The Algorithm for Using Transit-time Flow Measurement and High-resolution Epicardial Ultrasound for Intraoperative Grafts Assessment during Coronary Artery Bypass Surgery

Aim      To develop an algorithm for using ultrasonic flowmetry (USF) and epicardial ultrasonic scanning (EpiUSS) for intraoperative assessment of anatomic and functional viability of conduits.Material and methods  For viability assessment of 460 coronary grafts in 150 patients who were operated at the Bakulev National Medical Research Center for Cardiovascular Surgery (2018-2021 г.), markers of graft failure were analyzed using the USF and EpiUSS data confirmed by results of graft angiography. According to RОС analysis, the Qmean and PI values indicative of the graft failure were determined. A CHAID decision tree was developed for assessing the prognostic significance of the analyzed parameters. Based on this prognostic model, an algorithm was developed for intraoperative diagnosis of anatomic and functional graft viability during coronary bypass surgery.Results The Qmean ≤20.5 ml/min values were associated with an increased relative risk (RR) of detecting graft failure (RR, 8.2; 95 % confidence interval, CI, 4.4-15.2). The developed model shows a high accuracy of predicting the graft failure (AUC = 0.906±0.03). The RR of graft failure at PI ≥2.65 was 3.3 (95 % CI, 2.17-5.08). The prognostic model for PI (AUC = 0.745±0.042) was sufficiently accurate with respect of possible graft failure. Nodes of high and low risk for graft failure were determined in the developed decision tree. The obtained model was characterized by high sensitivity and specificity (100 and 84.3 %, respectively).Conclusion      The combined use of USF and EpiUSS allows a highly accurate assessment of both morphological and functional characteristics of graft flow. The developed algorithm for the intraoperative diagnosis of anatomic and functional graft viability can be recommended for clinical use.

Advanced measurements of coronary calcium scores: how does it affect current clinical practice?

Coronary artery calcium (CAC) scoring has emerged as a marker of the burden of atheromatous disease and has been included in scoring systems. The practice of myocardial revascularization, considering percutaneous procedures or surgical strategies, is dramatically changing over years and the prognostic significance of CAC scoring is gradually being conceived. In this interdisciplinary scenario, vessel specific calcium scoring, mapping of coronary calcification and its integration with functional assessment of coronary artery disease might change the future decisions in the catheterization lab and operative theaters. This article summarizes CAC evaluation techniques and its implications in clinical practice.

Improving coronary artery bypass grafting: a systematic review and meta-analysis on the impact of adopting transit-time flow measurement

Despite there being numerous studies of intraoperative graft flow assessment by transit-time flow measurement (TTFM) on outcomes after coronary artery bypass grafting (CABG), the adoption of contemporary TTFM is low. Therefore, on 31 January 2018, a systematic literature search was performed to identify articles that reported (i) the amount of grafts classified as abnormal or which were revised or (ii) an association between TTFM and outcomes during follow-up. Random-effects models were used to create pooled estimates with 95% confidence intervals (CI) of (i) the rate of graft revision per patient, (ii) the rate of graft revision per graft and (iii) the rate of graft revision among grafts deemed abnormal based on TTFM parameters. The search yielded 242 articles, and 66 original articles were included in the systematic review. Of those articles, 35 studies reported on abnormal grafts or graft revisions (8943 patients, 15 673 grafts) and were included in the meta-analysis. In 4.3% of patients (95% CI 3.3–5.7%, I² = 73.9) a revision was required and 2.0% of grafts (95% CI 1.5–2.5%; I²=66.0) were revised. The pooled rate of graft revisions among abnormal grafts was 25.1% (95% CI 15.5–37.9%; I²=80.2). Studies reported sensitivity ranging from 0.250 to 0.457 and the specificity from 0.939 to 0.984. Reported negative predictive values ranged from 0.719 to 0.980 and reported positive predictive values ranged from 0.100 to 0.840. This systematic review and meta-analysis showed that TTFM could improve CABG procedures. However, due to heterogeneous data, drawing uniform conclusions appeared challenging. Future studies should focus on determining the optimal use of TTFM and assessing its diagnostic accuracy.

[Role of intraoperative flowmetric assessment of coronary artery bypass grafts established on-pump]

AIM

This study was undertaken to evaluate the efficacy of three-stage measurement of the transit-time flow through coronary bypass grafts with the help of flowmetry for early verification of technical errors during on-pump coronary artery bypass graft surgery.

PATIENTS AND METHODS

We performed an intraoperative analysis of 214 bypass grafts with the help of three-stage flowmetry. The first stage of measuring was performed on-pump with and without the proximal loop test, the second stage of measurement was performed after weaning the patient off the heart-lung machine, and the third stage of measurement was carried out after heparin inactivation prior to chest wound closure.

RESULTS

Amongst the 214 transplants regarded as functioning, intraoperative flowmetry revealed insufficient blood flow in 9 (4.2%) cases. Technical surgical errors were confirmed in these shunts during revision thereof. In 6 (2.8%) of the 9 such grafts we detected non-optimal parameters of flowmetry during the first measurement (while the heart was stopped); of these, in 5 (2.3%) cases non-optimal blood flow was verified with the use of the proximal loop test on the target coronary artery and in 1 (0.47%) case without it. In another one (0.47%) of the nine such transplants, inadequate blood flow was revealed during the second measurement, which confirmed technical errors in proximal anastomoses. In a further 2 (0.93%) of the 9 such transplants we observed low parameters of blood flow during the third measurement, which was related to kinking of the shunts due to their excessive length. All surgical errors were corrected immediately at the stage of verification thereof.

CONCLUSION

The strategy of three-stage assessment of flowmetry makes it possible to ensure and confirm adequate functionality of coronary artery bypass grafts at all stages of the operation, thus allowing timely verification and immediate correction of any technical problems with coronary artery bypass grafts.