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Ann Thorac Surg 2000;70:100-105
© 2000 The Society of Thoracic Surgeons

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Original articles: Cardiovascular

Results of the double switch operation in the current era

^a Department of Pediatric and Congenital Heart Surgery and Cardiology, The Cleveland Clinic Foundation, Cleveland, Ohio, USA

Address reprint requests to Dr Mee, Department of Pediatric and Congenital Heart Surgery, M41 Cleveland Clinic Foundation, 9500 Euclid Ave, Cleveland, OH 44195-5066
e-mail: meer{at}ccf.org

	Abstract

Top Abstract Introduction Patients and methods Results Comment References

 
Background. In patients with atrioventricular and arterioventricular discordance congenitally corrected transposition, the morphologically right ventricle may progressively deteriorate while functioning in the systemic circuit. The double switch operation has been proposed to limit this functional deterioration.

Methods. From October 1993 to August 1998, the records of 27 patients with congenitally corrected transposition were reviewed. Age at operation ranged from 3 months to 55 years. Associated defects included ventricular septal defects in 18, pulmonary atresia in 7, and pulmonary stenosis in 11 patients. Twenty-two patients had double switch operations (10 arterial switch plus Senning procedures and 12 Rastelli plus Senning procedures). Five patients were not candidates for the double switch. Before the double switch, 6 patients required pulmonary artery banding and 10 had functioning systemic to pulmonary artery or cavopulmonary shunts.

Results. There was no early or late mortality. Two patients required pacemaker implantation, both later regained normal sinus rhythm. Tricuspid valve function improved in all patients except one. Moderate left ventricular dysfunction developed 5 months postoperatively in 1 patient.

Conclusions. The double switch operation can be performed in selected patients with minimal early morbidity and mortality. Longer follow-up is necessary to determine whether this complex approach is indeed warranted.

	Introduction

Top Abstract Introduction Patients and methods Results Comment References

 
Congenitally corrected transposition (ccTGA) is defined as atrioventricular (AV) and ventriculoarterial (VA) discordance. However, in many VA discordant hearts associated with a ventricular septal defect (VSD), the pulmonary artery significantly overrides the right ventricle; therefore, the VA relationship is similar to that of a double-outlet right ventricle.

Patients with AV discordance usually have an associated cardiac abnormality such as a VSD, pulmonary stenosis (PS), or pulmonary atresia (PA), and varying degrees of Ebstein’s malformation of the tricuspid valve (TV), malposition of the cardiac apex, and conduction defects [1–3]. The clinical presentation of ccTGA is dependent on the associated cardiac defects and their cumulative effect on pulmonary blood flow. Indication for operation is also determined by the nature and degree of the associated cardiac defects.

Conventional or "classic repair" for ccTGA connects the morphologically right ventricle (mRV) to the aorta by closing the VSD, relief of pulmonary outflow tract obstruction, and repair of the tricuspid valve [4–10]. The mRV and TV are thus in the systemic circulation. At follow-up, the mRV has shown a significant incidence of progressive dysfunction and TV regurgitation, especially if an Ebstein’s TV malformation exists.

The results of the classic repair for ccTGA have been disappointing [4–6], and a number of investigators have proposed the double switch operation as an alternative. The morphologically left ventricle (mLV) is placed into the systemic circuit by an atrial level switch plus an arterial switch (ASO) or a Rastelli operation [10–17].

Our experience with ccTGA and the double switch operation is presented.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment References

 
From October 1993 to August 1998, 27 consecutive patients with ccTGA were entered into a double switch program at the Cleveland Clinic Foundation. Age at operation ranged from 3 months to 55 years. Weight ranged between 3.4 and 84 kg. All patients had AV discordance and 23 had VA discordance. Four patients had a double-outlet right ventricle-type VA connection; 25 were situs solitus and 2 were situs inversus; 5 had situs solitus and dextrocardia and 1 had situs inversus and levocardia; 3 had bilateral superior vena cavae and 1 had an interrupted inferior vena cava with azygous continuation (no isomerism of the atrial appendages were noted). Twenty-three patients had VSD, 7 had PA, and 11 patients had PS. Varying degrees of Ebstein’s malformation of the tricuspid valve were present in 15 patients. One patient had partial anomalous pulmonary venous drainage, and one criss-cross heart arrangement was found.

Before the double switch, 6 patients required pulmonary artery banding; 5 patients were banded to precondition the mLV and one was banded to control congestive heart failure. One patient developed biventricular dysfunction after banding, requiring loosening of the band. A total of 16 systemic-to-pulmonary artery shunting procedures were performed in 10 patients. One patient had a bidirectional cavopulmonary shunt and another had a hemi-Fontan operation at another institution.

