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abbruzzese2007 PEDIATRIC JOURNAL

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PEDIATRIC JOURNAL
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  Copyright © Italian Federation of Cardiology Unauthorized reproduction of this article is prohibited Aortic coarctation: an overview Pietro Angelo Abbruzzese and Enrico Aidala In severe aortic coarctation in the neonatal period, surgicalrepair is required soon after clinical stabilization. Electiverepairofisolatedaorticcoarctationisnowadaysindicatedat3–6months of life or at the time of diagnosis. At present,no single operation appears to have a clear superiority.However, during the first months of life, an extendedend-to-end anastomosis is considered the best option bymostauthors,eventhoughweightatoperationandanatomyof the aortic arch are also significant determinants of laterecoarctation. In cases of aortic arch hypoplasia, whichoccurs in up to 70% of neonatal and infant coarctations,especially when associated anomalies are present, surgeryseemsthe treatmentof choice. After3months ofage and inthe adult population, balloon angioplasty and stentplacement are considered a suitable option. Recently, weadopted a median sternotomy approach without theuse of extracorporeal circulation for the treatment of aorticcoarctation with a hypoplastic aortic arch. We treated11 patients with satisfactory results at an average follow-upof 40months.  J Cardiovasc Med   8:123–128  Q 2007 ItalianFederation of Cardiology. Journal of Cardiovascular Medicine  2007,  8 :123–128 Keywords: aortic coarctation, cardiac surgery Division of Cardiac Surgery, ‘Regina Margherita’ Children’s Hospital, Turin, ItalyCorrespondence to Dr Pietro Angelo Abbruzzese, Divisione di Cardiochirurgia,Ospedale Infantile ‘Regina Margherita’, Piazza Polonia 94, 10126 Torino, ItalyE-mail: pa.abbruzzese@virgilio.it Definition and incidence Aortic coarctation is a congenital narrowing of thedescending thoracic aorta, next to the patent ductusarteriosus (PDA), severe enough to create a pressuregradient. Although the degree of stenosis may vary con-siderably, continuity of the aortic wall is maintained.Aortic coarctation is defined as isolated or pure, if noconcomitant congenital heart disease other than PDA ispresent. The classical classification of adult (post-ductal)and infantile (pre-ductal) type of coarctation [1] is nolonger used, as aortic coarctation is always periductal.Aortic coarctation accounts for 6.5% of congenital heartdisease [2] and occurs as an isolated lesion in 82% of patients born with this anomaly, whereas a ventricularseptal defect is present in 11%. Other anomalies, namelyatrial septal defect, left-sided obstructive lesions, trans-position of the great arteries, double outlet right ventricleandcompleteatrioventricularseptaldefect,arepresentin7% [3]. Conversely, only 35% of patients presentingduring the first year of life have an isolated coarctation. Pathophysiology The pathophysiology of aortic coarctation mainlydepends on the degree of obstruction after ductal closure,on the degree of developed collateral circulation, and onthe presence of associated cardiac lesions [4].In favourable cases, an isolated aortic coarctation resultsin mild-to-moderate obstruction after complete ductalclosure at 7–10days of life. This leads to the classic‘adult’ type of aortic coarctation, with a shelf oppositethe ductus and a collateral flow that starts developingduring fetal life and continues thereafter, thus maskingthelesionthatmaybediscoveredonlyaftermanyyearsordecades, mainly for its sequelae. These are representedby hypertension, occurring in almost 90% of patientsin childhood [3], left ventricular hypertrophy and sub-sequent congestive heart failure, aortic rupture or intra-cranial aneurysmal lesions, usually developing after thethird decade [5].Clinically, a pressure gradient between the arms and legsis present with absent or diminished femoral pulses.Chest roentgenogram shows cardiomegaly and rib notch-ing never before 3years of age [6].In the severe forms of aortic coarctation, the neonate orinfant quickly becomes severely symptomatic. In the‘neonatal’ type, collateral circulation is absent or inade-quate as long as the ductus remains open, and pulmonaryhypertension is always present. When the ductus is open,systemic hypertension may be present, although seldomsevere,femoral pulses are quitenormal, and there may bedifferential cyanosis. During the first 2weeks of life,closure of the ductus arteriosus may severely alter thecirculatory system [7]. The lower body becomes severelyhypoperfused, and acidosis and renal failure suddenlyoccur; the left ventricle acutely fails and dilates becauseof afterload mismatch, as systemic resistance abruptlyincreases. Mitral regurgitation and left-to-right shuntacross the stretched foramen ovale, together with rightventriculardilatation,contributetomassivecardiomegalyuniformly seen at chest roentgenogram. Clinically, the