Basis of Accounting, Policy [Policy Text Block]

Basis of presentation

The consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The Financial Accounting Standards Board (“FASB”) establishes these principles to ensure financial condition, results of operations, and cash flows are consistently reported. Any reference in these notes to applicable accounting guidance is meant to refer to the authoritative nongovernmental GAAP as found in the FASB Accounting Standards Codification ("ASC").

Concentration Risk, Credit Risk, Policy [Policy Text Block]

Concentrations of credit risk

The Company's financial instruments that are exposed to concentrations of credit risk consist primarily of cash and cash equivalents and accounts receivable. The Company generally maintains cash and cash equivalent balances in various operating accounts at financial institutions with high quality credit in amounts in excess of federally insured limits of $250,000. As of December 31, 2024, the Company had deposits in financial institutions in excess of federally insured limits of $2.6 million. The Company has not experienced any losses related to its cash and cash equivalents and does not believe that it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company has no significant off-balance sheet risk, such as foreign exchange contracts, option contracts, or other hedging arrangements.

The Company extends credit to customers in the normal course of business. Concentrations of credit risk with respect to accounts receivable exist to the full extent of amounts presented in the consolidated balance sheets. The Company does not require collateral from its customers to secure accounts receivable.

The Company had 3 customers that represented 62% and 67% of the Company's consolidated revenues for the years ended December 31, 2024 and 2023, respectively.

Segment Reporting, Policy [Policy Text Block]

Segment reporting

The Company operates in one reportable segment, which includes all activities related to the marketing, sales, and development of medical technologies in the cardiac electrophysiology field. While the commercial efforts that coordinate the marketing, sales, and distribution of these products are organized by geographic region and product, all of these activities are supported by a single corporate team and distribution channels. The determination of a single reportable segment is consistent with the consolidated financial information available and regularly reviewed by the Company’s chief operating decision maker (“CODM”).

The CODM is the Company’s chief executive officer, who reviews and evaluates consolidated net loss reported on the consolidated statements of operations for purposes of assessing performance, making operating decisions, allocating resources and planning and forecasting for future periods. As the Company’s operations are managed at the consolidated level, there are no differences between the measurement of the reportable segments’ profit or losses and the Company’s consolidated statements of operations. Segment asset measures are not used as a basis for the CODM to evaluate the performance of or to allocate resources to the segment.

The following table summarizes segment revenues and significant segment expenses included in the measure of segment profit or loss (consolidated net loss) reviewed by the CODM:

	*For the Year Ended*
	*December 31,*
	*2024*			*2023*
Revenues	$	420		$	442
Less:
Cost of revenues		42			30
Loss on impairment of goodwill		—			60,934
Depreciation and amortization expense		2,109			2,075
Stock-based compensation expense		54			1,217
Salaries and benefits expense		4,192			4,661
Professional fees		2,034			5,622
Research and development expenses		272			475
Interest income		(81	)		(347	)
Interest expense		91			—
Change in fair value of royalties payable due to related parties		2,239			(7,208	)
Income tax expense		3,141			—
Other segment items (1)		2,970			3,555
Segment net loss		(16,643	)		(70,572	)

Reconciliation of net loss
Adjustments and reconciling items		—			—
Consolidated net loss		(16,643	)		(70,572	)

(1) Other segment items include other expenses, net of $10 thousand, consulting fees of $505 thousand, investor relations and SEC fees of $459 thousand, insurance fees of $533 thousand, and other selling, general, and administrative expenses of $1,462 thousand for the year ended December 31, 2024. Other segment items include other expenses, net of $8 thousand, consulting fees of $730 thousand, investor relations and SEC fees of $691 thousand, insurance fees of $704 thousand, and other selling, general, and administrative expenses of $1,422 thousand for the year ended December 31, 2023. Other selling, general, and administrative expenses primarily consist of travel expenses, computer and information technology expenses, and rent expenses.

Fair Value Measurement, Policy [Policy Text Block]

Fair value measurements

Fair value represents the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants and is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. A three-tier fair value hierarchy is used to identify inputs used in measuring fair value as follows:

Level 1 - Observable inputs that reflect quoted market prices (unadjusted) for identical assets or liabilities in active markets;

Level 2 - Inputs other than the quoted prices in active markets that are observable either directly or indirectly in the marketplace for identical or similar assets and liabilities; and

Level 3 - Unobservable inputs that are supported by little or no market data, which require the Company to develop its own assumptions.

Cash equivalents, prepaid expenses, accounts receivable, accounts payable, and accrued expenses are reported on the consolidated balance sheets at carrying value which approximates fair value due to the short-term maturities of these instruments. The carrying value of our notes payable and notes payable due to related parties approximates the instruments' fair value due to the short-term maturities of these debt instruments.