All patients underwent preoperative echocardiography. Nineteen patients had cardiac catheterization to assess mLV function, pressures, as well as pulmonary vascular resistance and to delineate anatomy. Magnetic resonance imaging studies were done in 4 patients to evaluate anatomy, and indexed left ventricular mass and function [18]. The requirements for an ASO plus Senning procedure are that there is no more than moderate anatomic pulmonary outflow tract obstruction or valvular PS and that the systolic mLV pressure is more than 70% of the systolic systemic pressure. Mild PS or dynamic PS does not preclude ASO with Senning operation, in fact it may prove to be advantageous in that the mLV is preconditioned by this obstruction. In our group of patients before an ASO plus Senning, the mLV systolic pressure/mRV systolic pressure ratio was 96% ± 20%. In this double switch series, 14 patients had anatomic PS or PA. In these 14 patients, 8 had atrial situs and ventricular apex discordance (situs solitus with dextrocardia or situs inversus with levocardia). The remaining 8 patients did not have anatomic PS or PA; no patient had atrial situs and ventricular apex discordance (p < 0.05).

The requirement for a Rastelli operation plus Senning procedure is that there are two usable ventricles, and good-sized branch pulmonary arteries with a low pulmonary vascular resistance.

Five patients were unsuitable for the double switch (Table 1). In 2, the ascending aorta was too far to the left side and the left ventricle could not be channeled to the aorta through the VSD. In patient 5, the original diagnosis was ccTGA with a large perimembranous VSD, mild PS, and an Ebstein’s abnormality of the tricuspid valve. This patient was referred to us at 13 years of age. The VSD was occluded by the septal leaflet of the TV. Severe TV regurgitation and moderate-to-severe systemic mRV dysfunction was present. The mLV systolic pressure was estimated at 30% of systolic systemic pressure. We planned to precondition the mLV by pulmonary artery banding. After three bandings, the mLV systolic pressure was increased to 65% of systemic. However, 6 months after the third pulmonary artery banding, moderate-to-severe mLV dysfunction developed. While loosening the pulmonary artery band, intraoperative transesophageal echocardiography documented a dramatic increase in the mRV dimensions with severe tricuspid valve regurgitation as a result of a left-to-right shunt through the previously occluded VSD. This patient had the VSD closed through the right atrium, loosening of the pulmonary artery band, and a tricuspid valve annuloplasty. Five months postoperatively this patient has moderate biventricular dysfunction, moderate tricuspid regurgitation, and is in New York Heart Association functional class II.

Senning and arterial switch operation
For the Senning procedure, the technique is as previously described [19]. With discordance of the atrial situs and position of the cardiac apex, the Shumacker modification is used to complete the pulmonary venous atrium [20]. The pulmonary venous atrial vent is left in situ until the ASO is completed. The ASO technique and method of coronary artery transfer have been previously described [21]. If a VSD is present, it is closed through the right atrium using the technique described by de Leval and colleagues [7]. If there is discordance of the atrial situs and position of the cardiac apex, the VSD is closed through the left atrium.

Senning and Rastelli operation
The Senning procedure is performed first. The mRV is opened as far from the midline as possible (to enable safe future conduit changes). The VSD is closed through the mRV incision. The conduit (our preference is a woven Dacron tube graft with a porcine valve) is placed on a beating heart. In 2 patients, 1 hemi-Fontan and 1 with a bidirectional cavopulmonary shunt, the venous shunts were taken down and caval connections reestablished. For all patients, a pulmonary venous pressure line was inserted.

Cardiopulmonary bypass times ranged between 137 and 342 minutes, and aortic cross-clamp times between 66 and 149 minutes (Table 2). Additional surgical procedures are presented in Tables 3 and 4.

	Results

Top Abstract Introduction Patients and methods Results Comment References

 
There was no early or late mortality. Follow-up ranged from 1 to 58 months (mean, 27.8 ± 16.2 months). After the double switch, the intensive care unit stay ranged from 3 to 14 days (mean, 5.7 ± 3 days), mechanical ventilation was required for 2 to 8 days (mean, 3.4 ± 1.8 days), and hospital stay was 6 to 19 days (mean, 9.7 ± 3.6 days).

The comparison of patient profiles between ASO plus Senning and a Rastelli plus Senning is shown in Table 2. Patients who underwent an ASO plus Senning were slightly younger. Patients who underwent an ASO plus Senning also had a higher incidence of Ebstein’s tricuspid valve malformations with more than moderate tricuspid valve regurgitation (p < 0.05). No significant difference in cardiopulmonary bypass and aortic cross-clamp times between ASO and Rastelli was noted.

The degree of TV regurgitation before and after double switch operation is shown in Figure 1. Mean degree of TV regurgitation was significantly decreased from 1.5 ± 1.4 to 0.6 ± 0.9 after double switch operation (p < 0.05). Moderate TV regurgitation developed in 1 patient (patient 20) after a Rastelli plus Senning, caused by the VSD closure. Moderately severe mitral valve regurgitation developed in another patient (patient 15) after separating from cardiopulmonary bypass. Transesophageal echocardiography showed the mechanism to be poor leaflet coaptation due to shifting of the interventricular septum. This was corrected by revision of the Senning suture line and a mitral commissural annuloplasty suture.

