Reoperation for Aortic Coarctation

Transcription

1 COLLECTIVE REVIEW Reoperation for Aortic Coarctation Eric D. Foster, M.D. ABSTRACT Reoperation for aortic coarctation has become common because of several factors: (1) increased physician awareness that hypertensive cardiovascular disease continues to threaten the prognosis of the patient following coarctectomy and that investigation in some symptomatic individuals after coarctectomy will demonstrate a residual or recurrent coarctation, even many years after the primary repair; (2) the widespread application of stress testing, which can reveal marked arm-to-leg pressure gradients not observed at rest, to the routine postcoarctectomy follow-up examination; (3) improved noninvasive aortic evaluation techniques, such as ultrasound; and (4) higher salvage rates among infants undergoing urgent coarctation repairs and the recognition that these children subsequently are at high risk for recoarctation. A surgical decision-making process characterized by flexibility provides maximum patient safety; no single reoperation technique can be applied in all situations. Individual circumstances may dictate recoarctation repair by resection with end-to-end anastomosis, tube graft interposition, aortoplasty, or tube graft bypass. The need for a temporary aortic shunt or partial left atriofemoral bypass to maintain adequate distal aortic perfusion pressure during the repair means that these methods must be available at all reoperations. Diligent efforts to repair all hemodynamically significant residual and recurrent coarctations are necessary if the natural fate of premature death is to be avoided for patients with these lesions. Aortic coarctation was described in detail anatomically by Morgagni in 1760 [l]. Subsequent definition of the natural fate of patients with unrepaired coarctation reveals premature death at a mean age of 35 years [2]. Among the 304 necropsy cases in the combined series of Abbott [3] and Reinfenstein and colleagues [4], the four leading causes of death were heart failure (26%), bacterial endocarditis (25%), aortic rupture (21%), and intracranial hemorrhage (12%). The prognosis for the person with an aortic coarctation was dramatically improved by the surgical innovations of Crafoord and Nylin [5] and Gross [6], who successfully repaired this lesion in late 1944 and early 1945, respectively. Nevertheless, experience in the succeeding four decades has demonstrated that the long- From the Department of Surgery, Division of Cardiothoracic Surgery, Albany Medical College, ME 622, Albany, NY Presented in part at the Postgraduate Session of the Nineteenth Annual Meeting of The Society of Thoracic Surgeons, San Francisco, CA, Jan 16-19, term outlook after coarctation repair is not entirely benign. The risk of morbidity and mortality remains high in this patient population; complications and deaths are due primarily to associated cardiac lesions, infective endocarditis, persistent hypertension, and residual or recurrent coarctation [7]. In a report reflecting this prognosis, Olley [8] showed that for normal 1-year-old infants the projected death rate at the age of 20 years is 15 per 1,000, while for 1-year-old infants with coarctation who survive coarctectomy, the death rate at the age of 20 years is 51 per 1,000. Reoperation for aortic coarctation has become more common, largely because of the following factors: (1) increased physician recognition that hypertension may persist in patients following coarctation repair or may develop many years after operation, with subsequent diagnostic efforts defining a residual or recurrent coarctation; (2) appreciation that stress testing may unmask marked residual or recurrent coarctations that remain undetected on resting examinations; (3) improved noninvasive diagnostic methods, such as ultrasound techniques; and (4) higher salvage rates among infants who must undergo early coarctation repair because of heart failure unresponsive to medical therapy and the awareness that these patients are particularly prone to the later development of recurrent coarctation. Incidence The reported incidence of reoperation for residual or recurrent coarctation ranges widely from less than 5% to more than 50% [ This variability results primarily from differences among reports in definition of severe recoarctation, length of postoperative follow-up, and age of patients at initial repair. Representative incidence figures are provided in the study of Beekman and coworkers [14], who note that among 239 patients with repaired coarctations who were followed a mean of 7.2 years, the reoperation rate was 38% (16/42) for children whose initial repair occurred prior to 3 years of age but was only 1.5% (3/197) for patients whose coarctation was repaired after the age of 3 years. Etiology Residual Coarctation Residual coarctation exists if a pressure gradient of more than 10,mm Hg is present across the aortic repair site immediately after operation. The two most common causes of residual coarctation are a technically inadequate repair that limits the aortic lumen by 50% or more and hypoplasia of the aortic arch proximal to the repair site. The experimental work of Clatworthy and associates [15] has shown that marked obstruction occurs only when the aortic diameter is reduced by 50% or 81

