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Complex d-TGA status post Rastelli repair presenting with palpitations: cardiac CTA imaging findings and discussion of long-term outcomes.

HISTORY

A man 19 years of age with a history of complex dextrotransposition of the great arteries (d-TGA) repaired during infancy presented with intermittent palpitations at rest. He denied orthopnea, edema, paroxysmal nocturnal dyspnea, and exertional chest pain.

His cardiac history is significant for d-TGA with a ventricular septal defect (VSD) and sub-valvular and valvular pulmonary stenosis palliated with a balloon septostomy on day of life zero and right modified BlalockTaussig shunt at 10 days of age followed by a completion Rastelli repair at 10 months of age with VSD patch and placement of a right ventricle to pulmonary artery conduit. His postoperative course was complicated by left ventricular outflow tract obstruction secondary to restriction at the VSD and intermittent high-grade AV block, for which he had a pacemaker implanted. The pacemaker was subsequently removed at 4 years of age after resumption of normal sinus rhythm, however, he has retained epicardial leads. He has subsequently required multiple revisions of the pulmonary outflow shunt and pulmonary arteries, the last of which was performed at 14 years of age. Otherwise, he had been stable without symptoms for the past 5 years. His physical exam was significant for a grade III/VI harsh, crescendo-decrescendo systolic murmur at the left and right upper sternal borders and a widely split S2 with a prominent P2 component. Jugular venous distention, edema, heaves, and extra heart sounds were all absent. Electrocardiogram showed normal sinus rhythm with a right bundle branch block.

Echocardiography and cardiac computed tomography angiography were ordered to evaluate patency of his cardiovascular structures, given his history of congenital heart disease, prior pulmonary artery stenosis requiring arterioplasty, retained epicardial lead, and the symptoms described.

IMAGING FINDINGS

Figure 1 presents the volume rendered cardiac CT angiography image oriented in the left anterior oblique, cranial projection demonstrating the Rastelli conduit (open arrow) arising from the right ventricular (RV) free wall and anastomosing at the main pulmonary artery (not visualized). The left anterior descending (LAD) coronary artery (solid arrow) arises from the aorta (Ao) and courses in the anterior interventricular groove between the RV and left ventricle (LV). The lack of a branch vessel from the Ao origin coursing in the atrioventricular groove suggests an anomalous course of the left circumflex coronary artery. Figure 2 is a multiplanar reformat which demonstrates a repaired ventricular septal defect (arrow). The course of the Rastelli graft (1) immediately deep to the sternum is appreciated and the anastomosis with the main pulmonary artery is well visualized. The atrophic right pulmonary artery (*) is also seen coursing superior to the aortic root. Additionally, a mildly obstructive left ventricular outflow tract (LVOT) is shown (2) with good appreciation of the misalignment of the aorta with respect to the LVOT. Figure 3 is an axial image which shows the bifurcation of the main pulmonary artery (1). The size disparity between the normal left pulmonary artery (2), measuring 17 mm, and the atrophied right pulmonary artery (*), measuring 9 mm, is better appreciated. The left-sided aortic course (3) is appreciated, which is secondary to the leftward origin of the ascending aorta compared with normal anatomy.

Figures 4 and 5 depict apical 3- and 5-chamber views showing turbulence across the LVOT beginning below the aortic valve (in the baffle between VSD and aorta). Figure 6 is a high-parasternal-short-axis view showing turbulence in the RV-PA conduit. Conduits such as these are often difficult to visualize by echocardiography due to anatomical position, body habitus, or surgical scarring.

COMMENT

Transposition of the great arteries (TGA) is an uncommon congenital heart disease with a reported incidence of 2.3/10,000 births. (1) D-transposition (d-TGA) is a cyanotic lesion characterized by inappropriate ventriculoarterial connections leading to parallel pulmonary and systemic circulations that is best surgically corrected very early in life.

