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Ann Thorac Surg 2002;74:1612-1615
© 2002 The Society of Thoracic Surgeons
a Cardiothoracic Centre, All India Institute of Medical Sciences, New Delhi, India
Accepted for publication June 7, 2002.
* Address reprint requests to Dr Sharma, B-404 Adarsh Palace, Block-5, Jaya Nagar, Bangalore, India.
e-mail: rsharmacvs{at}hotmail.com
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Abstract |
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 Top Abstract IntroductionPatients and methodsResultsCommentReferences |
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Methods. Ten infants with D-transposition of the great arteries with essentially intact interventricular septum and severe pulmonary arterial hypertension underwent surgical treatment. Age ranged from 3 to 6 months (mean, 4.2 months). One of these patients had a large ductus with left to right shunting but the others had no intra- or extracardiac shunt to account for their pulmonary hypertension. All 10 had "prepared" left ventricles. The first 4 children underwent an arterial switch operation. Uneventful surgery was followed by prolonged ventilator dependence in all 4 with occurrence of severe pulmonary arterial hypertension every time weaning from ventilator was attempted. This was accompanied by metabolic acidosis and features of right heart failure. Only 1 patient with large ductus could be extubated and discharged from hospital. Subsequently, the other 6 infants underwent a Senning repair.
Results. There was no early mortality. All patients were separated from mechanical ventilation within 48 hours of surgery without blood gas derangement or heart failure despite elevated pulmonary artery pressure in all. The child with the arterial switch operation has pulmonary artery pressure of 50% systemic 4 years following repair; although among the Senning group, 2 patients continue to have pulmonary artery pressure more than 60% of systemic and 4 have normal pulmonary artery pressure at a mean follow-up of 1 year.
Conclusions. Atrial level repairs seem to perform better than arterial level repairs in children having TGA with persistent pulmonary artery hypertension without a correctable cause. Better tolerance of pulmonary arterial hypertension in this group is probably consequent to the superior ability of the left ventricle to tolerate a pressure load in the early postoperative period.
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Introduction |
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TopAbstractIntroductionPatients and methodsResultsCommentReferences |
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Patients and methods |
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TopAbstractIntroductionPatients and methodsResultsCommentReferences |
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All patients underwent cardiac catheterization and cineangiography. Pulmonary vascular resistance was not calculated because of its unreliability in transposition complexes. Left ventricular mass (indexed to body surface area) and posterior wall thickness was calculated echocardiographically by methods described in an earlier study [6]. Besides numerical values of these measurements to assess left ventricular preparedness, we relied significantly on the visual appearance of the left ventricle and the interventricular septum on the cross-sectional echocardiogram. In cross-sectional view, circular left ventricle with the interventricular septum convex towards the right ventricle, was considered favorable. The preoperative profile of these patients is summarized in the Table 1.
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The Senning operation was performed utilizing deep or moderate hypothermia using direct caval cannulation by the technique described by Quaegebeur and coworkers [8]. A pulmonary artery line was placed in all of these patients. A tiny VSD (2 mm) was left open in 2 of these patients.
Postoperative care
All patients were kept paralyzed and sedated until they were judged to have good cardiac output clinically. They were then allowed to awaken with continuous PAP monitoring. Weaning from the ventilator was commenced once arterial oxygenation was good and third space fluid had been mobilized. PAH crises were treated by sedation and hyperventilation with 100% oxygen. Nitric oxide was not utilized in any of these patients due to nonavailability in this time period.
Follow-Up
Clinical condition of the patients was noted. Ventricular function and status of the atrioventricular valves was obtained by echocardiography, performed at 1 month, 3 months, and 6 months after hospital discharge, and then every 6 months thereafter. All survivors underwent cardiac catheterization after an interval ranging from 6 months to 4 years.
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Results |
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Senning group (n = 6)
All 6 patients had uneventful repair and weaning from cardiopulmonary bypass. Here, as in the prior group, PAP ranged from 30% to 100% of the systemic arterial pressure and had a tendency to rise whenever ventilatory weaning was attempted. Bronchospasm also developed along with elevation of the PAP. There was, however, no metabolic acidosis or features of right heart failure. There was no echocardiographic aggravation of pulmonary valvular regurgitation at different levels of PAP as opposed to the ASO group. All 6 could be extubated, despite CO2 retention, with some sedation to combat the agitation that accompanied spontaneous ventilation. All 6 patients could be discharged from the hospital.
Follow-Up
In the single survivor following the arterial switch operation, the PAP had dropped to 50% of the systemic arterial pressure at 4 years after surgery. Of the patients who survived following atrial level repair, 4 had normal PAP, whereas 2 had 60% systemic level PAP at a mean follow-up of 1 year.
