Right Anterior Mini Thoracotomy

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Summary

Right Anterior Mini Thoracotomy
Right anterior mini thoracotomy is performed with the patient in the supine position with femoral cannulation, most commonly for both the venous and arterial cannulae. In cases where retrograde aortic blood flow is not desired (e.g. peripheral vascular disease), direct cannulation of the distal ascending aorta or right axillary can be performed along with percutaneous femoral venous cannulation. An incision is made over the right third intercostal space and the fourth costal cartilage is divided to allow exposure. Cardioplegia can be performed by direct antegrade coronary infusion through the aortic root or a retrograde coronary sinus catheter can be placed via the right jugular vein under transesophageal echocardiographic (TEE) and/or fluoroscopic guidance. It is also possible for the surgeon to place a retrograde catheter directly through the right atrium with echo guidance. A malleable aortic clamp is used for cross-clamping the aorta and aortotomy exposure is standard. Left ventricular vent (right superior pulmonary vein [RSPV]), replacement of the aortic valve, and suture placement is similar to standard sternotomy approach. Care must be taken to ensure the far corner of the aortotomy closure is secure before coming off cardiopulmonary bypass (CPB), as this area can be difficult to see in some patients after separation from bypass. The advantage of this approach is that it does not destabilize the sternum and the chest wall. Disadvantages can include occasional decreased exposure and the need to divide the right mammary artery in all cases. A preoperative chest computed tomography (CT) scan can be helpful for preoperative planning and delineation of aortic anatomy/orientation.

Mini Sternotomy
Mini sternotomy is carried out with the patient supine. A skin incision is made over the upper sternum. The third or fourth right intercostal space is exposed and opened next to the sternum. The sternum is divided from the sternal notch to this level and then ‘Jed’ off into the right interspace. Cannulation for bypass can be performed completely centrally or, more commonly, we use percutaneous femoral venous drainage and central aortic arterial return. This affords excellent exposure of the ascending aorta and aortic root similar to full sternotomy. Cardioplegia can be administered via direct antegrade infusion through the aortic root or combined with retrograde infusion via the coronary sinus. We can generally cannulate the coronary sinus under TEE guidance through the right atrium and the RSPV can be used to decompress the left ventricle. Both mini thoracotomy and mini sternotomy offer limited access, which can complicate de-airing, therefore, we use CO₂ insufflation. The advantage of the sternotomy approach is that it is familiar to more cardiac surgeons who are used to full median sternotomy, affords excellent exposure of the ascending aorta and aortic root, can be used with central cannulation, does not violate the pleural space, and is easily converted into a full sternotomy if needed. The fact that part of the sternum is divided is considered by some to be a disadvantage of this approach.

Outcomes for Minimally Invasive Surgical Aortic Valve Replacement
For minimally invasive sAVR to be successful, it should, at a minimum, pose no safety hazards and allow the same technical valve procedure as full sternotomy AVR. Additionally, it would be hoped that these approaches would improve mortality, morbidity, and cause less pain and faster recovery. A number of observation studies of minimally invasive sAVR have shown less blood loss and blood usage, shorter hospital stays, less atrial fibrillation, and faster return to functional activity.^5–7 Propensity matched studies of minimally invasive versus full sternotomy sAVR have confirmed the safety of these approaches, but have not shown a survival advantage in average risk patients.^8–10 The safety of this approach has even been shown in reoperative sAVR,¹¹ the elderly,¹² and high-risk patients.¹³ Small randomized studies have also started to appear in the literature.¹⁴ The overall consensus is that a minimal approach provides the same safety as the conventional approach, and offers some advantages including less blood loss, shorter hospital stay, faster recovery in the early phase, and better patient acceptance.