Residents' Learning Curve of Intraoperative Transit-time Flowmetry and High-frequency Ultrasound in CABG (LEARNERS) (LEARNERS)

December 29, 2025 updated by: Federico Cammertoni, Fondazione Policlinico Universitario Agostino Gemelli IRCCS

Cardiac Surgery Residents' Learning Curve of Intraoperative Transit-time Flowmetry and High-frequency Ultrasound in Coronary Artery Bypass Surgery: the LEARNERS Study

Transit-time flowmetry (TTFM) allows grafts quality assessment during coronary artery bypass surgery by measuring the flow volume through them. Recently the intraoperative epicardial high-frequency ultrasound (HFUS) was introduced, with the possibility of capturing bidimensional images of the anastomoses. When combined, these two techniques provide high diagnostic yield reaching a positive predictive value of 100 percent.

Despite current guidelines recommend the employment of TTFM and HFUS, they remain largely underused probably because of limited information and the lack of standardization. Furthermore, surgeons must overcome a learning curve to handle both techniques properly, but few data are available according the current literature.

The main purpose of this study is to evaluate the complexity of HFUS and TTFM learning curve. This is a prospective, observational, monocentric cohort study. Adult patients undergoing coronary artery bypass surgery will be enrolled.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

This is a prospective, observational, monocentric cohort study in which adult patients undergoing coronary artery bypass surgery will be enrolled.

Primary objective of this study is to evaluate the complexity of cardiac surgery residents' learning curve for grafts quality assessment with transit-time flowmetry (TTFM) and intraoperative epicardial high-frequency ultrasound (HFUS).

Secondary objectives are to evaluate the complexity of cardiac surgery residents' learning curve for grafts quality assessment with TTFM and HFUS as isolated techniques.

The study will last four months (three months for patients enrollment and data collection and one month for statistical analysis and scientific paper writing).

The trial will start after obtaining favourable opinion from the local Ethics Committee and could be considered completed when all the eight cardiac surgery residents involved have reached primary endpoint.

All patients with coronary artery disease and an indication for surgical revascularization (coronary artery bypass grafting) who meet the above-described inclusion and exclusion criteria will be enrolled by signing the informed consent the day before surgery.

Patient data (anamnestic data, surgery description, intraoperative echographic and flowmetric measurements) will be recorded in a dedicated database. All data recorded in the database are commonly acquired for all patients undergoing this type of surgery and no further examinations will be performed for patients included in the trial.

The study will involve cardiac surgery residents with different levels of training and an expert cardiac surgeon who acts as supervisor and benchmark. Each resident will sign a dedicated informed consent form in the presence of a doctor foreign to the study protocol (Cardiac Surgery ward cardiologist). The residents will be "blinded" about the trial objective and the adopted score system. They will undergo a specific training including a quick lesson and a practical workshop to familiarize with the equipment.

During surgery, every graft will be evaluated through transit time flowmetry (TTFM) and intraoperative ultrasound control (HFUS).

In details, the ultrasound control is carried out through a dedicated sterile ultrasound probe connected to a machine (MiraQ - MEDISTIM) as soon as each anastomosis is completed. The result of the evaluation is recorded together with surgery data. This evaluation is intended to confirm the correct realization of the anastomosis and provides a proof of its patency.

Once each graft is completed, the resident will be given 60 seconds to acquire two HFUS recordings (short and long axis). After that, the supervisor will perform his personal recording which will stand as benchmark. The following items will be evaluated:

A) Long axis recording acquired within 60 seconds [YES-> 1] [NO -> 0] B) Long axis recording judged as suitable by the supervisor [YES -> 1] [NO -> 0] C) Short axis recording acquired within 60 seconds [YES -> 1] [NO -> 0] D) Short axis recording judged as suitable by the supervisor [YES -> 1] [NO -> 0]

E) Correct interpretation of the anastomosis as adequate or inadequate [YES -> no penalty] [NO -> total score becomes 0 and the resident isn't allowed to perform TTFM]

Each resident will be given a HFUS-related score from a minimum of 0 to a maximum of 4.

Whenever one of the recordings will be judged as non-suitable by the supervisor and consequently useless for a correct interpretation of the anastomosis (score 0 for items A and/or C), item E won't be evaluated and the HFUS will be given a total score of 0.

Next step will be the TFM evaluation, which is carried out through a specific sterile device connected to the same machine (MiraQ - MEDISTIM) once the patient has been weaned from the cardiopulmonary bypass and before protamine administration. This recording is performed under EKG and pressure-controlled conditions. Although there is no general agreement on the optimal mean arterial pressure at which the measurement has to be recorded, the investigators will adopt the standard used in the REQUEST study protocol (16), that is an average pressure of 80 mmHg.