Current perspective 1558-2027    2007 Italian Federation of Cardiology  Copyright © Italian Federation of Cardiology Unauthorized reproduction of this article is prohibited patient is moribund and resuscitation must be startedimmediately together with prostaglandin E1 infusion,which results in ductus reopening and lower body per-fusion with reversal of congestive heart failure. There-fore, heart failure in isolated aortic coarctation has abimodal distribution. It occurs in about 65% of infants,it is uncommon between 1 and 30years of age, and itdevelops again in about 65% of patients surviving morethan 40years [8].Conversely, when a ventricular septal defect is present,the  fi ndings at birth may be more subtle. Pulmonaryartery pressure remains elevated for a longer periodand the pressure gradient can be very low; furthermore,left-to-right intracardiac shunt increases oxygen satura-tion in the descending aorta, thus making differentialcyanosis very uncommon. During the  fi rst month of life,however, a decrease in pulmonary artery resistance andclosure of the ductus may result in lung  fl ooding andhypoperfusion of the lower body. In such a situation, leftventricular failure occurs, mainly as a consequence of volume overload [4].Finally, when aortic coarctation is associated with com-plex cardiac anomalies, severe heart failure developswithin the  fi rst 2weeks of life and treatment is moredemanding. These neonates almost constantly showhypoplasia of the aortic arch and isthmus related todisturbances in fetal blood  fl ow [9,10]. Considerations for treatment A decrease in the lumen diameter at the site of coarcta-tion greater than 50% and/or a pressure gradient at rest of more than 20mmHg are usually considered indicationsfor surgery or balloon angioplasty [4].Isolated coarctation in a symptomatic neonate is usuallytreated surgically with excellent immediate results. Themost commonly used surgical techniques are extendedend-to-end anastomosis, subclavian  fl ap aortoplasty andpatch aortoplasty,with recent series mostly preferring the fi rst one [11,12]. The reason for such preference is thatthe risk of late recoarctation supposedly decreases withthis procedure. However, weight at operation, when verylow birth-weight neonates are concerned, and aortic archanatomy are also signi fi cant determinants of late recoarc-tation [13].After 3months of age, balloon angioplasty is considered asuitable option in several centres, reporting recoarctationrates similar to surgical series [14 – 16].In case of aortic arch hypoplasia, which occurs in up to70% of neonatal and infant coarctations [17,18], parti-cularly when associated anomalies are present, surgeryseems a better option than balloon aortoplasty at any age[11]. According to anatomical studies, the normal sizes of the proximal, distal and isthmic segments of the aorticarch are 60%, 50% and 40% of the diameter of theascending aorta, respectively [9]; Karl  et al  . [19] de fi neas hypoplastic a transverse arch with a diameter of lessthan 1mm/kg plus 1.After 1year of age, systemic hypertension is observed inabout 90% of patients, and surgery is more demandingwith a higher bleeding risk due to the developmentof collateral  fl ow. The same techniques employed inneonates and infants may be used, even though subcla-vian  fl ap aortoplasty is not indicated in older childrensince ischaemic and hypoxic lesions of the left arm arelikely to occur.In adult patients, an end-to-end anastomosis may bedif  fi cult to perform because of the complex mobilizationof the aorta and the presence of large, frail collateralarteries. Therefore, in selected cases, patch aortoplastymay be considered as well as resection of the coarctedsegment with graft interposition [20,21]. Extreme col-lateralization or aneurysmal changes in the coarctationzone further complicate the procedure, thus justifyingunusual surgical procedures such as bypass grafting fromthe subclavian artery or the ascending aorta to the distaldescending aorta. However, surgical treatment of aorticcoarctation in adults is nowadays seldom indicated, sinceballoon angioplasty with stent positioning is consideredthe  fi rst-choice treatment in many centres [22,23].When associated intracardiac anomalies are present inneonates or infants, one-stage and two-stage repairs canbe performed. In the two-stage approach, aortic coarcta-tion is  fi rst repaired through a left thoracotomy, with orwithout associated pulmonary artery banding, and intra-cardiac repair is postponed; in the one-stage approach,aortic coarctation is repaired through a median sterno-tomy, usually with the aid of extracorporeal circulation(ECC) and circulatory arrest, immediately before intra-cardiac repair [24]. In recent years, at the  ‘ ReginaMargherita ’  Children ’ s Hospital of Turin, we haveadopted a median sternotomy approach without theuse of ECC for the treatment of aortic coarctation witha hypoplastic aortic arch. Timing of treatment The critically ill or moribund neonate must