Long-term follow up of experimental microvascular grafts using Doppler ultrasound.

Non-directional Doppler ultrasound was used to determine patency in prosthetic microvascular grafts in 30 rats over 24 weeks. Examinations were carried out every two weeks and exploration and arteriography were used at intervals during the study to confirm the Doppler findings. Two rats died and were excluded from the study. Twenty-six grafts were patent at the time of examination and these were correctly assessed by the Doppler technique. However, only one of two occluded grafts was correctly identified. Our results suggest that while this technique is sensitive, its specificity is low, and graft exploration may still be required to confirm patency. Doppler ultrasound may prove a useful non-invasive tool for long-term follow-up of experimental microvascular grafts if the false positive rate can be reduced by improved technique and further experience.