Pictorial Review of the Role of Multidetector Computed Tomography Imaging in the Postoperative Evaluation of Congenital Heart Disease Jubal R. Watts Jr, MD, Sushilkumar K. Sonavane, MD, P. Hrudaya Nath, MD, and Satinder P. Singh, MD
Echocardiography and cardiac magnetic resonance imaging are the methods of choice for preoperative and postoperative assessments of most congenital heart diseases. However, multidetector computed tomographic angiography of the chest is a complementary imaging technique especially in postoperative evaluations. To accurately interpret those computed tomography examinations, an appropriate study protocol, knowledge of the details of surgical procedures, and their complications are essential. In this pictorial review, we discuss our computed tomography technique with a number of illustrative cases with varied postoperative appearances and complications after some of the commonly performed surgical procedures.
Introduction Advances in surgical technique and perioperative care have significantly improved the success rate and life expectancy in congenital heart disease (CHD). Echocardiography is the primary imaging method in many settings, as it is readily available and does not require radiation or contrast medium. It is useful for evaluating cardiac chambers, ventricular function, valves, and intracardiac shunts. However, echocardiography can be limited by lack of adequate acoustic windows and suboptimal depiction of the extracardiac vasculature, which can be important in the postoperative evaluation.1 Cardiac magnetic resonance imaging (CMR) gives excellent information about function and From the Cardiopulmonary Division, Department of Radiology, University of Alabama School of Medicine, Birmingham, AL. Reprint requests: Jubal R. Watts, MD, Cardiopulmonary Division, Department of Radiology, University of Alabama School of Medicine, Birmingham, AL 35294. E-mail: [email protected]. Curr Probl Diagn Radiol 2014;43:205–218. & 2014 Mosby, Inc. All rights reserved. 0363-0188/$36.00 + 0 http://dx.doi.org/10.1067/j.cpradiol.2014.04.001
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anatomy without radiation, allowing this modality to be used in serial examinations of patients with repaired CHD not amenable to echocardiographic evaluation. Poor acoustic windows and geometric assumptions may limit echocardiographic evaluation of right ventricular function as well as velocity and pressure gradient estimations in postoperative baffles and conduits in the postoperative patients with CHD. CMR is an excellent tool in these cases as well as for following up extracardiac repairs, for example, aortic coarctation. Because there is no radiation involved, multiphasic contrast injection protocols may also be performed with CMR to evaluate temporal flow dynamics in the various cardiac chambers. Unfortunately, CMR may be limited in uncooperative patients, those with significant arrhythmia, or presence of pacemaker or implantable cardioverter-defibrillator (ICD) leads, and requires sedation of younger patients. Multidetector computed tomography (MDCT), because of wide availability, short acquisition time, high spatial resolution, improved temporal resolution, and isotropic imaging, is an attractive alternative method. Its main disadvantages include radiation exposure and need for iodinated contrast. When performed with electrocardiogram (ECG) gating, computed tomography provides useful information about coronary arteries, valves, complex cardiac morphology, and cardiac function, especially in patients with previous surgery, the details of which are unknown. Cardiac catheterization is indicated in many patients with CHD for hemodynamic data, and especially where percutaneous interventions such as dilatation or stenting of stenoses, embolization of aortopulmonary collaterals, and closure of shunts such as atrial septal defects or patent ductus are necessary.
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MDCT Technique The MDCT protocol is tailored to each case. In patients with shunts or baffles, optimal contrast timing may be difficult because of differential flow. For example, patients with Fontan physiology may have the vast majority of flow to one lung via the bidirectional Glenn shunt and the bulk of the perfusion to the other lung supplied by the Fontan connection. A single upper extremity injection may fail to opacify the area of interest in problematic cases if the area of clinical concern regards something predominantly perfused by
the Fontan connection. Sometimes a dual-phase acquisition is useful without a saline flush to opacify the right and left sides of the heart or delayed phases to fully opacify later filling shunts and baffles. Sedation may be useful in small children to avoid motion. Heart rate control is usually not required for CHD unless coronary artery evaluation is needed. For intravenous contrast, we typically use iohexol 350 with a dose of approximately 2 mL/kg. When imaging infants, we have had the best results with contrast diluted 1:1 with normal saline and hand
TABLE. Common surgical procedures for congenital heart disease Procedure
Description
(A) To augment pulmonary blood flow (1) Classic BlalockSubclavian artery to ipsilateral pulmonary artery Taussig shunt (2) Modified BlalockGortex graft subclavian to ipsilateral pulmonary artery Taussig shunt (3) Central shunt Gortex graft from ascending aorta to main pulmonary artery (4) Classic Glenn shunt Surgical connection between the superior vena cava and transected ipsilateral pulmonary artery via end-to-end anastomosis (5) Bidirectional Glenn Connects the transected SVC to right pulmonary artery shunt via an end-to-side anastomosis (6) Kawashima Placement of bidirectional Glenn shunt in patients with procedure interrupted IVC and azygous continuation in heterotaxy syndrome (B) To decrease pulmonary blood flow (1) Pulmonary artery banding
(C) To improve mixing of systemic and pulmonary venous returns (1) Rashkind balloon septostomy (2) Blalock-Hanlon septectomy (3) Park-Blade septostomy at catheterization (4) Open atrial septectomy
Surgical excision of atrial septum to enlarge interatrial connection Used for thicker septum or when large interatrial communication is desired Similar to Blalock-Hanlon procedure
(D) Separation of systemic and pulmonary circulations (1) Fontan procedures (1) Systemic venous blood is routed directly to the lungs: bidirectional Glenn shunt or staged hemi-Fontan procedure. (2) Closure of ASD. (3) Classically systemic blood was routed to the lungs via a direct atriopulmonary connection, but modifications now include insertion of homograft valve in the inferior vena cava and placement of homograft valve conduit between right atrium and left pulmonary artery or using an intra-atrial baffle or an external conduit from inferior vena cava to the pulmonary artery
Comment
Usually on opposite side of arch Usually on same side as arch
No longer used because of creation of discontinuity of right and left pulmonary arteries. Common complication is development of pulmonary AVM Allows blood to flow to both lungs. Common complication is development of pulmonary AVM Redirect all systemic venous blood to the lungs, except hepatic and coronary venous circulation. Common complication is development of pulmonary AVM Usually done to palliate congestive heart failure in infancy with anticipated delayed repair. Common procedure in single ventricle, complete form of A-V canal Routinely performed in neonates with complete transposition of the great arteries to improve atrial mixing. In complete transposition of the great arteries when Rashkind procedure fails Transposition of the great arteries—not commonly performed Most commonly performed during repair of hypoplastic left heart (1) Operation bypasses the right ventricle via a surgically constructed connection and conducts blood to the lungs without the benefit of pulsatile ventricular flow, increasing risk for thrombosis, or suboptimal flow dynamics. (2) Initially used for tricuspid atresia, currently performed as final palliative procedure in hearts with single ventricle physiology—such as hypoplastic left heart syndrome, double inlet ventricle. Main complication is development of systemic venous hypertension and its sequelae
IVC, inferior vena cava; SVC, superior vena cava.