Patients with d-TGA are dependent upon intracardiac blood mixing for survival, usually through an atrial septal defect, VSD, or patent ductus arteriosus. (2) Early, frequently severe, cyanosis is a common presenting sign, however, if there is adequate mixing, visible cyanosis maybe under recognized and the patient may present with signs of heart failure due to pulmonary over circulation within a few weeks of life.

Palliative procedures are often initially performed, including the Rashkind catheter-directed balloon septostomy and the modified Blalock-Taussig shunt (if there is inadequate pulmonary blood flow in the setting of pulmonary outflow tract obstruction). The Rashkind procedure attempts to increase intracardiac blood mixing through balloon dilation of an atrial septal defect. (3) The modified Blalock-Taussig shunt is a systemic-to-pulmonary artery shunt that uses a PTFE interposition graft between the innominate artery and the right branch pulmonary artery (with left aortic arch) to palliate until definitive correction can be achieved. (4)

Atrial switch operations, the Senning and Mustard procedures, were developed around 1960 and became the standard operative correction. These procedures created an intracardiac baffle to direct deoxygenated blood from the right atrium to the left ventricle for oxygenation via the pulmonary circulation. Then oxygenated pulmonary venous return is directed through the tricuspid valve for distribution via the right ventricle to the systemic circulation. Several long-term complications were seen with these operations, including sinus node dysfunction, arrhythmias, tricuspid regurgitation, and right ventricular failure. (5) An arterial switch procedure, developed by Jatene in 1975, offered a more definitive method of correction by transection and translocation of the great vessels, translocation of the coronary arteries, and establishment of "normal" ventriculoarterial connections. (6)

About 13% of d-TGA is complicated by the presence of pulmonary outflow tract obstruction. The Rastelli operation was developed in patients with complex d-TGA and concomitant pulmonic outflow tract obstruction and a large VSD. This procedure allows the left ventricle to develop as the systemic ventricle, patches the VSD to direct blood flow from LV through the aorta, closes the congenitally stenotic pulmonic valve, and uses a grafted conduit between the right ventricle and pulmonary artery to direct blood to the lungs for oxygenation. (7)

Regardless of the type of surgical correction, all patients should have annual clinical evaluation. (5) Postoperative imaging evaluation of complex d-TGA cases involves assessment of the pulmonic and systemic outflow tracts, branch pulmonary arteries, conduit (if present) and coronary arteries (if they were involved in the procedure). (8,9) Imaging by echocardiogram can be obtained as needed for anatomic and hemodynamic assessment. (5) Echocardiography can have limitations such as poor windows due to obesity or scarring and lack of definition of thoracic great vessels. Although cardiac magnetic resonance imaging (MRI) improves upon these limitations, it may be contraindicated in patients with pacemakers or significant amounts of retained metal. Patients who need further imaging in addition to echocardiography, and have contraindications to MRI can be evaluated using cardiac computed tomography angiography. (8,9)

Given the rarity of these complex lesions and the relatively recent development of new procedures and their variations such as the Nahkaido and Reparation a l'Etage Ventriculaire procedures, data on long-term outcomes of Rastelli repair for complex d-TGA is still being compiled. Studies suggest that earlier corrective surgery is associated with reduced morbidity and mortality. (10) According to Brown et al who followed 40 patients with complex d-TGA corrected with the Rastelli operation from 1988 to 2008, freedom from death or cardiac transplant was 90% at 20 years postoperation. (11) Horer et al published data on 39 patients with complex d-TGA treated with Rastelli operation from 1977-2004. Their data showed freedom from death or transplantation at 20 years was 57.5% [+ or -] 15.1%. (12) Between 41% and 78% of patients with Rastelli repair will require reoperation for conduit replacement with stenosis and right ventricular outflow tract obstruction being the most common justification for replacement. (11,12) A permanent pacemaker was implanted for complete AV block or sick sinus syndrome in 14% to 25% of patients by 20 years postoperation. (11,12) Right bundle branch block at 20 years was seen in 64% to 77.5% of patients. (11,12) The vast majority (96% to 97%) of patients were NYHA Class I or II at final follow-up with 3% experiencing Class III symptoms. (11-13) Other long-term issues encountered by patients statuspost arterial switch operation are reduced exercise tolerance (85% of predicted), aortic regurgitation (21%), and reduced systemic ventricular function (7%). (14)

