Advertisement

Reverse Subclavian Flap Repair for Coarctation with Hypoplastic Arch

  • Richard A. Jonas
    Correspondence
    Address reprint requests to Dr. Richard A. Jonas, Department of Cardiovascular Surgery, Children’s National Medical Center, 111 Michigan Ave NW, Washington, DC 20010.
    Affiliations
    Department of Cardiovascular Surgery, Children’s National Medical Center, Washington, DC.
    Search for articles by this author
      A critical neonatal coarctation can be defined as one that is sufficiently severe to keep the neonate prostaglandin-dependent. Perfusion distal to the coarctation must be maintained by ensuring patency of the ductus arteriosus and maintaining elevation of pulmonary vascular resistance by appropriate ventilatory manipulation.
      • Jonas R.A.
      One of the complexities of managing the critical neonatal coarctation is that it is often associated with hypoplasia of the isthmus, distal aortic arch, or proximal aortic arch. It must be remembered that these segments of the aorta are normally smaller than the ascending aorta consequent to the branching of the aortic arch. In general, an isthmic diameter that is less than 40% of the ascending aortic diameter is inadequate. Likewise a distal aortic arch diameter that is less than 50% of the ascending aorta, or a proximal aortic arch that is less than 60% of the ascending aorta, is inadequate. It is exceedingly common to find severe hypoplasia of the isthmus so that resection of the isthmus or a slide plasty as illustrated here are almost routinely incorporated into the management of critical neonatal coarctation. Distal aortic arch hypoplasia is a less frequent but still not rare problem. Severe hypoplasia of the aortic arch proximal to the left common carotid artery is a very rare finding.
      The most common technique for dealing with the hypoplastic distal aortic arch has been to perform an extended end-to-end anastomosis as illustrated in the accompanying article by Tsang. However, an alternative approach that we have found particularly helpful in the neonate is to perform a reverse subclavian flap procedure.

      Disadvantages of the Left Subclavian Flap Approach

      The principal disadvantage of the left subclavian flap approach is that it requires division of the left subclavian artery. It is exceedingly rare for this to result in left upper limb ischemia so long as the branches of the left subclavian artery are not divided. There is a theoretical risk of a left subclavian steal but it is rare in our experience that this is functionally important during childhood.

      Advantages of the Left Subclavian Flap Approach

      The principal advantage of this approach is that there is less tension on the anastomosis. The toe of the extended end-to-end anastomosis can be difficult to expose, and tearing of tissue at the toe can result in bleeding that can be difficult to control. The relatively long anastomosis required for the extended end-to-end anastomosis also requires a considerably longer clamp time than is generally required for the left subclavian flap approach.

      Operative Technique

      The mediastinal pleura is dissected from the distal left subclavian artery to approximately the midpoint of the descending aorta. Retraction sutures are placed in the anterior pleural flap with care to avoid injury to the vagus nerve and the recurrent laryngeal nerve. The left subclavian artery is dissected free with care to avoid injury to the lymphatic vessel, which frequently passes over the proximal subclavian artery. This vessel when large should be ligated. When smaller the vessel can be carefully cauterized. When dissecting behind the origin of the left subclavian artery care should be taken to avoid injury to “Abbott’s artery,” which is frequently present in this location. The hypoplastic distal aortic arch is dissected free, and dissection is continued until the ascending aorta can be clearly visualized. The left common carotid artery is dissected free over at least its proximal two-thirds within the chest. The ductus arteriosus is dissected free as is the proximal ∼2 cm of the proximal descending aorta. Collateral vessels, usually the initial 2 or 3 intercostal vessels, are carefully preserved.