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injecting at roughly 2 mL/s. The scan is empirically timed and initiated when 50% of the contrast has been injected. We program the scanners for a zero second delay. Because of complex anatomy and requisite delays with bolus tracking, we have found consistently better results with empiric timing in neonates. In older patients, the contrast dose is
determined using the same weight-based formula, and scan initiation is determined using either a timed injection or a bolus tracking technique using injection rates of 3-5 mL/s for both the contrast and subsequent saline injections. Prospective gating, with its low radiation exposure, can be achieved even with higher heart rates. In
FIG 1. A 30-year-old male with complex congenital heart disease including double outlet right ventricle, multiple ventricular septal defects, and pulmonary atresia. (A) A patent classic right Blalock-Taussig (B-T) shunt (arrow), aorta (Ao), and right pulmonary artery (RPA). In (B), a modified left B-T shunt is noted to be thrombosed (arrow). (C) Axial image demonstrating multiple ventricular septal defects (arrows) and right ventricular hypertrophy. RV, right ventricle; LV, left ventricle. (Color version of figure is available online.)
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patients where cardiac functional information is desired, retrospective gating is essential. Other radiation dose–reduction measures include utilizing
80 kVp, lower mA 50-100, and limiting the field of view to the area of interest.
Procedures to Augment Pulmonary Blood Flow Various congenital heart defects result in diminished blood flow to the lungs. Various different surgical procedures may be performed to increase pulmonary blood flow (Table), many of which are
FIG 2. A child with a history of hypoplastic left heart. Examination was requested to evaluate patency of the previously placed bidirectional Glenn shunt. (A) Oblique coronal 3D volume rendered slab reconstruction demonstrating patency of the Glenn shunt (asterisk) anastomosed to the right pulmonary artery (RPA). Ao, aorta. (B) Axial MIP image demonstrating shunt patency at the Glenn anastomosis to the RPA. 3D, 3-dimensional; MIP, maximum intensity projection. (Color version of figure is available online.)
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FIG 3. A well-known long-term complication of Glenn procedure is development of pulmonary arteriovenous malformations. These can be of the small diffuse type as shown in catheter angiography (A). A contrast-enhanced CT of a different patient (B) demonstrates dilated tortuous vessels throughout the left lower lobe (circle), which was thought to be secondary to diffuse microscopic pulmonary arteriovenous malformations developing after a Glenn procedure. Patients may also acquire larger macroscopic fistulous connections. CT, computed tomography.
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no longer utilized. The most commonly encountered procedure is the Blalock-Taussig shunt, both classic and modified (Figs 1 and 2). 2
Noninvasive evaluation of shunt patency is more easily achieved with MDCT than with other techniques.
Separation of Systemic and Pulmonary Circulations In patients with only a single functioning ventricle (univentricular—atrioventricular physiology), a bidirectional Glenn procedure is often the first step, followed by a variant of the Fontan completion operation. Glenn shunts redirect the blood flow from the superior vena cava to the pulmonary circulation via the right pulmonary artery. 3 Complications of Glenn shunts include stenosis, thrombosis, and development of pulmonary arteriovenous malformations (AVMs) (Fig 3). The incidence of pulmonary AVMs after classic Glenn anastomosis has been reported in up to 25% of patients, and the etiology is not definitively known but is felt to be related to the diminished hepatic venous blood supplying the pulmonary parenchyma. There is likely some protective factor (nitric oxide or prostaglandin inhibitors of endothelial proliferation) in
FIG 4. Total cavopulmonary anastomosis. (A) Curved MPR reconstruction in oblique coronal plane showing end-to-side anastomosis of the superior vena cava (SVC) to the distal right pulmonary artery (RPA). The intra-atrial conduit (C) from the inferior vena cava (IVC) to the pulmonary artery bifurcation is also recognized. (B) Same patient, shallow right anterior oblique reconstruction showing the anastomosis of the IVC conduit to the pulmonary artery. LPA, left pulmonary artery; Ao, ascending aorta; RPV, right pulmonary vein; LV, left ventricle; MPR, multiplanar reconstruction. (Color version of figure is available online.)
