Intraoperative Transit Time Flow Measurement Research Articles

Preoperative Quantitative Flow Ratio, Intraoperative Transit Time Flow Measurement Parameters, and Their Predictive Value for Short-Term Graft Failure After Coronary Artery Bypass Grafting.

Studies on the relationship between the preoperative quantitative flow ratio (QFR) and parameters of intraoperative transit time flow measurement (TTFM) are extremely rare. In addition, the predictive value of QFR and TTFM parameters for early internal mammary artery (IMA) failure after coronary artery bypass grafting still needs to be validated.Methods and Results: We retrospectively collected data from 510 patients who underwent in situ IMA grafting to the left anterior descending (LAD) artery at Fuwai Hospital. Spearman correlation coefficients between preoperative QFR of the LAD artery and intraoperative TTFM parameters of the IMA were -0.13 (P=0.004) for mean graft flow (Qm) and 0.14 (P=0.002) for the pulsatility index (PI). QFR and TTFM exhibited similar and good predictive value for early IMA failure (5.7% at 1 year), and they were better than percentage diameter stenosis (area under the curve 0.749 for QFR, 0.733 for Qm, 0.688 for PI, and 0.524 for percentage diameter stenosis). The optimal cut-off value of QFR was 0.765. Both univariate and multivariable regression analyses revealed that QFR >0.765, Qm ≤15 mL/min, and PI >3.0 independently contributed to early IMA failure. There were statistically significant correlations between preoperative QFR of the LAD artery and intraoperative TTFM parameters (Qm, PI) of the IMA. Preoperative QFR and intraoperative Qm and PI exhibited excellent predictive value for early IMA failure.

Transit time flow measurement in off-pump surgery: is it a functional index of the biological graft integrity?

Transit-time flow measurement (TTFM) represents a valid tool in the assessment of the quality of the anastomosis during coronary artery bypass graft (CABG). Nevertheless, a high variability limits its standardized use, lacking univocally accepted cut-off flow values. Our study analyzes TTFM data collected from a study population that underwent off-pump CABG (OP-CABG), with the aim to differentiate into subgroups according to the presence of diabetes mellitus. Patients referred to the Cardiovascular Unit of S. Michele Hospital (Caserta, Italy) for coronary artery disease (CAD) and underwent OP-CABG between January 2015 and December 2019 were enrolled, and intraoperative TTFMs data were recruited and evaluated. Mean graft flow (MGF) and pulsatility index (PI) values were collected and analyzed. The study population was composed of 342 patients who underwent OP-CABG with TTFM data regarding 824 grafts. Diabetic patients shared a higher cardiovascular risk profile. The TTFM assessment showed better results for the use of the arterial grafts in diabetic patients, especially for those insulin-dependent; conversely, venous grafts showed worse data with lower MGF and higher PI values. In particular, the anastomoses of the saphenous vein graft with marginal obtuse (MO) coronary artery showed worse MGF results in the insulin-dependent rather than normoglycemic subgroup (28.66 vs. 38.44, p=0.003). Diabetic patients, especially in the insulin-dependent subgroups, have demonstrated lower MGF and higher PI values collected from venous anastomoses with, conversely, inverse results from the arterial one. These results might be correlated to an altered biological adaptability caused by the effects of the diabetic endocrine disorder.

Intraoperative transit time flow measurement predicts maturation of radiocephalic arteriovenous fistulas

ObjectiveThe arteriovenous fistula (AVF) is the first choice for gaining vascular access for hemodialysis. However, 20% to 50% of AVFs fail within 4 months after creation. Although demographic risk factors have been described, there is little evidence on the intraoperative predictors of AVF maturation failure. The aim of this study was to assess the predictive value of intraoperative transit time flow measurements (TTFMs) on AVF maturation failure. MethodsIn this retrospective cohort study, intraoperative blood flow, measured using TTFM, was compared with AVF maturation after 6 weeks in 55 patients. Owing to its significantly higher prevalence and risk of nonmaturation, the radiocephalic AVF (RCAVF) was the main focus of this study. A recommended cutoff point for high vs low intraoperative blood flow was determined for RCAVFs, using a receiver operating characteristic curve. ResultsThe average intraoperative blood flow in RCAVFs was 156 mL/min. Patients with an intraoperative blood flow equal or lower than the determined cutoff point of 160 mL/min, showed a 3.03 times increased risk of AVF maturation failure after 6 weeks, compared with patients with a higher intraoperative blood flow (P < .001). ConclusionsThe intraoperative blood flow in RCAVFs measured by TTFM provides an adequate means of predicting AVF nonmaturation 6 weeks after surgery. For RCAVFs, a cutoff point for intraoperative blood flow of 160 mL/min is recommended for maximum sensitivity and specificity to predict AVF maturation failure after 6 weeks.

