MRI to investigate iliac artery wall thickness in triathletes

Is There a Role for Heli-FX Endoanchors in Treating Type 1B Common Iliac Artery Endoleaks?

OBJECTIVES

The management of type 1B endoleaks following endovascular aortic aneurysm repair (EVAR) can be challenging. The Heli-FX Endoanchor system effectively treats proximal type 1A endoleaks but has not been used for type 1B common iliac artery endoleaks. This study demonstrates that it is both safe and effective in being used in the common iliac artery (CIA) limb of an EVAR.

METHODS

A retrospective review of patients identified through coding and medical records was performed to extract information on demographics, aneurysmal features, operative features, and postoperative outcomes. This was then collated and analysed thoroughly and compared to existing research.

RESULTS

Four patients with six type 1B CIA endoleaks were treated with Heli-FX Endoanchors in the CIA limbs of EVAR grafts. There was 100% technical success rate with complete exclusion of the endoleaks at 6 months. With mean follow up of 714 days, there were no Endoanchor-specific complications. One patient required explantation of the aortic endograft due to contralateral limb fracture, where it was found that an Endoanchor had penetrated the common iliac vein, requiring primary closure.

CONCLUSIONS

Heli-FX Endoanchors were effective within this cohort of patients, though key risks were identified. Adjacent anatomy to the CIA must be considered, which also have nearly half the arterial thickness compared to the aorta. Pre-operative planning is essential given the theoretical risk of placing Endoanchors.

Venous Biomechanics of Angioplasty and Stent Placement: Implications of the Poisson Effect

PURPOSE

To characterize the Poisson effect in response to angioplasty and stent placement in veins and identify potential implications for guiding future venous-specific device design.

MATERIALS AND METHODS

In vivo angioplasty and stent placement were performed in 3 adult swine by using an established venous stenosis model. Iron particle endothelium labeling was performed for real-time fluoroscopic tracking of the vessel wall during intervention. A finite-element computational model of a vessel was created with ADINA software (version 9.5) with arterial and venous biomechanical properties obtained from the literature to compare the response to radial expansion.

RESULTS

In vivo angioplasty and stent placement in a venous stenosis animal model with iron particle endothelium labeling demonstrated longitudinal foreshortening that correlated with distance from the center of the balloon (R² = 0.87) as well as adjacent segment narrowing that correlated with the increase in diameter of the treated stenotic segment (R² = 0.89). Finite-element computational analysis demonstrated increased Poisson effect in veins relative to arteries (linear regression coefficient slope comparison, arterial slope 0.033, R² = 0.9789; venous slope 0.204, R² = 0.9975; P < .0001) as a result of greater longitudinal Young modulus in veins compared with arteries.

CONCLUSIONS

Clinically observed adjacent segment narrowing during venous angioplasty and stent placement is a result of the Poisson effect, with redistribution of radially applied force to the longitudinal direction. The Poisson effect is increased in veins relative to arteries as a result of unique venous biomechanical properties, which may be relevant to consider in the design of future venous interventional devices.

Arterial endofibrosis in endurance athletes: Prospective comparison of the diagnostic accuracy of intra-arterial digital subtraction angiography and computed tomography angiography

PURPOSE

To prospectively compare the diagnostic capabilities of computed tomography angiography (CTA) to those of digital subtraction angiography (DSA) in endurance athletes with suspicion of arterial endofibrosis.

MATERIALS AND METHODS

Forty-five athletes (39 men, 6 women; median age: 30 years, interquartile range: 23-42 years) prospectively underwent DSA and CTA without (n=5) or with (n=40) electrocardiogram gating. DSA was interpreted by a single expert (experience of 15 years). CTA was independently interpreted by three other readers (experience of 5-8 years). Readers assessed the presence and degree of stenoses on iliac and femoral arteries and the overall diagnosis (negative, uncertain, positive) of endofibrosis at the limb level. Sensitivities and specificities of DSA and CTA were estimated at the limb level using histological findings and long-term follow-up as reference, and compared using the McNemar test.

RESULTS

For diagnosing and quantifying stenoses, concordance between DSA and CTA was moderate-to-good for common and external iliac arteries, moderate for lateral circumflex arteries and poor-to-moderate for the other branches of the deep femoral artery. It was good for all readers for the overall diagnosis of endofibrosis. After long-term follow-up (median, 95 months; interquartile range: 7-109 months), DSA sensitivity and specificity were respectively 88.6% (39/44; 95% confidence interval [CI]: 76-95%) and 75% (24/32; 95% CI: 57.9-86.7%); CTA sensitivity and specificity were respectively 88.6% (39/44; 95% CI: 76-95%; P>0.99) and 84.4% (27/32; 95% CI: 68.2-93.1%; P=0.51), 86.3% (38/44; 95% CI: 73.3-93.6%; P>0.99) and 75% (24/32; 95% CI: 57.9-86.7%; P>0.99), and 84.1% (37/44; 95% CI: 70.6-92.1%; P=0.68) and 75% (24/32; 95% CI: 57.9-86.7%; P>0.99) for the three readers.

CONCLUSION

CTA shows performances similar to those of DSA in predicting the long-term diagnosis of endofibrosis in endurance athletes with suggestive symptoms.