Influence of coronary territory on flow profiles of saphenous vein grafts

Outcomes of single versus sequential vein grafts in isolated coronary artery bypass surgery: Insights from a large tertiary care center

BACKGROUND

Saphenous venous grafts remain the most widely used conduits in coronary artery bypass graft surgery (CABG). Data comparing outcomes of single saphenous venous grafting (SinCABG) versus sequential venous grafting (SeqCABG), however, are limited.

METHODS

Between 2002 and 2012, 2375 patients with 3-vessel coronary artery disease underwent isolated elective CABG at the Leipzig Heart Center with a left internal mammary artery graft to left anterior descending artery and ≥2 distal saphenous vein graft anastomoses. Of these, 1278 received ≥2 singular saphenous venous grafts (SinCABG) and 563 received ≥1 sequential saphenous vein grafts with >1 distal anastomoses (SeqCABG). The primary end point was long-term survival. Secondary outcomes included short-term survival, early postoperative outcomes as well as early and late graft patency.

RESULTS

At 30 days, mortality was 1.3% after SinCABG as compared with 2.3% after SeqCABG (P = .13). The postoperative complications rate did not differ between groups. Early postoperative coronary angiographies were performed in 127 patients (7%), whereas clinically indicated follow-up coronary angiographies were performed in 372 patients (20%) over a median follow-up of 5 years (interquartile range, 1.7-8.9). No differences in early or late patency rates were found between both grafting techniques (P = .79 and P = .39, respectively). The median duration of long-term clinical follow-up was 8.4 years (interquartile range, 5.6-11.4). Long-term survival rates at 1, 5, 10, and 15 years in SinCABG versus SeqCABG were 95% versus 94%, 83% versus 82%, 63% versus 62%, and 47% versus 41%, respectively (P = .22).

CONCLUSIONS

Short- and long-term mortality as well as early and late graft patency rates did not differ in patients undergoing SinCABG as compared with patients undergoing SeqCABG.

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.

Effect of Papaverine on Left Internal Mammary Artery Flow: Topical Spraying versus Perivascular Injection Method

Objective

To analyze two techniques of papaverine application, topical spray on the harvested left internal mammary artery (LIMA) and perivascular injection, to find out their ability to improve LIMA flow.

Methods

Forty patients were randomized into two groups. In Group 1, papaverine was sprayed on the harvested pedunculated LIMA. In Group 2, papaverine was delivered into the perivascular plane. Drug dosage was the same for both groups. LIMA flow was measured 20 minutes after applying papaverine. Blood flow was recorded for 20 seconds and flow per minute was calculated. The systemic mean pressures were maintained at 70 mmHg during blood collection. The data collected was statistically evaluated and interpreted.

Results

The LIMA blood flow before papaverine application in the Group 1 was 51.9±13.40 ml/min and in Group 2 it was 55.1±15.70 ml/min. Statistically, LIMA flows were identical in both groups before papaverine application. The LIMA blood flow, post papaverine application, in Group 1 was 87.20±13.46 ml/min and in Group 2 it was 104.7±20.19 ml/min. The Group 2 flows were statistically higher than Group 1 flows.

Conclusion

Papaverine delivery to LIMA by the perivascular injection method provided statistically significant higher flows when compared to the topical spray method. Hence, the perivascular delivery of papaverine is more efficient than the spray method in improving LIMA blood flow.

Beyond patency: Functional assessment of adequacy using internal mammary artery grafting to the left anterior descending artery

INTRODUCTION

Arterial graft physiology influences the long-term outcome of coronary artery bypass grafting (CABG). We studied factors that can affect the overall resistance to flow using internal mammary artery grafting to the left anterior descending artery.

METHODS

This was a prospective, nonrandomized observational study of 100 consecutive patients who underwent elective on-pump isolated or combined valve surgery and CABG. Coronary stenoses were assessed using conventional and quantitative coronary angiography assessment. The flow and pulsatility index (PI) of the grafts were assessed by transit-time flowmetry during cardioplegic arrest and at the end of the operation. Fractional polynomials were used to explore linearity, followed by multivariable regression analysis.

RESULTS

Univariate analysis demonstrated higher flows at the end of the operation in patients who had higher flows with the cross-clamp on (P < .001), in males (P = .004), in patients with a low PI at the end of the operation (P = .04), and in patients with a larger size of the recipient artery (P = .005). Multivariable regression analysis showed that the graft flow at the end of the operation was significantly associated with the mean flow with the cross-clamp on (P < .001), sex (P = .003), and PI at the end of the operation (P = .003). Concomitant valve surgery did not influence flows. Male patients had 18 mL/min higher flow.

CONCLUSIONS

The graft flow at the end of the operation can be determined by the flow with the cross-clamp on, the PI with the cross-clamp off and coronary artery. We reported differences in the graft flows between sexes, and for first the time, we introduced the concepts of "adequate flow" and "resistance-to-forward-flow" for patent coronary grafts.