When is extra-anatomical bypass for the left subclavian artery required to prevent ischaemia after thoracic endovascular stent grafting?

In this series, delayed carotid/subclavian bypass may be required for chronic arm ischaemia and less so for SCI. The length of coverage of thoracic aorta during TEVAR is a factor in the development of delayed SCI and LAI occurrence. Carotid subclavian bypass is required for certain patients undergoing TEVAR (particularly if greater than 20 cm of thoracic aorta is covered).