Secrets of Bilateral Internal Thoracic Harvesting and Grafting

Many studies demonstrate the superiority of the bilateral internal thoracic artery (BITA) versus single internal thoracic artery (SITA) grafting technique when it comes to early and late survival and decreased need for repeat revascularization (1). Despite this, adherence to BITA grafting remains low in most centers. This is thought to be attributed to a longer and technically more demanding operation, concern for increased risk of sternal wound infection, and the results of the Arterial Revascularization Trial (ART) (1,2). In this video tutorial, the authors demonstrate technical tips in a seventy-five-year-old woman who received an all-arterial CABG with BITA grafts after suffering from non-ST elevation myocardial infarction.



The Surgery

First, surgeons demonstrate removal of mediastinal fat and opening of the pleura. Dissection of the mediastinal fat began with the electrocautery device at 60 watts in the inferior third of the sternum when dissecting the pleura, as it decreases risk of injury to the internal thoracic artery (ITA). To improve visualization, the authors recommend temporarily holding ventilation and opening the pleural space.

The electrocautery’s power was then reduced to 25-35 watts. Surgeons began opening the endothoracic fascia below the manubriosternal junction, 1-2 mm over the internal thoracic vein (ITV). They continued opening the endothoracic fascia until the ITA’s bifurcation. They then harvested the ITA largely without clips, as this reduces the formation of hematoma.

Next, skeletonization of the superior branches of the LITA was performed. Starting inferiorly from the bifurcation, the LITA was bluntly dissected to release it from its fascia and all superior branches were cut with electrocautery. The surgeons take care  not to cauterize the posterior branches, as this will injure the ITV.

The LITA was then split from the endothoracic fascia starting inferiorly. It is important to be delicate in this step when applying downward traction on the artery. With this maneuver, the endothoracic fascia and vein were pushed out of the dissection plane. Compared to mobilizing a pedicled ITA, even more care must be exercised, avoiding directly grabbing the artery, if possible, to minimize risk of injury and spasm. After releasing the LITA from the anterior thoracic wall, the branches were cauterized closer to the chest wall from the manubriosternal junction toward the bifurcation. There is often a large branch at the manubriosternal junction, which was cut while carefully avoiding injury to the ITV.

To complete dissection up to the proximal third of the sternum, the entire endothoracic fascia was opened until it exposed the artery and vein’s trajectory. If some problems with the vein occur, venous ligation is a viable option. However, it is essential to preserve at least one ITV. Additionally, it is important to cauterize only what is bleeding to minimize collateral damage. After completely mobilizing the LITA, surgeons wrapped it in a papaverine soaked sponge and delayed distal division until full heparinization after the RITA harvest.

The RITA harvest was commenced in the same fashion as the LITA. Notice the injury to the RITV in the video. The surgeon calmly applied pressure, visualized the site of injury, and attempted to cauterize the bleed. When this was unsuccessful, a clip was applied, which achieved hemostasis. Dissection continued as proximal to the subclavian vein as possible to maximize the length of the RITA. The artery was then released from the chest wall. Unlike pedicled ITAs, the entire length of the skeletonized ITA could be quickly visualized for signs of injury or concern, providing added reassurance to the quality of the conduit.

Heparin was then administered and papaverine-soaked gauze was applied to the ITAs. Two distal clips were placed and the ITA was cut. A clip was applied distally in preparation for the anastomosis. The papaverine was injected with a small needle and with enough pressure, then the artery was wrapped in gauze. The ITAs were then allowed to rest over the lungs in preparation for anastomosis.

In this patient, the RITA was too short and could not reach the third OM branch through the transverse sinus. In this circumstance, surgeons performed a RITA-LAD and LITA-OM anastomosis. Alternatively, the team could have used the RITA as a free graft off the aorta but believe this configuration may be associated with lower long-term patency. Given the patient’s age, the decision was made to accept this anastomotic configuration. Ideally, the RITA should not cross the anterior surface of the heart, as it can be injured if sternal re-entry is required.

The authors perform most of their coronary bypass on-pump on the arrested heart. However, they also use BITA in off-pump surgery using a no-touch aortic technique when patients have a severely calcified ascending aorta. Regardless, the distal bypass was performed with similar principles. The only difference was that a coronary shunt was used in off-pump surgery. The arteriotomy of the OM was performed with a beaver blade, 11 blade, and micro Potts scissors. The authors prefer using 8-0 Prolene sutures to complete all-arterial conduit anastomosis, as they find there is less bleeding and a more precise anastomosis. To optimize graft flows and minimize wall-shear stress, they also prefer an anastomosis length of at least 8 mm. Sutures must be symmetrical, and care must be taken to avoid grabbing the intima of the LITA to minimize vessel injury.

To complete coronary artery bypass with RITA-LAD anastomosis, the same sequence as with the LITA-OM anastomosis was performed. The same principles that were mentioned in the previous step apply. Another aspect to be discussed is how to pull down the ITA graft after some sutures. Some surgeons prefer the “parachute technique” which is excellent, however, the authors’ preference is to do three to four suture bites and pull down the artery after these stitches to avoid tension over the anastomosis, possible tears, or suture knots.

Surgeons then inspected the newly constructed anastomoses for any deformities, kinking, or bleeding. Bleeding is usually treated with additional sutures. If the anastomosis shape is subpar, or the vessel is kinked, surgeons may have to redo the anastomosis.

Using transit time flow measurements, surgeons achieved graft flows of more than 50 ml/min with a low pulsatility index and high diastolic fraction. They recommend checking flows pre- and post-protamine. If an additional suture is added to the anastomosis, a post-repair check should be performed. The patient must have adequate blood pressure and ideally be in sinus rhythm to accurately estimate graft flows with the transit time flow machine.

