Intangible Assets (Schedule of Finite-Lived Intangible Assets) (Details) (USD $)	3 Months Ended		9 Months Ended
	Jan. 27, 2012		Jan. 25, 2013		Jan. 27, 2012		Apr. 27, 2012
Finite-Lived Intangible Assets [Line Items]
Beginning balance gross carrying amount			$ 5,785,000		$ 5,844,401
Investments			2,500,000		500,000
Impairment of Intangible Assets, Finite-lived					(559,401)
Ending balance gross carrying amount	5,785,000		8,285,000		5,785,000
Accumulated amortization	(1,104,061)		(1,908,617)		(1,104,061)
Net	4,680,939		6,376,383		4,680,939		4,509,612
Write-off of accumulated amortization	76,800
Developed Technology Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Beginning balance gross carrying amount			5,660,000	[1]	5,370,000	[1]
Investments			2,500,000	[1]	500,000	[1]
Impairment of Intangible Assets, Finite-lived					(210,000)	[1]
Ending balance gross carrying amount	5,660,000	[1]	8,160,000	[1]	5,660,000	[1]
Accumulated amortization	(1,091,875)	[1]	(1,882,677)	[1]	(1,091,875)	[1]
Net	4,568,125	[1]	6,277,323	[1]	4,568,125	[1]
License Agreements [Member]
Finite-Lived Intangible Assets [Line Items]
Beginning balance gross carrying amount					474,401	[2]	125,000	[2]
Impairment of Intangible Assets, Finite-lived					(349,401)	[2]
Ending balance gross carrying amount	125,000	[2]	125,000	[2]	125,000	[2]	125,000	[2]
Accumulated amortization	(12,186)	[2]	(25,940)	[2]	(12,186)	[2]
Net	$ 112,814	[2]	$ 99,060	[2]	$ 112,814	[2]

[1] Developed Technology Rights include purchased exclusive patent and know-how licenses with finite lives, primarily related to seizure detection algorithms, wireless communication technology, rechargeable battery technology and a magnetic resonance imaging (“MRI”) compatible implantable lead.

[2] License Agreements include purchased non-exclusive technology licenses with finite lives primarily related to chip architecture for the detection and processing of heart signals.