BRACHYTHERAPY IN INSTENT RESTENOSIS PSCC Experience (One-year follow-up)
Dr. Saad Al Kasab, FRCP, FACC, FCCP
Senior Consultant Interventional Cardiologist
Prince Sultan Cardiac Center
Vascular Brachytherapy
Vascular Brachytherapy (VBT): New therapy utilizing radiation in the vasculature (coronary or peripheral arteries) intended to inhibit restenosis.
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Results: Vascular brachytherapy significantly inhibited neointimal formation after balloon injury1
Control
Treated
1 Waksman, et al. Circulation, 1995.;91:1533-1539.
Emory University – Atlanta, Georgia USA
Animal Trials with Novoste? System Post PTCA
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Results: Vascular brachytherapy significantly inhibited neointimal formation adjunctive to stent implantation1
Control
Treated
1 Waksman, et al. Circulation, 1995;92: 1383-1386.
Animal Trials with Novoste? System Post Stent
Emory University – Atlanta, Georgia USA
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I Basics of Radiation II Restenosis definition III Clinical Trials of Radiotherapy IV Long-Term Effect of Brachytherapy for coronary artery disease.
I Basics of Radiation
Main Index
Radiation Review
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2
3
4
Types of Radiation
Alpha
Beta
Gamma & X-rays
Neutrons
2 neutrons + 2 protons
2 positive charges
Short range in tissue
Electron
Travels max. 1cm in tissue
Positive or negative charge
Uncharged particle
Photons
Electromagnetic radiation
Long range, very penetrating
Radiation Choices for VBT
Beta (electrons)
Deeply penetrating, delivers
significant dose to normal tissue
Dwell times of 12-15 minutes
Requires shielded room
Clinicians and staff must leave
during treatment
Auxiliary shielding required for
patient
Gamma (photons)
Short, finite (<1 cm) range
Rapid deposit of energy in
tissue ( 2.5 - 4 minutes)
Minimal shielding requirements
(shielded by 1-2 cm of plastic)
Clinician remains in room
during treatment
*Radiation for Restenosis, Diamond & Vessely, JVIR, ‘98
Radiation: Biological effects
Direct effect: DNA damage - interact with tissue electron to produce fast recoil electron which directly affect ionization of DNA I.e. radiation induce single or double strand DNA, breakage ? to cause lethal chromosomal aberration.
Indirect effect:
70% of cells are water
Water molecules are ionized / excited
Result: H2O + H2O + ? OH + H3O+
(Free radial - seeks an electron for stability )
OH + OH ? H2O2
(Hydrogen peroxide is a powerful oxidizing agent)
OH and H202 cause molecular damage in the DNA
Consists of two components:
Transfer Device
containing Radiation
Source Train
Delivery Catheter
The Beta-Cath? System
MT-180-02 05/01
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Usable life Single use
Outer diameter 5 French (Old) - 3.5 French (New)
Catheter Type ?-Rail? Delivery Catheter
rapid-exchange type catheter (25 cm distal rail length)
Wire requirements <0.014” (0.36mm) steerable guidewire
Delivery Catheter
MT-180-02 05/01
Three Causes of Restenosis
Recoil - Immediate loss of lumen diameter.
Remodeling - Gradual vascular contraction caused by cell growth outside artery wall.
Hyperplasia - Cell growth in lining of arterial wall.
Clinical Experience at Prince Sultan Cardiac Center (One-year follow-up)
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35 patients
37 procedures
Sex - 33 males
- 2 females
Age range - 38 - 75
? 59 year
RISK FACTORS
Smoking - 11
D.M. - 12 - 10 non-insulin dependent
- 2 insulin dependent
Hypertension - 12
Renal dysfunction - 1
Previous MI - 12
CLINICAL DATA
Angina Stable U.A.
24 17 7
No symptoms - 10 pts - positive stress test
CARDIAC CATH DATA
A) Vessels involved:
LAD Cx RCA Diagonal
23 2 11 1
No. of diseased vessels: Single Two 3-vessel
25 6 4
No. of treated vessels: Single vessel Two-vessel
33 pts 2 pts
CARDIAC CATH DATA
1) All patient has restenosed Bare metal stent except two patients:
one patient has Drug-eluting stent (Taxus)
one patient has Drug-coated stent (Dexa)
2) One patient has Gamma radiation to stented RCA
CARDIAC CATH DATA
B) Vessels involved:
Ref diameter 2.5 - 4.0 mm mean 3.1 mm
Diameter of stenosis (mm) 0 - 0.9 ? 0.7
Diameter of