Download Avoiding Restenosis

Avoiding Restenosis
New Advances in the fight against
CAD
Two types of Restenosis
Early Restenosis
Early onset, usually within hours. Attributed
to thrombus formulation at the trauma site
during surgery. On the whole it is treated
successfully with anti clotting drugs and
blood thinners.
Late Restenosis.
Onset is months after surgery. Several theories
regarding its causes.
Restenosis is an extremely
prevalent problem
What Causes Restenosis? There are two
popular theories regarding this
1. Blood Flow Theories
2. Mesh Wounds theories
The Blood Flow theory
1. Stent Introduced into blood stream.
2. Normal Blood currents are disrupted.
3. New Blood flow creates areas of low flow and eddies.
Likened to throwing a rock in a river.
4. Areas of low blood flow, for some reason seam to cause
irritation and inflammation of the tissues.
5. This irritation causes erratic tissue growths.
6. This erratic tissue growths, not original intervention, is
what causes the restenosis.
Mesh Wounds Theory
1. Stent is placed in diseased artery.
2. Tissue heals around the mesh but leaves
edges of tissue unhealed.
3. Unhealed epithelial tissue attracts both
platelets and more scare tissues.
4. These platelets and scare tissue are believed
to be what causes the increased wall
thickness. Again the original artery problem
that recieved the intervention is not believed
to be the cause of the restenosis.
Healing and Regrowth
Brachytherapy: Radiation
Treatment
• Radiation Emitting Stent
• High Dose, Short time radiation
treatment.
The high dose radiation treatment
currently seems to have the greatest
potential.
Radiation Emitting Stents
• Stent is placed in the artery
• Slowly releases radiation, theoretically
killing the hyperplasic tissues and
leaving healthy tissue in place.
Why are Not Currently a
Feasible Solution?
Radiation is causes several reactions
1. Increased platelets following exposure to
radiations
2. Irritates the surrounding tissues, causing
platelets to stick to the tissue
These Greatly increase the risk of thrombus. In
fact the risk is so great that the FDA
cautioned the medical community against
using them
Endovascular Radiation
Short time high dose
A specialized catheter is advanced to the
site of the restenosis and slowly filled
with a radioactive substances.
30-50% decrease in restenosis
Risks of Endovascular Radiation
Therapy
• exposure to the patient
• radiation can endanger the vein, with
concern regarding vasculitis and
aneurysm
• barbell” growth
• dissecting the vessel
Conclussion
Generally the drug eluting stents seem to
be a more effective and feasible
treatment option.
Advances with brachytherapy seem to be
extremely promising while radioactive
stents seem to have to many side
effects to be a decent alternative.