Purse string effect revealed by TTFM and HFUS


This case from the REQUEST Study describes how the combined use of Transit Time Flow Measurement (TTFM) and High frequency ultrasound (HFUS) revealed a compromised anastomosis, enabling the surgeon to handle the situation appropriately.
The patient was originally scheduled for an on-pump CABG with three grafts:



The LIMA grafts were uneventful, but TTFM of the SVG-PDA provided unsatisfactory results. The mean flow was of 14 ml/min was lower than expected and PI was high (4,5). DF% was also slightly low for this type of graft (46%), see image 1. This all indicates that there is an issue with the graft.

HFUS confirmed this as an over-sutured anastomosis to the PDA. The annotations in the image above show how the opening of the anastomosis is narrowed by the sutures.

During revision a new and wider anastomosis was made using a piece of vein. The new connection was made to the RCA.


The post-revision TTFM and HFUS show an improved result as seen in image 2. Mean flow and DF% is up while PI is down. A dobutamine test was performed and flow was observed to increase to 29 ml/min and PI held at 3.8. Also confirmed with troponin levels close to zero.

This case shows how the combination of TTFM and HFUS gives both an indication that something may be wrong with a graft and the images that help the surgeon identify and correct the issue.

Patient information

  • 71-year-old male
  • BMI 27.1


Taggart et al. JTCVS 2020;159:1283-92.


Case Attachments