Mechanochemical ablation in the treatment of superficial venous incompetence

Mohamed, Abduraheem

October 2021

Thesis or dissertation

© 2021 Abduraheem Mohamed. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.

The routine management of venous incompetence has undergone considerable changes in the last two decades led by the introduction of minimally invasive endovenous techniques. At the heart of these changes has been a drive to offer patients effective symptomatic relief whilst minimising disruption to patient quality of life and periprocedural pain. Endovenous thermal ablation (EVTA) has been the main mode of treatment in this minimally invasive era, however, non-thermal methods are challenging this established order and include mechanochemical ablation (MOCA) which is an exciting new technique that combines liquid sclerotherapy with mechanical damage to vessel intima.
The studies contained within this thesis aim to assess the evidence supporting the use of MOCA for the treatment of venous incompetence, to independently validate these results, to optimise a strategy of performing MOCA, and to test the efficacy and clinical effectiveness of MOCA against EVTA.
Study 1 is a systematic review of the current literature of MOCA, focusing on objective assessment of clinical success including duplex ultrasound (DUS) measurements and health related patient reported outcomes (PROMS). Study 2 is a cohort study of symptomatic patients with superficial venous incompetence (SVI), treated with MOCA and 1.5% Sodium tetradecyl sulphate (STS). Outcomes included clinical examination, DUS, health related PROMS at baseline and weeks 1,6,26 and 52. Study 3 compares the approach of treating varicose tributaries with phlebectomy at the time of performing MOCA (MOCAP) against sequential treatment of tributary varicosities at a later date (MOCAS). A similar outcomes assessment and follow up strategy to study 2 was adopted. Study 4 takes forward the results of the previous studies and compares endovenous laser ablation (EVLA) to MOCA in a randomised controlled study comparing the clinical and technical outcomes of each intervention at baseline and weeks 1,6,26 and 52.
Study 1: MOCA is a safe and effective method of treating SVI in the short-term, however, the evidence for the longevity of its results beyond 6 months is poor. Moreover, the data on anatomical occlusion rates is questionable and may not match those of EVTA.
Study 2: Thirty-two patients were recruited to the study. Complete target vein occlusion at one year was achieved in 21 (75%) patients. Six patients (21.4%) required secondary procedures, of which three had axial EVLA and three required ambulatory phlebectomy with perforator ligation. There was a significant improvement in the median (interquartile range) Venous Clinical Severity Score (VCSS) from baseline 6 (5–8) to a score of 1 (0–2) at one year (p<0.001). There was also a significant improvement in health-related quality of life (HRQoL), both generic (p<0.001) and disease specific (p<0.001). One patient (3.1%) had a post-procedural non-fatal pulmonary embolus.
Study 3: Fifty patients underwent MOCAP and 33 patients MOCAS. The two groups were comparable at baseline. MOCAP was associated with lower (better) AVVQ scores at six weeks (3.4 (0.5–6.0) vs. 6.1 (1.8–12.1); p=0.009) and at six months (1.6 (0.0–4.5) vs. 3.34 (1.8–8.4); p=0.009) but by one year the difference was no longer statistically significant (1.81 (0.0–4.5) vs. 3.81 (0.2–5.3); p=0.099). MOCAP was associated with longer procedural duration (45 min (36–56) vs. 30 min (25–37); p<0.001) and higher maximal periprocedural pain (31 (21–59) vs. 18 (7–25); p<0.001). VCSS at all time points was lower in MOCAP group compared to MOCAS (0 (0–1) vs. 1 (0–3); p<0.001). MOCAP was associated with fewer episodes of clinically significant thrombophlebitis (6 of 50 (12%) vs. 10 of 33 (30%); p=0.039) and lower numbers of secondary procedures (2 (4%) vs. 6 (18%); p=0.032)
Study 4: One hundred and fifty patients were randomised equally between MOCA and EVLA. Both groups reported low intraprocedural pain scores; on a 100 mm visual analogue scale, pain during axial EVLA was 22 (9-44) compared to 15 (9-29) during MOCA; p=0.210. At 1 year, duplex derived anatomical occlusion rates after EVLA were 63/69 (91%) compared to 53/69 (77%) in the MOCA group; p=0.020. Both groups experienced significant improvement in VCSS and AVVQ after treatment, without a significant difference between groups. Median VCSS improved from 6 (5-8) to 0 (0-1) at one year; p<0.001. Median AVVQ improved from 13.8 (10.0-17.7) to 2.0 (0.0-4.9); p<0.001. One patient in the MOCA group experienced DVT.
MOCA with 1.5% STS is safe, effective and leads to significant improvement in patient health related quality of life (HRQoL) outcomes up to 1 year follow up. However, the anatomical occlusion rates achieved with MOCA are lower than has been previously reported in the literature and do not match EVLA results. Patient HRQoL gains are better when MOCA is combined with concomitant phlebectomy of varicose tributaries and using this approach HRQoL gains following MOCA are equivalent to those achieved by EVLA. Long-term follow up is needed however to ascertain the effect of the increased recanalisation following MOCA on disease recurrence and progression.

Hull York Medical School, The University of Hull and the University of York
Chetter, Ian; Carradice, Daniel; Wallace, Tom, MD
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