2 82 The Annals of Thoracic Surgery Vol 38 No 1 July 1984 Fig 1. Aortic coarctation repair with residual obstruction seconda y to restoration of less than 50% of normal aortic caliber. Fig 2. Aortic coarctation repair with residual obstruction secondary to proximal aortic arch hypoplasia. more. Coarctation repairs that fail to meet the minimum structural standard of restoring intraluminal aortic size to more than half of normal caliber condemn patients to residual obstructive lesions (Fig 1). Aortic arch hypoplasia, most often located between the left common carotid and left subclavian arteries proximal to an aortic coarctation, can result in residual obstruction if ignored and if vascular repair is limited to only the isthmus lesion (Fig 2) [16]. Tubular hypoplasia of the aortic arch is common among infants with coarctations requiring operative management; Campbell and co-workers [ 111 reported a surgical series of neonates with coarctation and noted that 42% (21/50) had arch hypoplasia. Recurrent Coarctation Recurrent coarctation exists if a pressure gradient of more than 10 mm Hg across the aortic repair site develops over a period following operation. Suggested mechanisms in the pathogenesis of recurrent coarctation include failure of adequate anastornotic growth, active scarring with fibrosis and aortic narrowing at the repair site, thrombosis on the suture line, and retention in the vascular repair of abnormal tissue, possibly related to the ductus arteriosus, that can proliferate to narrow the aortic lumen. Failure of growth at the anastomosis is judged to be the primary cause of recurrent coarctation, although lim- itation of aortic lumen size by fibrotic scarring, or residual ductal tissue, or both may be involved in some instances. Moss and associates [17] established an important anatomical factor relating to age and the need for growth at the aortic repair site following coarctation procedures when they demonstrated angiographically that by the age of 3 years, the child's descending aorta has grown to 55% of its adult diameter. Provided the structural criteria established by Clatworthy and co-workers [15] are met, the requirement of continued aortic growth at the repair site appears less important if the coarctation repair is performed after the child is 3 years of age than before. Surgical technical factors cited as potentially influencing growth of the aortic anastomosis are type of suture material, suturing technique, and method of coarctation repair (e.g., resection with end-to-end anastomosis or angioplasty). The relationship between recurrent coarctation and type of suture material, or the suturing technique employed at the original repair site, or both factors has not been clearly defined. The current standard is to employ nonabsorbable suture for coarctation repair; the less reactive synthetic, monofilament materials are favored over silk, which can result in an excessive inflammatory reaction that narrows the anastomotic site. Theoretically, an interrupted suturing technique is preferable to a continuous one, particularly in end-to-end

3 83 Collective Review: Foster: Reoperation for Aortic Coarctation Fig 4. Coarctation repair by aortoplasty with prosthetic patch graft. Fig 3. Coarctation repair by resection with end-to-end anastomosis. anastomoses, as the single circumferential sutures must fix aortic lumen size. In fact, recurrent coarctations have been reported following an initial repair with all types of nonabsorbable sutures and suturing methods. In 1982, Myers and associates [18] reported on experiments in which synthetic absorbable sutures were used for vascular anastomoses in growing vessels in laboratory animals. The results appear promising for future clinical application in coarctation surgery. The type of coarctation repair used and its relationship to future aortic growth and recurrent stenosis have received considerable attention in young children, particularly infants. Coarctation