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Comment |
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TopAbstractIntroductionPatients and methodsResultsCommentReferences |
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In all of the 10 patients included in this study varying degree of difficulty was encountered in separating the patients from mechanical ventilation. Common to these was persistently elevated PAP that had a tendency to rise to systemic level whenever the effort of spontaneous respiration was sought to be enrolled. Respiratory insufficiency was evidenced in all children by way of different magnitudes of elevation of carbon dioxide in the blood gas reports. The differentiating feature between the two groups was the absence of features of cardiac compromise in the children who had undergone the Senning procedure. We postulate this to be primarily because of the superiority of the left ventricle in the pulmonary position. Another factor of importance may be unaltered pulmonary valve function following a Senning rather than an arterial level repair. Some neopulmonary incompetence is anticipated in all arterial switch operations with persistent PAH and would necessarily worsen right-sided hemodynamics.
The right ventricle (RV) is well known to misbehave in the face of increased afterload, while the LV is known to function well in the presence of pressure load. Extending this corollary to repaired D-TGA with an RV versus an LV as the pulmonary ventricle, it seems logical that residual PAH would be better tolerated by the morphologic LV.
The paradox of incriminating a ventricle that is capable of supporting the systemic circulation for a lifetime in most patients [9], for failure to withstand the pulmonary afterload is glaring. PAP in most of the instances here was subsystemic and only intermittently systemic. To explain this paradox it may be assumed that intermittent drops in PAP may render the RV less effective to face a systemic level elevation when it does occur. The damaging effects of myocardial anoxia sustained during aortic clamping at the time of repair can also be invoked except that the same right ventricle tolerates systemic afterload much better than pulmonary afterload following repair.
Successful arterial level repair has been reported in literature for neonates with TGA IVS and persistent pulmonary hypertension. Invariably, the postoperative course has been extremely stormy and management involved the use of inhaled nitric oxide and even extracorporeal membrane oxygenation at times [10, 11]. The single denominator for the successful outcome has been the subsidence of PAH in these patients all of who were neonates in the postoperative period. Our patients were well beyond the neonatal period and although all were still in infancy, no early subsidence of PAH could be expected except in the child with the large PDA and left to right shunt.
Given the extremely poor early results of the ASO in the subgroup of patients with systemic level PAH, we propose that the procedure of choice for patients of TGA who are likely to have important PAH in the period following repair is an atrial level switch. We are loath to label these atrial level repairs in all patients in the category of simple TGA with PAH as "palliative" [12–14] for the reason that postoperative PAP elevations may not be to systemic level and the possibility of regression to normal level still remains a definite possibility especially in the younger patients. In our experience, normalization of PAP has taken place in 4 of the survivors following atrial level repair. In those patients where the procedure is likely to be palliative in view of advanced age or severely elevated PAP, creation of a VSD [13] does not seem to be necessary based on our experience of complete freedom from right-sided failure with the LV as pulmonary ventricle. This we attribute to the LV being perfectly adapted to the situation and not manifesting any failure even in the face of severe PAH, thus obviating the need for decompression.
The downside of having a systemic RV obviously detracts from the ideal situation of a systemic LV. Failure of the RV to function in the systemic circulation in the long run is one of the drawbacks of atrial level repair of TGA [9]. Revision surgery for systemic ventricular failure [15, 16] can still be contemplated if PAP normalizes in those patients where it is strongly indicated.
The need to make this compromise of shifting from arterial switch as the strategy for all TGA with severe PAH would not arise if effective treatment of PAH existed. The much heralded advent of inhaled nitric oxide (iNO) has sadly, in our and in other’s experience, not met with any benefit to the late presenters of congenital heart disease with severe PAH [17]. Postoperative management of residual PAH is, therefore, fraught with the possibility of RV failure in response to either sustained or episodic elevation of PAP. In this situation, where effective predictable treatment of PAH is not existent, it behooves us to devise surgical strategies that provide the patient with congenital heart disease with PAH, who presents late, with a better chance of survival than that exist with accepted methodologies, until better methods of medical management of PAH become available. The shift from arterial switch to atrial level repairs for patients of simple TGA with severe PAH would be one such step.
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This article has been cited by other articles:
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  R K Kumar and S Shrivastava Paediatric heart care in India Heart, August 1, 2008; 94(8): 984 - 990. [Abstract] [Full Text] [PDF]
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 A. Dodge-Khatami, A. Kadner, F. Berger, H. Dave, M. I. Turina, and R. Pretre In the Footsteps of Senning: Lessons Learned From Atrial Repair of Transposition of the Great Arteries Ann. Thorac. Surg., April 1, 2005; 79(4): 1433 - 1444. [Abstract] [Full Text] [PDF]
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