      Discussion

      There is little doubt that the technique of coarctation resection with extended end-to-end anastomosis incorporating the hypoplastic aortic arch is the most popular technique for dealing with arch hypoplastia in association with coarctation. However, individual anatomy can dictate under certain circumstances that the reverse subclavian flap procedure is a preferable approach. For example, more severe degrees of arch hypoplasia are probably best treated with the flap procedure. If there is a long aortic isthmus or if there are other factors that increase the tension on an extended end-to-end anastomosis, then the reverse subclavian flap may be preferable. It should be remembered that the principal advantage of the reverse subclavian flap procedure is that it does reduce the amount of tension on the anastomosis so that long-term outcome, particularly freedom from recoarctation, is likely to be reduced with this procedure.
      One report describing a large series of patients undergoing the reverse subclavian flap procedure was published by Kanter and coworkers from Emory University in 2001.
      • Kanter K.R.
      • Vincent R.N.
      • Fyfe D.A.
      Reverse subclavian flap repair of hypoplastic transverse aorta in infancy.
      One-hundred sixty-two infants less than 3 months of age underwent repair of coarctation after 1988. Of these, 46 had a reverse subclavian flap aortoplasty at a median age of 11 days and a mean weight of 3.2 kg. There were two hospital deaths, one in a patient who subsequently underwent a Norwood procedure and the other from sepsis. At a mean follow-up of 38 months, 5 patients had recurrent obstruction, of which three were at the coarctation site rather than at the arch repair. The authors concluded from this series that the reverse subclavian aortoplasty procedure is an excellent technique for relief of arch hypoplasia with a low recurrence rate and acceptable operative and intermediate-term survival.
      Variations of the reverse subclavian flap procedure have been described. For example Giamberti and coworkers
      • Giamberti A.
      • Pome G.
      • Butera G.
      • et al.
      Extended end-to-end anastomosis with modified reverse subclavian flap aortoplasty.
      from Italy described a procedure in 2001 in which the left subclavian artery was left in continuity. This is very likely a more technically challenging procedure than the standard reverse flap procedure. Nevertheless it does offer the important advantage that the left subclavian artery is left in continuity so there is no risk to perfusion of the left arm. The authors describe 5 neonates with a mean age of 4 days and a mean weight of 2.4 kg who underwent this technique in association with coarctation resection and standard end-to-end anastomosis. There were no hospital or late deaths. No patient presented with recurrent coarctation.
      In conclusion, coarctation can be a deceptively complex problem that requires careful individual tailoring of the operative approach according to the specific anatomical situation. The reverse subclavian flap procedure provides a helpful tool in the armamentarium for the surgeon who must deal with important distal aortic arch hypoplasia in association with coarctation of the aorta.
      Figure thumbnail gr1
      Figure 1The child should be positioned with the left side up in the right lateral decubitus position. Ideally the arterial monitoring catheter should be inserted in the right radial artery. Pulse oximeter probes should be placed on the right hand and on one of the lower extremities. The child should be placed on the cooling/warming blanket to allow manipulation of body temperature. In general, it is advisable to maintain the rectal temperature between 34 to 35°C during the cross-clamp period. A left posterior (rather than posterolateral) thoracotomy incision is performed and the chest is entered through the third or fourth intercostal space.
      Figure thumbnail gr2
      Figure 2The left lung is retracted anteriorly with malleable retractors. Generally one malleable retractor is placed above the hilum of the lung to retract the upper lobe while a second malleable retractor is placed below the hilum of the lung to retract the lower lobe. A moist sponge stretched across the hilum between the two retractors protects the lung and prevents slipping of the malleable retractor.
      Figure thumbnail gr3
      Figure 3First clamp phase: reverse subclavian flap. A clamp is placed across the aortic isthmus in such a way that continuing perfusion of the distal body will occur through the patent ductus. Usually, a slightly angled clamp or an aortic cross-clamp style of clamp is appropriate for clamping the isthmus. A “C” clamp is placed across the proximal aortic arch and incorporates the left common carotid artery, which should be clamped across its middle. By this time the left subclavian artery has been ligated distally. It is not considered essential that the vertebral artery branch of the left subclavian artery should be ligated, although there is a theoretical risk of a subclavian steal phenomenon developing.
      Figure thumbnail gr4
      Figure 4After division of the left subclavian artery, it is filleted open along its rightward face, i.e., the side of the subclavian artery that faces toward the common carotid artery. The incision is carried across the superior surface of the distal aortic arch and then turns cephalad along the leftward face of the left common carotid artery over a distance of 3 to 4 mm.
      Figure thumbnail gr5
      Figure 5The left subclavian artery is now turned down as a flap with the toe of the flap being sutured initially to the most distal extent of the incision in the left common carotid artery. The posterior wall of the flap can be sutured from within the lumen using continuous 6/0 Prolene. The anterior layer is then completed using the same suture.
      After release of the clamps, perfusion is reestablished to the left common carotid artery. Perfusion continues through the ductus.
      Figure thumbnail gr6
      Figure 6Second clamp phase: resection of coarctation. The ductus arteriosus is ligated with a 5/0 Prolene suture ligature. A distal clamp is applied across the most distal extent of dissection of the descending aorta with the clamp incorporating the proximal intercostal vessels. In the neonate, these vessels are sufficiently thick-walled and elastic to allow composite clamping with the descending aorta. The proximal clamp is applied across the newly enlarged distal aortic arch, with flow maintained through the left common carotid artery.
      Figure thumbnail gr7
      Figure 7The juxtaductal coarctation is now excised though the isthmic segment does not need to be removed with the excised specimen. It is preferable to perform a slide plasty advance of the descending aorta and use the tissue of the isthmic segment. An incision is extended from the point of division of the distal isthmus across the inner curve of the aorta to the undersurface of the newly enlarged distal aortic arch. A longitudinal incision is made in the descending aorta on its outer curve, i.e., the leftward face of the descending aorta. The length of the incision should be adequate to match the circumference of the ascending aorta with the length of the aortotomy in the isthmus and undersurface of the distal aortic arch.
      Figure thumbnail gr8
      Figure 8The anastomosis is now fashioned using continuous 6/0 Prolene beginning with an inside-to-outside suture on the distal aortic arch with the same needle being brought outside to inside on the distal aorta. The posterior wall should be run first and then the other needle of the same suture should be brought across the anterior wall of the anastomosis. It is particularly important to take care with the toe of the anastomosis. Closely spaced bites should be taken proximally with wider spaced bites being taken on the descending aorta.
      Figure thumbnail gr9
      Figure 9The repair has been completed. After release of the clamps the patient’s body temperature should be gradually returned toward normothermia. Aggressive rewarming should be avoided.

      References

        • Jonas R.A.
        Comprehensive Surgical Management of Congenital Heart Disease. Arnold, London, UK2004: 207-224
        • Kanter K.R.
        • Vincent R.N.
        • Fyfe D.A.
        Reverse subclavian flap repair of hypoplastic transverse aorta in infancy.
        Ann Thorac Surg. 2001; 71: 1530-1536
        • Giamberti A.
        • Pome G.
        • Butera G.
        • et al.
        Extended end-to-end anastomosis with modified reverse subclavian flap aortoplasty.
        Ann Thorac Surg. 2001; 72: 951-952