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FIG 5. Fontan physiology. 3-D reconstruction in coronal projection. Superior vena cava (SVC) is connected to the right atrium (RA), which also receives the inferior vena cava blood flow (IVC). The superomedial aspect of the right atrium is anastomosed to the junction of the right (RPA) and left (LPA) pulmonary arteries. Ao, aortic arch; LAA, left atrial appendage; LA, left atrium; LV, left ventricle; 3-D, 3-dimensional. (Color version of figure is available online.)
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hepatic venous blood that prevents pulmonary AVMs from developing, and redirecting hepatic venous blood to the lungs may cause established AVMs to regress.4
FIG 6. Hypoplastic left heart. A 6-month-old female infant with hypoplastic left heart syndrome after stage I Norwood repair with RV to pulmonary artery conduit (Sano shunt), bidirectional Glenn procedure, coil embolization of the aortopulmonary collaterals, and stent placement in a stenotic left pulmonary artery. The right pulmonary artery is less opacified owing to mixing of nonopacified blood from the Glenn shunt ((B) arrows) as the contrast injection was made in the foot. The residual hypoplastic native ascending aorta ((A) arrow) is connected to neoaortic arch made by extensive reconstruction using main pulmonary artery. The dilated and hypertrophied right ventricle serves as the systemic ventricle. The patient had a large unrestricted atrial septal defect facilitating adequate mixing of pulmonary venous and systemic blood. RV, right ventricle. (Color version of figure is available online.)
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The Fontan procedure redirects blood return from the inferior vena cava to the pulmonary artery, a procedure that allows the single functioning ventricle to act as the systemic ventricle (Figs 4 and 5). Complications of the Fontan procedure include right atriomegaly and hepatic congestion, stenosis or leak in the Fontan pathway, thromboembolism due to the prothrombotic circulation, ventricular outflow obstruction, arrhythmias, plastic bronchitis, and protein-losing enteropathy.5 Plastic bronchitis and protein-losing enteropathy are relatively rare complications seen subsequent to a Fontan procedure. The causes are unclear but may be due to elevated systemic venous pressures and elevated intrathoracic lymphatic pressures in protein-losing enteropathy and plastic bronchitis, respectively. Potentially the elevated systemic venous pressure is transferred to the hepatic or portal circulation causing hypoproteinemia, hypocalcemia, immunodeficiency, and coagulopathies. Likewise, elevated intrathoracic pressures or lymphatic obstruction may precipitate the development of noninflammatory mucinous casts in the tracheobronchial tree, obstructing the airway and possibly causing asphyxiation.6 The most common treatment for hypoplastic left heart syndrome is staged reconstruction in which a series of operations, usually 3, are performed to reconfigure the cardiovascular system to be as efficient as possible despite the lack of an adequate left ventricle and hypoplastic ascending aorta (Fig 6).7 The first surgery is the Norwood operation, typically performed in the first week of life, and after the operation, the right ventricle becomes the main systemic ventricle. A “neo” aorta is created from a portion of the pulmonary artery and the native hypoplastic aorta, which is reconstructed or enlarged to provide systemic blood flow, including the coronary circulation. Finally, to provide flow to the lungs, a small tube graft is placed either from a systemic artery to the pulmonary artery (modified Blalock-Taussig shunt) or from the right ventricle to the pulmonary artery (Sano modification). The subsequent operations are the bidirectional Glenn procedure (typically done at 3-6 months of age) and the Fontan operation (typically done after 2 or 3 years of age).
Revising Transposed Connections Before the development of the arterial switch, the preferred surgery for complete or d-transposition was the atrial or venous switch procedure. Many patients who had the latter in infancy are seen in practice as
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FIG 7. Adult with history of atrial switch (Senning) procedure. (A) Axial oblique 3D volume rendered reconstruction illustrating the pulmonary venous flow baffled to the right atrium (RA). LIPV, left inferior pulmonary vein; RIPV, right inferior pulmonary vein. (B) Axial oblique 3D volume rendered reconstruction showing the ascending aorta (Ao) (arising from the right ventricle) directly anterior to the pulmonary trunk (MPA) that was connected to the left ventricle. (C) Coronal oblique volume rendered reconstruction shows the rerouted systemic venous return to the left atrium (LA). SVC, superior vena cava; IVC, inferior vena cava; 3D, 3-dimensional. (Color version of figure is available online.)
adults (Fig 7). We have performed ECG-gated MDCT in individuals with a clinical suspicion of baffle stenoses and nondiagnostic magnetic resonance examinations. Most frequently MDCT is performed to assess stenosis of the pulmonary or systemic venous baffles; however, if retrospective gating is used, we can also evaluate the function of the systemic (morphologic right) ventricle, which may fail over time
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(Fig 8). The current procedure of choice, which avoids systemic ventricular failure seen after venous switch procedures, is the Jatene arterial switch. The aorta and pulmonary artery are reconnected to the proper morphologic ventricles with reimplantation of the coronary arteries.8 Complications include coronary artery stenosis, branch pulmonary artery stenosis due to mobilization of the pulmonary arteries and
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FIG 8. Atrial switch with baffle stenosis. A 38-year-old woman with transposition of great vessels after initial Mustard (venous switch) operation during early childhood; subsequently, she had SVC obstruction, which was managed with another Mustard repair and placement of a stent in the SVC. She also required RF ablation and ultimately transvenous ICD for multiple episodes of recurrent atrial tachycardia. (A) CTA performed with right arm contrast injection showed significant narrowing of the SVC (red arrows) and IVC (green arrows) baffles at their anastomoses. Note the retrograde opacification of inferior vena cave via the azygous and hemiazygous venous systems. (B) There is significant narrowing of the SVC baffle near its junction with a small-size neo–systemic atrium (red asterisk). (C) The pulmonary venous confluence is connected to the right atrium (yellow arrows). CTA, computed tomography angiography; IVC, inferior vena cava; RF, radio frequency; SVC, superior vena cava. (Color version of figure is available online.)