resection with end-to-end anastomosis (Fig 3) is the most common method of primary repair in the medical literature, which reports a large number of patients followed postoperatively for many years. Resection is the standard against which other repair methods are judged. The angioplasty techniques-prosthetic patch graft (Fig 4) [ll, 19-22] and left subclavian artery flap (Fig 5) [23-25]-avoid circumferential aortic suture lines; in theory, possibilities for future vascular growth thereby are enhanced at the repair site. Both types of angioplasty have disadvantages. The patch graft employs prosthetic material, which may degenerate, lead to aneurysm formation, or become a site for infective endocarditis. The subclavian artery is sometimes too small to effect an adequate coarctation repair. Use of the subclavian artery sacrifices a major arch vessel, producing potential risk for subclavian steal syndrome and left arm ischemia. To avoid these vascular complications, Hvass and Binet [26] recommend reimplanting the distal segment of the subclavian artery in the left carotid artery, a maneuver that has not gained wide acceptance. Although now favored over end-toend anastomoses, particularly in children less than 1 year old, angioplasty techniques await the passage of sufficient postoperative follow-up time for documentation of their superiority in preventing recurrent coarctation. Diagnosis Residual or recurrent coarctation is suggested clinically by the presence of persistent hypertension; headaches; lower limb claudication, with diminished or absent femoral pulses; decreased exercise tolerance with dyspnea on exertion; and spontaneous episodes of intracranial or nasal bleeding. Hypertension is more indicative of severe recoarctation if the initial repair was performed at an early age than if it was done in later life. Idiopathic hypertension is often found following primary coarctation repair performed in older age groups. Expected normal values for blood pressure measurements in children by age and body build have been established [27, 281. The report by

4 84 The Annals of Thoracic Surgery Vol 38 No 1 July 1984 Fig 5. Coarctation repair by aortoplasty with left subclavian artery Pap graft. Nanton and Olley (291 on 190 children aged more than 1 year to 15 years old who were followed for a mean of 4.5 years after coarctectomy emphasizes that the earlier the age of operation, the better the reduction in blood pressure postoperatively. Nevertheless, these authors noted a 26% (49/190) incidence of persistent hypertension after operation. Residual or recurrent coarctation was found in 11% (20/190) and idiopathic hypertension in 15% (29/ 190) of their patients. In contrast, Maron and co-workers [30] reported that among 59 patients having coarctation repair at a mean age of 22 years, only 6.8% (4/59) had residual or recurrent coarctation on follow-up studies, while 31% (18/59) demonstrated idiopathic hypertension postoperatively. Establishing the clinical diagnosis of residual or recurrent coarctation is closely related to the extent and frequency of postoperative examinations of patients. Campbell and associates [ll] reported on a series of 38 newborns surviving coarctectomy performed prior to 6 weeks of age and followed for a mean of 4.25 years after operation; they found that only 5% (2/38) of the children demonstrated clinical evidence of residual or recurrent coarctation. Although these authors did not indicate the frequency of postoperative examinations of their patients, they did state that good pedal pulses were found in 95% (36/38) of them. Upper and lower extremity blood pressure measurements were recorded in 45% (17/38) of the children. In the 2 patients with clinical evidence of residual or recurrent coarctation, pressure gradients of 30 mm Hg and 52 mm Hg were found at catheterization. The child with the higher gradient underwent reoperation. The authors concluded that only 2.6% (1/38) of their patients required repeat repair. In contrast, Williams and colleagues [12] found that in their series of 118 patients surviving coarctation repair done prior to 1 year of age and followed a mean of 5 years after operation, 33% (39018) had clinical evidence of residual or recurrent coarctation. These authors had followed all of their patients postoperatively, examining each within 6 months of repair and every 1 to 2 years thereafter. All children had arm and leg blood pressure measurements with an oscillometer and an appropriatesized cuff. Recoarctation was defined clinically as being present when a higher blood pressure was found in the arm than the leg and the gradient was greater than 