Professor Johannes Lammer, distinguished Interventional Radiologist at the University Hospital in Vienna, Austria, was awarded the honorary membership of the British Society of Interventional Radiology (BSIR) at its yearly meeting in November 2008 in Manchester, UK. Thereby, he carries forward the illustrous list of recent laureates including Professor Sven Seldinger, Professor Roger Greenhalgh and Professor Jim Reekers. In his keynote lecture after receiving the award he followed the tradition and addressed a fascinating application of interventional radiology in current vascular therapy: the endovascular management of aortic rupturs.
Endovascular repair of traumatic rupture of descending thoracic aorta established
Lammer structured his lecture into two parts and reminded the audience of the fundamental differences between ruptures of the descending thoracic aorta and the abdominal aorta. “Most ruptures of the descending aorta are of traumatic nature,” Lammer explained. “Hence, these patients are often relatively young and have sustained multiple trauma in addition to their thoracic injury.” Together with the complexity of open surgery in this anatomical region, the endovascular approach seems to confer crucial advantages conceptually. Lammer showed some of his own fascinating cases of successful thoracic endovascular aortic repair of traumatic ruptures and reviewed the current literature critically.
“The advantages of the endovascular approach seem already so clear-cut and extensive based on current data that randomised comparison are ethically difficult to envisage,” he explained. The series he cited had observed between 64 and 128 patients with traumatic and acute thoracic aortic ruptures and reported 30 day mortality rates relatively consistently around 7% (0–30%) for endovascular repair, whereas they ranged around 24% (20–55%) after open repair. Rates for major complications displayed similar differences (0–5% after endovacular repair and 3–16% after open repair). This documented an impressive reduction of early mortality from 24% to 7% by endovascular techniques. “However, we are still facing some distinct endovascular challenges in the descending aorta and the aortic arch, which need to be solved to ensure long-term durability,” Lammer warned, and alluded to the importance of graft compliance for sufficient seal in the aortic arch and the preservation of the supraaortic branches during the intervention. “Newer devices will have to address these problems satisfactorily by enhanced conformability and sidebranches that can be deployed precisely,” he added.
Abdominal aortic rupture: assessment of anatomical suitability is key
In the second part of his lecture, Lammer turned to the treatment of ruptures of the abdominal aorta. “These of course are almost exclusively due to ruptures of aortic aneurysms and our first concern should be their prevention by appropriate screening,” he explained citing the results of the UK MASS study (multi-centre aneurysm screening study) which showed a significant reduction of aneurysm (i.e. rupture) related deaths after screening. In the event, however, the most important decision to make currently is probably whether the patient’s anatomy is suitable for endovascular repair. “Commonly, surgeons have concerns regarding the delay dedicated imaging might cause. But there is fairly robust evidence that taking time for careful assessment does not endanger the patient,” he said. Among the studies he cited an Canadian report had shown no differences of overall mortality if patients were transferred to another hospital which increased their time-to-operation from three to six hours. “In addition, natural history studies have shown that 90% of patients survive the first two hours after hospital admission and that the median time-to-death is almost 11 hours after admission,” Lammer explained. Therefore, the time needed for a CT scan seems unlikely to affect the prognosis of the patient. Thus, Lammer proposed an algorithm based on these findings that included initial hypotensive resuscitation of the patient at a mean blood pressure of 70mmHg followed by a contrast CT. “Based upon the anatomical assessment tailored treatment in a dedicated Hybrid operating theatre becomes possible and is likely to confer most benefit to the patient,” Lammer said.
It is important to note, however, that only around 50% of patients can be estimated to be anatomically suitable for endovascular repair. “Maybe it is a subset of patients with unsuitable endovascular anatomy that is more prone to rupture,” Lammer speculated on these findings from the Amsterdam Acute Aneurysm Trial. “If endovascular repair is feasible, however, metaanalyses have shown quite consistently low operative mortality rates even below 20% and acceptable morbidity rates at 44%,” Lammer said, illustrating potential advantages of endovascular repair over open repair where respective figures still range around 35–40% (operative mortality) and 55% (morbidity), respectively. “Thus, the ability to offer both endovascular and open repair seems to improve patients’ survival significantly with a 3.8% increase in survival for each 10% increase in EVAR application,” Lammer summarised and cited a systematic review of 1200 patients. Thus, the important take home messages of this state of the art lecture were that a CT scan did probably not increase patients’ mortality and was even unlikely to delay therapy significantly, that 45–67% of patients could currently be expected to be suitable for endovascular repair, and that each 10% increase in use of endovascular repair had the potential to lessen mortality of the whole patient population by 3.5%. Imminent developments in endovascular technology and imaging possibilties are likely to even excel these impressive improvements of interdisciplinary management of ruptured abdominal aortic aneurysm in the near future.