Intraoperative behavior of arterial grafts in the elderly and the young: a flowmetric systematic analysis

Transit time flow measurement of coronary bypass grafts before and after protamine administration

Background

Intraoperative graft assessment with tools like Transit Time Flow Measurement (TTFM) is imperative for quality control in coronary surgery. We investigated the variation of TTFM parameters before and after protamine administration to identify new benchmark parameters for graft quality assessment.

Methods

The database of the REQUEST (“REgistry for QUality AssESsmenT with Ultrasound Imaging and TTFM in Cardiac Bypass Surgery”) study was retrospectively reviewed. A per graft analysis was performed. Only single grafts (i.e., no sequential nor composite grafts) where both pre- and post-protamine TTFM values were recorded with an acoustical coupling index > 30% were included. Grafts with incomplete data and mixed grafts (arterio-venous) were excluded. A second analysis was performed including single grafts only in the same MAP range pre- and post- protamine administration.

Results

After adjusting for MAP, we found a small increase in MGF (29 mL/min to 30 mL/min, p = 0.009) and decrease in PI (2.3 to 2.2, p <  0.001) were observed after the administration of protamine. These changes were especially notable for venous conduits and for CABG procedures performed on-pump.

Conclusion

The small changes in TTFM parameters observed before and after protamine administration seem to be clinically irrelevant, despite being statistically significant in aggregate. Our data do not support a need to perform TTFM measurements both before and after protamine administration. A single TTFM measurement taken either before or after protamine may suffice to achieve reliable data on each graft’s performance. Depending on the specific clinical situation and intraoperative changes, more measurements may be informative.

Trial registration

Clinical Trials Number: NCT02385344, registered February 17th, 2015.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13019-021-01575-y.

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.

Coronary artery surgery in octogenarians: evolving strategies for the improvement in early and late results

The purpose of this study was to investigate retrospectively early and late outcomes of coronary artery bypass grafting (CABG) in a large series of octogenarians. We retrospectively reviewed the data of 241 octogenarian patients who underwent CABG between April 2002 and April 2009 at our institution. Mean age was 84.7 ± 1.8 years. Patients affected by concomitant coexistent organic aortic, mitral, or tricuspid valve disease were excluded from the study. Patients with functional secondary ischemic mitral incompetence were included in the study. The majority of the patients were male. Angina pectoris functional class III/IV accounted for 164 patients (68%). Left ventricular ejection fraction ≤35% was diagnosed in 38 patients (15.8%). Early mortality rate was 5.8% (14 patients). Causes of death were cardiac related in 10 patients. Preoperative independent predictors of in-hospital mortality obtained with multivariate analysis were extracardiac arteriopathy, New York Heart Association class III/IV, and previous percutaneous transluminal coronary angioplasty (PTCA). The overall mean follow-up was 41.6 ± 25.9 months (range 1-87.6 months). Among the 222 contacted survivors, there were 16 (7.2%) deaths during the follow-up. The actuarial survival was 91.9% at 1 year and 83.5% at 5 years. On multivariate analysis, time to late death was adversely affected by preoperative extracardiac arteriopathy and previous PTCA. Advanced age alone should not be a deterrent for CABG if it has been determined that the benefits outweigh the potential risk. A careful selection of optimal candidates, based on the evaluation of their systemic comorbidities, appears mandatory in order to obtain the greatest benefit for these high-risk patients.