Persistent Intraluminal Pressure After Endovascular Stent Grafting for Type B Aortic Dissection.

Area of Science:

• Cardiovascular Surgery
• Medical Devices
• Biomedical Engineering

Background:

• Thoracic endovascular stent graft repair (TEVAR) is used for Stanford Type B aortic dissection (TBAD).
• Long-term follow-up shows persistent false lumen dilation despite successful TEVAR.
• Understanding the hemodynamic mechanisms is crucial for improving outcomes.

Purpose of the Study:

• To investigate the hemodynamic mechanisms behind persistent false lumen dilation after TEVAR in TBAD.
• To analyze pressure dynamics in different stages of post-TEVAR TBAD using ex vivo models.

Main Methods:

• Twenty-eight ex vivo porcine TBAD models were created: patent false lumen (Model A), distal re-entry only (Model B), and thrombosed false lumen with re-entry (Model C).
• Synchronous pressure waveforms were recorded from true and false lumens.
• Pressure differences were quantified using systolic index (SI), diastolic index (DI), mean pressure index (MPI), and area under curve index (AUCI).

Main Results:

• False lumen pressure indices (SI, MPI, AUCI) were significantly higher in Model A and B compared to Model C (p < .001).
• No significant differences in pressure indices were observed between Model A (pre-TEVAR) and Model B (post-TEVAR).
• In Model C (thrombosed false lumen), pressure was reduced but still significant, with the false lumen area under curve being 80% of the true lumen's.

Conclusions:

• False lumen pressure can remain elevated even after sealing the primary entry tear, particularly in non-thrombosed segments.
• Significant intraluminal pressure persists in thrombosed false lumens, potentially contributing to late aneurysmal development.
• These hemodynamic findings highlight a mechanism for post-TEVAR false lumen expansion in TBAD.