What would Albert Einstein do if he had another abdominal aortic aneurysm (AAA)? Would he opt for a traditional open surgical repair or undergo endovascular repair with a stent-graft? Or would he wait with the procedure until we come up with a better way for a safe, less-invasive and permanent fix via a hybrid laparoscopic procedure?
In 1948, when Albert Einstein was the world’s most famous scientist, he underwent state-of-the-art AAA treatment at that time: his “large” and aymptomatic AAA was cellophane wrapped. And sure enough, Albert Einstein survived the major procedure for 6 1⁄2 years before passing away due to a fatal AAA rupture in 1955.
Because Albert Einstein decided to refuse another painful major operation, he did not benefit from the brand new technique of opening the aneurysm sac and replacing the deceased part of the aorta in sewing in a Dacron tube graft, a technique developed in the 1950s.Due to the invasiveness, high mortality rate, prolonged pain and other adverse effects of this open surgical technique, there have been recent attempts to treat AAA with minimally invasive procedures. And today with state-of-the-art, less invasive AAA repair devices like covered stent-grafts and endoluminal delivery devices, would Mr. Einstein again reject a recommended urgent treatment on the grounds of the reported clinical failures and limitations of endovascular AAA repair? Or would he change his mind and test his good luck, trusting that the new stent-graft AAA repair technique has received early acceptance by many vascular and interventional specialists and is used with increasing frequency?
To answer these questions it might help to determine how to define and evaluate the likelihood of success with the endovascular AAA repair technique. Unfortuanately, periprocedural death, early or late conversion of endograft repair to conventional open surgical repair, increase in maximal AAA sac diameter of 5 mm or greater after endograft exclusion, and AAA rupture after endoluminal aneurysm treatment are clinical failures reported by physicians doing the stent-graft repair. The cause of all these failures seems to be for two perceived shortcomings of covered stent-grafts:
endoleak and inferior durability resulting in migration of the device. On top of the bad news, endoleaks may result in an adverse event such as aneurysm sac growth, late conversion to open repair, or rupture of the AAA, which was the cause of death of Mr. Einstein, who objected to the call of a reintervention due the clinical problems of the AAA repair technique of his time.
The frequency of secondary interventions to repair a stent-graft may be concerning to a patient recently diagnosed with the disease and penerate uncertainty about the proper role of endovascular AAA repair. Albert Einstein might have investigated the “secondary outcome success” of these reinterventions and carefully examined the concept of “assisted patency” in stent-grafts as a principles of vascular surgical care. Mr. Einstein would have probably been reminded that it requires quite a long time to determine with certainty the benefits of a new method of a AAA treatment and usually longer still to be certain of the harmful
disadvantages.The importance of stent-graft durability cannot be overemphasized considering the SAAAVE law being in effect starting January 2007. The prevalence of AAAs found in population-based ultrasound screening studies from various countries ranges from 4.2-8.8% in men, and 0.6-1.4% in women. Mandatory screening for AAA during the “Welcome to Medicare/Medicaid exam” for 65 year old senior citizens of the USA may lead to a large number of patients with clinically significant aneurysms.
This new relatively young group of AAA patients are different from the elective group of elderly, many 85 years and older, who choose stentgraft repair techniques as a more doable operation considering most have overt comorbid chronic medical conditions. No longer will vascular surgery be called “the surgery of ruins” – the patient population will be the aging baby boomers with a life expectancy of more than 20 years.
This new AAA patient population will carefully consider their choices, and weigh their decision as a “trade-off” between the benefits of opting for the less invasive stent-graft procedure with the consequence of a less certain and less permanent repair and a higher rate of reintervention, on top of the need for lifelong follow-up.
There is no doubt in my mind that an endovascular aneurysm repair technique holds many promising advantages and that innovations in the field and further advances in technology will continue to widen application to patients that are currently excluded from the procedure due to anatomical limitations. However the second and third generation stent-graft devices still seem to have considerable difficulties to cope with changing AAA sac morphology, a major mode of late failures andcomplications.
Suprarenal fixation of stent-grafts seems to fail in the treatment of with short infrarenal necks, and endoluminal stapling and fixation techniques have not produced promising clinical results. What we need are methods and devices to improve security and reliability at endograft attachment sites and endografts that are more durable. This can probably not be achieved in an endoluminal fashion.
The possibility of a new hybrid surgical approach that is less invasive than open AAA repair and combines all advantages of endoluminal and laparoscopic surgery has generated a lot of nervous excitement. The less invasive combined laparoscopic and endoluminal approach may be applied to management of persistent Type I or II endoleaks by means of banding, automated suturing and endoluminal graft delivery.
The excitement is fueled by the fact that this hybrid approach would get rid of the stent inside the endograft and therefore is applicable to all the patients who currently do not have the suitable anatomy to be considered for endoluminal repair. Ongoing research is being conducted to create protocols that support new technologies.
AAA repair needs progress as more and more AAA patients may think twice about the current stent-graft devices and more and more physicians may find themselves without stent-graft patients.
Further – the future ain’t what it used be.
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