Taking an “individualized approach to treatment” has been a hot topic at meetings recently. What you think that is and what does that look like in your practice?
Dissection is a highly complex clinical condition with considerable inter-patient variability. We have traditionally classified these patients as either ‘complicated’ or ‘uncomplicated’ and this system has directed further management; complicated patients typically receive best medical therapy and endovascular treatment, whereas uncomplicated patients receive best medical therapy alone. However even within this broad classification there is still considerable variation in terms of how individual complications are defined, for example malperfusion, and what is meant by best medical and endovascular treatment for an individual patient. This is well demonstrated by the published data that show treatment failures with both modalities – some patients that have had endovascular treatment still go on to suffer an aortic-related death, as do uncomplicated patients treated with best medical therapy
A change in the current paradigm is required to prevent these aortic-related deaths and this may be achieved by extending our knowledge of dissection and by using a patient-specific or individualized approach. Some of the recent clinical and imaging studies have shown that each patient is unique, for example in terms of the length of the dissection, the size of the true and false lumens, the size and position of the entry tears, the amount of flow in the true and false lumens and across the entry tears, and so on, and the classifications that we routinely use do not probably appreciate these differences. In our practice we try to understand and appreciate these inter-patient differences and to tailor the best medical and endovascular treatment to each individual patient.
What advice do you have for fellows coming out of their programs who don’t have experience treating disease pathologies like dissection?
Dissection is a difficult pathology to treat, whether using best medical therapy alone or in conjunction with endovascular treatment. Experience is obviously important and so when starting out it is sensible to link up with a colleague who already has some experience of treating this condition.
There are some practical aspects that fellows can work on such as standardizing their approach in the operating room, knowing the procedural steps well, developing a thorough understanding of the device platform and by taking great care when managing these patients peri-operatively and during follow up. One of the most complex aspects of the management of dissection is accurately risk stratifying patients and selecting appropriate patients for endovascular treatment. Some guidance on this can be found by looking to the literature, where there is a plethora of articles identifying patient and anatomical factors that identify high-risk patients.
How is your approach to dissection treatment different than a thoracic aneurysm?
This is an excellent question. We have traditionally extrapolated much of the experience gained in the treatment of thoracic aneurysms and applied it to the management of thoracic dissection. These two conditions however are not the same, and this can be appreciated from studies that have evaluated dissection from a molecular and cellular level right up to an organ level. This is perhaps the reason why device technology that was developed for the treatment of aneurysmal disease is less effective for the treatment of dissection. In the treatment of aneurysmal disease the primary aim of treatment is to exclude the aneurysm sac from the circulation. In dissection, in the acute phase, the aim is to try to treat the complications of the dissection such as malperfusion, with the longer-term aims of promoting positive aortic remodeling and improving survival. Type B dissection frequently involves a long segment of the descending thoracic aorta and so it is common in the management of dissection to plan a procedure with more than one stage, for example, an initial thoracic endovascular repair to relieve the complications of the acute dissection, followed later by a fenestrated component to treat the distal disease involving the visceral segment.
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Rachel Clough, MD, PhD is a paid consultant of Cook Medical.