Bilateral internal mammary arteries: a very important missing trick for coronary artery bypass grafting

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.

Bilateral Internal Mammary Artery Bypass Grafting: Sternal Wound Infection in High-Risk Population. Should Sternal Infection Scare Us?

Background

Bilateral internal mammary arteries (BIMAs) remain underused in coronary artery bypass grafting (CABG), especially in elderly, diabetic, and obese patients. This study investigated incidence of sternal wound infection (SWI), sternal instability (SI), and reintervention for bleeding (RIB) in this high-risk population.

Methods

A single-center retrospective observational study was performed in "Grand Hôpital de Charleroi, Gilly, Belgium." A total of 319 patients undergoing CABG from December 2011 to December 2015 were included. Three main outcome measures (SWI, SI, and RIB) were investigated in obese vs nonobese, diabetic vs nondiabetic, and elderly vs younger patients.

Results

In all, 14 SWI, 11 SI, and 6 RIB were discounted. Death rate was as follows: SWI: 2/14 vs 17/305 (P = .178), SI: 2/11 vs 17/308 (P = .081), and RIB: 2/6 vs 17/313 (P = .004). In obese (n = 113) vs nonobese (n = 206) patients, there was no difference for SWI (P = .263), SI (P = .565), and RIB (P = .332). In diabetic (n = 118) vs nondiabetic (n = 201) patients, there was no difference for SWI (P = .642), SI (P = .497), and RIB (P = .298). In elderly (n = 62) vs younger (n = 257) patients, there was no difference for SWI (P = .619), SI (P = .915), and RIB (P = .385).

Conclusions

Obesity, age, and diabetes treated by insulin (or not) do not seem to be risk factors for developing SWI, SI, or RIB in patients receiving a CABG using BIMA. Nevertheless, mortality was higher in RIB group.

Noninvasive Quantification of Blood Flow in Epicardial Coronary Arteries, Coronary Artery Bypass Grafts, and Anastomoses

OBJECTIVE

Direct flow measurement in native epicardial coronary arteries, bypass conduits, and anastomoses is severely limited by the invasiveness and inaccuracy of existing technologies. As a result, less than 25% of patients undergoing coronary artery bypass grafting (CABG) worldwide have any intraoperative evaluation performed. A simple, accurate, and noninvasive technology to directly quantify blood flow and rheology surrounding anastomotic sites is a critical unmet need in CABG.

METHODS

Existing technology limitations drove development of a different technology solution. With an optical physics approach, flow in conduits and tissue can be quantified in real time with nonionizing broad-spectrum imaging as well as temporal and spatial analyses. Cardiac motion, calibration, and combining anatomy + physiology in imaging were challenges requiring solutions.

RESULTS

This patented imaging technology was developed and tested in an established porcine cardiac experimental model and in clinical proof-of-concept studies. Flow velocities and flows in epicardial coronary arteries vary physiologically with the cardiac cycle and with acute ischemia, as predicted by previous studies using traditional technologies. Imaging data are captured from a 30-cm viewing distance, analyzed and displayed in real time as a video. The field of view enables capture of flow in the proximal and distal epicardial coronary, the conduit, at the anastomosis and in the distal myocardium simultaneously.

CONCLUSIONS

Rheologic flow interaction between conduit and native coronary at the anastomosis remains the most poorly understood technical aspect of CABG. A noninvasive, noncontact, no-risk imaging technology as simple as a snapshot can provide this critical physiologic information, validate and document intraoperative quality, and improve even further CABG outcomes.

Physiology of in-situ arterial revascularization in coronary artery bypass grafting: Preoperative, intraoperative and postoperative factors and influences

Surgical revascularization with coronary artery bypass grafting (CABG) has become established as the most effective interventional therapy for patients with moderately severe and severe stable ischemic heart disease (SIHD). This recommendation is based on traditional 5-year outcomes of mortality and avoidance of myocardial infarction leading to reintervention and/or cardiac death. However, these results are confounded in that they challenge the traditional CABG surgical tenets of completeness of anatomic revascularization, the impact of arterial revascularization on late survival, and the lesser impact of secondary prevention following CABG on late outcomes. Moreover, the emergence of physiologic-based revascularization with percutaneous cardiovascular intervention as an alternative strategy for revascularization in SIHD raises the question of whether there are similar physiologic effects in CABG. Finally, the ongoing ISCHEMIA trial is specifically addressing the importance of the physiology of moderate or severe ischemia in optimizing therapeutic interventions in SIHD. So it is time to address the role that physiology plays in surgical revascularization. The long-standing anatomic framework for surgical revascularization is no longer sufficient to explain the mechanisms for short-term and long-term outcomes in CABG. Novel intraoperative imaging technologies have generated important new data on the physiologic blood flow and myocardial perfusion responses to revascularization on an individual graft and global basis. Long-standing assumptions about technical issues such as competitive flow are brought into question by real-time visualization of the physiology of revascularization. Our underestimation of the impact of Guideline Directed Medical Therapy, or Optimal Medical Therapy, on the physiology of preoperative SIHD, and the full impact of secondary prevention on post-intervention SIHD, must be better understood. In this review, these issues are addressed through the perspective of multi-arterial revascularization in CABG, which is emerging (after 30 years) as the “standard of care” for CABG. In fact, it is the physiology of these arterial grafts that is the mechanism for their impact on long-term outcomes in CABG. Moreover, a better understanding of all of these preoperative, intraoperative and postoperative components of the physiology of revascularization that will generate the next, more granular body of knowledge about CABG, and enable surgeons to design and execute a better surgical revascularization procedure for patients in the future.

