Multi-layer Flow-modulating Stents for Thoraco-abdominal and Peri-renal Aneurysms: The UK Pilot Study

OBJECTIVE

There remains a population of patients with aortic aneurysms that cannot be treated by conventional endovascular means. Multi-layer flow modulating stents (MFMS) are a novel approach for the treatment of aortic aneurysm; this study reports outcomes of a UK pilot study of first-generation MFMS in thoraco-abdominal (TAAA) and perirenal aneurysms (PAA) in patients who were also unfit for open surgery.

METHODS

Patients with TAAA and PAA unfit for open surgery and with no conventional options for endovascular repair were recruited. Follow-up included CTA at 1, 3, 6, and 12 months, then annually. Outcome measures included 30 day mortality, growth-free survival, branch vessel patency, complications, re-intervention, and maximal aortic diameter.

RESULTS

MFMS were implanted in 14 patients (6 PAA, 8 TAAA) between October 2011 and March 2014 with one (7%) 30 day death and 11 (79%) surviving to 12 months. The median aneurysm growth was 9 mm in the first 12 months following implantation. On mean follow-up of 22.8 months, seven (50%) patients had died including one confirmed rupture. AAA diameter remained stable in only two of the surviving patients. Fifty of 51 covered aortic branches remained patent with no embolic episodes or symptoms of ischaemia in any patient. MFMS dislocation occurred in four patients, leading to re-intervention in two. A total of six re-interventions were performed in five patients (35%) with one post-re-intervention death.

CONCLUSION

These first-generation MFMS were unstable and dislocated frequently. It is uncertain whether MFMS implantation influenced the natural history of these aneurysms as none decreased in size, but two remain stable after a mean of 22.8 months. Although side branch patency was maintained, our results do not support the continued use of these first-generation devices. Further development is needed if this technology is to have a role in treatment of aortic aneurysm.

Deliberate self-harm: developing clinical guidelines

Nurses in an acute admissions psychiatric ward are using reflective practice to develop clinical guidelines for the management of patients who deliberately self-harm. In this article, they describe the cyclical learning processes and reflective techniques involved.

Field conjugate acoustic lenses for ultrasound hyperthermia

Multipoint foci have been synthesized by applying the pseudoinverse field conjugation method to a single ultrasonic transducer coupled to a polystyrene lens. The lens design is based on phased array calculations are then fabricated on a computer-controlled milling machine. The measured beam patterns from the lenses agree closely with the beam patterns predicted by theory for the equivalent phased arrays. Temperature distributions from thermal modeling and those measured in tissue equivalent phantoms show that the lens system is capable of generating strongly localized, controlled temperature fields for hyperthermia.

Rapid heating: critical theoretical assessment of thermal gradients found in hyperthermia treatments

There is increasing evidence that many hyperthermia failures are closely related to the large variability of temperatures found in the treatment field. These are linked to thermal gradients near the treatment boundary, vascular perfusion differences, localized cooling, and poor distribution of energy deposition in the tissues. One way of reducing the temperature gradients is to replace traditional heating treatments of 30-60 min by a rapid heating technique, in which the treatment time is a few seconds combined with higher treatment temperatures. The purpose of this paper is to model potential advantages of using various rapid heating protocols, and to compare them with traditional treatments. Theoretical models (in agreement with clinical treatments) suggest that traditional hyperthermia treatments often do not produce the necessary temperature homogeneity needed to kill the last malignant cells in the tumour due to cooler regions in the field. The simulations presented in this paper suggest that much shorter treatment times (1-10 s) should give significant improvements in the treatment field for both the temperature homogeneity and equivalent thermal doses.