The resident will acquire the TTFM recording after each graft is completed. To make the comparison as accurate as possible, the resident will perform TTFM evaluation on one graft at a time and successively the supervisor will do the same for each graft (making sure that delta between the pressure during the two recordings is lower than 10 percent and that no drug has been administered). The following items will be evaluated:

F) Time necessary to acquire the measures [< 30 sec -> 1] [> 30 sec, < 60 -> 0.5] [> 60 sec -> 0] G) Need for multiple measurements before the final one: [>2 -> 0] [1 -> 0.5] [ 0 -> 1] H) Need to change probe dimensions: [NO -> 0] [YES-> 1]

I) ACI [delta between resident and supervisor measurements < 10%-> 1] [> 10%, < 20% -> 0.5] [> 20% -> 0] L) Mean Flow [delta between resident and supervisor measurements < 10%-> 1] [> 10%, < 20% -> 0.5] [> 20% -> 0] M) Pulsatility Index [delta between resident and supervisor measurements < 10%-> 1] [> 10%, < 20% -> 0.5] [> 20% -> 0] N) Backward Flow [delta between resident and supervisor measurements < 10%-> 1] [> 10%, < 20% -> 0.5] [> 20% -> 0] O) Diastolic Filling [delta between resident and supervisor measurements < 10%-> 1] [> 10%, < 20% -> 0.5] [> 20% -> 0]

P) Correct interpretation of the graft quality as working [YES -> no penalty] [NO -> total score becomes 0]

Each resident will be given a TTFM-related score from a minimum of 0 to a maximum of 8.

The final score for each graft will be the sum of the two scores (HFUS and TTFM), from a minimum of 0 to a maximum of 12.

The same procedure will be repeated for each graft performed during the surgery.

Each resident will continue until reaching a ratio between total score and number of evaluated anastomoses of 11.

Our cardiac surgery unit performs between 5 and 10 coronary artery bypass grafts surgeries per week on average. Considering the inclusion and exclusion criteria and assuming that some patient may not give their informed consent, the investigators expect to enroll 4 patients per week. Considering that the involved residents (8 in total) will take part to the procedures in turn and that around 10 surgeries are needed to become autonomous, the investigators estimate to enroll 80 patients during a period of 3 months.

Data will be collected in a specific database (Microsoft Excel worksheet). The Kolgomorov-Smirnoff test was used to check for variables distribution. Continuous variables with a normal distribution are summarized by mean and standard deviation. Continuous variables with a non-normal distribution are expressed with median and interquartile range.

Categorical variables are reported as absolute frequency distribution and percentage. Continuous data are analyzed using the unpaired t-test or the Mann - Whitney test according to their distribution. Categorical data are compared with the Fisher's exact test. Statistical findings were considered significant if p value was less than 0.05. Statistical analysis will be performed with the statistic software SPSS (IBM).

Study Type

Observational

Enrollment (Actual)

80

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Italy
    • RM
      • Roma, RM, Italy, 00168
        • Fondazione Policlinico Universitario "A. Gemelli" IRCCS

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

All patients with coronary artery disease and an indication for surgical revascularization (coronary artery bypass grafting) who meet the above-described inclusion and exclusion criteria will be enrolled by signing the informed consent the day before surgery.

Description

Inclusion Criteria:

  • Age >= 18 years old;
  • Written informed consent;
  • Indication to CABG surgery (both "on-pump" and "off-pump");
  • Stable angina, unstable angina or acute coronary syndrome without ST elevation (NSTEMI).

Exclusion Criteria:

  • Age >= 18 years old;
  • Written informed consent;
  • Indication to CABG surgery (both "on-pump" and "off-pump");
  • Stable angina, unstable angina or acute coronary syndrome without ST elevation (NSTEMI).

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Group 1
adult patients undergoing coronary artery bypass surgery
Procedure: Coronary artery bypass graft
All patients included will undergo coronary artery bypass graft surgery. During surgery, every graft will be evaluated through transit time flowmetry (TTFM) and intraoperative ultrasound control (HFUS).

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Number of anastomoses needed to reach a ratio (total score/n. of anastomoses) >= 11
Time Frame: This evaluation will require from 1 to 3 months.
Number of anastomoses needed to reach a ratio between total score and the number of studied anastomoses of 11 or more
This evaluation will require from 1 to 3 months.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Number of anastomoses needed to reach a ratio (HFUS score/n. of anastomoses) = 4
Time Frame: This evaluation will require from 1 to 3 months.
Number of anastomoses needed to reach a ratio between the HFUS score and the number of studied anastomoses of 4
This evaluation will require from 1 to 3 months.
Number of anastomoses needed to reach a ratio (TTFM score/n. of anastomoses) >=7
Time Frame: This evaluation will require from 1 to 3 months.
Number of anastomoses needed to reach a ratio between the TTFM score and the number of studied anastomoses of 7 or more
This evaluation will require from 1 to 3 months.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Fondazione Policlinico Universitario Agostino Gemelli IRCCS

Investigators

  • Principal Investigator: Federico Cammertoni, Dr., Fondazione Policlinico Universitario A. Gemelli, IRCCS

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

September 15, 2024

Primary Completion (Actual)

April 1, 2025

Study Completion (Actual)

April 1, 2025

Study Registration Dates

First Submitted

August 27, 2024

First Submitted That Met QC Criteria

September 5, 2024

First Posted (Actual)

September 19, 2024

Study Record Updates

Last Update Posted (Estimated)

January 2, 2026

Last Update Submitted That Met QC Criteria

December 29, 2025

Last Verified

September 1, 2024

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 6735

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

Clinical Trials on Coronary Artery Disease

Clinical Trials on Coronary artery bypass graft

Search Similar Trials

Sponsors and Collaborators

Medical Conditions

Drug Interventions

CROs by country

CROs in Zimbabwe

Conditions

Rare Diseases

Drug Interventions

Dietary Supplements

Sponsor/Collaborators

Locations

Subscribe