Intraoperative transit-time flow measurement of caval veins before and after bidirectional cavopulmonary anastomosis.

Haemodynamic changes in caval venous flow distribution occurring during bidirectional cavopulmonary anastomosis operation are still largely unknown. Transit time flow measurements were performed in 15 cavopulmonary anastomosis operations. Superior and inferior caval vein flows were measured before and after the cavopulmonary anastomosis. Ratio of superior caval vein to overall caval veins flow was calculated. Mean superior caval vein flow ratio before cavopulmonary anastomosis was higher than previously reported for healthy children. Superior caval vein flow ratio decreased in 14/15 patients after cavopulmonary anastomosis: mean 0.63 ± 0.12 before versus 0.43 ± 0.14 after. No linear correlation between intraoperative superior caval vein pressure and superior caval vein flow after cavopulmonary anastomosis was found. Neither Nakata index nor pulmonary vascular resistance measured at preoperative cardiac catheterisation correlated with intraoperative flows. None of patients died or required a take down. The higher mean superior caval vein flow ratio before cavopulmonary anastomosis compared to healthy children suggests flow redistribution in univentricular physiology to protect brain and neurodevelopment. The decrease of superior caval vein flow ratio after cavopulmonary anastomosis may reflect the flow redistribution related to trans-pulmonary gradient. The lack of correlation between superior caval vein pressure and superior caval vein flow could be explained by limited sample size and multifactorial determinants of caval veins flow, although pressure remain essential. Larger sample of measurements are needed to find flow range potentially predictive for clinical failure. To authors' knowledge, this is the first intraoperative flow measurement of both caval veins during cavopulmonary operations.

Effects of Fractional Flow Reserve on Coronary Artery Bypass Graft Flow to Left Anterior Descending Artery.

The relationships between preoperative fractional flow reserve (FFR) values of the left anterior descending artery (LAD), FFRLAD, and intraoperative transit time flow measurement (TTFM) variables in coronary artery bypass grafting (CABG) remain unclear.Methods and Results: We retrospectively collected data for 74 in situ left internal thoracic artery (LITA) grafts and 27 saphenous vein grafts (SVGs) to the LAD that were shown to be patent on postoperative angiography. Spearman correlation coefficients were determined between FFRLADand TTFM parameters of the LITA graft, as follows: maximum flow (Qmax), -0.22 (P=0.077); minimum flow (Qmin), -0.40 (P=0.014); mean flow (Qm), -0.35 (P=0.039); pulsatility index (PI), 0.33 (P=0.008); diastolic filling (DF): 0.01 (P=0.83); and systolic reverse flow (SRF), 0.37 (P=0.002). Spearman correlation coefficients between FFRLADand TTFM parameters of the SVG to LAD were: Qmax, -0.65 (P=0.004); Qmin, -0.43 (P=0.044); Qm, -0.75 (P=0.001); PI, 0.53 (P=0.033); DF, 0.14 (P=0.48); and SRF, 0.61 (P=0.009). Both LITA grafts and SVGs to the LAD show negative correlations for FFRLADwith Qminand Qm, but positive correlations for FFRLADwith PI and SFR. These relationships between FFRLADand TTFM variables of CABG grafts to the LAD should be recognized.

Do chronic total occlusive lesions affect patency of coronary bypass grafts to the right coronary artery?