subsequent traction, right ventricular outflow tract (RVOT) obstruction, and dilation of the neoaortic root.9 In patients with transposition of the great arteries with pulmonary outflow tract obstruction and sufficiently large subaortic ventricular septal defect, a Rastelli operation may be performed, placing a baffle
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in the left ventricle redirecting oxygenated blood to the aorta through the ventricular septal defect and conduit placement between the right ventricle and pulmonary artery.10 Late complications of the Rastelli procedure that may be evaluated with MDCT include conduit calcification and obstruction.11 With
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as the patient's age and potential for future growth, different types of repairs may be performed. Resection of the coarctation and an end-to-end anastomosis is preferable if the anatomy is suitable.12 In patients with long-segment coarctation or older patients with
FIG 9. Aortic coarctation after endovascular stent repair and atrial septal defect, also repaired endovascularly. 3D-MIP CT reconstruction demonstrating appropriately positioned Amplatzer occluder device in atrial septum (arrows). Note the stent across the aortic coarctation. 3D-MIP, 3-dimensional maximum intensity projection; CT, computer tomography.
retrospective ECG gating, the assessment of right ventricular function can also be performed.
Repair of Associated Anomalies Treatment of CHD may require repair of associated anomalies such as intracardiac defects, aortic coarctation, and anomalous coronary arteries. In aortic coarctation, depending on the location, extent, as well FIG 10. A young adult with history of anomalous right coronary artery (RCA) with interarterial course. The patient had a previous saphenous venous bypass to the anomalous artery but had recurrent chest pain. We performed a coronary CTA to evaluate the patency of the graft to the anomalous RCA. (A) Axial oblique thin-section volume rendered reconstruction demonstrating the anomalous origin of the right coronary artery from the left coronary cusp (arrow) taking an interarterial course. AA, ascending aorta; RVOT, right ventricular outflow tract. (B) 3D cut surface volume rendered reconstruction illustrating the patent saphenous graft from the ascending aorta to the right coronary artery. Arrow identifies the graft anastomosis to the native anomalous right coronary artery. RV, right ventricle; PA, pulmonary artery. After the coronary CTA, the etiology of the chest pain was thought to be musculoskeletal in origin. CTA, computed tomography angiography; 3D, 3-dimensional. (Color version of figure is available online.)
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significant atherosclerotic disease, subclavian flap aortoplasty, endovascular stent placement (Fig 9), or patch aortoplasty may be performed.13 Complications may occur and are poorly visualized with echocardiography. MDCT is excellent at assessing these postprocedural complications, including recoarctation as well as pseudoaneurysm formation. Pseudoaneurysm occurs especially after patch aortoplasty with reported incidence between 5% and 38%.14-16 Surgical repair of anomalous coronary arteries with an interarterial course include division and reimplantation of the origin, coronary artery bypass grafting, and unroofing of an intramural segment (Figs 10-12). Unroofing is preferred if the anatomy is suitable. Graft occlusion is frequent in patients treated only with coronary artery bypass, as there is good perfusion through the native vessel in nonstress conditions.
Repair of Combined Anomalies: Tetralogy of Fallot
FIG 11. A 47-year-old man with syncope and exercise-induced transient ventricular tachycardia. During catheter angiography, the right coronary artery (RCA) could not be catheterized, and an anomalous coronary was suspected. (A) The anomalous RCA arising from the left cusp (asterisk) and taking an interarterial course (arrow). Ao, aorta; RVOT, right ventricular outflow tract. (B) An oblique MPR demonstrating mixed plaque (arrow) in the RCA, which was thought to cause a moderate stenosis preoperatively. LV, left ventricle; RV, right ventricle; MPR, multiplanar reconstruction.
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Initial therapy for severe tetralogy of fallot (TOF) is frequently a palliative procedure to increase blood flow to the pulmonary arteries. Definitive repair occurs after any necessary palliative procedures have been performed and involves the closure of the ventricular septal defect and relief of the RVOT obstruction. The latter may be achieved via a valvotomy, resection of the infundibular muscle, RVOT patch, transannular patch, or extracardiac conduit between right ventricle and pulmonary artery.17,18 The role of imaging in patients with TOF after palliative procedures or definitive repair or both includes the determination of any residual defects, assessment of the patency of shunts, status of systemic-pulmonary collaterals, main pulmonary artery and branches (obstruction, distortion from shunts, or aneurysmal dilation), evaluation of RVOT aneurysm, assessment of cardiac function— especially right ventricular function, aortic root measurements, and identification of associated coronary artery anomalies (Figs 13 and 14). Common postoperative complications include residual ventricular septal defect, pulmonic stenosis, pulmonary regurgitation, right ventricular enlargement and dysfunction, tricuspid regurgitation, RVOT aneurysm (related to transannular patch, extensive infundibular muscle resection or ischemic insult), conduit obstruction, and left ventricular dysfunction.19
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FIG 12. The patient in Figure 11 underwent reimplantation of the anomalous right coronary artery (RCA) as well as a right internal mammary graft to the proximal RCA. Shortly after the operation, the patient developed refractory ventricular fibrillation that was felt owing to ischemia. The patient was reopened, and intraoperative probing demonstrated complete occlusion of the mid-RCA. Additional saphenous vein grafts (SVG) were placed to the distal RCA and LAD, and the patient fully recovered. A follow-up CTA was performed 10 months later. (A) Axial oblique MPR illustrating patent RCA origin (arrow) reimplanted on the aorta (Ao). (B) Oblique MPR demonstrating occlusive mixed plaque in the mid–right coronary artery at the previous site of moderate narrowing (arrow). (C) Oblique MPR again illustrating RCA occlusion (arrow) that was adjacent to the first right internal mammary graft anastomosis (not pictured). (D) 3D volume rendered reconstruction showing patent aorta to distal RCA vein graft (arrow). Patent graft to left anterior descending artery is partially imaged (asterisk). Clips from the occluded right internal mammary graft are seen within the center of the image (circle). This case illustrates the importance of evaluating and documenting the presence of atherosclerotic disease in the anomalous artery especially in patients not selectively catheterized during coronary angiography. CTA, computed tomography angiography; LAD, left anterior descending artery; MPR, multiplanar reconstruction. (Color version of figure is available online.)
