Methods: Between March 2024 and August 2024, a total of 29 patients (24 males, 5 females; mean age: 60.1±8.3 years; range, 56 to 66 years) who were scheduled for elective coronary artery bypass grafting were included in this prospective study. An ultrasound-guided bilateral deep parasternal intercostal plane block was performed with 15 mL of 0.25% bupivacaine per side after anesthesia induction. Left internal thoracic artery peak systolic velocity, end-diastolic velocity, and resistive index, along with heart rate and mean arterial pressure, were recorded immediately before the block (T0) and 30 min after (T1). Demographics, body mass index, and comorbidities of the patients were noted.

Results: After deep parasternal intercostal plane block administration, the left internal thoracic artery resistivity index decreased significantly (p=0.041), and the left internal thoracic artery diameter increased significantly (p=0.004). Although the peak systolic velocity increased and the end-diastolic velocity decreased following the block, these changes were not statistically significant (p=0.145 and p=0.135, respectively).

Conclusion: Our study findings suggest that deep parasternal intercostal plane block administration may prevent left internal thoracic artery vasospasm by increasing arterial conduit diameter and reducing the resistivity index. Based on these findings, we believe that this method can be safely applied under ultrasound guidance without complications.