If the patient is in atrial fibrillation and ablation surgery is contemplated, the left atrial appendage is excised at this stage. The heart is lifted up, exposing the left atrial appendage. This is excised with scissors. It is then oversewn with 4/0 prolene leaving 5–10 mm above the base of the left atrial appendage. Other methods have also been used, such as stapling the left atrial appendage, ligating it from outside, either with a simple silk tie or by placing a purse string suture, or ligating it from inside by placing a purse string around its base and tightening this. However, these other methods have a higher failure rate compared to excision and suture.

Another important step, especially if ablation surgery is to be performed, is to separate out the back of the heart at the oblique sinus from the oesophagus to minimise trauma to it from the energy waves. While the heart is lifted up with the left hand, the fingers of the right hand are placed onto the back of the heart at the oblique sinus to separate it from the oesophagus. This space will fill with blood or water, thus, forming an insulating layer.

Our preferred approach to the mitral valve is through a left atriotomy. An incision is made midway between the inter-atrial septum and the origin of the right superior pulmonary vein and extended inferiorly along the left atrium towards the left inferior pulmonary vein, ending a few millimetres inferior to it. The incision is then extended superiorly a few millimetres beyond the end of the right superior pulmonary vein onto the roof of the left atrium. This incision is facilitated by the previous dissection on the SVC. Two small mitral retractors are then inserted and lifted up together, opening up the left atrium and exposing the mitral valve.

We have found that this approach to the mitral valve, together with the steps described earlier which free up the heart and allow its rotation, provides excellent exposure to the mitral valve. To improve visualisation of the mitral valve further, the incision can be extended superiorly and medially underneath the SVC and onto the roof of the left atrium.

If surgery to the right side of the heart is also to be performed, e.g. to the tricuspid valve, the transseptal approach can be used. A vertical incision is made in the right atrium from the right atrial appendage to the inter-atrial septum. The septum is then incised at the foramen ovale.

Alternatively, an incision is made in the right atrium parallel to the inter-atrial groove about 2 cm above it. The incision is extended superiorly to the junction with the left atrium. The septum is then incised horizontally at the lower edge of the foramen ovale. It is extended superiorly to join the right atrial incision, continuing onto the roof of the left atrium. The retractor is then placed on the septum or a stay suture is applied to expose the mitral valve.