Conclusions

Many observational studies with long-term follow up report that patients with BITA grafts have a lower incidence of coronary reintervention at 10 and 15 years postoperatively and greater long-term survival (1,3,4). Despite this, adherence to BITA grafting remains low among surgeons and could be explained by a longer and technically more demanding surgery, concern for increased risk of sternal wound infections, and results of the ART Trial (1,2). The ART trial is the only randomized controlled trial comparing BITA to SITA and showed that BITA grafting did not conclusively demonstrate survival benefit and a decreased need for reintervention over SITA over a ten-year period. However, the ART Trial was met with criticism, particularly among the fervent supporters of arterial revascularization. The reason was that, in this trial, 36 percent of the patients enrolled did not receive the assigned treatment (crossover) of BITA, while 22 percent of patients in the SITA group received a second arterial graft in the form of a radial artery (5). In other words, in the ART Trial, only 83.6 percent of the patients randomized to BITA received the assigned treatment compared to 96.1 percent in the conventional CABG group. This high crossover rate in the BITA series is a testament to the higher technical complexity of the operation, and it is even more meaningful if one considers that only expert BITA surgeons were allowed to participate in ART. It also raises the possibility that the BITA surgeons were not all equally experienced in BITA grafting because the crossover rate varied from zero percent to 42.9 percent on a center level and from zero percent to 100 percent for the 168 participating surgeons, suggesting the need for appropriate and documented experience for participation in trials involving complex technical procedures. Gaudino et al., in a meta-analysis, demonstrated that centers with a high adoption of BITA grafting have shown to have greater long-term survival and less incidence of deep sternal wound infections (DSWI) versus centers that have a lower adoption of BITA grafting (4). This suggests that a specific volume-to-outcome relationship could exist for BITA grafting and could be the key for superior outcomes.

Skeletonized ITA grafts can be harvested at their maximal length to reach their target coronary artery in all three anatomic territories without tension. To ensure maximal length of the ITA, the skeletonized technique should extend proximally up to the subclavian vein and distally at least to the ITA’s bifurcation and, if size allows, further distally towards the costal margin. Another option to extend a RITA is to use it as a T-graft with LITA-LAD with RITA to the lateral wall or Y-graft with the RITA to the LAD and LITA to the lateral wall. Another benefit of a skeletonized thoracic artery is that sequential anastomoses are easier to perform, as the artery is free from endothoracic fascia and fat. Skeletonizing does increase the risk of vessel injury versus pedicled arterial grafts. The authors recommend utilizing a clipless technique, decreasing the power of the cautery to 25-35 watts, and prioritizing blunt dissection over burning the fascia to mitigate this risk.

Sternal wound infections and the need for sternal wound reconstruction are found to be significantly higher in BITA versus SITA grafting (2,3). This is true across both diabetic and non-diabetic patients. However, compared to a pedicled technique, skeletonized BITAs seem to decrease the risk of sternal wound infections by increasing sternal perfusion while decreasing postoperative chest wall pain (6).

Bilateral internal thoracic artery grafts may improve long-term survival, reduce the need for repeat revascularization, and provide superior long-term patency versus SITA with saphenous vein graft. Though there is good evidence in favor of BITA for CAB, it may be less beneficial in patients who have a high risk of developing DSWIs, including patients with diabetes, renal disease, COPD, and previous mediastinal radiation. Ideally, the RITA should be used to graft target vessels with good vessel run-off to perfuse a large myocardial territory. Coronary surgery is nuanced, and surgeons must consider patients’ comorbidities, their age, weight, and their coronary anatomy to determine the best possible revascularization strategy. Drawing from the authors’ experience, they find that a skeletonized approach to BITA harvest provides excellent graft quality for use in CAB, with minimal additional operative time and risk.

References

1. Davierwala PM, Mohr FW. Bilateral internal mammary artery grafting: rationale and evidence. Int J Surg. 2015 Apr;16(Pt B):133-9.
2. Taggart DP, Altman DG, Gray AM, Lees B, Gerry S, Benedetto U, Flather M; ART Investigators. Randomized Trial of Bilateral versus Single Internal-Thoracic-Artery Grafts. N Engl J Med. 2016 Dec 29;375(26):2540-9.
3. De Paulis R, de Notaris S, Scaffa R, Nardella S, Zeitani J, Del Giudice C, De Peppo AP, Tomai F, Chiariello L. The effect of bilateral internal thoracic artery harvesting on superficial and deep sternal infection: The role of skeletonization. J Thorac Cardiovasc Surg. 2005 Mar;129(3):536-43.
4. Gaudino M, Bakaeen F, Benedetto U, et al. Use Rate and Outcome in Bilateral Internal Thoracic Artery Grafting: Insights From a Systematic Review and Meta-Analysis. J Am Heart Assoc. 2018;7(11).
5. Navia D, Espinoza J, Vrancic M, Piccinini F, Camporrotondo M, Dorsa A, Seoane L. Bilateral internal thoracic artery grafting in elderly patients: Any benefit in survival? J Thorac Cardiovasc Surg. 2022 Aug;164(2):542-549.
6. Boodhwani M, Lam BK, Nathan HJ, Mesana TG, Ruel M, Zeng Wet al. Skeletonized internal thoracic artery harvest reduces pain and dysesthesia and improves sternal perfusion after coronary artery bypass surgery: a randomized, double-blind, within-patient comparison. Circulation 2006;114:766–73.

Disclaimer

The information and views presented on CTSNet.org represent the views of the authors and contributors of the material and not of CTSNet. Please review our full disclaimer page here.