To evaluate the impact of chronic total occlusion (CTO) lesions on the patency of bypass grafts to the right coronary artery territory. Two hundred patients undergoing primary isolated coronary artery bypass grafting with revascularization to the right coronary artery territory between April 2015 and July 2022 were retrospectively analyzed. Study patients were divided into two groups according to their right coronary artery lesion: patients with CTO lesions (n = 76) and those without CTO lesions (n = 124). Graft flow of the right coronary artery territory was evaluated by intraoperative transit time flow measurement and patency of the bypass graft was evaluated by multidetector row computed tomography. A total of 200 patients (76 patients with CTO and 124 patients without CTO) were included in this study. Intraoperative transit time flow measurement demonstrated that there was no significant difference in the median mean graft flow (30 ml/min vs. 25 ml/min; p = 0.114), pulsatility index (2.1 vs. 2.4; p = 0.079), and diastolic filling rate (65% vs. 64%; p = 0.844) between patients with CTO and those without CTO. Postoperative multidetector row computed tomography demonstrated that the patency of bypass grafts to the right coronary artery territory was similar between the groups (94.7% in patients with CTO vs. 96.0% in those without CTO; p = 0.733). In patients with CTO, the patency of bypass graft tended to be worse in subgroup with rich collateral blood flow (Rentrop grade 3). Chronic total occlusion lesions do not affect the patency of bypass grafts to the right coronary artery territory.

The preoperative myocardial perfusion and internal mammary artery graft blood flow relationship in patients with ischemic cardiomyopathy

Objective. The purpose of this study was to determine the association between preoperative myocardial perfusion data (obtained by SPECT) with transit time blood flow characteristics in left internal mammary artery (LIMA) to left anterior descending artery (LAD) grafts in patients with ischemic cardiomyopathy.Methods. The study group consisted of 57 patients with ischemic cardiomyopathy. Intraoperative transit-time flow measurement (TTFM) of LIMA-LAD grafts were performed in all patients. All patients were also examined with preoperative stress and rest myocardial perfusion SPECT with 99m Tc-MIBI. Anastomotic patency was considered satisfactory with a normal waveform of blood flow, diastolic-dominant blood filling, and a mean flow value greater than 11.5 ml/min.Results. All 57 patients with LIMA-LAD grafts were divided into two groups; those with graft satisfactory patency (n = 40) and those with unsatisfactory patency (n = 17) as determined by TTFM. We found differences among these groups in values of global summed rest score (20.7 ± 7.5 vs. 29.8 ± 4.0; p = 0.002), global total perfusion deficit (TPD) at rest (32.0 ± 11.4 vs. 43.0 ± 7.2; p = 0.01), and regional TPD at rest in the LAD territory (20.7 ± 7.5 vs. 29.8 ± 4.0; p = 0.002). Additionally, the flow characteristics were different in patients with and without surgical left ventricle reconstruction (Q (ml/min): 17 (11.5, 40.8) vs. 47 (25, 69.5), p = 0.013; PI: 3.9 (3.2, 7.4) vs. 2.4 (2.0, 3.6), p = 0.001; DF (%): 63.5 (44.5, 70.8) vs. 74 (66.0, 79.7), p = 0.019). TPD at rest was the best predictor of the LIMA-LAD graft satisfactory: area under curve = 0.771, cut-off value = 26.85 with 83.3% sensitivity and 78.1% specificity.Conclusions. Preoperative myocardial perfusion characteristics are associated with blood flow in LIMA-LAD graft in patients with ischemic cardiomyopathy. TPD at rest (assessed globally and in the LAD region) as well as global SRS value are potential predictors of early graft failure.

Evaluation of anastomosis quality with intraoperative transit time flowmeter in minimally invasive multi-vessel coronary artery bypass grafting via left anterior mini-thoracotomy.

In this study, we aimed to describe our intraoperative transit-time flow measurement results as an integral component of the operation and evaluate the graft patency and anastomosis quality in patients who underwent minimally invasive multi-vessel coronary artery bypass grafting via mini-thoracotomy. Between May 2020 and September 2021, a total of 45 consecutive patients (32 males, 13 females; mean age: 51.2±8.6 years; range, 41 to 72 years) who underwent minimally invasive multi-vessel coronary artery bypass grafting via left anterior mini-thoracotomy were retrospectively analyzed. We used the technique of intraoperative transit-time flowmetry in all patients. The patients were operated under cardiopulmonary bypass. A saphenous vein graft was used in all anastomoses, except for the left internal thoracic artery. The mean left internal mammary artery flow rate was 36.2±14.1 mL/min, mean flow rate of the diagonal grafts was 48.2±13.1 mL/min, mean flow rate of the circumflex grafts was 41.2±21.1 mL/min, and mean flow rate of the right coronary artery grafts was 52.2±11.3 mL/min. Wave patterns and flow parameters of all grafts were normal in the intraoperative measurements, since the pulsatility index values in all anastomoses were within normal limits. The operation was completed after anastomotic openings and graft patency were ensured. The use of an intraoperative flowmeter to show the graft patency and anastomosis quality gives confidence both to the surgeon and the patient. In multi-vessel coronary artery bypass grafting via mini-thoracotomy, anastomosis quality can be evaluated well with this technique.