The following table details the fair value measurements within the fair value hierarchy of the Company’s financial instruments:

			December 31, 2024
	Total		Level 1		Level 2		Level 3
Assets:
Cash Equivalents
Mutual fund	$	2,803	$	2,803	$	—	$	—
Money market fund		12		12		—		—
Total assets	$	2,815	$	2,815	$	—	$	—

Liabilities
Royalties payable due to related parties	$	9,213	$	—	$	—	$	9,213
Total liabilities	$	9,213	$	—	$	—	$	9,213

			December 31, 2023
	Total		Level 1		Level 2		Level 3
Assets:
Cash Equivalents
Mutual fund	$	3,397	$	3,397	$	—	$	—
Money market fund		10		10		—		—
Total assets	$	3,407	$	3,407	$	—	$	—

Liabilities
Royalties payable due to related parties	$	6,974	$	—	$	—	$	6,974
Total liabilities	$	6,974	$	—	$	—	$	6,974

The fair value measurement of royalties payable due to related parties includes unobservable inputs that are not supported by any market data. Royalties payable due to related parties equals the present value of estimated future royalty payments, wherein the Company applies an internally developed, revenue adjusted discount rate (“RADR”) to discount back the forecasted royalty payments. The RADR is based on the Company’s weighted average cost of capital (“WACC”) adjusted for the product revenue’s risk profile. The risk-free rate used to determine the cost of equity for the RADR is adjusted to be commensurate with the term of the royalty agreements. Furthermore, the Beta and Risk Premium used to determine the cost of equity are also adjusted to reflect the product revenue's volatility. All other inputs for the RADR and the Company’s WACC are the same.

The following tables summarize the significant unobservable inputs used in the fair value measurement of Level 3 instruments:

	*December 31, 2024*
Instrument	Valuation Technique	Unobservable Input	Input Range
Royalties payable due to related parties	Discounted future cash flows	Revenue adjusted discount rate		22.5	%

	*December 31, 2023*
Instrument	Valuation Technique	Unobservable Input	Input Range
Royalties payable due to related parties	Discounted future cash flows	Revenue adjusted discount rate		28.0	%

Increases or decreases in the fair value of royalties payable due to related parties can result from updates to assumptions, such as changes in discount rates, projected cash flows, among other assumptions. Judgment is used in determining these assumptions as of the initial valuation date and at each subsequent reporting period. Changes or updates to assumptions could have a material impact on the reported fair value, the change in fair value, and the results of operations in any given period.

The table below summarizes the change in fair value of royalties payable to related parties for the years ended December 31, 2024 and 2023 (in thousands):

	*2024*		*2023*
Beginning Balance at January 1,	$	6,974	$	—
AMIGO royalty payable recognized in connection with the Merger		—		160
LockeT royalty payable recognized in connection with the Merger		—		14,022
Change in fair value of royalties payable due to related parties		2,239		(7,208	)
Ending Balance at December 31,	$	9,213	$	6,974

Inventory, Policy [Policy Text Block]

Inventories

Inventories are stated at the lower of cost (determined by the first-in, first-out method) or net realizable value. Cost includes materials, labor, and manufacturing overhead related to the purchase and production of inventories. The Company reduces the carrying value of inventories for those items that are potentially in excess, obsolete or slow-moving based on changes in customer demand, technological developments or other economic factors.

Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]

Impairment of long-lived assets

In accordance with ASC 360, Impairment and Disposals of Long-lived Assets, the Company periodically reviews its long-lived assets for impairment whenever events or changes in circumstances indicate that such assets might be impaired and the carrying value of the long-lived assets may not be recoverable. If events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable and the expected undiscounted future cash flows attributable to the asset are less than the carrying amount of the asset, an impairment loss equal to the excess of the assets carrying value over its fair value is recorded in the Company’s consolidated statements of operations at that date.

As a result of the sustained decline of the Company's stock, the Company assessed its long-lived assets for impairment. To evaluate whether the carrying amount of the long-lived asset group is recoverable, the Company determined the estimated future cash flows of the group for a period consistent with that of the primary assets of the group. The sum of the undiscounted cash flows was then compared to the carrying amount of the long-lived assets as of December 31, 2024. The Company concluded there was no impairment as of December 31, 2024.

Royalties Payable [Policy Text Block]

Royalties payable due to related parties

The Company is obligated to pay royalties related to sales of LockeT and AMIGO System under various royalty agreements executed by Old Catheter. The Company recognizes a liability for royalty fees incurred and payable based on actual sales of products under current portion of royalties payable due to related parties in the consolidated balance sheets. The Company recognizes a liability for future, estimated royalty payments at fair value under the royalties payable due to related parties in the consolidated balance sheets. The royalties payable due to related parties is remeasured at each reporting period. Changes in fair value of royalties payable due to related parties are recorded on the consolidated statements of operations in the period in which they occur. See Note 10, Royalties Payable for additional information.

