* Methods now only rarely used.
Surgical treatment for aortic isthmus stenosis
The following principles should be followed with surgical procedures. Firstly, to prevent re-stenoses from occurring, the resection or bridging of the aortic isthmus stenosis is always carried out at a wide distance from the immediate constriction. The aim here is particularly to achieve complete resection of scattered ductal tissue. Secondly, simultaneous continuous invasive arterial blood pressure measurement should be carried out at the radial artery and femoral artery intraoperatively. Thirdly, the mean arterial blood pressure in the upper half of the body should always be kept in the high normal range in order to avoid spinal cord ischemia and paraplegia. Fourthly, young adults and older patients are ventilated with a double-lumen tube so that the left lung can be immobilized for the duration of the surgical procedure.
End-to-end anastomosis
The technique for resection of aortic isthmus stenosis and end-to-end anastomosis described by Crafoord and Nylin (1945) is mainly used in small children and is currently regarded by many surgeons as the preferable correction method (Schmid and Asfour 2009; Karck et al. 2003). The technique can also be used with an “enlarged” end-to-end anastomosis to correct aortic arch hypoplasia. After mobilization of the aorta and ligation and transection of the ductus arteriosus, the aorta is adequately clamped well proximally and distally to the aortic isthmus stenosis. The stenotic area is resected and the distal and proximal aortic stumps are anastomosed. To keep the anastomosis as tension-free as possible, the aorta has to be adequately mobilized during this process. In the enlarged end-to-end anastomosis described by Amato et al. (1977), the small curvature of the aortic arch is further incised in order to enlarge a hypoplastic segment of the aortic arch. The distal segment of the aorta is connected to the lower side of the aortic arch, as in a side-to-end anastomosis (Fig. 2.1-31) (Amato et al. 1977).
Fig. 2.1–31 The various surgical techniques for correcting an aortic isthmus stenosis.
Indirect isthmus plasty (patch enlargement plasty)
The technique of isthmus plasty, in which the area of the aortic isthmus is enlarged using a patch, was introduced by Vossschulte in 1957 (Vossschulte 1956/1957). After proximal and distal clamping of the aorta, the vessel is split lengthwise over the area of the stenosis, followed by cross-suturing. In this process, a diamond-shaped or rhomboid patch of polytetrafluoroethylene (PTFE), also known as Gore-Tex or Teflon, is introduced using a continuous suture. This procedure is only suitable for very short stenoses in aortae with few degenerative changes. The advantages of the indirect isthmus plasty procedure are that there is no need to mobilize the aorta, the intercostal arteries are preserved and the technique is suitable for correcting re-stenoses. Disadvantages include residual ductal tissue, use of a synthetic material, and local aneurysm development, which occurs frequently even without the use of Dacron, which is associated with a particularly high risk for localized aneurysm formation (Schmid and Asfour 2009; Karck et al. 2003; von Kodolitsch et al. 2002).
Waldhausen subclavian flap plasty
In the subclavian flap plasty technique, developed by Waldhausen and Nahrwold in 1966, the left subclavian artery is used as a patch to bridge the aortic isthmus stenosis (Waldhausen and Nahrwold 1966). The left subclavian artery is removed distally, so that the blood supply to the left arm is ensured only if there is adequate collateral circulation. The advantages of this procedure are that it can be used with a long stenosis and that foreign material is avoided (Schmid and Asfour 2009). However, malperfusion with trophic disturbances or growth retardation in the left arm occurs in some patients. A subclavian steal phenomenon is also observed if the vertebral artery is not ligated. The technique is nowadays hardly used any more due to these complications.
Interposition of a tubular prosthesis
After resection of the stenotic aortic segment, a vascular prosthesis can be inserted. This consists of synthetic material such as Dacron, Teflon, or Gore-Tex; an aortic homograft is rarely used. The technique is used when an end-to-end anastomosis is not possible—e.g., with long stenoses or stenoses in atypical locations, when there is a prestenotic or post-stenotic aortic aneurysm, when the vascular wall has been lacerated during attempted end-to-end anastomosis, for primary correction of an aortic isthmus stenosis in adults, when the aorta has massive atherosclerotic changes, or in surgery for recurrences of the stenosis. As the tubular prosthesis used has a rigid diameter, this procedure should be used only in older adolescents, in order to avoid disparities between the prosthesis diameter and the aortic diameter.
Interventional therapy for aortic isthmus stenosis
Balloon angioplasty is an alternative to surgical treatment for isolated aortic isthmus stenosis. The procedure for dilating an aortic isthmus stenosis was first used in a postmortem case by Sos et al. (1979); in 1982, Singer et al. carried out balloon angioplasty successfully for the first time to treat re-stenoses in patients with aortic isthmus stenoses that had previously been operated on. Sperling et al. (1983) used balloon angioplasty in previously untreated aortic isthmus stenoses. Since then various research groups have reported on primary dilation of a previously untreated aortic isthmus stenosis, with varying success rates. The American Heart Association recommends this procedure only as the primary treatment option for adults with aortic isthmus stenosis in cases of re-stenosis, while a surgical approach is still recommended for longer re-stenoses and in patients with a simultaneous hypoplastic aortic arch (Warnes et al. 2008). To reduce the risk of re-stenosis, balloon angioplasty with stent placement can be carried out in patients whose body weight is over 25 kg (Warnes et al. 2008). In smaller patients, there are no advantages with primary stent placement. Of note, stents can be dilated further later on, therefore can be used in children in whom growth has not yet been completed. The indication for using stents to treat long stenoses is a matter of controversy and this is not currently recommended (Warnes et al. 2008).
Results in adults after corrected aortic isthmus stenosis
Successful correction of an aortic isthmus stenosis is currently regarded more as a palliative procedure, rather than as a cure for the condition (Krieger and Stout 2010). In a series of 248 patients who underwent successful surgery for an aortic isthmus stenosis, for example, a 25-year follow-up period showed a 12% mortality rate, with a mean age at death of 34 years (Maron et al. 1973). The main causes of death