The use of intraoperative transit time flow measurement can reduce preoperative myocardial injury.

Journal of Cardiac SurgeryVolume 37, Issue 12 p. 4254-4255 COMMENTARY The use of intraoperative transit time flow measurement can reduce preoperative myocardial injury Federico Benetti MD, Federico Benetti MD [email protected] Department of Cardiac Surgery, Benetti Foundation, Rosario, ArgentinaSearch for more papers by this author Federico Benetti MD, Federico Benetti MD [email protected] Department of Cardiac Surgery, Benetti Foundation, Rosario, ArgentinaSearch for more papers by this author First published: 19 September 2022 https://doi.org/10.1111/jocs.16814 Correspondence: Federico Benetti, Benetti Foundation, Alem 1846, Rosario 2000, Argentina. Email: [email protected] Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume37, Issue12December 2022Pages 4254-4255 RelatedInformation

The use of intraoperative transit time flow measurement can reduce postoperative myocardial injury.

This study investigates the relationship between the use of transit time flow measurement (TTFM) and postoperative myocardial injury in off-pump coronary artery bypass grafting (OPCABG). In this retrospective study, we collected basic data from patients hospitalized for OPCABGin the Department of Cardiothoracic Surgery, Changzhou Second People's Hospital Affiliated with Nanjing Medical University. According to the academic research consortium (ARC)-2 definition of significant myocardial injury, we used cardiac troponin I >2380 ng/L as a criterion for significant postoperative myocardial injury. We use logistic regression and forest plots to assess the association of TTFM use with myocardial injury outcomes. One hundred and forty-six patients were included in this study. The overall median age of these patients was 65.05 years, and 32 (21.92%) experienced a postoperative myocardial injury. TTFM was independently associated with the incidence of postoperative myocardial injury (odds ratio = 0.34 [95% confidence interval = 0.15-0.78]; p = .01), and we found similar trends in regression analyses across subgroups of sex, age, number of bridging vessels, hypertension, diabetes mellitus, BMI, and percutaneous coronary revascularization. One hundred andsixpatients were followed for 1-year vessel permeability, and sevenpatients (6.6%) were occluded. The use of TTFM is independently associated with a reduced incidence of postoperative myocardial lesions during off-pump coronary bypass surgery. The TTFM procedure in OPCABGdeserves to be actively promoted to reduce the incidence of postoperative myocardial injury.

Graft flow evaluation with intraoperative transit-time flow measurement in off-pump versus on-pump coronary artery bypass grafting.

ObjectiveWe aimed to compare transit-time flow measurement (TTFM) parameters for on-pump (ONCAB) and off-pump (OPCAB) coronary artery bypass procedures.MethodsThe database of the Registry for Quality AssESsmenT with Ultrasound Imaging and TTFM in Cardiac Bypass Surgery (REQUEST) study was retrospectively reviewed. Only single grafts were included (ie, no sequential or Y/T grafts). Primary end points were mean graft flow (MGF), pulsatility index (PI), diastolic fraction (DF), and backflow (BF). Unadjusted and propensity score-matching comparisons were performed.ResultsOf 1016 patients in the REQUEST registry, 846 had at least 1 graft for which TTFM was performed. Of these, 512 patients (60.6%) underwent ONCAB and 334 (39.4%) OPCAB procedures. Mean arterial pressure (MAP) during measurements was higher in the OPCAB group. After propensity score-matching, 312 well balanced pairs were left. In these matched patients, MGF was higher for the ONCAB versus the OPCAB group (32 vs 28 mL/min, respectively, for all grafts [P < .001]; 30 vs 27 mL/min for arterial grafts [P = .002]; and 35 vs 31 mL/min for venous grafts [P = .006], respectively). PI was lower in the ONCAB group (2.1 vs 2.3, for all grafts; P < .001). Diastolic fraction was slightly lower in the ONCAB group (65% vs 67.5%; P < .001). The backflow was also lower in the ONCAB group (0.6 vs 1.3; P < .001) with trends similar to MGF and PI for venous and arterial grafts. There were 21 (3.3%) revisions in the OPCAB group and 14 (2.1%) in the ONCAB group (P = .198).ConclusionsONCAB surgery was associated with higher MGF and lower PI values, especially in venous grafts. Different TTFM cutoff values for ONCAB versus OPCAB surgery might be considered.

