Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities
Net loss	$ (41,291)	$ (45,040)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	978	1,142
Amortization of intangible assets	220	0
Stock-based compensation expense	2,898	1,362
Accretion of discounts/(amortization of premiums) on marketable securities, net	5	(19)
Amortization of debt issuance costs	314	17,309
Amortization of right-of-use assets	336	312
Loss on debt extinguishment		1,398
Change in fair value of warrant liability and embedded derivative	1,872	605
Change in fair value of contingent consideration	(1,584)
Changes in operating assets and liabilities, net of effect from business combination:
Accounts receivable	(597)	(280)
Inventory	(3,616)	(1,961)
Prepaid expenses and other current assets	666	(43)
Other assets	8	(12)
Accounts payable	5,286	1,682
Accrued liabilities	155	1,810
Operating lease liabilities	(411)	(349)
Net cash used in operating activities	(34,761)	(22,084)
Cash flows from investing activities
Purchases of available-for-sale marketable securities		(22,208)
Sales of available-for-sale marketable securities	17,095
Maturities of available-for-sale marketable securities	40,000	8,100
Purchases of property and equipment	(4,445)	(316)
Cash paid, net of cash acquired for the Rhythm Xience Acquisition		(3,000)
Net cash provided by (used in) investing activities	52,650	(17,424)
Cash flows from financing activities
Proceeds from issuance of debt and warrants		77,000
Repayment of debt		(15,000)
Payment of issuance and extinguishment costs related to debt		(2,332)
Payment of contingent consideration	(2,619)
Proceeds from issuance of convertible preferred stock, net of issuance costs		38,226
Payment of deferred offering costs	(701)
Proceeds from stock options exercises	205	57
Net cash (used in) provided by financing activities	(3,115)	97,951
Effect of exchange rate changes on cash, cash equivalents and restricted cash	69	(12)
Net change in cash, cash equivalents and restricted cash	14,843	58,431
Cash, cash equivalents and restricted cash, at the beginning of the period	9,602	9,775
Cash, cash equivalents and restricted cash, at the end of the period	24,445	68,206
Supplemental disclosure of cash flow information:
Cash paid for income taxes
Cash paid for interest	2,376	1,168
Supplemental disclosure of noncash investing and financing activities:
Issuance of Series D convertible preferred stock for 2018 Convertible Notes and 2019 Convertible Notes		68,476
Issuance of Series D convertible preferred stock for Biotronik asset purchase	5,000
Issuance of Series D convertible preferred stock for Rhythm Xience Acquisition	2,197
Change in unrealized (gain) loss on marketable securities	41	(7)
Warrants issued in conjunction with OrbiMed debt		872
Right-of-use assets exchanged for operating lease liabilities		2,978
Unpaid purchases of property and equipment	55	$ 77
Unpaid deferred offering costs	$ 1,805