6.   Goodwill and Intangible Assets. The change in the carrying amount of goodwill for the nine-month period ended September 30, 2022 is detailed as follows (in thousands):

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Total accumulated goodwill impairment losses aggregated $8.3 million as of September 30, 2022 and December 31, 2021. We did not have any goodwill impairments for the nine-month periods ended September 30, 2022 and 2021. The total goodwill balances as of September 30, 2022 and December 31, 2021 were related to our cardiovascular segment.

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Other intangible assets at September 30, 2022 and December 31, 2021 consisted of the following (in thousands):

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Aggregate amortization expense for the three and nine-month periods ended September 30, 2022 was $12.1 million and $36.3 million, respectively. Aggregate amortization expense for the three and nine-month periods ended September 30, 2021 was $12.4 million and $37.3 million, respectively.

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We evaluate long-lived assets, including amortizing intangible assets, for impairment whenever events or changes in circumstances indicate that their carrying amounts may not be recoverable. We perform the impairment analysis at the asset group for which the lowest level of identifiable cash flows is largely independent of the cash flows of other assets and liabilities. We determine the fair value of our amortizing assets based on estimated future cash flows discounted back to their present value using a discount rate that reflects the risk profiles of the underlying activities. During the nine-month period ended September 30, 2022, we identified indicators of impairment associated with certain acquired intangible assets based on our qualitative assessment, which led us to complete an interim quantitative impairment assessment. The primary indicator of impairment was our divestiture on April 30, 2022 of the STD Pharmaceutical Products Limited (“STD Pharmaceutical”) business acquired in our August 2019 acquisition of Fibrovein Holdings Limited. We recorded an impairment charge for the carrying value of $1.7 million of intangible assets during the nine months ended September 30, 2022, all of which pertained to our cardiovascular segment.

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During the nine-month period ended September 30, 2021, we identified indicators of impairment associated with certain acquired intangible assets based on our qualitative assessment, which led us to complete an interim quantitative impairment assessment. During the nine-month period ended September 30, 2021, the primary indicator of impairment was our planned discontinuance of the Advocate™ Peripheral Angioplasty Balloon product line, sold under our license agreements with ArraVasc Limited (“ArraVasc”). We recorded an impairment charge for the remaining carrying value of ArraVasc intangible assets of approximately $1.6 million during the nine-month period ended September 30, 2021, all of which pertained to our cardiovascular segment. 

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Estimated amortization expense for developed technology and other intangible assets for the next five years consisted of the following as of September 30, 2022 (in thousands):

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