Transit Time Flow Measurement in Robotic Totally Endoscopic Coronary Artery Bypass: What Do the Numbers Mean?

Transit time flow measurement (TTFM) is valuable for assessing intraoperative graft patency in coronary artery bypass surgery (CAB). The significance of competitive native coronary flow on patency, as predicted by percentage of backflow (%BF) on TTFM, is unknown. This study aims to evaluate intraoperative TTFM parameters, and specifically %BF, in predicting graft patency in robotic totally endoscopic CAB (TECAB). We reviewed TTFM parameters in 311 patients undergoing robotic off-pump TECAB at our institution between February 2016 and January 2020. Patients with sequential or Y grafts were excluded, leaving 277 patients with a total of 387 isolated end-to-side grafts (248 left internal mammary artery [LIMA], 149 right IMA [RIMA]). Mean graft flow, diastolic flow, pulsatility index, and %BF were measured intraoperatively. Early postoperative angiograms were obtained in 83 patients undergoing percutaneous coronary intervention for hybrid revascularization, with a total of 125 grafts. Angiograms were independently analyzed and separated into 2 groups based on IMA graft patency, which were patent (FitzGibbon A/B) and nonpatent (FitzGibbon O) groups. Early angiographic patency at a median of 31.0 days after surgery showed 123 (97.1%) patent grafts and 3 (2.9%) occluded grafts in both LIMA and RIMA grafts to both left anterior descending (LAD) and non-LAD targets. Mean graft flow was 77.4 ± 41.6 mL/min. There was no difference in mean flow, pulsatility index, or %BF between the patent and occluded grafts. Excellent intraoperative flow parameters and early angiographic patency can be obtained via robotic, off-pump TECAB. Our data did not demonstrate an association between intraoperative TTFM evidence of competitive native coronary flow and early angiographic graft outcomes.

Transit time flow measurement predicts graft patency in off-pump coronary artery bypass grafting upon 5-year angiographic follow-up

ObjectiveThis retrospective study sought to evaluate the efficacy of transit time flow measurement (TTFM) as a means of predicting bypass graft patency as assessed by coronary artery angiography upon 5-year follow-up.MethodsOf 311 patients undergone isolated off-pump coronary artery bypass graft surgery from January 2014 through December 2014, 202 (65%) underwent both intraoperative TTFM and angiography at follow-up. 610 grafts, 202 left internal mammary artery grafts and 408 saphenous vein grafts were checked. Any grafts that exhibited Fitzgibbon type B or O lesions upon angiographic evaluation were considered to be failing. Receiver operating characteristic curves were used to identify the optimal TTFM values for predicting graft patency.ResultsA total of 610 grafts were included in this analysis, including 202 LIMA grafts and 408 SV grafts, of which 107, 129, 129, and 43 anastomosed to DIAG, OM, PDA, and PLA, respectively. LIMA, DIAG, OM, PDA, and PLA bypass grafts had overall patency rates of 95.0%, 74.8%, 73.6%, 71.5%, and 74.4%, respectively, upon 5-year follow up. No significant differences in TTFM values (MGF, PI, and DF) were observed when comparing outcomes associated with individual or sequential SV grafting. MGF was found to be predictive of graft failure regardless of the target vessel (P < 0.05). While PI was found to predict LIMA, OM, and PDA graft failure (P < 0.05), it was not associated with the failure of grafts associated with DIAG and PLA vessels. Similarly, DF was found to predict OM and PDA graft failure (P < 0.05), but was not significantly associated with the failure of grafts associated with LIMA, DIAG, or PLA vessels.ConclusionLIMA bypass grafts were associated with better 5-year graft patency relative to SV bypass grafts. Similar graft patency rates were observed for both individual and sequential bypass grafts. MGF was able to predict bypass graft failure in patients that underwent off-pump CABG surgery.