10 mm Hg. Reoperation was required in 10.2% (12/118) of their patients. The duration of postoperative follow-up time after coarctectomy contributes to the rate at which recoarctation is diagnosed clinically. While residual coarctation should be noted immediately after the initial repair, an extended period is required to monitor the patient for possible recurrent coarctation. Emphasizing this time factor, Beekman and associates [14] reported the average interval from initial repair to reoperation to be 7.4 f 1.0 years (range, 21 months to 17.5 years). Accurate measurement of gradients of arm-to-leg blood pressure, both at rest and under stress or exercise conditions, is now recognized as an integral part of the follow-up examination of patients with repaired coarctation [31, 321. Children with mild or no arm-leg pressure gradients at rest may be found under exercise conditions to have notable gradients (greater than 3.5 mm Hg). Waldman and associates [32], employing a noninvasive technique for simultaneous measurement of arm and leg blood pressures, noted that 82% (23/28) of their patients had no gradients at rest following coarctectomy; however, 39% (9/23) of those children without gradients at rest had demonstrable arm-leg pressure differences under stress conditions, including 2 patients in whom the gradient exceeded 35 mm Hg. As pointed out by James and Kaplan [33], a severe recoarctation can occasionally exist in the absence of an arm-leg pressure gradient. While noninvasive ultrasound can give an accurate structural assessment of the thoracic aorta, a repeat catheterization is recommended for any patient with symptoms or marked arm-leg pressure gradients following coarctectomy. Although arm-leg pressure measurements obtained during stress testing give a more accurate gradient value than that observed under the sedated conditions of catheterization, it is still essential to have angiographic demonstration of the coarctation site, aortic arch, and collateral vessels prior to reoperation.

5 85 Collective Review: Foster: Reoperation for Aortic Coarctation Fig 6. Coarctation repair by resection and interposition of a prosthetic tube graft. Fig 7. Coarctation repair by prosthetic tube graft bypass from the left subclavian artery to the descending thoracic aorta. Indications for Reoperation Any symptomatic patient found after coarctectomy to have an arm-leg pressure gradient greater than 35 mm Hg at rest or with exercise and whose recoarctation has been visualized angiographically should be considered a candidate for reoperation. Reoperative Methods General Considerations The operative techniques for repair of residual or recurrent coarctation include repeat resection of the coarctation and either direct end-to-end anastomosis (see Fig 3) or interposition of a tube graft to restore aortic continuity (Fig 6); aortoplasty utilizing either a subclavian artery flap (see Fig 5) or prosthetic patch graft (see Fig 4); and coarctation bypass with a prosthetic tube graft (Figs 7, 8). One method is not applicable in all situations; the surgeon must be flexible in selecting a technique designed to meet each patient s circumstances. Factors that need to enter into the surgeon s decision-making process regarding reoperation for coarctation are type of initial coarctation repair performed, length of aortic narrowing, degree of intrathoracic scarring encountered, collateral vessel status, and requirement for temporary aortic shunt or left heart bypass. A repeat end-to-end resection or prosthetic patch graft angioplasty can be performed, but this is obviously not the case with a left subclavian artery flap angioplasty. The surgeon should recognize, however, that if a subclavian artery flap angioplasty was initially performed and recoarctation occurs, an important source of collateral blood supply around the obstruction has been lost through the left internal mammary artery and scapular vessels, which no longer receive antegrade flow. Intraoperative preservation of remaining collateral sources is essential under these circumstances to maintain adequate distal aortic blood flow during recoarctation repair. If the primary repair involved a prosthetic patch graft angioplasty, or if the recoarctation is the result of a long length of aortic narrowing due to tubular hypoplasia in the arch and isthmus, it is unlikely that resection with end-to-end anastomosis can be accomplished. The scarred mediastinum usually prevents adequate mobilization to allow easy apposition of the ends of the two aortic segments. The aorta is often found to be friable at the recoarctation site; in many instances, histological examinations have revealed severe disruption of the lamina elastica with fibrous tissue thickening of the intima [12]. Surgeons who find themselves committed to re-

