A novel transit-time flow metric, diastolic resistance index, detects subcritical anastomotic stenosis in coronary artery bypass grafting

Objective

Transit time flow measurement (TTFM) can detect critical anastomotic stenosis during coronary artery bypass grafting. However, the identification of subcritical stenosis remains challenging. We hypothesized that diastolic resistance index (DRI), a novel TTFM metric, is more effective in evaluating subcritical stenosis than the currently available TTFM metrics. DRI is used to measure changes in the diastolic versus systolic resistance of distal anastomosis.

Methods

A total of 123 coronary bypass anastomoses in 35 patients were prospectively analyzed. During coronary artery bypass grafting, the mean graft flow (Q_mean), pulsatility index, and diastolic filling were obtained. DRI was calculated using the intraoperative recordings of TTFM and arterial pressure. Postoperatively, stenosis of anastomoses was categorized into successful (<50%), subcritical (50%-74%), and critical (≥75%) via multidetector computed tomography scan.

Results

In total, 93 (76%), 13 (10%), and 17 (14%) anastomoses were graded as successful, subcritical, and critical, respectively. DRI and diastolic filling could distinguish subcritical from successful anastomoses (P < .01 and < .01, respectively), whereas Q_mean and pulsatility index could not (P = .12 and .39, respectively). The receiver operating characteristic curves were established to evaluate the diagnostic ability for detecting ≥50% stenosis. In left anterior descending artery grafting (n = 55), DRI had the highest area under the curve (0.91), followed by diastolic filling (0.87), Q_mean (0.74), and pulsatility index (0.65).

Conclusions

DRI and diastolic filling had a reliable diagnostic ability for detecting ≥50% stenosis during coronary artery bypass grafting. In left anterior descending artery grafting, DRI had a more satisfactory detection capability than other TTFM metrics.

Apico-Aortic Conduit for severe aortic stenosis: Technique, applications, and systematic review

Patients referred for aortic valve replacement are often elderly and may have increased surgical risk associated with ascending aortic calcification, left ventricular dysfunction, presence of coronary artery disease, previous surgery, and/or presence of several co-morbidities. Some of these patients may not be considered candidates for conventional surgery because of their high risk profile. While transcatheter aortic valve replacement constitutes a widely accepted alternative, some patients may not be eligible for this modality due to anatomic factors. Apico-Aortic Conduit (AAC) insertion (aortic valve bypass surgery) constitutes a possible option in those patients. Apico-Aortic Conduit is not a new technique, as it has been used for decades in both pediatric and adult populations. However, there is a resurging interest in this technique due to the expanding scope of elderly patients being considered for the treatment of aortic stenosis. Herein, we describe our surgical technique and provide a systematic review of recent publications on AAC insertion, reporting that there is continued use and several modifications of this technique, such as performing it through a small thoracotomy without the use of the cardiopulmonary bypass.