View larger version (18K): [in this window] [in a new window]   Fig 1. Degree of tricuspid valve regurgitation (TR) before and after double switch operation in 17 patients.

	Comment

Top Abstract Introduction Patients and methods Results Comment References

 
Congenitally corrected transposition is uncommon, comprising less than 1% of all congenitally malformed hearts [22]. There are several case reports describing 50- to 80-year-old survivors with ccTGA and no associated cardiac lesions [23, 24]. In ccTGA the clinical presentation and natural history are variable, and dependent on the associated cardiac defects. Most patients with ccTGA will have an associated cardiac defect: 80% of patients have a VSD, 50% of patients will have varying degrees of pulmonary outflow tract obstruction, and 90% have a variable degree of Ebstein’s malformation of the TV [1–3]. Forty percent of patients develop complete heart block over a 20-year period [23].

The mRV functions as a systemic ventricle after an atrial level switch operation (Senning or Mustard procedure), or a modified Fontan operation for a mRV variant single ventricle. The natural history of the mRV functioning in the systemic circuit after these operations is unknown. Turina and colleagues [24] reported that 12% of patients with transposition of the great arteries developed systemic mRV dysfunction 15 years after atrial level correction.

Likewise, classic repair of ccTGA places the mRV in the systemic circulation. Sano [5] and Szufladowicz [9] and their colleagues reported 10-year survivals after classic repair of 85% and 81%, respectively. Termignon and associates [6] reported a 10-year survival of patients with ccTGA, VSD with and without PS were 50% and 71%, respectively. Metcalfe and Somerville [8] have documented that 58% of patients who had a classic repair developed more than moderate TV regurgitation.

The conduction tissue in ccTGA is abnormally situated [1]. In a Rastelli plus Senning procedure, because the VSD is closed through the right ventriculotomy, the risk of developing surgical AV block should be less than in the classic repair. Two of our patients developed complete AV block; however, both recovered normal sinus rhythm in time.

The Senning operation has a potential for causing systemic and pulmonary venous obstruction, as well as atrial arrhythmias [24]. In our series, no patient thus far has developed systemic or pulmonary venous obstruction or atrial arrhythmia, but our follow-up period is short.

Malformations of the TV are common in patients with AV discordance [3]. Most frequently, variable degrees of Ebstein’s malformation and straddling of the TV are encountered. In our series, 82% of patients had varying degrees of TV regurgitation. Van Son and colleagues [4] reported the surgical results of 40 patients with more than moderate TV regurgitation after TV replacement with ccTGA. They demonstrated a survival of 78% at 5 years and 60% at 10 years, particularly poor results were obtained with mRV dysfunction before TV replacement.

Before the double switch operation, the TV is the systemic AV valve. After the double switch the TV will function in the pulmonary circuit, under a reduced working pressure. This is reflected in our series by the reduction of the degree of TV regurgitation without the need for TV repair. In this double switch series, only 1 patient needed a TV annuloplasty, with a satisfactory outcome.

In previous reports of the double switch, the numbers of Rastelli plus Senning or Mustard procedures were much larger than that of ASO plus Senning procedures [11, 14, 15, 17]. In our series, the number of ASO plus Senning procedures and Rastelli plus Senning procedures were almost equal. In patients subjected to ASO plus Senning, a higher prevalence of more than moderate TV regurgitation and higher incidence of Ebstein’s TV malformation was present preoperatively. This higher incidence of TV regurgitation is not only due to the anatomic substrate of the valve, but also due to the lower mLV pressure. The interventricular septum thus shifts toward the mLV and the leaflets of the TV are unable to coapt. In the presence of PS or PA, the right and the left ventricular pressures are nearly equal. This prevents the interventricular septum from moving toward the mLV and the leaflets of the TV can thus coapt more easily.

In conclusion, the double switch operation can be performed with a low mortality and morbidity as assessed by early and intermediate-term follow-up. To establish the mLV as the systemic ventricle would appear to be favorable, especially in the presence of mRV dysfunction or significant TV regurgitation. Further experience and longer follow-up are needed to assess whether this complex surgical approach is indeed warranted.

	Footnotes

 
This article has been selected for the open discussion forum on the STS Web site: http://www.sts.org/section/atsdiscussion/

	References

Top Abstract Introduction Patients and methods Results Comment References

 

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This Article Abstract Full Text (PDF) Online Discussion Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Jonathan J. Drummond-Webb Lourdes R. Prieto Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Imamura, M. Articles by Mee, R. B.B. Search for Related Content PubMed PubMed Citation Articles by Imamura, M. Articles by Mee, R. B.B.