Distal coronary anastomoses were completed with the aid of the Flex A distal anastomotic device or in rare occasions using U clips. Transit time flow measurements were completed at the end of the procedure using the size 4 Flexible Medistim flow probe (Medistim, Oslo, Norway).
From January 2008 to April 2015, robotic beating heart TECAB with anastomotic connectors was performed in 404 patients. The operative technique has previously been described.5 Multivessel TECAB was performed in 194 patients (48%), and a RIMA graft was used in 140 patients (35%). These 140 patients undergoing RIMA grafting using a TECAB approach constitute the patient population for this retrospective review. The lead author performed 597 coronary bypass procedures during the same period. Of these, 97.2% were off-pump procedures and 68% were robotic TECABs. The percentage of CABG procedures that were TECABs increased from 57% in the first 5 years of the study to 94% in the last 2 years. Of note, the total number of robotic cardiac procedures in this time frame was 739 procedures.
The demographic profile of the study population includes the following: mean age of 63.4 years, male sex in 76% of patients, diabetes in 31%, and hypertension in 72%. Single-vessel disease was noted in 9% of patients, whereas 69% had two-vessel disease and 25% had three-vessel coronary artery disease (Table 1).
Single-vessel bypass was performed in 14 patients (10%), double-vessel bypass in 104 patients (74%), and triple-vessel bypass in 22 patients (16%). There were 25 patients (18%) who had hybrid revascularization procedures (Table 2).
A total of 131 RIMA grafts were harvested via left-sided ports and grafted to left coronary targets (of these, 126 were in combination with the LIMA in multivessel procedures, and five were single-vessel procedures). A total of nine RIMA conduits were harvested via right-sided ports and grafted to the right coronary artery (RCA) for isolated RCA disease. The ports in this case are mirror image to the standard left-sided ports previously described.5
The RIMA graft was used as an in situ graft in 124 cases (84%) and as a free T-graft in 24 cases (16%). Targets for all RIMA grafts are shown in Table 3.
Intraoperative transit time flow measurement (Medistim) was obtained in all grafts. Flow was greater than 25 mL/min (pulsatility index < 2) in 95% of grafts. Two grafts required intraoperative revision because of poor flow (1.4%), and both revisions were completed using U clips.
Seven procedures (5.3%) could not be completed using the intended off-pump endoscopic approach. Two patients (1.4%) were converted to sternotomy, one for bleeding and one for hemodynamic intolerance. Five patients (3.6%) required on-pump beating heart TECAB using femoro-femoral cardiopulmonary bypass (CPB) (four patients for hemodynamic and space issues or intolerance to one lung ventilation, and one patient because of arrhythmias). All conversions were undertaken electively with the patient in a stable condition (Table 2).
Outcomes are shown in Table 4. The perioperative mortality was 0.7%, and the mean ± standard deviation length of hospital stay (LOS) was 3.1 (1.5) days. The one perioperative death was in a preliver transplant patient with advanced cirrhosis/portal hypertension and poor left ventricle function.
Right internal mammary artery graft use in all TECABS increased from 23% in the first 5 years to 53% in the last 2 years (Fig. 5).
It is well documented that using bilateral IMA grafts for CABG surgery improves outcomes by increasing survival and decreasing the need for reoperations.2,3 It is also well known that BIMA grafting is significantly underused as documented in the STS database with only 5% of patients receiving bilateral internal mammary arteries.4 General explanations for this include the increased risk of sternal wound infections especially in obese and diabetic patients.6 This is despite the fact that diabetic patients have been shown to have a survival benefit from bilateral IMA use.7 Another often cited reason is the inability of the RIMA conduit to reach far away left coronary targets.
Multiple series of coronary bypass using a robotic TECAB approach have reported higher use of BIMA grafting than is reported in the STS database.8,9
In this report, we reviewed our TECAB procedures involving the use of a RIMA conduit for a 7-year time frame.
We believe that employing a sternal sparing totally endoscopic robotic approach in CABG surgery increases the ability to use both IMAs while eliminating the risk of sternal infection. Furthermore, because the sternum is intact during the grafting process, the RIMA is rendered closer to the heart than during sternotomy and this allows it to be grafted to a wider range of left coronary targets. We have seen that when it is skeletonized and harvested up to and beyond its bifurcation, the RIMA can easily reach the distal third of the left anterior descending (LAD), diagonal branches, ramus branch, and first and second obtuse marginal branches.