be stabilizedbefore coarctation repair. This can be achieved by start-ing prostaglandin E1 infusion [25] together with resusci-tation manoeuvres, as indicated.Elective repair of isolated aortic coarctation is nowadaysindicated at 3 – 6months of life or at the time of diagnosis.In fact, ductal remodelling is complete at this age, thusdecreasing the risk of recoarctation, whereas long-termsurvival and late normotensive state are not differentfromneonatalrepair[26].Nonetheless,itshouldbenoted 124  Journal of Cardiovascular Medicine  2007, Vol 8 No 2  Copyright © Italian Federation of Cardiology Unauthorized reproduction of this article is prohibited that late systemic hypertension is a poorly understoodphenomenon, and abnormalities of the peripheral vas-cular tone, of the left ventricular kinesis and of baro-receptor sensitivity are implicated, regardless of residualobstruction [27,28]. Surgical and interventional techniques Advantages and disadvantages among the different tech-niques should becompared in terms of mortality, recoarc-tation and complications such as aneurysm, paraplegia,chylothorax, nerve injury, left arm dysfunction, andbleeding. At present, no single operation appears to havea clear superiority. Since the introduction of prostaglan-dins, mortality following coarctation repair has becomevery low and not signi fi cantly different among the differ-ent techniques; furthermore, technique-related compli-cations are rare and comparable, except for aneurysmfollowing patch aortoplasty and arm discomfort followingsubclavian  fl ap aortoplasty. Moreover, no de fi nitive dataconcerning the incidence of recoarctation with each tech-nique are available, as a result of different criteria, agegroupsandfollow-upperiods[4,29,30],oftenmakingselec-tion of the appropriate technique an institutional choice.During the  fi rst months of life, an extended end-to-endanastomosisisconsidered thebestoptionbymostauthors[13,31], and good results have been reported even whenhypoplasia of the distal arch is present [11]. In olderinfants, extended end-to-end anastomosis and subclavian fl ap aortoplasty are both widely used. Patch aortoplastyand other techniques are used in selected cases.Percutaneous angioplasty is considered in some centresthe  fi rst-choice procedure even in neonatal coarctation,but doubts exist as satisfactory results occur only inapproximately half of the cases [14,32]. Conversely,excellent results are obtained with percutaneous tech-niques in case of recoarctation.Stent positioning in grown-up patients leads to excellentresults [23], and new types of stents will further increaseindications for these procedures. Patch aortoplasty Patch aortoplasty was widely used in the past, because itrequires minimal dissection and a very short clamp time.Nowadays, its indications are greatly diminished mainlyfor the documented high risk of aneurysm formationopposite the patch [33,34]. It can still be very useful incases of discrete recoarctation not improved by balloonangioplasty, in cases of long, narrow aortic segments, andthe rare moribund neonates unresponsive to prostaglan-din E1 infusion [4].Technically, it must be kept in mind that adequate patchsizing is critical: an excessive width with consequentballooning may lead to late aneurysm formation on theopposite aortic wall [35,36] and, conversely, patch widthshould exceed three times the increase in diameter thatone wants to obtain in the coarctation area. Subclavian  fl ap aortoplasty Advantages of subclavian patch aortoplasty include theuse of autologous tissue, avoidance of a circumferentialsuture, limited dissection and low tension on the anasto-mosis. Some disadvantages have been described as well:the main blood source to the left arm is interrupted,possibly leading to discomfort and growth retardation of the arm [37]; ductal tissue is usually left in place, possiblyfavouring recoarctation; and aortic arch hypoplasia cannotbe treated. When aortic arch hypoplasia is present, how-ever, a  ‘ reverse ’  subclavian  fl ap technique may be used toaugment the aortic arch between the left carotid and theleft subclavian arteries and an extended end-to-endanastomosis may be associated to treat the coarctationitself  [38,39]. Finally, some authors [40] advocate this technique (or patch aortoplasty) in patients with border-line left ventricular function, should a PDA be desirable. Extended end-to-end anastomosis This technique has replaced the simple end-to-endanastomosis as it provides an ample suture line andenlarges the distal aortic arch [11,41]. Proximal extensionof the anastomoses in the concavity of the aortic archalong with complete resection of the abnormal coarcta-tion tissue are considered essential steps for the preven-tion of recoarctation by the supporters of this technique.Technically, extensive dissection of the aortic arch anddescending aorta are required to obtain a tension-freeanastomosis. Division of the  fi rst intercostal branches isoften necessary; however, the