Vascular News attended the recent Masterclass V – Modern Management of Thoracic Aortic Dissection, at Guy’s Hospital, London, UK, in May 2005. The Masterclass meeting focuses primarily on endovascular procedures in the thoracic aorta and aims to cover developments in the field with leading international speakers.
This year’s meeting concentrated exclusively on thoracic aortic dissection, one of the most difficult conditions to manage. The event was sponsored by Cook (UK), WL Gore, Lombard Medical Technologies, Medtronic Vascular and Vascutek. The Masterclass was organised by Dr Peter Taylor, London Bridge Hospital, and Dr John Reidy, Guy’s Hospital, London, UK.
Dr Michael D Dake, Professor and Chairman, Department of Radiology, University of Virginia Health System, began the meeting discussing the interrelated pathologies of thoracic dissection. Dake said a stent graft should be utilised when treating Type A intramural haematoma, a penetrating atherosclerotic ulcer and a Type B thoracic aorta dissection with persistent pain or an increase in pleural effusion. He stated that current in-hospital (all treatments) mortality rates were 17%, whilst in hospital mortality due to disease progression was 8%. Therefore, Dake believes that stent grafts have “the potential to be a very useful alternative” in the treatment of in thoracic aorta.
Following Dake, Dr Jan Blankensteijn, Professor and Chief of Division of Vascular Surgery, University Medical Centre, Nigmegen, Netherlands, discussed which cross-sectional imaging technique was more beneficial. He summarised the relative merits of CTA and MRA, stressing that dynamic imaging was needed in order to see the blood flowing and assisted in decision making. He acknowledged that MRA has longer acquisition times, limited patient monitoring and inferior spatial resolution.
Nevertheless, Blankensteijn concluded by stating that therapeutic decisions should not be driven by Type A or B.
In the subsequent session, Dr John Chambers, Consultant Cardiologist, Guy’s and St Thomas’ NHS Foundation Trust, London, discussed transoesophageal echocardiography (TOE) claiming the technique assisted in the choice of the entry site and was the technique of choice in hyperacute dissection. Chambers also stated that TOE also provided complementary information to CT or MR in chronic dissection and provided flow information after deployment. However, he stressed that the technique provided no information on abdominal branches, concluding that TOE should used if a specialist is present.
Discussing the medical management of Type A dissection, Professor James Ritter, Professor of Clinical Pharmacology, King’s College, London, cited a series of studies in Hungary, which were confirmed in Italy, where there was a low incidence rate of Type A dissection. When a patient reports chest pain, the myocardial infarction rate is 400/100,000 but thoracic dissections are 3/100,000. However, Ritter acknowledged that there was no randomised controlled trials data and that there was a lack of licensed drugs in the area. Ritter claimed that the patient should be treated with Beta adrenoreceptor antagonist (Esmolol, Propandol, Labetalol) unless contra-indicated, and in such circumstances Nitroprusside can be utilised. Otherwise, Trimethaphan can be used although Ritter claimed these old but useful drugs can become unreliable if seldom used – once stable surgery can be performed (Type A) or treated with oral anti-hypertension drugs (uncomplicated Type B).
Christoph Nienaber, Chief of Cardiology, University of Rostock Germany, discussed the endovascular management of chronic dissection. He believes that all patients with the diagnosis of dissection should be monitored in intensive care units and should receive antihypertensive medication and sedation.
In addition, due to the high risk of death, patients with type A dissection (involving the ascending aorta) should undergo emergent surgical aortic reconstruction with or without aortic valve replacement. Nienaber revealed that the INSTEAD study, a randomised, controlled trial that aims to compare the one-year outcome of type B dissection treated with thoracic stent graft and conventional antihypertensive versus conventional antihypertensive treatment, has completed enrolment and patient follow-up has been prolonged to 24 months. He stated that chronic dissection is neither chronic nor acute and is not a very benign disease, as a third of patients die if they are only treated medically.
Professor Krassi Ivancev, Chief of Endovascular Center, Department of Radiology, Malmo University Hospital, Sweden, presented research on Cook’s TX2 graft stent system, stating that the controlled deployment minimised manipulation in the arch. In this study, 46pts were treated for Acute Type B, whilst 15pts were treated for Chronic Type B. Ivancev said that treating the Acute Type B with a stent graft was a ‘very good alternative’ to surgery, whilst Chronic Type B dissection was difficult to exclude due to the multiple re-entries in the abdominal aorta. Ivancev stated that it is necessary to stent the whole length of the thoracic aorta to cover as many tears as possible to the level of the diaphragm. Ivancev did acknowledge that the research did experience paraplegia and that there were problems with the rigidity of stent grafts.
As discussion evolved towards the end of the day it became apparent that this is an area driven by expert opinion rather than evidence, and expert opinion is often divided. For example, Dake believes that one should not stent too long for dissections as this risks paraplegia. On the other hand, Ivancev believes that one should stent the whole length of the thoracic aorta to cover the tears and give seal (shuts off the intercostal arteries). Until there is firm clinical evidence, it appears as though this fascinating debate will continue.