Arterial wall strength after endovascular photodynamic therapy

Area of Science:

• Vascular biology
• Medical engineering
• Photochemistry

Background:

• Vascular photodynamic therapy (PDT) is explored for inhibiting intimal hyperplasia (IH) post-angioplasty.
• IH reduction by PDT may compromise arterial wall integrity and strength.
• Bursting pressure is a key indicator of arterial wall strength.

Purpose of the Study:

• To evaluate the short-term and long-term effects of vascular PDT on arterial wall strength after angioplasty.
• To assess the impact of different PDT energy levels (50 J/cm and 100 J/cm) on arterial integrity.
• To investigate potential risks such as aneurysmal dilatation associated with PDT.

Main Methods:

• Thirty male Wistar rats underwent balloon injury (BI) to induce IH in iliac arteries.
• Experimental groups received PDT at 50 J/cm or 100 J/cm diffuser length.
• Control group received no PDT.
• Arterial bursting pressure was measured 2 hours and 1 year post-procedure.

Main Results:

• Short-term (2 hours): PDT significantly increased bursting pressure compared to controls (BI+PDT 50: 3.37 bar; BI+PDT 100: 3.96 bar vs. BI: 2.20 bar).
• Long-term (1 year): Bursting pressure remained elevated in the BI+PDT 50 group (3.18 bar) but returned to baseline in the BI+PDT 100 group (2.02 bar vs. BI: 2.10 bar).
• Aneurysmal dilatation was observed in 3 of 5 rats in the BI+PDT 100 group after 1 year.

Conclusions:

• Endovascular PDT enhances short-term arterial wall strength post-angioplasty.
• While long-term wall strength is maintained at lower PDT doses, high-energy PDT (100 J/cm) can lead to detrimental aneurysmal changes.
• High-energy PDT may pose risks, potentially limiting its application in treating vascular hyperplasia.