The decision of where to attach the RIMA in our experience depended on multiple factors; however, our preference has emerged to use it as an in situ graft over a T-graft configuration if possible and to use it on obtuse marginal branches of the Cx (if it reaches) to preserve the LIMA for the LAD. We have no indication to believe that in situ RIMA LAD patency is any less than LIMA LAD patency, and the literature does not support this. Raja et al10 compared between 546 propensity-matched patients receiving either in situ LIMA graft or in situ RIMA graft to the LAD. They found no difference after 7 years in the composite of death and need for repeat revascularization. However, we do feel that the lie of the RIMA conduit underneath the innominate vein is more protected when grafted to high marginal and ramus or diagonal branches (as opposed to the distal LAD for example).
In this series of RIMA grafts during TECAB, most were harvested and grafted from left-sided ports to left coronary branches. The mechanics and execution of this should be no different than using the LIMA, and therefore, the patency should be no different. Tatoulis et al11 published their results in 991 RIMA conduits evaluated angiographically and found that 10-year RIMA and LIMA patencies were identical to the LAD (95% vs 96%) and to the circumflex artery (91% vs 89%).
In a smaller number of patients in our series, the RIMA was harvested via right-sided ports and used to graft the RCA. This approach can easily be performed using a mirror image configuration of port placement and orientation but is useful only for very proximal RCA disease. Distal posterior descending artery targets can rarely be reached using the attached RIMA.
Patients with multivessel disease including the RCA or distal circumflex branches in our practice are candidates for a hybrid revascularization with PCI. The incidence of hybrid revascularization in this series of TECAB patients with RIMA grafts was 18%. The hybrid cases in this series could be labeled “complex hybrids” because they all involved two or more grafts with bilateral IMA. As described in a previous publication, most our hybrids received the TECAB first and a staged PCI after discharge. A handful of hybrids received the PCI first because of an acute presentation related to the RCA. The only simultaneous hybrids at our institution are ones involving one IMA (LIMA-LAD) and a straightforward PCI.
As has been reported in the literature for sternotomy patients undergoing bilateral IMA grafting,12 in our experience as well, harvesting and use of the RIMA during single-single or multivessel robotic TECAB did not compromise perioperative mortality rates (0.7%) or LOS. These were comparable with our previously reported LOS for all TECAB patients.5 We believe that the shorter LOS in our TECAB patients is related to absence of sternotomy and to early extubation and mobilization. Early mobilization is enhanced by setting preoperative expectations for both patient and family and by removing chest tubes as early as possible to help in minimizing the need for postoperative narcotic use.
The two conversions to sternotomy (1.6%) in this series occurred early in our experience. Over time, the use of CPB to complete the TECAB procedure on a beating heart became our preferred strategy for patients not tolerating an off-pump approach either because of hemodynamic issues or because of difficulty with single-lung ventilation. This occurred in five patients (3.9%), was performed via left fem-fem bypass, and allowed us to avoid sternotomy in these patients.
This low conversion rate is directly related to the surgical team's strict attention to the patient's hemodynamic and respiratory status throughout the case. Continuous open communication with the anesthesia team is essential for these cases to be conducted smoothly. Some points in that regard are the following: two-lung ventilation was used liberally when oxygenation or ventilation was compromised by single-lung ventilation. Carbon dioxide insufflation was adjusted continuously throughout the case to maximize both hemodynamics and exposure. Low-dose inotropes were used to enhance hemodynamics as necessary.
During the 7 years of this study, we have seen a significant increase in our use of BIMA grafts with increasing TECAB experience (Fig. 6) in a wide range of patients, not significantly limited by body habitus. The only patients excluded from this approach were emergencies, patients with very poor left ventricle function, and those with fused left pleural space. The Endowrist stabilizer is not only vital during grafting on the beating heart but also during RIMA harvesting. This can be taken advantage of by using it to help expose the distal part of the RIMA by gently depressing the heart and the proximal part of the RIMA by depressing the anterior mediastinal fat. When it is used as an in situ graft to left-sided targets, the RIMA graft is tucked high under the innominate vein and protected by the anterior mediastinal fat from injury during possible future sternotomy.
A word on the cost of this form of the TECAB procedure is in order. The robotic disposables currently cost approximately US $3500 and the anastomotic connector approximately US $1200. We have seen that these costs are offset by eliminating the cost of CPB, endoscopic vein harvesting systems, shorter hospital stay, and low blood transfusion rates.
This study was intended to be a retrospective review of the technical aspects surrounding the use of RIMA grafts during robotic beating heart TECAB procedures. Limitations of this study include its retrospective and single surgeon nature, as well as the lack of long-term clinical and patency follow-up. These questions will be addressed in future longer-term studies.
