of Permanent Pacemakers in infants and Children

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1 Intermuscular Abdominal Implantation of Permanent Pacemakers in infants and Children Joseph J. Amato, M.D., Douglas D. Payne, M.D., Harold F. Rheinlander, M.D., and Richard J. Cleveland, M.D. ABSTRACT Pacemaker implantation in infants and young children presents technical problems because of the relatively large size of the units. Various implantation sites have been employed to avoid the problems of unsightliness, migration, skin necrosis with infection, and patient discomfort. We are presenting a new technique which obviates these difficulties. The pacemaker generator is located in a space developed between the muscles and fascia of the abdominal wall. This site will accept even the largest of demand pacemakers with cosmetically acceptable results. The correction of complex congenital heart lesions during infancy and early childhood is being performed with increasing frequency. Concomitantly, there has been an increase in the need for permanent pacemaker implantation in some of these patients because of postoperative sinus bradyarrhythmias or heart block. These dysrhythmias may persist for several months or may be permanent. Children who require permanent pacing present particular problems not encountered in the older patient. The power pack must deliver a rate of 100 beats per minute or more in order to meet the physiological stresses of the immediate postoperative period. The pacing unit must be placed in such a fashion as to minimize complications and provide a cosmetic result which is acceptable to the parent and the child. During the past 36 months, 21 pacemaker generators have been inserted in 16 patients. Of the 395 pediatric open-heart procedures performed during this same period 6 patients developed bradytachycardia syndrome and 6 patients had complete atrioventricular block. Two of this last group reverted back to From the Department of Cardiothoracic Surgery, New England Medical Center Hospital and Tufts University School of Medicine, Boston, MA. Accepted for publication July 22, Address reprint requests to Dr. Amato, Tufts-New England Medical Center, 171 Harrison Ave., Boston, MA sinus rhythm after the permanent pacemaker had been implanted. Two patients who had developed atrioventricular block prior to 1974 were referred for pacemaker generator changes. Two additional patients required permanent pacing because of congenital heart block. The patients ranged in weight from 1.9 to 24 kg. Because of dissatisfaction with the cosmetic results in the first 9 patients, we have developed a technique for intermuscular implantation in the anterior abdominal wall. This procedure, which was used in the last 7 patients, is presented in this report. Technique The patient is placed in a supine position with the lateral abdominal wall elevated slightly by posterior padding. A transverse incision is made in the skin beginning in the midline slightly above the umbilicus and extending laterally to the costal arch (Fig 1). The incision is deepened to the fascia, and the subcutaneous tissue is separated from the fascia and retracted. A vertical incision is then made in the lateral border of the anterior rectus sheath approximately 6 to 8 cm in length depending on the size of the child and the pacemaker battery to be used. The anterior rectus sheath is separated from the rectus muscle for 1 cm along the entire length of the incision. This is done easily except for the areas of the tendinous inscriptions (Fig 2). The rectus muscle is elevated from the posterior rectus sheath, and care is taken to ligate and divide the neurovascular bundles which supply the rectus muscle from the lower ribs. The external oblique aponeurosis which forms part of the anterior rectus sheath is incised vertically for a distance of 6 to 8 cm and is reflected laterally away from the internal oblique muscle (Fig 3). The internal oblique aponeurosis is incised vertically for the same length and reflected laterally (Fig 4). The developed space, which is bounded anteriorly by the rectus and internal oblique by The Society of Thoracic Surgeons

2 244 The Annals of Thoracic Surgery Vol 25 No 3 March 1978 Fig I. A skin incision is made down to anterior muscle fascia. Dotted line shows the subcutaneously placed lead. Fig3. The external oblique fascia and muscle are dissected away from the rectus attachment. The rectus muscle is shown elevated from the posterior rectus sheath. Fig 2. The anterior rectus fascia has been dissected away from rectus muscle, and the rectus muscle is now being dissected from the posterior rectus sheath. Fig 4. Retraction of rectus muscle showing posterior rectus fascia, and retraction of external oblique muscle. lncision of the internal oblique muscle from the posterior fascia and transuersus muscle is shown. muscles, posteriorly by the posterior rectus sheath and transversalis muscle, medially by the linea alba, and laterally by the limits of the dissection, is adequate to accept even a large pacemaker battery (Fig 5). At the time of repair of a congenital heart lesion any child exhibiting a serious or prolonged intraoperative conduction disturbance has two separate epicardial electrodes implanted with the ends buried in the subcutaneous tissue of the abdominal wall. If dysrhythmias persist, one of the previously placed leads in the subcutaneous tissue is removed through the described skin incision by burrowing between the subcutaneous tissue and fascia. The lead is delivered into the area of the formed pocket and connected to the pacemaker battery (Fig 6). The pacemaker battery is then placed within the pocket so that the internal oblique muscle can be approximated to the rectus muscle without tension. These two structures are sutured in a continuous fashion using a nonabsorbable material

