Note 2 - Summary of Significant Accounting Policies (Details Textual)	3 Months Ended		12 Months Ended
	Mar. 31, 2022 USD ($) $ / shares shares	Mar. 31, 2021 USD ($) shares	Dec. 31, 2021 USD ($) shares	Mar. 14, 2022 shares	Jan. 31, 2021 shares	Nov. 26, 2019 shares
Number of Financial Institutions	1
Accounts Receivable, Allowance for Credit Loss, Ending Balance	$ 37,000		$ 66,000
Accounts Receivable, Allowance for Credit Loss, Writeoff	28,000	$ 64,000
Revenue from Contract with Customer, Excluding Assessed Tax	1,641,000	1,450,000
Contract with Customer, Asset, after Allowance for Credit Loss, Total	0		0
Contract with Customer, Liability, Total	4,000		7,000
Capitalized Contract Cost, Net, Total	28,000		$ 84,000
Capitalized Contract Cost, Amortization	17,000	14,000
Capitalized Contract Cost, Impairment Loss	0
Equity Method Investment, Other than Temporary Impairment	$ 0	$ 0
Series B Preferred Stock [Member]
Preferred Stock, Shares Outstanding, Ending Balance (in shares) | shares	41,767	36,937	40,504
Convertible Preferred Stock, Shares Issued upon Conversion (in shares) | shares	2,729,869	2,414,283	2,647,320			2,729,869
Series B Preferred Stock [Member] | Conversion From Series B Preferred Stock to Common Stock [Member]
Preferred Stock, Convertible, Conversion Ratio	65.36
Preferred Stock, Liquidation Preference Per Share (in dollars per share) | $ / shares	$ 1,000
Preferred Stock, Convertible, Conversion Price (in dollars per share) | $ / shares	$ 15.30
Series C Preferred Stock [Member]
Preferred Stock, Shares Outstanding, Ending Balance (in shares) | shares	0		0	0	0
Convertible Preferred Stock, Shares Issued upon Conversion (in shares) | shares	1
Rental [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 261,000	$ 366,000
Contract with Customer, Liability, Current	506,000	452,000
Contract with Customer, Liability, Revenue Recognized	$ 197,000	$ 230,000
Minimum [Member]
Warranty Period (Year)	1 year
Minimum [Member] | Viveve Systems [Member]
Lessor, Operating Lease, Term of Contract (Month)	6 months
Maximum [Member]
Warranty Period (Year)	3 years
Maximum [Member] | Viveve Systems [Member]
Lessor, Operating Lease, Term of Contract (Month)	12 months
Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Concentration Risk, Number of Customers	1	1
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | One Customer [Member]
Concentration Risk, Percentage	41.00%	17.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member]
Concentration Risk, Number of Customers			1
Customer Concentration Risk [Member] | Accounts Receivable [Member] | One Customer [Member]
Concentration Risk, Percentage			10.00%