The overall aim of this procedure is to create myocardial infarction in mice. This is accomplished by first making a skin incision along the mid axillary line. Next, the heart is exposed by a left thoracotomy between the third and fourth ribs.
Then a ligation is made at the proximal segment of the left anterior descending artery. Finally, the chest is closed and the mouse is placed back into a cage for spontaneous recovery. Ultimately, the myocardial infarction can be examined through electrocardiography or echocardiography.
Visual demonstration of this method is critical as the ligation of coronary artery close to the left is difficult to learn. An adequate myocardial infection is ensured by placing the ligation just below the oracle of the left. Hm.But it's important not to puncture the left AUM as it may cause lethal bleeding.
To begin surgery, anesthetize a mouse that is six weeks of age or older by inhalation with two to 5%is of fluorine. Perform a toe pinch to confirm that the animal is sufficiently anesthetized. Once the mouse is thoroughly sedated, transfer it to the surgical area and place it on.
Its back on a warm pad. To maintain a constant temperature of 37 degrees Celsius, secure the mouse to an intubation device with an isof fluorine field chamber using 0.2 centimeter in a diameter tubing and a mixture of 2%isof fluorine in air. Insert the tube into the mouse's trachea.
Shave the precordial chest on the left side, and then disinfect the area with Betadine. Then 75%ethanol three times each. Also apply ophthalmic ointment to the mouse's eyes using sterile scissors.
Make a 1.5 centimeter incision along the mid axillary line. This approach facilitates subsequent echocardiographic assessment. Scissors are used rather than a scalpel to avoid injury to the underlying tissue in these young mice.
Then using blunt tip vessel forceps, dissociate and retract the precordial muscle from the chest wall. Perform a left thoracotomy between the third and fourth ribs to visualize the anterior surface of the heart and left lung.Further. Retract the thoracic wall using a suitable eyelid retractor.
In order to improve visualization and accessibility using tooth forceps and blunt tip scissors, remove the pericardium. Next, prepare a seven zero lon suture and needle for ligation of the artery. Ligate the left coronary artery by placing the needle beneath the artery with a band of myocardium between the ligature and the artery.
Close the chest by placing two stitches on the third and fourth ribs. Decrease the isof fluorine concentration to 0.5%and use five zero ethylene suture to close the skin in three stitches. For postoperative analgesia, administer an intraperitoneal injection of 0.05 milligrams per kilogram buprenorphine.
Finally, place the mouse in a warm cage for spontaneous recovery and provide 0.6 milligrams per milliliter of buprenorphine in the drinking water. Closely monitor the mouse for the first 24 hours after surgery to investigate the effects of myocardial infarction. The best invasive way is to evaluate cardiac function with echocardiography several days after surgery.
Using this protocol, the ligation of the left coronary artery induces myocardial ischemia that engages around 40%of the left ventricle. This induces significant ECG changes in the ST segment as shown in these representative ECGs measured before and after ligation. Before myocardial infarction.
QRS complexes recorded with the ECG are narrow and short. After myocardial infarction, there is obvious ST segment elevation that is buried into QRS complexes to make QRS much wider and taller than those recorded before myocardial infarction. To investigate the effects of myocardial infarction, evaluate the cardiac function with echocardiography several days after MI operation.
Shown here is an echocardiography recording taken from sham operated mice. In contrast to the good cardiac contractions seen in sham operated mice. In MI mice.
72 hours after mi, there is noticeable akinesia in the left free ventricular wall at systolic stage. After watching this movie, you should have a good understanding of this mouse model for myocardial infarction, and you should be able to set it up in your own laboratory.
