In redo sternotomy, the sternal wires are untwisted and removed or they can be left in place after dividing and separating them to prevent the oscillating saw from cutting too deep. Three thick strong sutures are placed through the costal cartilage on either side of the sternum about 2–3 cm from the midline. The assistant lifts these up during the redo sternotomy to separate the sternum from the underlying tissues. The dissection is started at the bottom under direct vision by lifting up the xiphisternum. Almost the lower third of the sternum can be freed of adhesions. The anaesthetist is then asked to hyperinflate the lungs to a maximum pressure of 30 cm of H₂O. This manoeuver widens the potential retrosternal space between the sternum and the heart to minimise injury [1]. Hyperinflation, by generating positive pressure inspiration, decreases caval flow and right ventricular (RV) dimensions. The sternum is divided with the oscillating saw. As the sternum is split, the sternal edges are separated and kept apart with the help of a flat instrument (e.g. flat end of sternal saw key) and underlying tissue is cut with curved Mayo scissors. The lungs are kept hyperinflated without deflation during sternotomy, although this may be repeated with intermittent normal ventilation to prevent hypoxia until complete sternal division. Once fully divided, standard ventilation is recommenced. A backhand or cat’s paw retractor is then used to lift the posterior table of the sternum for further dissection on both sides. This is continued until the sternum is completely separate and can be safely retracted.

It may sometimes be desirable to place a sling around the aorta. The aorta has to be mobilised for this and this ensures that when the cross-clamp is applied, it is placed across the full diameter of the aorta. The pulmonary artery is separated from the aorta, usually at the site where the curvature of the aorta is most anterior, by a combination of sharp and blunt dissection. Dissection should be parallel to the aorta and pulmonary artery to avoid damage to either of the great vessels. The pulmonary artery can sometimes be very thin-walled and care must be taken to avoid damage to it. The dissection in such cases should be more towards the aorta. Once a sufficient plane has been developed, the thumb and index finger is placed around the aorta in the transverse sinus to ensure that the back wall of the aorta is also free of tissue. A Semb clamp is then advanced around the back of the aorta while in contact with the index finger. It is withdrawn back after grabbing an umbilical tape.