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FIG 13. Adult with history of repaired tetralogy of Fallot. (A) Axial thin-section 3D volume rendered reconstruction demonstrating main pulmonary artery (MPA) enlargement as well as left greater than right enlargement of the branch pulmonary arteries due to significant, long-standing pulmonary regurgitation. LPA, left pulmonary artery; RPA, right pulmonary artery; AA, ascending aorta; DA, descending aorta. (B) Axial image demonstrating dilation of the right ventricular outflow tract (RVOT) frequently seen in adult postoperative patients with tetralogy of Fallot. LA, left atrium; RA, right atrium. (C) Axial image illustrating right ventricular hypertrophy (RV) and dilated right atrium from chronic pulmonary regurgitation. LV, left ventricle; 3D, 3-dimensional.
Conclusion MDCT is playing an increasingly important role in the postoperative imaging and surveillance of patients with CHD with its unique capabilities to characterize anomalies and complications that may be difficult to evaluate with other techniques. Use of prospective ECG gating
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can lower radiation dose to less than annual background, and MDCT's future role in the assessment and follow-up of these patients will likely increase. This pictorial essay attempts to illustrate the breadth of its applications and will hopefully be educational to those involved in the imaging and care of patients with CHD.
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FIG 14. A 39-year-old man with history of tetralogy of Fallot after complete repair and tricuspid valve replacement. The patient had undergone conventional coronary angiography for ventricular tachycardia that suggested a coronary artery anomaly and had an ICD placed. The anomalous coronary anatomy could not be adequately characterized with conventional angiography and a coronary CTA was performed. (A) Axial MIP demonstrates both the left anterior descending artery (LAD) and the right coronary artery (RCA) arising from the right coronary cusp (asterisk). The right coronary cusp was abnormally rotated presumably owing to the patient's altered anatomy and right-sided chamber enlargement. The RCA took the normal course in the right atrioventricular groove. The LAD took a prepulmonic course (benign) and further traveled along the anterior interventricular septum. The diminutive left circumflex (not pictured) also arose from the right coronary cusp and took a retroaortic course to the left atrioventricular groove (also a benign course). Coronary CTA allowed us to define this unusual but benign coronary artery anomaly that could not be adequately characterized with catheter angiography. A prepulmonic LAD, although intrinsically benign, is an important anomaly in patients with TOF as unintentional iatrogenic injury during a right ventricular outflow tract repair can occur. RVOT, right ventricular outflow tract; Ao, aorta; PA, pulmonary artery. (B) Is a volume rendered axial CTA image demonstrating narrowing of the right ventricular outflow tract (circle) with poststenotic dilatation. CTA, computed tomography angiography; MIP, maximum intensity projection.
REFERENCES 1. Haramati LB, Glickstein JS, Issenberg HJ, et al. MR imaging and CT of vascular anomalies and connections in patients with congenital heart disease: Significance in surgical planning. Radiographics 2002;22:337-47 [discussion 348349]. 2. de Leval MR, McKay R, Jones M, et al. Modified BlalockTaussig shunt: Use of subclavian artery orifice as flow regulator in prosthetic systemic-pulmonary artery shunts. J Thorac Cardiovasc Surg 1981;81:112-9. 3. Lamberti JJ, Spicer RL, Waldman JD, et al. The bidirectional cavopulmonary shunt. J Thorac Cardiovasc Surg 1990;100: 22-9. 4. Srivastava D, Preminger T, Lock JE, et al. Hepatic venous blood and the development of pulmonary arteriovenous malformations in congenital heart disease. Circulation 1995; 92:1217-22. 5. Jacobs ML, Pelletier G. Late complications associated with the Fontan circulation. Cardiol Young 2006;6(suppl 1):80-4.
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6. Fredenburg TB, Johnson TR, Cohen MD, et al. The Fontan procedure: Anatomy, complications, and manifestations of failure. Radiographics 2011;31(2):453-63. 7. Bardo DM, Frankel DG, Applegate KE, et al. Hypoplastic left heart syndrome. Radiographics 2001;21:705-17. 8. Freedom RM, Lock J, Bricker JT. Pediatric cardiology and cardiovascular surgery: 1950-2000. Circulation 2000;102 (20 suppl 4):IV58-68. 9. Wernovsky G, Mayer JE Jr, Jonas RA, et al. Factors influencing early and late outcome of the arterial switch operation for transposition of the great arteries. J Thorac Cardiovasc Surg 1995;109:289-301. 10. Rastelli GC. A new approach to anatomic repair of transposition of the great arteries. Mayo Clin Proc 1969; 44:1-12. 11. Kreutzer C, De Vive J, Oppido G, et al. Twenty-five-year experience with Rastelli repair for transposition of the great arteries. J Thorac Cardiovasc Surg 2000;120:211-23. 12. Crafoord C. Classics in thoracic surgery: Correction of aortic coarctation. Ann Thorac Surg 1980;30:300-2.