6 86 The Annals of Thoracic Surgery Vol 38 No 1 July 1984 Fig 8. Coarctation repair by prosthetic tube graft bypass from the ascending aorta to the descending thoracic aorta. section of the recoarctation segment should interpose a prosthetic tube graft to restore aortic continuity, rather than attempt to pull together the friable aorta for an end-to-end anastomosis under tension. The degree of intrathoracic scarring encountered at reoperation, particularly in the mediastinum around the initial repair site, varies widely and cannot be predicted prior to the surgical procedure. Surgeons planning on recoarctation repair by resection with either an end-toend anastomosis or tube graft interposition should abandon these plans if they find dense mediastinal scarring obscuring the aorta, collateral vessels, and surrounding vital structures. Instead, a repair method should be selected that does not require extensive aortic mobilization and control of collateral vessels, such as prosthetic patch graft angioplasty or tube graft bypass. An inflexible approach with persistent dissection into a scarred mediastinum can lead to uncontrollable hemorrhage from hidden collateral vessels or to injury of the left recurrent laryngeal and phrenic nerves. An appraisal of the collateral vessel status should be made preoperatively by careful analysis of the angiogram. Determination of the number, size, and location of collaterals, particularly in relation to the recoarctation site, should aid in selecting the repair method. Multiple large collateral vessels in close proximity to the recoarctation site would require identification and control in order to perform a repair by resection and end-to-end anastomosis; this might influence the surgeon to select an alternative technique, such as prosthetic patch graft angioplasty. Likewise, demonstration by catheterization that only a few small collaterals exist should influence the choice of a repair method that preserves these premium vessels and allows uninterrupted distal aortic perfusion, as would occur if prosthetic tube graft bypass were employed. The collateral vessel status, type of initial recoarctation repair, and need to utilize a temporary aortic shunt or partial left heart bypass during reoperation are all closely interrelated. A prime concern is avoidance of the dreaded operative complication of spinal cord ischemic injury, which may result in paraplegia, by maintaining adequate distal aortic pressure during recoarctation repair (341. A prolonged period of complete aortic crossclamping, or occlusion of collateral vessels, or both can produce spinal cord injury as a result of lack of blood perfusion. Based on laboratory and clinical experience, Laschinger and associates [35] have suggested that maintenance of distal aortic pressure greater than 70 mm Hg will preserve spinal cord blood flow, although neurological injury was not observed in their studies until distal aortic pressure was allowed to fall to less than 40 mm Hg. Coles and co-workers [36] have recommended serial measurement of somatosensory cortical evoked potentials generated by peripheral nerve stimulation during surgical procedures on the thoracic aorta as a means of monitoring 'long-tract neural conduction and guarding against spinal cord ischemic damage. If adequate distal perfusion (mean aortic pressure, greater than 50 mm Hg) cannot be maintained after aortic occlusion during performance of the recoarctation repair selected, a temporary shunt or partial left heart bypass should be instituted. An additional indication for utilization of a shunt or partial left heart bypass during recoarctation repair is the usefulness of these techniques in controlling and managing massive hemorrhage if this complication should occur during the operation. Substantial blood loss during recoarctation repairs can be anticipated. The blood conservation techniques described by Utley and associates [37] should be familiar to all surgeons performing these procedures, particularly methods to collect and reinfuse autologous blood from the operative field during operation and from the chest drains postoperatively. Operative Technique Each patient undergoing reoperation is ptepared by placement of right radial artery and right femoral artery catheters to allow simultaneous monitoring of pressures proximal and distal to the coarctation site. Two largebore venous catheters are placed to allow access for rapid drug infusion and blood transfusion as required.