Distinguishing Liabilities From Equity [Policy Text Block]

Distinguishing liabilities from equity

The Company evaluates equity or liability classification for freestanding financial instruments, including convertible preferred stock, warrants, and options, pursuant to the guidance under ASC Topic 480, Distinguishing Liabilities from Equity (“ASC 480”). The Company classifies as liabilities all freestanding financial instruments that are (i) mandatorily redeemable, (ii) represent an obligation to repurchase the Company’s equity shares by transferring assets, or (iii) represent an unconditional obligation (or conditional obligation if the financial instrument is not an outstanding share) to issue a variable number of shares predominantly based on a fixed monetary amount, variations in something other than the fair value of the Company’s equity shares, or variations inversely related to changes in fair value of the Company’s equity shares.

If a freestanding financial instrument does not represent an outstanding equity share and does not meet liability classification under ASC 480, the Company then assesses whether the freestanding financial instrument is indexed to its own stock and meets equity classification pursuant to ASC 815-40, Derivatives and Hedging (“ASC 815”). The Company further assesses whether the freestanding financial instruments should be classified as temporary equity. Freestanding financial instruments that are redeemable for cash or other assets at a fixed or determinable date, at the option of the holder, or upon the occurrence of an event are classified in temporary equity in accordance with ASC 480. Otherwise, the freestanding financial instruments are classified in permanent equity.

Shipping and Handling, Policy [Policy Text Block]

Shipping and handling costs

Shipping and handling costs charged to customers are included in net product sales, while all other shipping and handling costs are included in selling, general and administrative expenses in the accompanying consolidated statements of operations.

Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block]

Patents

The Company expenses patent costs, including related legal costs, as incurred and records such costs as selling, general and administrative expenses in the accompanying consolidated statements of operations.

Share-Based Payment Arrangement [Policy Text Block]

Stock-based compensation

The Company recognizes stock-based compensation expense associated with stock options, restricted stock awards (“RSAs”) and restricted stock units (“RSUs”) issued to employees, members of the Company’s board of directors and consultants in accordance with ASC Topic 718, Compensation – Stock Compensation (“ASC 718”). The Company evaluates whether stock-based awards should be classified and accounted for as liability or equity awards on the date of grant. Furthermore, the Company measures all stock-based awards granted based on the fair value of the award on the date of grant. Stock options are measured at fair value using the Black-Scholes option pricing valuation model (the “Black-Scholes model”), which incorporates various assumptions, including expected term, volatility and risk-free interest rate. Stock-based compensation expense for all stock-based awards is recognized over the requisite service period, which is generally the vesting period of the respective stock award. Stock-based compensation expense for stock-based awards with a performance condition is recognized when the achievement of such performance condition is determined to be probable. If the outcome of such performance condition is not probable or is not met, no stock-based compensation expense is recognized, and any previously recognized compensation expense is reversed. Forfeitures are recognized as a reduction of stock-based compensation expense as they occur.

As a result of the Merger, all unvested Old Catheter stock options were subject to accelerated vesting and became fully vested as of the closing date of the business combination. The Company recognized the fair value of the replacement options as included in consideration transferred to the extent they do not exceed the fair value of the equivalent Old Catheter options. Any incremental fair value was recognized in stock-based compensation expense in the post-combination period, with this recognized as a Day 1 expense due to the Old Catheter options becoming fully vested concurrent with the closing of the business combination.

Earnings Per Share, Policy [Policy Text Block]

Basic and diluted net loss per share of common stock

Earnings per share attributable to common stockholders is calculated using the two-class method, which is an earnings allocation formula that determines earnings per share for the holders of the Company’s common shares and participating securities. The Company’s Series A Convertible Preferred Stock, Series X Convertible Preferred Stock, and outstanding warrants are participating securities as they contain participating rights in distributions made to common stockholders. Since the participating securities do not include a contractual obligation to share in the losses of the Company, they are not included in the calculation of net loss per share in the periods that have a net loss. In addition, common stock equivalent shares (whether or not participating) are excluded from the computation of diluted earnings per share in periods in which they have an anti-dilutive effect on net loss per common share.

Diluted net loss per share is computed using the more dilutive of (a) the two-class method or (b) the if-converted method and treasury stock method, as applicable. In periods in which the Company reports a net loss attributable to common stockholders, diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. Diluted net loss per share is equivalent to basic net loss per share for the periods presented herein because common stock equivalent shares from warrants, stock options, non-vested restricted stock awards, restricted stock units, Series A Convertible Preferred Stock, and Series X Convertible Preferred Stock were anti-dilutive (see Note 12, Net Loss per Share).

Net loss attributable to common stockholders consists of net income or loss, as adjusted for actual and deemed dividends declared. The Company recorded a deemed dividend for the modification of existing warrants and issuance of new warrants of $5.2 million and $0.8 million for the years ended December 31, 2024 and 2023, respectively. The deemed dividend is added to net loss in determining the net loss available to common stockholders for the years ended December 31, 2024 and 2023.