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13. Vossschulte K. Plastic surgery of the isthmus in aortic isthmus stenosis. Thoraxchirurgie 1957;4:443-50 [in German]. 14. Aebert H, Laas J, Bednarski P, et al. High incidence of aneurysm formation following patch plasty repair of coarctation. Eur J Cardiothorac Surg 1993;7:200-4. 15. Ala-Kulju K, Heikkinen L. Aneurysms after patch graft aortoplasty for coarctation of the aorta: Long-term results of surgical management. Ann Thorac Surg 1989;47: 853-6. 16. Clarkson PM, Brandt PW, Barratt-Boyes BG, et al. Prosthetic repair of coarctation of the aorta with particular reference to
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Dacron onlay patch grafts and late aneurysm formation. Am J Cardiol 1985;56:342-6. 17. Fraser CD Jr, McKenzie ED, Cooley DA. Tetralogy of Fallot: Surgical management individualized to the patient. Ann Thorac Surg 2001;71:1556-61. 18. Starnes VA, Luciani GB, Latter DA, et al. Current surgical management of tetralogy of Fallot. Ann Thorac Surg 1994; 58:211-5. 19. Aeba R, Katogi T, Kashima I, et al. Left atrial appendage insertion for right ventricular outflow tract reconstruction. Ann Thorac Surg 2001;71:501-5.
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Echocardiography and cardiac magnetic resonance imaging are the methods of choice for preoperative and postoperative assessments of most congenital heart diseases. However, multidetector computed tomographic angiography of the chest is a complementary imaging technique especially in postoperative evaluations. To accurately interpret those computed tomography examinations, an appropriate study protocol, knowledge of the details of surgical procedures, and their complications are essential. In this pictorial review, we discuss our computed tomography technique with a number of illustrative cases with varied postoperative appearances and complications after some of the commonly performed surgical procedures.
Introduction Advances in surgical technique and perioperative care have significantly improved the success rate and life expectancy in congenital heart disease (CHD). Echocardiography is the primary imaging method in many settings, as it is readily available and does not require radiation or contrast medium. It is useful for evaluating cardiac chambers, ventricular function, valves, and intracardiac shunts. However, echocardiography can be limited by lack of adequate acoustic windows and suboptimal depiction of the extracardiac vasculature, which can be important in the postoperative evaluation.1 Cardiac magnetic resonance imaging (CMR) gives excellent information about function and From the Cardiopulmonary Division, Department of Radiology, University of Alabama School of Medicine, Birmingham, AL. Reprint requests: Jubal R. Watts, MD, Cardiopulmonary Division, Department of Radiology, University of Alabama School of Medicine, Birmingham, AL 35294. E-mail: [email protected]. Curr Probl Diagn Radiol 2014;43:205–218. & 2014 Mosby, Inc. All rights reserved. 0363-0188/$36.00 + 0 http://dx.doi.org/10.1067/j.cpradiol.2014.04.001
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anatomy without radiation, allowing this modality to be used in serial examinations of patients with repaired CHD not amenable to echocardiographic evaluation. Poor acoustic windows and geometric assumptions may limit echocardiographic evaluation of right ventricular function as well as velocity and pressure gradient estimations in postoperative baffles and conduits in the postoperative patients with CHD. CMR is an excellent tool in these cases as well as for following up extracardiac repairs, for example, aortic coarctation. Because there is no radiation involved, multiphasic contrast injection protocols may also be performed with CMR to evaluate temporal flow dynamics in the various cardiac chambers. Unfortunately, CMR may be limited in uncooperative patients, those with significant arrhythmia, or presence of pacemaker or implantable cardioverter-defibrillator (ICD) leads, and requires sedation of younger patients. Multidetector computed tomography (MDCT), because of wide availability, short acquisition time, high spatial resolution, improved temporal resolution, and isotropic imaging, is an attractive alternative method. Its main disadvantages include radiation exposure and need for iodinated contrast. When performed with electrocardiogram (ECG) gating, computed tomography provides useful information about coronary arteries, valves, complex cardiac morphology, and cardiac function, especially in patients with previous surgery, the details of which are unknown. Cardiac catheterization is indicated in many patients with CHD for hemodynamic data, and especially where percutaneous interventions such as dilatation or stenting of stenoses, embolization of aortopulmonary collaterals, and closure of shunts such as atrial septal defects or patent ductus are necessary.