7 87 Collective Review: Foster: Reoperation for Aortic Coarctation RIGHT RADIAL I RIGHT COMMOh FEMORAL ARTERY MONITOR LINE - 7- SWAN-GAN 2 CATHETER IN RIGHT JUGULAR ACCESS TO LEFT COMMON FEMORAL VESSELS FOLEY CATHETER Fig 9. Patient positioned on operating table with the appropriate hemodynamic monitoring catheters in place for recoarctation repair. One of these venous lines should be positioned to provide readings of central venous pressure. In older patients, a Swan-Ganz catheter inserted through the right internal jugular vein has been found helpful in providing additional hemodynamic monitoring and calculation of vascular resistance. These measurements allow more accurate manipulation of intraoperative hemodynamic status by drugs. Nearly all recoarctation patients are hypertensive, and some are extremely labile; therefore, the anesthesiologist must be prepared to induce anesthesia in a manner that avoids hypertensive crises. Throughout the operation, but particularly during aortic cross-clamp periods, the anesthesiologist will be required to control upper body pressures within a range that allows for adequate lower body perfusion by collateral flow. A urinary catheter is placed in all patients. Diuretics are administered prior to complete aortic occlusion, as it is known that kidneys in a state of diuresis are better able to withstand ischemic periods. Except in the most complex forms of recoarctation repair when more than one incision may be required, a standard left lateral thoracotomy is employed. The patient is placed on the operating table in a right lateral prone position with the left leg positioned for exposure to the left groin (Fig 9). Access for exposure of the left common femoral vessels is desirable if cannulation for partial left heart bypass should be required. Specific Methods of Reoperation Resection with end-to-end anastomosis (see Fig 3) is most applicable for recoarctation repair if the primary operation was also resection with end-to-end anastomosis; if an isolated short-segment coarctation exists with- out proximal arch hypoplasia; if little intrathoracic scarring is encountered, allowing easy aortic mobilization and identification of major mediastinal structures; and if the ends of the resected aorta can be reapproximated without tension and the need to sacrifice collateral vessels. If the distal mean aortic pressure cannot be maintained at a minimum of 50 mm Hg on complete aortic cross-clamping or following control of collateral vessels at the repair site required to perform the end-to-end anastomosis, a temporary shunt or partial left atriofemoral bypass should be employed to provide adequate perfusion. Repeat end-to-end anastomosis is usually impossible to achieve because of lack of aortic mobility if the primary repair involved a prosthetic patch graft angioplasty or if a long segment of aortic narrowing exists. Under these circumstances it is preferable to interpose a prosthetic tube graft to restore aortic continuity, rather than attempt to pull together the friable aorta for an endto-end anastomosis under tension (see Fig 6). In a combined series [12, 14, 161, resection with end-to-end anastomosis was possible as the technique of recoarctation repair in 35.1% (26/74) of patients, while resection with tube graft interposition was employed in 9.5% (7/74). Patch graft angioplasty is most applicable for recoarctation repair if the primary repair was aortoplasty or resection with end-to-end anastomosis; a long segment of aortic coarctation or arch hypoplasia exists; or dense scarring is encountered at the primary repair site, immobilizing the aorta and obscuring vital mediastinal structures. Advocates of aortoplasty emphasize that this repair technique requires minimal mediastinal dissection and control of collateral vessels, as the entire aortotomy site can usually be included within a single large vascular clamp [38]. Although distal aortic perfusion must be carefully monitored after clamp application to ensure a mean pressure higher than 50 mm Hg, a temporary shunt or partial left atriofemoral bypass is seldom needed during recoarctation repair by angioplasty, since this technique does not usually require sacrifice or temporary occlusion of large numbers of collateral vessels. A notable exception is the patient with tubular hypoplasia of the arch and isthmus (see Fig 2) in whom repair by a large aortoplasty necessitates temporary occlusion of antegrade flow through the left subclavian artery, thereby diminishing a major source of collateral flow. Prosthetic patch graft angioplasty (Fig 10) is a particularly flexible technique that allows aortic enlargement over a long distance, as dictated by the extent of coarctation or arch hypoplasia, without suture line tension. Despite its previously cited disadvantages, left subclavian artery flap angioplasty (see Fig 5) may be the ideal technique for recoarctation repair when the surgeon wishes to avoid extensive aortic mobilization within a scarred mediastinum and use of prosthetic material. Use of the living subclavian artery flap provides maximum potential for vascular growth at the repair site. In the three series mentioned earlier [12, 14, 161, an aortoplasty was employed for recoarctation repair in 35.1% (26/74) of the patients.