3 245 How to Do It: Amato et al: Permanent Pacemakers in Infants and Children ANT. RECTUS SHEATH POST. RECTUS SHEATH Fig 5. Retraction of rectus muscle medially and of internal and external oblique muscles laterally, showing posterior rectus fascia. Dashed circle demonstrates intended bed for pacemaker. The transverse muscle is seen at the bed of the incision. Inset shows a cross-sectional view of the pocket. TRANSVERSE RECTUS MUSCLE \ /... INTERNAL OBLIQUE M -yw?,aw# J Fig 6. Extraction of lead from subcutaneous tissue. Fig 7. The internal oblique muscle is sutured to the rectus muscle. (Fig 7). The external oblique muscle and aponeurosis are approximated to the anterior rectus sheath by using a continuous suture of nonabsorbable material. The subcutaneous tissue and skin are closed. Comment Postoperative management of a child or infant with dysrhythmias is difficult because of the technical problems involved in placement of pacemakers [l, 31. Because of the relatively large size of the pacemaker in relation to the size of the patient, the smaller fixed-rate units were used. The current trend is to use the demand type [l, 4, 51. We believe that the programmable extended-range pacemaker should be used whenever possible. Among our last 14 patients, we have been able to implant this type of unit+ in *Omnistanicor pacemakers, Cordis Corporation, Miami, FL.

4 246 The Annals of Thoracic Surgery Vol 25 No 3 March and to implant demand pacemakers with a rate of over 100 beats per minute* in 2. The earlier implants were either subcutaneous or retroperitoneal. The subcutaneous implants were unsightly. In spite of every effort to make large pockets, the scanty subcutaneous fat and exposed position of the unit always stretched the skin over the edges of the pacemaker, inviting necrosis or infection. Skin erosion and infections have been reported [7]. The retroperitoneal placement of these units provides a technical challenge when the battery pack needs replacement, and the possibility of migration and interference with retroperitoneal structures made this approach unacceptable to us. We have not used the intrapleural, subdiaphragmatic, or intrapelvic sites [4] because these all require invasion of major body cavities. These sites of implantation provide little possibility for fixation of the units and may produce interference with major organs contained therein. Generator packs in these positions are also difficult to program. The preperitoneal space, recently suggested [2], has not been utilized in children because we have seen downward migration of the battery unit from this space into the pelvis result from this technique. Various techniques *CPI minilith model 501, Cardiac Pacemakers Inc, St. Paul, MN. C-Mos I Interlith, Model 223, Intermedics Inc, Freeport, TX. Fig 8. Posteroanterior and lateral views ofa child who has had intramuscular placement of a large programmable pacemaker. involving the anterior abdominal wall for an implantation site have been described. However, the patients under discussion all have median sternotomy incisions with placement of mediastinal chest tubes. Consequently, the subrectus space between the xiphoid and umbilicus as suggested for use in adults and older children [9] cannot be utilized. The technique described for adult implantation utilizing the space beneath the external oblique muscle is too narrow to be used in children. [6]. Initially, we attempted to combine these techniques and develop a space beneath the rectus and external oblique muscles, but we found this to be inadequate. Recently, another procedure has been described that involves the subrectus space. This procedure involves dissecting the origin of the transversus muscle away from the transversalis fascia [8]. This maneuver is technically difficult and adds little if any space to the pocket area. Concerning our technique, it must be emphasized that the internal oblique muscle must be dissected free of the transversus muscle and from the external oblique as far laterally as possible. This final dissection is easily accomplished and provides adequate space to accommodate even a relatively large battery pack in the smallest infant. Our experience in exchanging a defective lead indicates that battery changes should be easy in this accessible position. Programming has also been performed without difficulty in the intermuscular space. The superior cosmetic result and more secure posi-

5 247 How to Do It: Amato et al: Permanent Pacemakers in Infants and Children tioning of the unit compared with subcutaneous 4. Lillehei CW, Sellers RD, Bonnabeau RC, et al: implantation are illustrated in Figure 8. Finally, Chronic Postsurgical complete heart block. J Thoracic Cardiovasc Surg 46:436, 1963 this technique has been without complication 5. Lindesmith GG, Stiles QR, Meyer BW, et al: Exand is much more to the perience with an implantable synchronous paceparent, child, and medical personnel. References 1. Benrey J, Gillette PC, Nasrallah AT, et al: Permanent pacemaker implantation in infants, children, and adolescents: long term follow-up. Circulation 53:245, Donahoo JS, Haller JA, Zonnebelt BS, et al: Permanent cardiac pacemakers in children: technical considerations. Ann Thorac Surg 22:584, Furman S, Young D: Cardiac pacing in children and adolescents. Am J Cardiol39:550, 1977 maker in children. Ann Thorac Surg 6:358, Mansour KA, Fleming WH, Hatcher CR: Initial experience with a sutureless screw-in electrode for cardiac pacing. Ann Thorac Surg 16:127, Marco JD, Codd JE, Barner HB, et al: Implantable pacemakers in children. Arch Surg 110:880, Salama FD: A suggested site for the implantation of myocardial pacemakers in infants and young children. Thorax 31:346, Williams GD, Campbell GS: Pacemaker installation in the pediatric patient: an improved technique. Surgery 46:412, 1969 Notice from the American Board of Thoracic Surgery The 1979 annual certifying examination of the Please address all communications to the Ameri- American Board of Thoracic Surgery (written can Board of Thoracic Surgery, E Seven and oral) will be held Mar 22-24, 1979, in Mile Rd, Detroit, MI Chicago, IL. Final date for filing application is Aug 1, 1978.