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MDCT Technique The MDCT protocol is tailored to each case. In patients with shunts or baffles, optimal contrast timing may be difficult because of differential flow. For example, patients with Fontan physiology may have the vast majority of flow to one lung via the bidirectional Glenn shunt and the bulk of the perfusion to the other lung supplied by the Fontan connection. A single upper extremity injection may fail to opacify the area of interest in problematic cases if the area of clinical concern regards something predominantly perfused by
the Fontan connection. Sometimes a dual-phase acquisition is useful without a saline flush to opacify the right and left sides of the heart or delayed phases to fully opacify later filling shunts and baffles. Sedation may be useful in small children to avoid motion. Heart rate control is usually not required for CHD unless coronary artery evaluation is needed. For intravenous contrast, we typically use iohexol 350 with a dose of approximately 2 mL/kg. When imaging infants, we have had the best results with contrast diluted 1:1 with normal saline and hand
TABLE. Common surgical procedures for congenital heart disease Procedure
Description
(A) To augment pulmonary blood flow (1) Classic BlalockSubclavian artery to ipsilateral pulmonary artery Taussig shunt (2) Modified BlalockGortex graft subclavian to ipsilateral pulmonary artery Taussig shunt (3) Central shunt Gortex graft from ascending aorta to main pulmonary artery (4) Classic Glenn shunt Surgical connection between the superior vena cava and transected ipsilateral pulmonary artery via end-to-end anastomosis (5) Bidirectional Glenn Connects the transected SVC to right pulmonary artery shunt via an end-to-side anastomosis (6) Kawashima Placement of bidirectional Glenn shunt in patients with procedure interrupted IVC and azygous continuation in heterotaxy syndrome (B) To decrease pulmonary blood flow (1) Pulmonary artery banding
(C) To improve mixing of systemic and pulmonary venous returns (1) Rashkind balloon septostomy (2) Blalock-Hanlon septectomy (3) Park-Blade septostomy at catheterization (4) Open atrial septectomy
Surgical excision of atrial septum to enlarge interatrial connection Used for thicker septum or when large interatrial communication is desired Similar to Blalock-Hanlon procedure
(D) Separation of systemic and pulmonary circulations (1) Fontan procedures (1) Systemic venous blood is routed directly to the lungs: bidirectional Glenn shunt or staged hemi-Fontan procedure. (2) Closure of ASD. (3) Classically systemic blood was routed to the lungs via a direct atriopulmonary connection, but modifications now include insertion of homograft valve in the inferior vena cava and placement of homograft valve conduit between right atrium and left pulmonary artery or using an intra-atrial baffle or an external conduit from inferior vena cava to the pulmonary artery
Comment
Usually on opposite side of arch Usually on same side as arch
No longer used because of creation of discontinuity of right and left pulmonary arteries. Common complication is development of pulmonary AVM Allows blood to flow to both lungs. Common complication is development of pulmonary AVM Redirect all systemic venous blood to the lungs, except hepatic and coronary venous circulation. Common complication is development of pulmonary AVM Usually done to palliate congestive heart failure in infancy with anticipated delayed repair. Common procedure in single ventricle, complete form of A-V canal Routinely performed in neonates with complete transposition of the great arteries to improve atrial mixing. In complete transposition of the great arteries when Rashkind procedure fails Transposition of the great arteries—not commonly performed Most commonly performed during repair of hypoplastic left heart (1) Operation bypasses the right ventricle via a surgically constructed connection and conducts blood to the lungs without the benefit of pulsatile ventricular flow, increasing risk for thrombosis, or suboptimal flow dynamics. (2) Initially used for tricuspid atresia, currently performed as final palliative procedure in hearts with single ventricle physiology—such as hypoplastic left heart syndrome, double inlet ventricle. Main complication is development of systemic venous hypertension and its sequelae
IVC, inferior vena cava; SVC, superior vena cava.
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injecting at roughly 2 mL/s. The scan is empirically timed and initiated when 50% of the contrast has been injected. We program the scanners for a zero second delay. Because of complex anatomy and requisite delays with bolus tracking, we have found consistently better results with empiric timing in neonates. In older patients, the contrast dose is
determined using the same weight-based formula, and scan initiation is determined using either a timed injection or a bolus tracking technique using injection rates of 3-5 mL/s for both the contrast and subsequent saline injections. Prospective gating, with its low radiation exposure, can be achieved even with higher heart rates. In
FIG 1. A 30-year-old male with complex congenital heart disease including double outlet right ventricle, multiple ventricular septal defects, and pulmonary atresia. (A) A patent classic right Blalock-Taussig (B-T) shunt (arrow), aorta (Ao), and right pulmonary artery (RPA). In (B), a modified left B-T shunt is noted to be thrombosed (arrow). (C) Axial image demonstrating multiple ventricular septal defects (arrows) and right ventricular hypertrophy. RV, right ventricle; LV, left ventricle. (Color version of figure is available online.)
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patients where cardiac functional information is desired, retrospective gating is essential. Other radiation dose–reduction measures include utilizing
80 kVp, lower mA 50-100, and limiting the field of view to the area of interest.
Procedures to Augment Pulmonary Blood Flow Various congenital heart defects result in diminished blood flow to the lungs. Various different surgical procedures may be performed to increase pulmonary blood flow (Table), many of which are
FIG 2. A child with a history of hypoplastic left heart. Examination was requested to evaluate patency of the previously placed bidirectional Glenn shunt. (A) Oblique coronal 3D volume rendered slab reconstruction demonstrating patency of the Glenn shunt (asterisk) anastomosed to the right pulmonary artery (RPA). Ao, aorta. (B) Axial MIP image demonstrating shunt patency at the Glenn anastomosis to the RPA. 3D, 3-dimensional; MIP, maximum intensity projection. (Color version of figure is available online.)
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FIG 3. A well-known long-term complication of Glenn procedure is development of pulmonary arteriovenous malformations. These can be of the small diffuse type as shown in catheter angiography (A). A contrast-enhanced CT of a different patient (B) demonstrates dilated tortuous vessels throughout the left lower lobe (circle), which was thought to be secondary to diffuse microscopic pulmonary arteriovenous malformations developing after a Glenn procedure. Patients may also acquire larger macroscopic fistulous connections. CT, computed tomography.
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no longer utilized. The most commonly encountered procedure is the Blalock-Taussig shunt, both classic and modified (Figs 1 and 2). 2
Noninvasive evaluation of shunt patency is more easily achieved with MDCT than with other techniques.
Separation of Systemic and Pulmonary Circulations In patients with only a single functioning ventricle (univentricular—atrioventricular physiology), a bidirectional Glenn procedure is often the first step, followed by a variant of the Fontan completion operation. Glenn shunts redirect the blood flow from the superior vena cava to the pulmonary circulation via the right pulmonary artery. 3 Complications of Glenn shunts include stenosis, thrombosis, and development of pulmonary arteriovenous malformations (AVMs) (Fig 3). The incidence of pulmonary AVMs after classic Glenn anastomosis has been reported in up to 25% of patients, and the etiology is not definitively known but is felt to be related to the diminished hepatic venous blood supplying the pulmonary parenchyma. There is likely some protective factor (nitric oxide or prostaglandin inhibitors of endothelial proliferation) in
FIG 4. Total cavopulmonary anastomosis. (A) Curved MPR reconstruction in oblique coronal plane showing end-to-side anastomosis of the superior vena cava (SVC) to the distal right pulmonary artery (RPA). The intra-atrial conduit (C) from the inferior vena cava (IVC) to the pulmonary artery bifurcation is also recognized. (B) Same patient, shallow right anterior oblique reconstruction showing the anastomosis of the IVC conduit to the pulmonary artery. LPA, left pulmonary artery; Ao, ascending aorta; RPV, right pulmonary vein; LV, left ventricle; MPR, multiplanar reconstruction. (Color version of figure is available online.)
