# Vessel Curvature and Microcatheter-Detachable Coil Compatibility in Arterial Coil Embolization

## TL;DR

This study finds that sharp bends in arteries and mismatched equipment increase the risk of coil delivery failure during non-neuro arterial embolization procedures.

## Contribution

The study identifies that both sharp vessel angulation and microcatheter-coil mismatch independently predict coil maldelivery in non-neuro embolization.

## Key findings

- Coil failure occurred in 6.2% of cases, with sharp vessel angulation (≥90-180°) at the catheter tip being a strong predictor.
- Microcatheter-coil mismatch also independently increased the risk of coil maldelivery.
- Most mismatch-related failures were resolved by correcting the mismatch or using alternative coils.

## Abstract

Background

Non-neuro arterial embolization is widely performed for various clinical indications, with support systems implemented to ensure procedural safety. However, when the target vessels are highly tortuous or have significant bends at the peripheral level, the microcatheter and coil must traverse lengthy, sharply curved paths, raising concerns about coil maldelivery.

Purpose

To examine whether sharp vessel angulation (≥90-180°) and microcatheter-coil compatibility independently increase coil maldelivery in non-neuroarterial embolization.

Materials and methods

This single-center, IRB-approved analysis from February 2023 to December 2024 included 451 arterial branch-detachable coil combinations (BCCs) in 119 patients (mean age 64 years, range 32-87). Angulations of 90-180° at the proximal catheter segment and distal tip were evaluated on digital subtraction angiography. Technical failure was defined as the inability to deploy the coil as intended, including unraveling or coil shape distortion. A 1:3 propensity score matching (28 failed vs 61 successful BCCs), balanced coil features, and target-vessel factors. Mismatch was recorded if the coil's primary diameter exceeded or fell below microcatheter thresholds. A generalized linear mixed model accounted for within-patient clustering.

Results

Coil failure occurred in 28 of 451 BCCs (6.2 %). A 90-180° inversion at the catheter tip (odds ratio (OR), 22; p = 0.008) and mismatch (OR, 4.9; p = 0.03) independently predicted failure. A proximal 90-180° inversion also contributed (OR, 4.5; p = 0.03). Of 28 failures, 21/28 (75%) were mismatched: 16/21 (76%) resolved via mismatch correction, and 5/21 (24%) required repositioning or an alternate coil gauge/length. Proper-match failures (n=7) were treated with thinner or more flexible coils in 6 (85.7%; p < 0.0001).

Conclusions

Sharp vessel angulation (≥90-180°) and microcatheter-coil mismatch independently increase the risk of maldelivery in non-neuro arterial embolization.