great elasticity of neonatalaorta certainly makes this procedure easier in the young-est age groups. Median sternotomy and end-to-side anastomosis Aortic coarctation with severe hypoplasia of the entireaortic arch represents a formidable surgical challenge,since adequate positioning of the proximal aortic clamp isoften unachievable via left thoracotomy, and residualstenosis at the site of anastomosis frequently occurs.Conversely, a median sternotomy has been extensivelyused for one-stage correction of aortic coarctation withassociated intracardiac anomalies; however, ECC with orwithout circulatory arrest has been uniformly employedin such cases [12].At the  ‘ Regina Margherita ’  Children ’ s Hospital of Turin,we have used a median sternotomy approach without theuse of ECC for treatment ofaorticcoarctationwith severehypoplasia of the entire aortic arch. More recently, thesame technique has been adopted for one-stage repairof associated anomalies in order to decrease ECC time.Technically, we perform an end-to-side anastomosisbetween the descending aorta and the ascending aorta Aortic coarctation  Abbruzzese and Aidala 125  Copyright © Italian Federation of Cardiology Unauthorized reproduction of this article is prohibited uptotheoriginoftheaortic arch.Adequatepositioningof the proximal aortic clamp without impairment of theforward aortic  fl ow is simpler; extensive dissection of the arch, neck vessels, descending aorta and ductusarteriosus is necessary to perform a tensionless suture,which can be performed without the use of ECC (Fig. 1).Attention should be paid to the recurrent laryngeal nerveduring dissection, as well as to potential haemodynamicimpairment due to manipulation of the heart and PDA.After completionofdissection,simplestitchesareusedtoclose the aortic isthmus and the ductus, clamps areapplied and the PDA and coarctation areas are resected.An incision is made on the posterior segment of the distalascending aorta with extension to the srcin of the arch.The stump of the descending aorta is tailored and ana-stomosed to the proximal incision using a continuousreabsorbable mono fi lament suture.Eleven patients were operated on using this technique.Demographic data, and anatomic details and results aresummarized in Table 1. One early death occurred in a1.7kg neonate with a hypoplastic left ventricle, and onelate death occurred among  fi ve subsequent correctiveprocedures. Comment Adult aortic coarctation has become a rare  fi nding in thewestern world. Prenatal and postnatal echocardiographicdiagnosis [42], along with increased awareness of thedeleterious effects of long-standing aortic coarctation,contributes to a prompt treatment of this lethal disease.Nowadays, neonatal and infant surgery is the rule [11 – 13,31], whereas rare, late diagnoses are usually followedby angioplasty and stenting with excellent results [22,23].This avoids complications such as bleeding and paraple-gia, which were frequently associated with surgery inadult patients.Occasional indications for surgery, however, still occur inadults and excellent mastering of the different options istherefore needed [21]. Customizing the operation isnecessary to minimize risks and optimize results: incertain cases, patch aortoplasty or a tube graft interposi-tion may be more appropriate choices than the riskierend-to-end anastomosis. Surgery is still the primaryoption in neonatal and infant coarctation, whereas inter-ventionaltechniquesare reserved to older children and tocases of recoarctation in most centres [15,22].Isolated aortic coarctation is nowadays preferentiallytreated by extended end-to-end anastomosis; the sameholds true for aortic coarctation associated with hypo-plasia of the distal aortic arch. Satisfactory short- andlong-term results are obtained with this technique[11,13,31,38], as the long elliptical anastomosis prevents 126  Journal of Cardiovascular Medicine  2007, Vol 8 No 2 Fig. 1 Dissection has been completed, the stump of the patent ductusarteriosus is retracted, and clamps are applied to perform theanastomosis. Table 1  Repair of aortic coarctation associated with hypoplastic aortic arch via median sternotomy without cardiopulmonary bypass (forassociated procedures, cardiopulmonary bypass was utilized after coarctation repair) Patient Age (days) Weight (kg) Associated malformation Associated procedure Follow-up (months) NYHA class Gradient (mmHg)LF 18 3 VSD VSD closure 76 I 0FE 12 3 MA PAB 73 II 0SD 21 1.7 MA PAB, atrial septectomy Early death  – – RV 6 2.5 VSD PAB 70 II 19DG 4 2.5  – –  63 I 0CA 43 2.7 VSD VSD closure 54 I 0BE 560 5.7 PA stenosis PA patch 29 I 0CL 17 3.4 DORV PAB 6 Late death  – AN 9 3  – –  11 I 26LA 17 3 VSD PAB 9 II 35CT 14 3 TGA, VSD PAB 7 I 17NYHA, New York Heart Association; VSD, ventricular septal defect; MA, mitral atresia; PAB, pulmonary artery banding; PA, pulmonary artery; DORV, double outlet rightventricle; TGA, transposition of the great arteries.
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