Anne-Marie Koop

204 2.2.6. Open the second intercostal space and spread the ribs by using adapted paper clips, allowing the left heart ear, left lung, and the pulmonary artery to become visible. 2.2.7. Separate the arteria pulmonalis from the aorta. Place a suture loop around the pulmonary artery with a blunt 25 G needle that contains a 6-0 suture and place a lose 2-1-1 ligature around the arteria pulmonalis. 2.2.8. Place a 23 G needle parallel to the arteria pulmonalis within the 6-0 suture and first fix the most proximal suture knot and then distal knot of the 2-1-1 suture. Remove the 23 G needle. Make sure the knot is adequate. 2.2.9. Close the thorax with two or three separate sutures with a monofilament polypropylene 5-0 suture. Release the m. pectoralis superficalis and m. pectoralis profundus. 2.2.10. Suture the skin with a pure polyglycolic acid 5-0 suture. Use a continuous suture technique to minimize scar formation in the tissue; scar tissue will influence the image quality of the echocardiography. 2.2.11. Turn off the isoflurane while continuing ventilation with oxygen during recovery from anesthesia until the mouse regains its own, spontaneous respiration as can be observed from movement of the abdomen. 2.2.12. Uncouple the endotracheal tube from the ventilator. Check for spontaneous respiration, extubate only when spontaneous respiratory action is visible. When spontaneous respiration is not seen, connect the tube to the ventilator again and return to step 2.2.12. 2.2.13. Observe the mouse until it regains consciousness. 2.3 Sham surgery 2.3.1. Perform the above procedure with the exception of the banding (steps 2.2.2– 2.2.6). 2.4. Postsurgical period 2.4.1. House the mouse individually in an incubator (37 °C) for 24 h. 2.4.2. Observe the mouse daily during the first 3 postoperative days. In case of any signs of discomfort, inject 0.1 mg/kg buprenorphine subcutaneously 2x daily for postoperative analgesia.