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[Quantitative hemodynamic assessment of internal thoracic artery grafts using transthoracic duplex imaging]
H Takemura1, M Kawasuji, N Sakakibara
1Department of Surgery (I), Kanazawa University School of Medicine, Japan.
Insights
Internal thoracic artery (ITA) grafts show increased diameter and diastolic-dominant blood flow after coronary artery bypass grafting (CABG). ITA blood flow competes with native coronary arteries in moderate stenosis.
Area of Science:
- Cardiovascular Surgery
- Medical Imaging
- Hemodynamics
Background:
- Internal thoracic artery (ITA) grafts are crucial for coronary artery bypass grafting (CABG).
- Understanding ITA graft hemodynamics is essential for optimizing surgical outcomes.
- Pre- and post-operative assessment of ITA blood flow is important.
Purpose of the Study:
- To investigate the hemodynamic changes in ITA grafts following CABG.
- To analyze blood flow patterns and velocities in ITA grafts.
- To determine the relationship between ITA blood flow and native coronary artery stenosis.
Main Methods:
- Transthoracic duplex imaging with a 7.5 MHz probe was used to assess ITA grafts in 37 patients.
- B-mode imaging measured ITA diameter and area.
- Doppler signals determined blood flow velocity (Vs, Vd, Vm, Ved) and calculated flow (Fs, Fd, Ftotal).
Main Results:
- ITA diameter increased post-CABG.
- Hemodynamic patterns shifted from systolic-dominant pre-CABG to diastolic-dominant post-CABG.
- ITA blood flow varied across patient groups with different coronary artery stenosis levels, indicating competition with native flow.
Conclusions:
- CABG significantly alters ITA graft hemodynamics, favoring diastolic flow.
- ITA blood flow demonstrates a competitive relationship with native coronary artery flow, particularly in cases of moderate stenosis.
- These findings have implications for graft selection and surgical strategy in CABG procedures.
Abstract:
The hemodynamics of blood flow in internal thoracic artery (ITA) grafts were studied using transthoracic duplex imaging prior to and following coronary artery bypass grafting (CABG) in 37 patients. Transthoracic images of the ITA were obtained through the first intercostal space using a 7.5 MHz probe, and their diameter and area were measured by B-mode imaging. Systolic, diastolic, mean and end-diastolic blood flow velocity (Vs, Vd, Vm, and Ved) were determined based on Doppler signals and systolic, diastolic, and total blood flow (Fs, Fd, and Ftotal) were calculated by the following formula: Flow = Vm x area x 60/10(3). The diameter of the ITA increased following CABG. Prior to CABG, Vs, and Fs, were dominant, while following CABG, the hemodynamic pattern was diastolic dominant, although individual variation existed. The ITA blood flow was measured in 4 groups, in patients who had had a previous anterior myocardial infarction and no redistribution on myocardial scintigraphy (group I), in patients with 99-100% coronary artery stenosis who had not had an anterior myocardial infarction or who had an anterior myocardial infarction and had redistribution (group IIa), in patients with the same criteria as group IIa but who had 90% coronary stenosis (group IIb), and in patients with 75% coronary stenosis who had not had anterior myocardial infarction (group IIc). Blood flow was 57, 73, 44mL and 34 mL/min, and the percentage of diastolic flow was 72, 69, 61, 59% respectively. These results show that ITA blood flow competes with native coronary artery flow in patients with moderate coronary stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)