Hi, look for a protocol (old) used by Jean Noel Fabiani, a long time ago. I don't have the reference right away, but it was clean and smart.

Start from here. DOI:10.1007/BF00433588

I had his medecine thesis in hands in 1982 and if I remember well, that was a partial occlusion and he ligated the artery from outside after chest occlusion with a ligature.

Hi, a right lateral thoracotomy between ribs, followed by the placement of a spacer is a good way to proceed. You will get access to the pericardium and then to the LAD. Try to find studies on Myocardial Infarction on rodents to check their methodology.

Good luck !

Left Coronary Artery Ligation/Myocardial Infarction Model Anesthetic: Sodium Pentobarbital (IP)

Rats of bodyweight 50gms or greater are anesthetized with sodium pentobarbital (IP). A 2 cm craniocaudal skin incision is made parallel and slightly to the left of the sternum to expose the ribs. A loose purse string suture is placed in the pectoral muscles to rapidly close the chest at the completion of the ligation procedure. The patient is placed on artificial ventilation and a thoracotomy is performed by cutting the fifth and sixth ribs to expose the heart. The pericardium is opened and the heart is exteriorized by gentle pressure on the rib cage. The heart is positioned so that the apex is pointed cranially and to the patient's right. A 5/0 silk ligature, entering the heart on the left margin of the pulmonary cone and exiting near the insertion of the left auricular appendage is placed and tied. After tying the ligature; occlusion of the left coronary artery is determined visually by the rapid blanching, caused by lack of arterial blood flow, of the left ventricular musculature. The ends of the occluding ligature are trimmed , the heart returned to the thoracic cavity and the chest closed by tying the purse string suture. The skin incision is closed with wound clips and the patient removed from the ventilator.

This is an old version published. Now we do not cut ribs.

Thanks Mikhail for your help. This is really an old protocol. Problem is that depending of what you are looking for behind (I mean the goal of your study), you'll get massive and not reversible infarction and most of the time mortality will be elevated, which is the drawback of such a technic. Second point, using pentobarbital, is convenient in rats, but has to some extent at least for a period of time a protective effect. Partial occlusion is a better method may be, regarding the original question ? But, lets the author answer on this point.

Dear colleagues (Dr Renaud and Dr Mikhail),

Thank you for your detailed and helpful explanation.

I am going to evaluate the effects of some treatments in reversing a replacement and established myocardial fibrosis induced by LAD ligation. Actually, I want to examine the REVERSAL of fibrosis rather than PREVENTING that. Since Fibrosis is a dynamic process, reversal of collagen deposition may be feasible. Of course, some articles have also confirmed that!

I want to confirm the fibrosis due to LAD ligation and then try to reverse that. I want to keep the rats for a month after LAD ligation to see and approve the established fibrosis.

Your advice and suggestions will be much appreciated and welcomed.

The outcome of coronary artery occlusions is age-, species, severity of occlusion, duration, coronary collateral blood flow during ischemia (compared to baseline), operator and drugs used to support and stabilize hemodynamic.

In experimental models, regional ischemia is complicated by the above-mentioned factors and contributes to lack of reproducibility in the same laboratory and in literature.

It is seldom to see authors report complications, arrhythmia, fibrillation and mortality that why young investigators waste time and resources by following prior publications that do not report pitfalls of their studies. Swine model lacks coronary collateral, that is why pigs die with small risk areas (occlusion close to the apex) from arrhythmia and cardiac arrest not from infarction. Investigators treat all groups with lidocaine to attenuate arrhythmia and ventricular fibrillation, yet some more lidocaine and other inotropic drugs are used to minimize mortality.

Unlike regional ischemia, global ischemia and measuring load-independent indices of cardiac performance and correlating that to myocardial bioenergetics, marker enzymes of ischemia and infarction and the end-point of infarct size.

To obtain reproducible studies and results you must design experiments that have clinical relevance and try to minimize variations within same group and amongst other groups and time. GOOD LUCK

Article A Simple and Efficient Methodology for the Study of Cardiopr...

Para diminuir a mortalidade não realizo a ligadura muito próximo da origem (base) da Artéria. Desse forma, consegui reduzir consideravelmente a mortalidade. Dessa forma, protejo o tecido excito-condutor.

Hi

I think you must use from placement of a spacer is a good way to proceed

and if you can study my paper A New Pattern Recognition Method for Detection and Localization of Myocardial Infarction Using T-Wave Integral and Total Integral as Extracted Features from One Cycle of ECG Signal you can find your better answer

Hi. I have video how we do coronary occlusion. Leave your e-mail pls and I will send you. Maybe it will helps.

Hi I think you must use from placement of a spacer is a good way to proceed and if you can study my paper A New Pattern Recognition Method for Detection and Localization of Myocardial Infarction Using T-Wave Integral and Total Integral as Extracted Features from One Cycle of ECG Signal you can find your better answer

Dear all,

Thank you for taking the time to share all of that great information with me. Your support and advice have been extremely helpful.

Best wishes

I hope it is not too late. MI is a very tricky technique specially in determining the exact location of the LAD. Depending on the animal strain you may have varying degrees of MI.

Please, have a look to this protocol for permanent ligation. I found it very useful when I was starting with this technique:

https://www.jove.com/video/55353/murine-left-anterior-descending-lad-coronary-artery-ligation-an

Good luck