Total arterial anaortic off-pump coronary artery bypass grafting for diffuse coronary disease - A case report

Surgical treatment of diffuse coronary artery disease remains challenging. We present here a diabetic patient, with diffuse coronary disease, revascularized using total arterial anaortic off-pump coronary artery bypass grafting. He received total nine distal grafts. He continues to be asymptomatic after more than 2 years. CT angiography follow-up shows eight out of nine grafts are patent. Anaortic off-pump coronary artery bypass grafting has the least incidence of stroke and arterial grafts have the best long-term patency rate. This is the first case report of nine arterial bypass graft performed off-pump using both internal mammary and both radial arteries. Anaortic total arterial off-pump coronary artery bypass grafting has achieved excellent intermediate term result in this patient of diffuse coronary artery disease.

Bilateral Internal Mammary Artery Use for Coronary Artery Bypass Grafting Remains Underutilized: A Propensity-Matched Multi-Institution Analysis

BACKGROUND

Bilateral internal mammary arterial (BIMA) grafts have repeatedly demonstrated superior outcomes compared with single IMA (SIMA) after coronary artery bypass grafting (CABG). Despite known survival benefits with BIMA use, perceived perioperative challenges often preclude BIMA use. We hypothesized that the use of BIMA remains underutilized, even in low-risk patients.

METHODS

A total of 43,823 primary, isolated CABG patients in a regional Society of Thoracic Surgeons Database were evaluated. Patients were stratified by BIMA versus SIMA use. Surgical candidates considered "low risk" for BIMA use included the following: age less than 70 years; no or mild chronic lung disease; body mass index less than 30; and absence of diabetes. The BIMA patients (n = 1,333) were 1:1 propensity matched to SIMA patients (n = 1,333) and outcomes were compared.

RESULTS

Overall, BIMA use was 3%; 24% (n = 10,327) of patients met "low-risk" criteria for BIMA use. Among "low-risk" patients, BIMA utilization was 6%. Propensity-matched comparisons revealed similar preoperative risk profiles between BIMA and SIMA patients (Predicted Risk of Mortality [PROM] 1.1% vs 1.1%, p > 0.05). The BIMA use was associated with longer cross-clamp time (71 vs 62 minutes, p < 0.05). Importantly, BIMA use was not associated with increased postoperative mortality, morbidity, or hospital length of stay (all p > 0.05). However, hospital readmission within 30 days was 41% greater for BIMA patients compared with SIMA patients (p = 0.01).

CONCLUSIONS

Bilateral IMA graft use appears to remain underutilized in the modern surgical era, even in low surgical risk patients. The BIMA use does not appear to increase the risk of postoperative morbidity, although requires longer operative times and a higher risk for readmission. Efforts to more clearly understand surgeon motivators for the use of BIMA grafting are needed.

Off-pump Bilateral Internal Thoracic Artery Grafting

BACKGROUND

The long-term benefit of bilateral internal thoracic grafts (BITA) is well established. BITA grafting is often avoided in diabetic, female, obese, elderly and other high-risk patients because of concerns for deep sternal wound infection. The objective of this study is to analyse early results of our BITA grafting and to establish the safety of BITA use in all patients.

METHODS

All cases of isolated consecutive unselected CABG were included in this retrospective study. BITA were used in-situ - one was used to graft left anterior descending artery and the other was used as inflow for a composite graft with radial artery. Dual inflow using in situ BITA grafting allows easy bailout by using an additional vein graft.

RESULTS

BITA was used in 574 patients out of 602 (95.35%). Incidence of early death was 1.33% (8/602), stroke 0.5% (3/602), reoperation for bleeding 0.17% (1/602). Deep sternal wound infection was not seen in any patient but nine patients (1.5%) had superficial wound infection which healed with dressing.

CONCLUSION

We have used BITA in 95% of our unselected, consecutive off-pump CABG patients without any major wound complications. Our limited experience has shown off-pump CABG using BITA grafting can be safely adopted routinely with excellent early result.

Off-pump coronary artery bypass grafting in India

Off-pump Coronary Artery Bypass Grafting (OPCAB) is the latest innovation in cardiac surgery. However OPCAB is not adopted universally. Even there have been suggestions of abandoning OPCAB in a special report. In India, OPCAB has been successfully adopted across the board. There are various evidences which favor OPCAB and are discussed in this review. The purpose of this review is to put forward the perspective of the OPCAB surgeons of our country and critically look at the suggestion of abandoning OPCAB.

Bilateral internal mammary arteries: evidence and technical considerations

Bilateral internal mammary artery (BIMA) grafts are used for coronary revascularisation by only a minority of surgeons, despite a growing body of evidence suggesting improved survival when compared to use of only one internal mammary artery with additional saphenous vein grafts. Herein we review the evidence supporting revascularisation with BIMA and suggest reasons why the majority of surgeons use only one internal mammary artery. We discuss technical considerations, various graft combinations and the use of BIMA to facilitate anaortic off-pump coronary artery bypass (OPCAB).