Routine use of the RIMA in robotic beating heart TECAB is a safe and reproducible technique. Sternal sparing and skeletonization of the RIMA allow it to reach various left coronary targets. Using the Endowrist stabilizer to create space in the chest to improve visualization of the proximal and distal RIMA is key to making robotic-assisted RIMA harvesting a routine part of the TECAB procedure. This is one of the most important findings of our experience.
Further studies including long-term patency evaluation are ongoing and are necessary for this approach to impact the adaption of robotic-assisted multiarterial grafting.
The authors thank Sarah Nisivaco, BS, for her help in the chart review for this study.
1. Loop FD, Lytle BW, Cosgrove DM, et al. Influence of the internal-mammary-artery graft on 10-year survival and other cardiac events. N Engl J Med
2. Lytle BW, Blackstone EH, Loop FD, et al. Two internal thoracic artery grafts are better than one. J Thorac Cardiovasc Surg
3. Kurlansky PA, Traad EA, Dorman MJ, Galbut DL, Zucker M, Ebra G. Thirty-year follow-up defines survival benefit for second internal mammary artery in propensity-matched groups. Ann Thorac Surg
4. Tatoulis J, Buxton BF, Fuller JA. The right internal thoracic artery: is it underutilized? Curr Opin Cardiol
5. Balkhy HH, Wann LS, Krienbring D, Arnsdorf SE. Integrating coronary anastomotic connectors and robotics toward a totally endoscopic beating heart approach: review of 120 cases. Ann Thorac Surg
6. Deo SV, Shah IK, Dunlay SM, et al. Bilateral internal thoracic artery harvest and deep sternal wound infection in diabetic patients. Ann Thorac Surg
7. Dorman MJ, Kurlansky PA, Traad EA, Galbut DL, Zucker M, Ebra G. Bilateral internal mammary artery grafting enhances survival in diabetic patients: a 30-year follow-up of propensity score-matched cohorts. Circulation
8. Bonaros N, Schachner T, Lehr E, et al. Five hundred cases of robotic totally endoscopic coronary artery bypass grafting: predictors of success and safety. Ann Thorac Surg
9. Bonatti J, Lehr EJ, Schachner T, et al. Robotic total endoscopic double-vessel coronary artery bypass grafting—state of procedure development. J Thorac Cardiovasc Surg
10. Raja SG, Benedetto U, Husain M, et al. Does grafting of the left anterior descending artery with the in situ right internal thoracic artery have an impact on late outcomes in the context of bilateral internal thoracic artery usage? J Thorac Cardiovasc Surg
11. Tatoulis J, Buxton BF, Fuller JA. The right internal thoracic artery: the forgotten conduit—5766 patients and 991 angiograms. Ann Thorac Surg
12. Berreklouw E, Schönberger JP, Bavinck JH, et al. Similar hospital morbidity with the use of one or two internal thoracic arteries. Ann Thorac Surg
This is a very interesting report fromBalkhy et al at the University of Chicago reporting their experiencewith right internalmammary artery (RIMA) grafts in 140 patients undergoing beating heart robotic totally endoscopic coronary artery bypass (TECAB) grafting. The RIMAwas used as an in situ graft in 124 cases and as a free T-graft in 24 cases. The robotic stabilizer was used not only to facilitate exposure of the coronary targets but also to aid in the RIMA harvest using a skeletonized approach. Graft flow measurements were routinely obtained. The RIMA flow was greater than 25 mL/min (pulsatility index <2) in 95% of the grafts. There were only two intraoperative anastomotic revisions, and perioperative mortality was 0.7%. These are excellent results and clearly establish the feasibility of being able to use bilateral internalmammary artery grafts during TECAB with excellent results.
The study has several limitations. First of all, this is a retrospective review from an expert group, and these findings may not be reproducible in other centers. Moreover, the only follow-up was intraoperative flow, and they did not have angiographic assessment of their RIMA grafts, which is the gold standard for anastomotic evaluation. There was no late follow-up provided. Finally, as the authors remarked in their discussion, this is quite a costly procedure with the robotic disposables currently costing US $3500 per case and the anastomotic connector US $1200. However, the authors are to be commended on their excellent results with this minimally invasive technique. They have established that the routine use of the RIMA in a robotic beating heart TECAB is effective and reproducible. Further studies will be needed to assess long-term patency of this graft.
Keywords:©2017 by the International Society for Minimally Invasive Cardiothoracic Surgery
Robotically-assisted surgery; Totally endoscopic coronary artery bypass (TECAB); Bilateral internal mammary artery (BIMA)