The use of a novel imaging technique to evaluate patency of coronary grafts
Bibliographic record
Abstract
Early failure of coronary artery grafts is a major cause of morbidity and mortality after cardiac surgery and has been noted in up to 5-20% of patients [1]. There are particular concerns regarding the quality of the anastomoses during off-pump surgery [2]. Unfortunately it is clinically difficult to assess the patency of the grafts at the time of surgery. Several techniques have been described including electromagnetic, ultrasound, Doppler and thermal coronary angiography. These all have their limitations and are very often operator dependant. We describe our early experiences with a novel indocyanine green (ICG) fluorescence imaging technique (SPY Novadaq Technologies Inc. Toronto, Canada). ICG binds extensively to plasma proteins and fluoresces when illuminated at 806 nm. This can then be detected by a charged couple device video camera. Using this technique a bolus of ICG is injected into a central vein. The heart is then illuminated with an 806-nm laser diode. A camera positioned over the heart detects the fluorescing blood in the superficial epicardial vessels and graft conduits. This is clearly displayed on a screen in the operating theatre. We have used this technique in over 80 patients and observed 213 conduits. One surgeon, utilising arterial conduits with pedicled composite grafts, performed all the operations. Three quarters of the cases were off-pump. The imaging technique was simple to perform, taking about 3 min per graft. There were no noted adverse side effects from injection of ICG. All conduits were viewed. Absent flow was detected in four grafts (5% of patients). In all these cases the surgeon either revised his anastomoses or added a distal graft. Satisfactory blood flow was then noted using the SPY camera. Our early experience with this technique suggests that it is a safe, reproducible and speedy method of assessment of conduits’ patency at a time when it is still possible to revise the grafts surgically. Real-time observation of blood flow in the conduits was reassuring for both surgeon and anaesthetist. Further validation studies are planned.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".