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Flow dynamics in internal thoracic artery grafts 10 years after coronary artery bypass grafting
Yukio Ichikawa1, Hirokazu Kajiwara, Yasuharu Noishiki
1First Department of Surgery, Yokohama City University School of Medicine, Yokohama, Japan.
Insights
Internal thoracic artery grafts maintain distinct flow dynamics, shifting to diastolic predominance, especially distally, even 10 years post-surgery. This altered hemodynamics may contribute to their excellent long-term patency rates.
Area of Science:
- Cardiovascular Surgery
- Medical Imaging
- Hemodynamics
Background:
- Long-term flow dynamics of internal thoracic artery grafts are not well understood.
- Assessing hemodynamics at 10 years post-surgery provides crucial insights into graft performance.
Purpose of the Study:
- To investigate the flow dynamics of internal thoracic artery grafts at the 10-year mark.
- To compare graft hemodynamics with native internal thoracic arteries.
Main Methods:
- Doppler examination of native internal thoracic arteries (control) and internal thoracic artery grafts.
- Graft assessment at 6 months, 5 years, and 10 years post-coronary artery bypass grafting.
Main Results:
- Grafts exhibited a diastolic-to-systolic peak velocity ratio >1.0 distally, unlike controls (<1.0).
- Distal diastolic peak velocity was significantly faster in grafts; proximal systolic peak velocity was significantly lower.
- No significant differences in flow velocities or graft diameter were observed among graft groups over time.
Conclusions:
- Internal thoracic artery grafts demonstrate a shift towards diastolic predominance, particularly distally.
- These hemodynamic changes remain stable even after 10 years.
- The altered hemodynamics are a potential factor in the superior long-term patency of these grafts.
Background:
Flow dynamics in internal thoracic artery grafts 10 years after surgery are not known.
Methods:
Doppler examination was performed in native internal thoracic arteries as a control (n = 8) and in internal thoracic artery grafts to the left anterior descending coronary artery 6 months postoperatively (group A, n = 25), at 5 years (group B, n = 14), and at 10 years (group C, n = 11).
Results:
Each graft group showed a diastolic to systolic peak velocity ratio of less than 1.0 at the proximal end, and more than 1.0 at the distal end, but the control group showed a ratio of less than 1.0 throughout the length of the artery. The diastolic peak velocity of the graft groups was significantly faster than that of the control group at the distal end (versus group A, p < 0.01; versus group B, p < 0.005; and versus group C, p < 0.05). The systolic peak velocity of the graft groups was significantly lower than that of the control at the proximal end (versus group A, p < 0.0001; versus group B, p < 0.005; and versus group C, p < 0.0005). There were no significant differences of flow velocities among the graft groups and graft diameter among the four groups.
Conclusions:
Although the internal thoracic artery is systolic predominant, when native artery is used as graft, it changes its hemodynamics to diastolic predominance, especially at the distal end. Even after 10 years, graft flow dynamics are unchanged. This hemodynamic character may be one of the factors related to the superior long-term patency.