8 88 The Annals of Thoracic Surgery Vol 38 No 1 July 1984 Fig 10. Coarctation repair by an extended prosthetic patch graft angioplas ty. Recoarctation repair by prosthetic tube graft bypass [39, 401 is most applicable in patients with complex forms of coarctation involving long segments of aortic narrowing or arch hypoplasia, or with recoarctation associated with multiple aneurysmal collaterals buried in dense scar within the mediastinum, or when collaterals do not provide adequate distal aortic perfusion during vascular clamping and the surgeon does not wish to use a temporary aortic shunt or left heart bypass. Bypass grafting avoids potentially dangerous dissection and aortic clamping within a scarred mediastinum around the initial repair site. If a normal-caliber aortic arch and a large left subclavian artery are present, the tube graft is anastomosed end-to-side to the subclavian artery; distally the graft is joined end-to-side to the descending thoracic aorta beyond the coarctation (see Fig 7). If aortic arch hypoplasia coexists with complex recoarctation, the bypass tube graft is anastomosed end-to-side proximally to the ascending aorta (see Fig 8). Exposure of the ascending aorta is best obtained by extension of the left thoracotomy transversely across the sternum or through a separate midline vertical sternotomy incision. Among the patients reported in the combined series [12, 14, 161, 20.3% (15/74) underwent recoarctation repair utilizing the tube graft bypass technique. Immediate and Late Results of Reoperation The reports in the combined series [12, 14, 161 place operative mortality for repair of residual and recurrent coarctation between 5 and 10%. Uncontrollable hemorrhage is cited as the most frequent cause of operative death. Common operative complications are injury to the left recurrent laryngeal nerve, manifested by hoarseness; damage to the left phrenic nerve with left hemidiaphragm paralysis; chylothorax; and intrathoracic sepsis. Fortunately, spinal cord ischemic injury resulting in lower extremity paralysis is extremely rare; it was not noted in any of the three reports cited [12, 14, 161. Unfortunately, a high incidence of residual arm-leg blood pressure gradients has been noted on late followup examinations after recoarctation repair. Beekman and co-workers [14] noted that 35% (7/20) of their patients who survived operation for recurrent coarctation had detectable arm-leg pressure gradients as high as 20 mm Hg at rest. Castaneda and Norwood [16] found a 29.7% (11/37) incidence of residual gradients exceeding 40 mm Hg postoperatively. These reports emphasize the need for continued long-term observation of all patients following coarctation repair procedures with evaluation of residual arm-leg pressure gradients and upper body hypertension both at rest and with exercise. Only early detection of an aortic obstruction followed by prompt surgical repair can hope to alter the patient s natural fate of premature death due primarily to hypertensive cardiovascular disease. References 1. Morgagni JB: De sedibus et causis morborum. Epist 18, art 6, Campbell M: Natural history of coarctation of the aorta. Br Heart J 32:633, Abbott MD: Coarctation of the aorta of the adult type. Am Heart J 3:392, Reifenstein HG, Levine SA, Gross RE: Coarctation of the aorta: a review of 104 autopsied cases of the adult type 2 years of age or older. Am Heart J 33:146, Crafoord C, Nylin G: Congenital coarctation of the aorta and its surgical treatment. J Thorac Surg 14:347, Gross RE: Surgical correction for coarctation of the aorta. Surgery 18:673, Maron BJ: Coarctation of the aorta in the adult. In Roberts WC (ed): Congenital Heart Disease in Adults. Philadelphia, Davis, 1979, pp Olley PM: The late results of coarctectomy performed after one year of age. In Tucker BL, Lindesmith GC (eds): Congenital Heart Disease. New York, Grune & Stratton, 1979, pp Hartmann AF Jr, Goldring D, Hernandez A, et al: Recurrent coarctation of the aorta after successful repair in infancy. Am J Cardiol 25:405, Pennington DG, Liberthson RR, Jacobs M, et al: Critical review of experience with surgical repair of coarctation of the aorta. J Thorac Cardiovasc Surg 77:217, Campbell J, Delorenzi R, Brown J, et al: Improved results in newborns undergoing coarctation repair. Ann Thorac Surg 30:273, Williams WG, Shindo G, Trusler GA, et al: Results of repair

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