Some perturbations on the ultrasonic measurements in phantoms using transit-time flow-metering systems

AbstractTransit-time flow measurement (TTFM) has been increasingly applied to detect graft failure during coronary artery bypass grafting (CABG), because TTFM is less invasive, more reproducible, and less time consuming. Many authors have attempted to validate TTFM and to gain the clear cutoff values and algorithm in TTFM to predict graft failure. The TTFM technology has also been shown to be a useful tool to investigate CABG graft flow characteristics and coronary circulation physiology. It is important to recognize the practical roles of TTFM in the cardiac operating room by review and summarize the literatures.

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The procedure for intraoperative graft verification in coronary surgery: Is high resolution epicardial imaging useful in addition to Transit-Time flow measurement to reduce postoperative failures?

Journal of Cardiothoracic Surgery ◽

10.1186/1749-8090-10-s1-a279 ◽

2015 ◽

Vol 10 (S1) ◽

Author(s):

Gabriele Di Giammarco ◽

Daniele Marinelli ◽

Massimiliano Foschi ◽

Tariq Mobariki ◽

Donato Micucci ◽

...

Keyword(s):

High Resolution ◽

Transit Time ◽

Flow Measurement ◽

Coronary Surgery ◽

Time Flow

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Transit-time flow measurement verifies patency of coronary artery grafts: An observational study

Heart Lung and Circulation ◽

10.1016/j.hlc.2014.12.044 ◽

2015 ◽

Vol 24 ◽

pp. e19-e20

Author(s):

Mohammad R. Azari ◽

Ajay Hirikannawar ◽

Hugh Wolfenden ◽

Bruce French ◽

Manish Jain ◽

...

Keyword(s):

Coronary Artery ◽

Observational Study ◽

Transit Time ◽

Flow Measurement ◽

Time Flow

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The Accuracy of Transit Time Flow Measurement in Predicting Graft Patency after Coronary Artery Bypass Grafting

Innovations Technology and Techniques in Cardiothoracic and Vascular Surgery ◽

10.1097/imi.0000000000000021 ◽

2013 ◽

Vol 8 (6) ◽

pp. 416-419 ◽

Cited By ~ 14

Author(s):

Patrick F. Walker ◽

William T. Daniel ◽

Emmanuel Moss ◽

Vinod H. Thourani ◽

Patrick Kilgo ◽

...

Keyword(s):

Coronary Artery ◽

Coronary Artery Bypass Grafting ◽

Transit Time ◽

Pulsatility Index ◽

Flow Measurement ◽

Artery Bypass ◽

Graft Patency ◽

Bypass Grafting ◽

Flow Measurements ◽

Time Flow

Objective Transit time flow measurement (TTFM) is a method used to assess intraoperative blood flow after vascular anastomoses. Angiography represents the criterion standard for the assessment of graft patency after coronary artery bypass grafting (CABG). The purpose of this study was to compare flow measurements from TTFM to diagnostic angiography. Methods From October 9, 2009, to April 30, 2012, a total of 259 patients underwent robotic-assisted CABG procedures at a single institution. Of these, 160 patients had both TTFM and either intraoperative or postoperative angiography of the left internal mammary artery to the left anterior descending coronary artery graft. Transit time flow measurements were obtained after completion of the anastomosis and after administration of protamine before chest closure. Transit time flow measurement assessment included pulsatility index, diastolic fraction, and flow (milliliters per minute). Angiograms were graded according to the Fitzgibbon criteria. The patients were grouped according to angiographic findings, with perfect grafts defined as FitzGibbon A and problematic grafts defined as either Fitzgibbon B or O. Results Overall, there were 152 (95%) of 160 angiographically perfect grafts (FitzGibbon A). Of the eight problematic grafts, five were occluded (Fitzgibbon O) and three had significant flow-limiting lesions (FitzGibbon B). Two patients had intraoperative graft revision after completion angiography, one had redo CABG during the same hospitalization, and five were treated with percutaneous coronary intervention. A significant difference was seen in mean ± SD flow (34.3 ± 16.8 mL/min vs 23.9 ± 12.5 mL/min, P = 0.033) between patent and nonpatent grafts but not in pulsatility index (1.98 ± 0.76 vs 1.65 ± 0.48, P = 0.16) or diastolic fraction (73.5% ± 8.45% vs 70.9% ± 6.15%, P = 0.13). Conclusions Although TTFM can be a useful tool for graft assessment after CABG, false negatives can occur. Angiography remains the criterion standard to assess graft patency and quality of the anastomosis after CABG.