Intraoperative transit time flow measurement in patients with diffuse coronary artery disease in the prevention of aortocoronary bypass graft occlusion

Aim. To study the parameters of transit time flow measurement (TTFM) for coronary bypass grafts in patients with diffuse lesions with different diameter of target coronary arteries.Material and methods. The study included 150 patients with diffuse coronary artery disease. All patients underwent microscope-assisted coronary artery bypass grafting (CABG), during which the TTFM parameters were evaluated. Depending on the diameter of target coronary arteries, patients were divided into 3 groups: group 1 included grafts to arteries ≤1 mm (n=101), group 2 — 1-1,5 mm (n=138), group 3 — ≥1,5 mm (n=308). Comparative analysis of TTFM parameters was performed.Results. Mostly participants were male (76%); mean age was 62,9±7,6 years. During hospitalization, we recorded 1 death, 2 perioperative myocardial infarctions (1,3%) and 1 cerebrovascular accident (0,7%). TTFM analysis showed the worst hemodynamic parameters and a higher rate of suboptimal function in group 1; blood flow parameters were comparable in groups 2 and 3. The additional analysis in group 1 and combined groups 2 and 3 allows us to make an opinion about the negative impact of coronary artery diameter less than 1 mm on optimal blood flow through the grafts (odds ratio=2,1, 95% confidence interval, 1,2-3,8, p=0,011).Conclusion. Diffuse coronary atherosclerosis with a diameter of target coronary arteries less than 1 mm significantly increase the risk of suboptimal graft function that requires considering more aggressive secondary prevention. TTFM demonstrate high effectiveness of microscope-assisted CABG in target coronary artery diameter of 1-1,5 mm and higher.

Intraoperative transit time flow measurements during off-pump coronary artery bypass surgery: The impact of coronary stenosis on competitive flow.

BackgroundCombining preoperative angiography findings with intraoperative transit time flow measurements (TTFM) may improve patency of coronary artery bypass grafts. Nevertheless, graft flow might be impaired by native coronary flow based on the severity of stenoses, with inferior long‐term outcomes. This study investigates the impact of left anterior descending artery (LAD) stenosis on competitive flow measured in left internal mammary artery (LIMA) grafts during off‐pump coronary artery bypass grafting.MethodsFifty patients were included in this prospective single‐center cohort study. LAD stenosis was assessed with quantitative coronary analysis (QCA) and stratified into three groups based on its severity. TTFM of LIMA grafts were performed with LAD open and temporarily occluded. Change in mean graft flow after LAD snaring was the primary endpoint. Secondary endpoints included further TTFM parameters, clinical outcomes, and competitive flow index (CFI), defined as the ratio of mean graft flow with open or closed LAD.ResultsMean LAD stenosis as objectified with QCA was 58 ± 15%. Mean LIMA graft flow increased from 20 ml/min with open LAD to 30 ml/min with snared LAD (p < .001). TTFM cut‐off values for graft patency improved in 26%–42% of patients after LAD occlusion. Median CFI was 0.66 (IQR: 0.56–0.82). Postoperative myocardial infarction occurred in 2.0% of patients, 120‐day mortality was 0%, and 2‐year mortality was 6.0%.ConclusionsRoutine snaring of the LAD with CFI calculation during coronary artery bypass grafting is useful to detect significant competitive flow in LIMA grafts, potentially preventing unnecessary intraoperative graft revisions.

The Use of Intraoperative Transit Time Flow Measurement for Coronary Artery Bypass Surgery: Systematic Review of the Evidence and Expert Opinion Statements.

Transit time flow measurement (TTFM) allows quality control in coronary artery bypass grafting but remains largely underused, probably because of limited information and the lack of standardization. We performed a systematic review of the evidence on TTFM and other methods for quality control in coronary artery bypass grafting following PRISMA standards and elaborated expert recommendations by using a structured process. A panel of 19 experts took part in the consensus process using a 3-step modified Delphi method that consisted of 2 rounds of electronic voting and a final face-to-face virtual meeting. Eighty percent agreement was required for acceptance of the statements. A 2-level scale (strong, moderate) was used to grade the statements based on the perceived likelihood of a clinical benefit. The existing evidence supports an association between TTFM readings and graft patency and postoperative clinical outcomes, although there is high methodological heterogeneity among the published series. The evidence is more robust for arterial, rather than venous, grafts and for grafts to the left anterior descending artery. Although TTFM use increases the duration and the cost of surgery, there are no data to quantify this effect. Based on the systematic review, 10 expert statements for TTFM use in clinical practice were formulated. Six were approved at the first round of voting, 3 at the second round, and 1 at the virtual meeting. In conclusion, although TTFM use may increase the costs and duration of the procedure and requires a learning curve, its cost/benefit ratio seems largely favorable, in view of the potential clinical consequences of graft dysfunction. These consensus statements will help to standardize the use of TTFM in clinical practice and provide guidance in clinical decision-making.