Capt Ross Pinson, MC, USAF

MAJ Dustin Thomas, MC, USA

Maj S. Jared Bentley, MC, USAF

REFERENCES

(1.) Reller MD, Strickland MJ, Riehle-Colarusso T, Mahle WT, Correa A. Prevalence of congenital heart defects in metropolitan Atlanta, 1998-2005. J Pediatr. 2008;153(6):807-813.

(2.) Goor DA, Edwards JE. The spectrum of transposition of the great arteries: with specific reference to developmental anatomy of the conus. Circulation. 1973;48(2):406-415.

(3.) Rashkind WJ, Cuaso CC. Transcatheter closure of patent ductus arteriosus. Pediatr Cardiol. 1979;1(1):3-7.

(4.) Singh SP, Chauhan S, Choudhury M, Malik V, Hote MP, Devagourou V. Modified Blalock Taussig shunt: comparison between neonates, infants and older children. Ann Card Anaesth. 2014; 17(3):191-197.

(5.) Warnes CA. Transposition of the great arteries. Circulation. 2006;114(24):2699-2709.

(6.) Jatene AD, Fontes VF, Paulista PP, de Souza LC, Neger F, Galantier M, Souza JE. Successful anatomic correction of transposition of the great vessels: a preliminary report. Arq Bras Cardiol. 1975;28(4):461-464.

(7.) Rastelli GC. A new approach to the "anatomic" repair of transposition of the great arteries. Mayo Clin Proc. 1969;44(1):1-12.

(8.) Dos L, Pen V, Silversides C, Provost Y, Oechslin E, Horlick E, Paul N. Images in cardiovascular medicine. Cardiac magnetic resonance imaging and multidetector computed tomography scan illustrating Damus-Kaye-Stansel operation. Circulation. 2007;115(18):e440-e442.

(9.) Han BK, Lesser JR. CT imaging in congenital heart disease: an approach to imaging and interpreting complex lesions after surgical intervention for tetralogy of fallot, transposition of the great arteries, and single ventricle heart disease. J Cardiovas Comput Tomogr. 2013;7(6):338-353.

(10.) Anderson BR, Ciarleglio AJ, Hayes DA, Quaegebeur JM, Vincent JA, Bacha EA. Earlier arterial switch operation improves outcomes and reduces costs for neonates with transposition of the great arteries. J Am Coll Cardiol. 2014;63(5):481-487.

(11.) Brown JW, Ruzmetov M, Huynh D, Rodefeld MD, Turrentine MW, Fiore AC. Rastelli operation for transposition of the great arteries with ventricular septal defect and pulmonary stenosis. Ann Thorac Surg. 2011;91(1):188-194.

(12.) Horer J, Schreiber C, Dworak E, Cleuziou J, Prodan Z, Vogt M, Holper K, Lange R. Long-term results after the Rastelli repair for transposition of the great arteries. Ann Thorac Surg. 2007;83(6):2169-2175.

(13.) Marcelletti C, Mair DD, McGoon DC, Wallace RB, Danielson GK. The Rastelli operation for transposition of the great arteries. Early and late results. J Thorac Cardiovasc Surg. 1976;72(3):427-434.

(14.) Ruys TP, van der Bosch AE, Cuypers JA, et al. Long-term outcome and quality of life after arterial switch operation: a prospective study with a historical comparison. Congenit Heart Dis. 2013;8(3):203-210.
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Author:Pinson, Ross; Thomas, Dustin; Bentley, S. Jared
Publication:U.S. Army Medical Department Journal
Date:Apr 1, 2015
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