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An Implantable Transit-Time Aortic Flow Probe Using Capacitive Micromachined Ultrasound Transducers: Design and Optimization

ASME 2007 Summer Bioengineering Conference ◽

10.1115/sbc2007-176579 ◽

2007 ◽

Author(s):

Jessica Liu ◽

Robin Shandas

Keyword(s):

Cardiac Output ◽

Transit Time ◽

Ultrasound Transducers ◽

Flow Probe ◽

Design And Optimization ◽

Post Surgery ◽

Time Flow ◽

Type Flow ◽

Operative Recovery ◽

Pharmaceutical Agents

Monitoring cardiac output continuously post-surgery for children with congenital heart disease is an important part of post-operative recovery, especially given the potential for large changes in vascular pressure as a side-effect of pharmaceutical agents given to help recovery. Current methods to monitor cardiac output are limited by the requirement for invasiveness (cuff-type flow probes), or do not provide continuous monitoring (ultrasound Doppler). Using a combination of analytical and finite element modeling, we explore the design and optimization of a unique ultrasonic transit-time flow probe that extends the capability of current devices by providing greater miniaturization, better sensitivity, and lower cost through the use of capacitive micromachined ultrasound transducer (cMUT) technology.

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Intraoperative use of transit time flow measurement improves patency of newly created radiocephalic arteriovenous fistulas in patients requiring hemodialysis

The Journal of Vascular Access ◽

10.1177/1129729820916561 ◽

2020 ◽

Vol 21 (6) ◽

pp. 990-996

Author(s):

Anna E Cyrek ◽

Johannes Bernheim ◽

Benjamin Juntermanns ◽

Peri Husen ◽

Arkadius Pacha ◽

...

Keyword(s):

Blood Flow ◽

Arteriovenous Fistula ◽

Transit Time ◽

Intraoperative Ultrasound ◽

Low Flow ◽

Flow Measurements ◽

Technical Problems ◽

Arteriovenous Fistulas ◽

Time Flow ◽

Observation Period

Background: The autologous arteriovenous fistula is the primary choice to establish hemodialysis access without high failure rates. Intraoperative ultrasound flow measurements of newly created autologous arteriovenous fistulas represent a possibility of quality control and may therefore be a tool to assess their functionality. The aim of our study was to correlate intraoperative blood flow with access patency. Methods: Between March 2012 and March 2015, intraoperative transit time flow measurements were collected on 89 patients. Measurements were performed 5–10 min after the creation of a standardized anastomosis using 3–6 mm flow probes. To examine the correlation between intraoperative blood flow and access patency, groups of patients with high (> 200 mL/min) versus low flow (< 200 mL/min) were enrolled. Patients were assessed clinically and with ultrasound every 3 months. Data were analyzed retrospectively. Results: In the current short-term follow-up, including 89 patients (age 62 ± 3 years), 61 (68.5%) of the autologous arteriovenous fistulas were currently being used in an observation period ranging from 3 months to 3 years (mean observation period 546 ± 95 days) postoperatively. The intraoperative blood flow in patients with functioning autologous arteriovenous fistula (78) was significantly higher than that of patients without functioning autologous arteriovenous fistulas (407 ± 25 vs 252 ± 42 mL/min, respectively; p < 0.005) (11). Conclusion: The intraoperative measurement of blood flow is a useful tool to predict the outcome of maturation in autologous arteriovenous fistula. With this method, technical problems can be detected and corrected intraoperatively. Routine implementation of intraoperative flow measurements has to be examined by prospective controlled trials.

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Enhancement of flow measurement for graft verification

Asian Cardiovascular and Thoracic Annals ◽

10.1177/0218492319881034 ◽

2019 ◽

Vol 27 (8) ◽

pp. 646-651

Author(s):

Yury Y Vechersky ◽

Vasily V Zatolokin ◽

Boris N Kozlov ◽

Aleksandra A Nenakhova ◽

Vladimir M Shipulin

Keyword(s):

Coronary Artery ◽

Transit Time ◽

Flow Measurement ◽

Artery Bypass ◽

Coronary Bypass ◽

Flow Measurements ◽

Technical Problems ◽

Technical Errors ◽

Time Flow ◽

Coronary Bypass Grafts

Background We aimed to evaluate multiple transit-time flow measurements during coronary artery bypass grafting. Methods Transit-time flow measurements were performed first on the arrested heart both with and without a proximal snare on the target coronary artery, second, after weaning from cardiopulmonary bypass, and third, before chest closure. Results Among the 214 grafts considered, 9 (4.2%) were patent and 6 (2.8%) were failing. In the failed grafts, an abnormal transit-time flow was found during the first measurement, in 5 (2.3%) cases with a proximal snare and in one (0.47%) without a snare. In these cases, technical errors with the distal anastomoses were found and immediately corrected. A problem with the proximal anastomosis was found in one graft during the second measurement and corrected right away. Bending due to excessive length was found in 2 (0.93%) grafts during the third measurement, and graft repositioning was performed. The first transit-time flow measurement showed that mean graft flow was significantly decreased with a proximal snare compared to without a proximal snare, throughout the entire coronary territory. Pulsatility index during the first transit-time flow measurement was higher with a proximal snare than without one. Conclusions The 3-time transit-time flow measurement strategy makes it possible to verify and immediately correct technical problems with coronary bypass grafts.

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