
Purchases of short-term marketable securities	(8,001)	(1,502)
Proceeds from the sale and maturity of short-term marketable securities	7,000	5,000
Proceeds from the sale of WorldHeart common stock		456
Expenditures for property and equipment	(1,137)	(591)
Net cash (used in) provided by investing activities	(2,138)	3,363
Financing activities:
Proceeds from the exercise of stock options	7,800	343
Proceeds from the issuance of stock under the employee stock purchase plan	197	153
Net cash provided by financing activities	7,997	496
Effect of exchange rate changes on cash	(62)	(61)
Net decrease in cash and cash equivalents	(493)	(637)
Cash and cash equivalents at beginning of period	5,831	4,788
Cash and cash equivalents at end of period	5,338	4,151
Supplemental disclosures:
Fixed asset additions included in accounts payable	$ 44	$ 18