Intraoperative transit-time flow measurement and high-frequency ultrasound in coronary artery bypass grafting: impact in off versus on-pump, arterial versus venous grafting and cardiac territory grafted.

Despite society guideline recommendations, intraoperative high-frequency ultrasound (HFUS) and transit-time flow measurement (TTFM) use in coronary artery bypass grafting (CABG) has not been widely adopted worldwide. This retrospective review of the REQUEST (REgistry for QUality assESsmenT with Ultrasound Imaging and TTFM in Cardiac Bypass Surgery) study assesses the impact of protocolled high-frequency ultrasound/TTFM use in specific technical circumstances of CABG. Three REQUEST study sub-analyses were examined: (i) For off-pump (OPCAB) versus on-pump (ONCAB) procedures: strategy changes from preoperative plans for the aorta, conduits, coronary targets and graft revisions; and for all REQUEST patients, revision rates in: (ii) arterial versus venous grafts; and (iii) grafts to different cardiac territories. Four hundred and two (39.6%) of 1016 patients undergoing elective isolated CABG for multivessel disease underwent OPCAB procedures. Compared to ONCAB, OPCAB patients experienced more strategy changes regarding the aorta [14.7% vs 3.4%; odds ratios (OR) = 4.03; confidence interval (CI) = 2.32-7.20], less regarding conduits (0.2% vs 2.8%; OR = 0.09; CI = 0.01-0.56), with no differences in coronary target changes or graft revisions (4.1% vs 3.5%; OR = 1.19; CI = 0.78-1.81). In all REQUEST patients, revisions were more common for arterial versus venous grafts (4.7% vs 2.4%; OR = 2.05; CI = 1.29-3.37), and inferior versus anterior (5.1% vs 2.9%; OR = 1.77; CI = 1.08-2.89) and lateral (5.1% vs 2.8%; OR = 1.83; CI = 1.04-3.27) territory grafts. High-frequency ultrasound/TTFM use differentially impacts strategy changes and graft revision rates in different technical circumstances of CABG. Notably, patients undergoing OPCAB experienced 4 times more changes related to the ascending aorta than ONCAB patients. These findings may indicate where intraoperative assessment is most usefully applied. ClinicalTrials.gov: NCT02385344.

Clinical outcomes of radial artery as the second arterial conduit in coronary artery bypass

Objective: To examine the clinical experience and outcomes of coronary artery bypass grafting (CABG) using radial artery as the second arterial graft. Methods: Totally 585 patients in whom both left internal thoracic artery and radial artery as arterial conduits were used in CABG in Department of Cardiovascular Surgery, Nanjing Hospital Affiliated to Nanjing Medical University from April 2008 to August 2019 were consecutively enrolled. There were 436 males and 149 females, aging (63±10) years (range: 36 to 86 years). There were 40.7% (238/585) of patients had diabetes and 75.6% (442/585) of them had multivessel disease (two-vessel or three-vessel diseases). From January 2017, transit time flow measurement was performed on every patient. Demographic and perioperative data were retrospectively collected, as well as follow-up data for patients who underwent CABG from January 2014 to August 2019. Analysis were made on their early and late outcomes. Results: 81.9%(479/585) Most patients in this cohort (81.9%) received on-pump CABG and 11 patients had intraoperative intro-aortic balloon counterpulsation (prior to CABG) support. Forty-three patients had concomitant valve procedures. The number of distal anastomosis was 3.6±0.9 (range: 2 to 6) and number of arterial distal anastomosis was 2.1±0.3. Radial artery was anastomosed to left obtuse marginal artery in 95.8% (560/585) patients. All target vessels for radial artery conduit had significant proximal stenosis (>70%) and 72.5% (424/585) of target vessels had proximal stenosis which was >90%. Intraoperative transit-time flow measurement of 151 cases showed that radial artery conduits had a flow of (29.8±10.2) ml/minutes (range: 10 to 150 ml/min), and pulsatility index of 2.5±1.4 (range: 0.7 to 5.0). There was no operative death. Two in-hospital death occurred more than 30 days after index surgery. There was no perioperative myocardial infarction. There were 188 patients who received CABG from January 2014 to August 2019 followed-up for a median duration of 3.2 years. There were two noncardiac death. No patient had myocardial infarction or to receive myocardial revascularization. Conclusions: Radial artery as the second arterial conduit is a safe and effective strategy for CABG. Good selection of target vessel and intraoperative transit-time flow measurement may help achieve good patency, as well as the short and mid-term outcome.

