Will mechanical stapling devices ever provide a fixation equal to or better than sutures? Will a stapler provide a completed laparoscopic anastomosis that is smooth and provides proximal fixation strength and sealing characteristics? Are the graft integrity, graft patency, and attachment seal compromised by calcified deposit in the artery wall?
Stent-graft fixation for the repair of abdominal aortic aneurysm (AAA) relies on the radial overextension of the stent scaffold at the inner walls of the aorta and iliac arteries. Oversizing can result in metal fatigue, as well as proximal stent-graft migration and endoleaks due to the pressures within the aorta that can range from 120 mm Hg pressure up to 200 mm Hg pressure. Without adequate attachment, a stent-graft leaks around the edges. The constant blood flow and regular peristaltic oscillations of the abdominal aorta, causes the stent-graft to migrate from its original position, which could result in the death of the patient because of the subsequent rupture of the aneurysm sack.
At least five device companies are currently in a design and test phase to provide secure fixation of the proximal edge of a stent-graft to the infrarenal aorta. In the past, several attempts have been undertaken for designing an endoluminal stapler device that is suitable for the task. If the walls of the aortic neck of an aneurysm are calcified and covered by calcium plaques, substantial forces are required for drilling staple holes through the walls of the stent-graft and the aortic wall. Therefore the progress in developing a reliable stapling device has been quite slow in view of the many difficulties in applying mechanical anastomosis techniques.
Next to the endoluminal stapling attempts a hybrid procedure for a mechanical connection between aortic neck and vascular graft performed in a laparoscopic aortic surgery technique is currently under trial. In its latest embodiment, this stapling device consists of a outwardly directed anvil head, a stapler head adjustably positioned opposite of the anvil and a handle. The head contains a single use 10-clip cartridge with radially loaded clips.
A non-stented vascular graft is placed in the aortic stapling device and secured outside the head. The graft is mounted on the stapler with a special clamp to grip the aorta externally while the stapling takes place. The vascular graft is everted to form a cuff over the head and the cuff is inserted into the dissected neck of the aneurysm. The staples open at both ends and fix the graft to the aortic wall of the neck. An end-to-end anastomosis between aorta and vascular graft inside out is performed with stainless steel staples.
Using a standard graft versus a stent-graft has several advantages: stent-graft usage is limited to cases with an infrarenal neck larger than 10 mm, having no thrombi in the neck, and less that 30% of the circumference of the neck being calcified.
In contrast to the laparoscopic hybrid technique, the delivery of a stent-graft has numerous inclusion criteria such as no major tortuosity of the two iliac axes and an aortoiliac angle greater than 80 degrees, with an external iliac diameter of at least 8 mm. Furthermore, an angle between the interrenal aorta and the neck of greater than 45 degrees would make the delivery of the stent-graft very difficult.
A main advantage of replacing sutures as the means for fixation with staples or fasteners is the reduction in complication rates due to a reduction in aortic clamping time. With the exception of stent-graft repairs, all anastomoses on aneurysm are done manually and innovators aim to reduce the amount of clamping time needed during AAA surgery.
Laparoscopic suturing techniques pose a steep learning curve for a surgeon which highlights the potential of the stapling device for intracorporeal assembly of the handle, the stapler arm, the staple cartridge and the staple driver for use in hand-assisted laparoscopic surgery. However, to this date all automated suture device require time consuming assembly procedures, considerable dexterity and specialized skills.
Unfortunately the stapler described above does not truly replace laproscopic suturing of the graft: in case of a bifurcated graft, the last step of the procedure involves a suture that closes the incision for the introduction of the stapler into the Y graft.
Further - the future ain’t what it used to be.
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