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A Novel Method to Determine the Cause of Left Internal Mammary Artery Instant Non-Patency Based on Transit Time Flow
Boyan Mao1, Yue Feng2,3, Mengyao Duan1
1School of Life Sciences, Beijing University of Chinese Medicine, Beijing, China.
Insights
Distinguishing between competitive flow and anastomotic stenosis in left internal mammary arteries after coronary artery bypass grafting is crucial. Graft flow waveform shape and the F0/H2 ratio effectively differentiate these causes of poor graft patency.
Area of Science:
- Cardiovascular Surgery
- Biomedical Engineering
- Medical Imaging
Background:
- Poor instant patency of left internal mammary arteries (LIMAs) after coronary artery bypass grafting (CABG) is often due to competitive flow or anastomotic stenosis.
- Differentiating these causes non-invasively remains a clinical challenge.
Purpose of the Study:
- To develop and validate a computational model to distinguish between competitive flow and anastomotic stenosis in LIMAs post-CABG.
- To identify reliable indicators for determining the cause of LIMA non-patency.
Main Methods:
- A 0D-3D coupled multiscaled computational model simulating anastomotic stenosis and competitive flow in CABG was constructed.
- Analysis of LIMA flow waveforms, including shape, common clinical parameters (average flow, pulsatility index, diastolic fraction), and Fast Fourier Transform (FFT) ratios (F0/H1, F0/H2).
Main Results:
- Common clinical parameters showed no significant difference between anastomotic stenosis and competitive flow groups.
- LIMA waveform shape and FFT ratio (particularly F0/H2) significantly differed between the two groups.
- Competitive flow was associated with systolic backflow and a high F0/H2 ratio (>14.89), while anastomotic stenosis showed a bimodal waveform and normal F0/H2 (approx. 1.17).
Conclusions:
- Graft flow waveform shape and the F0/H2 ratio are effective tools for determining the cause of poor instant LIMA patency after CABG.
- This non-invasive method aids in diagnosing LIMA non-patency without interfering with native coronary arteries.
Abstract:
Objective: After coronary artery bypass grafting (CABG) surgery, the main causes of poor instant patency of left internal mammary arteries (LIMAs) are competitive flow and anastomotic stenosis, but how to determine the cause of LIMA non-patency without interfering with the native coronary artery is still a difficult problem to be solved urgently. Methods: In this study, a 0D-3D coupled multiscaled CABG model of anastomotic stenosis and competitive flow was constructed. After calculation, the flow waveform of the LIMA was extracted, and the waveform shape, common clinical parameters (average flow, PI, and DF), and graft flow FFT ratio results (F0/H1 and F0/H2) were analyzed. Results: For LIMA, these three common clinical parameters did not differ significantly between the anastomotic stenosis group and competitive flow group. However, the waveform shape and FFT ratio (especially F0/H2) of the competitive flow group were significantly different from those of the anastomotic stenosis group. When the cause was competitive flow, there was systolic backflow, and F0/H2 was too high (>14.89). When the cause was anastomotic stenosis, the waveform maintained a bimodal state and F0/H2 was in a normal state (about 1.17). Conclusion: When poor instant patency of the LIMA is found after CABG, the causes can be determined by graft flow waveform shape and F0/H2.