Aspirin plus ticagrelor or clopidogrel on graft patency one year after coronary bypass grafting: a single-center, randomized, controlled trial.

BackgroundDual antiplatelet therapy (DAPT) improves early post-operative graft patency, but the optimal DAPT strategy for the patients after coronary artery bypass grafting (CABG) has not been confirmed. We sought to evaluate the effect of aspirin plus ticagrelor versus aspirin plus clopidogrel on saphenous vein graft (SVG) patency within 1 year after CABG.MethodsBetween October 2017 and December 2018, 147 consecutive patients undergoing elective CABG at Changhai Hospital were randomized into two groups: group AT, receiving aspirin 100 mg/d plus ticagrelor 2×90 mg/d; group AC, receiving aspirin 100 mg/d plus clopidogrel 75 mg/d. Both DAPTs should be administered within 24 h when clinical stability was ensured. 64-multislice computed tomography angiography (MSCTA) was used to assess the graft patency at 12 months after CABG.CYP2C19 gene variants were measured to assess the clopidogrel efficacy on graft patency.ResultsAmong the 147 participants who completed the study, one (0.7%) patient from the AC group died at 5 weeks after surgery due to severe infection. All other patients were treated with DAPT for 12 months and underwent 64-MSCTA according to schedule. There were no significant differences in pre-operative characteristics and intraoperative transit-time flow measurement findings between the two groups. Besides, no significant differences in the incidence of major adverse cardiac events (MACEs) and major bleeding were observed. A 64-MSCTA showed that SVG patency was 91.0% (141 of 155) in the AT group and 89.9% (161 of 179) in the AC group (P=0.751). No significant associations were found between different CYP2C19 genotypes and SVG patency (P>0.05).ConclusionsEither aspirin plus ticagrelor or aspirin plus clopidogrel can maintain a fairly high graft patency rate in the early phase after CABG, regardless of CYP2C19 genotypes.

Correlation between Preoperative Coronary Artery Stenosis Severity Measured by Instantaneous Wave-Free Ratio and Intraoperative Transit Time Flow Measurement of Attached Grafts.

Background and Objectives: To assess the correlation between the degree of target coronary artery stenosis measured by instantaneous wave-free ratio (iFR) and the intraoperative transit time flow measurement (TTFM) of attached grafts as well as evaluate flow competition between the native coronary artery and the attached graft according to the severity of stenosis. Materials and Methods: In total, 89 grafts were subjected to intraoperative transit time flow measurement after coronary artery bypass grafting (CABG) in 25 patients with multivessel coronary artery disease (CAD). The iFR was evaluated for all coronary arteries with grafts. The coronary artery stenoses were divided into three groups based on the iFR value: iFR < 0.86 (group 1); iFR 0.86–0.90 (group 2); and iFR > 0.90 (group 3). Results: The mean graft flow (MGF) was 46.9 ± 18.4 mL/min for group 1, 45.3 ± 20.9 mL/min for group 2, and 31.3 ± 18.5 mL/min for group 3. A statistically significant difference was confirmed between groups 1 and 3 (p = 0.002) and between groups 2 and 3 (p = 0.025). The pulsatility index (PI) was 2.49 ± 1.20 for group 1, 2.66 ± 2.13 for group 2, and 4.70 ± 3.66 for group 3. A statistically significant difference was found between groups 1 and 3 (p = 0.006) and between groups 2 and 3 (p = 0.032). Backward flow was detected in 7.5% of grafts for group 1, in 16.6% of grafts for group 2, and in 16% of grafts for group 3. A statistically significant difference was found between groups 1 and 2 (p = 0.025) and between groups 1 and 3 (p = 0.029). Conclusions: The iFR is a useful tool for predicting the impact of competitive flow observed between a native artery and an attached graft. The effect of competitive flow significantly increases when the graft is attached to a vessel with mild coronary stenosis. In a coronary artery where the iFR was not hemodynamically significant, the MGF was lower, the PI was higher, and a larger proportion of grafts with backward flow (BF) was detected compared to when there was significant stenosis (iFR < 0.86).