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Secrets of Bilateral Internal Thoracic Harvesting and Grafting

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posted on 2024-06-20, 15:49 authored by Manuel Roque Cervetti, Mathieu Rheault-Henry, Michael W. A. Chu

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.

Reference(s)

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.

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