Jaya over AtheroSclerosis Beyond Balloon, Stents and By-pass
The ELAN (Epiarterial Laser ANgioplasty) Procedure
Biological Processes Following ELAN Procedure: The atheroma (or plaque) is enveloped in a capsule made of fibrous tissue (the vessel wall healing reaction). In histological sections, it is called the fibrous cap on the lumen side (the tunica intima side) and fibrous tissue / wall / capsule on the opposite side (tunica media side). The ELAN procedure is a controlled injury to the arterial wall. It disrupts / incises the fibrous capsule enveloping the plaque along the length of the plaque and the artery. The incision exposes the previously encapsulated plaque elements to the natural defense mechanisms (white cells) of the body. Healing, following the ELAN procedure, is by secondary intention. In contrast, arterial repairs and arterial anastomoses heal by primary intention.
Events post ELAN procedure are:
1. Acute controlled injury to arterial wall (tunica adventitia and media) by ELAN Procedure.
2. Acute remodeling of arterial wall due to the ELAN procedure.
3. Acute return of pulsatality and flexibility to the arterial wall.
4. Acute disruption of Vasa vasora (more so, if a combination of longitudinal and transverse incisions is used to restore flexibility to a tough fibrotic or calcified plaque).
5. Monocytes / lymphocytes / leucocytes appear in the serous exudate on the arterial adventitial surface and inside the cuts (troughs) on artery external surface.
6. Mobilisation and complete removal of all molecules deemed foreign by the scavenger cells (except the fibrous capsule, all plaque elements are removed by the scavenger cells).
7. Appearance of fibroblasts in the trough of the incision on the arterial external (adventitial) surface.
8. Laying down of collagen and fibrous (repair) tissues at site of intervention in an arterial wall that is constantly pulsating. (Compare this with dynamic healing and re-modeling in a fractured long bone which is allowed controlled weight bearing).
9. A flexible pulsating arterial wall (laid down and repaired by fibroblasts while the artery was pulsating).
10. Photomicrograph Day 23 post-procedure; An incision 150 microns deep was made on the surface of a normal Carotid artery. The residual wall thickness as measured by OCT, immediately post procedure was 50 microns. The following photo-micrograph shows the healing process of the subsequent 23 days.
The yellow curve demarcates the newly laid down elements (collagen, elastin and matrix) following the 150 micron deep incision in the artery wall. The residual wall, of just 50 micron thickness at the end of ELAN procedure, has been repaired and the original wall thickness almost restored in 23 days.