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FIG 5. Fontan physiology. 3-D reconstruction in coronal projection. Superior vena cava (SVC) is connected to the right atrium (RA), which also receives the inferior vena cava blood flow (IVC). The superomedial aspect of the right atrium is anastomosed to the junction of the right (RPA) and left (LPA) pulmonary arteries. Ao, aortic arch; LAA, left atrial appendage; LA, left atrium; LV, left ventricle; 3-D, 3-dimensional. (Color version of figure is available online.)
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hepatic venous blood that prevents pulmonary AVMs from developing, and redirecting hepatic venous blood to the lungs may cause established AVMs to regress.4
FIG 6. Hypoplastic left heart. A 6-month-old female infant with hypoplastic left heart syndrome after stage I Norwood repair with RV to pulmonary artery conduit (Sano shunt), bidirectional Glenn procedure, coil embolization of the aortopulmonary collaterals, and stent placement in a stenotic left pulmonary artery. The right pulmonary artery is less opacified owing to mixing of nonopacified blood from the Glenn shunt ((B) arrows) as the contrast injection was made in the foot. The residual hypoplastic native ascending aorta ((A) arrow) is connected to neoaortic arch made by extensive reconstruction using main pulmonary artery. The dilated and hypertrophied right ventricle serves as the systemic ventricle. The patient had a large unrestricted atrial septal defect facilitating adequate mixing of pulmonary venous and systemic blood. RV, right ventricle. (Color version of figure is available online.)
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The Fontan procedure redirects blood return from the inferior vena cava to the pulmonary artery, a procedure that allows the single functioning ventricle to act as the systemic ventricle (Figs 4 and 5). Complications of the Fontan procedure include right atriomegaly and hepatic congestion, stenosis or leak in the Fontan pathway, thromboembolism due to the prothrombotic circulation, ventricular outflow obstruction, arrhythmias, plastic bronchitis, and protein-losing enteropathy.5 Plastic bronchitis and protein-losing enteropathy are relatively rare complications seen subsequent to a Fontan procedure. The causes are unclear but may be due to elevated systemic venous pressures and elevated intrathoracic lymphatic pressures in protein-losing enteropathy and plastic bronchitis, respectively. Potentially the elevated systemic venous pressure is transferred to the hepatic or portal circulation causing hypoproteinemia, hypocalcemia, immunodeficiency, and coagulopathies. Likewise, elevated intrathoracic pressures or lymphatic obstruction may precipitate the development of noninflammatory mucinous casts in the tracheobronchial tree, obstructing the airway and possibly causing asphyxiation.6 The most common treatment for hypoplastic left heart syndrome is staged reconstruction in which a series of operations, usually 3, are performed to reconfigure the cardiovascular system to be as efficient as possible despite the lack of an adequate left ventricle and hypoplastic ascending aorta (Fig 6).7 The first surgery is the Norwood operation, typically performed in the first week of life, and after the operation, the right ventricle becomes the main systemic ventricle. A “neo” aorta is created from a portion of the pulmonary artery and the native hypoplastic aorta, which is reconstructed or enlarged to provide systemic blood flow, including the coronary circulation. Finally, to provide flow to the lungs, a small tube graft is placed either from a systemic artery to the pulmonary artery (modified Blalock-Taussig shunt) or from the right ventricle to the pulmonary artery (Sano modification). The subsequent operations are the bidirectional Glenn procedure (typically done at 3-6 months of age) and the Fontan operation (typically done after 2 or 3 years of age).
Revising Transposed Connections Before the development of the arterial switch, the preferred surgery for complete or d-transposition was the atrial or venous switch procedure. Many patients who had the latter in infancy are seen in practice as
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FIG 7. Adult with history of atrial switch (Senning) procedure. (A) Axial oblique 3D volume rendered reconstruction illustrating the pulmonary venous flow baffled to the right atrium (RA). LIPV, left inferior pulmonary vein; RIPV, right inferior pulmonary vein. (B) Axial oblique 3D volume rendered reconstruction showing the ascending aorta (Ao) (arising from the right ventricle) directly anterior to the pulmonary trunk (MPA) that was connected to the left ventricle. (C) Coronal oblique volume rendered reconstruction shows the rerouted systemic venous return to the left atrium (LA). SVC, superior vena cava; IVC, inferior vena cava; 3D, 3-dimensional. (Color version of figure is available online.)
adults (Fig 7). We have performed ECG-gated MDCT in individuals with a clinical suspicion of baffle stenoses and nondiagnostic magnetic resonance examinations. Most frequently MDCT is performed to assess stenosis of the pulmonary or systemic venous baffles; however, if retrospective gating is used, we can also evaluate the function of the systemic (morphologic right) ventricle, which may fail over time
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(Fig 8). The current procedure of choice, which avoids systemic ventricular failure seen after venous switch procedures, is the Jatene arterial switch. The aorta and pulmonary artery are reconnected to the proper morphologic ventricles with reimplantation of the coronary arteries.8 Complications include coronary artery stenosis, branch pulmonary artery stenosis due to mobilization of the pulmonary arteries and
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FIG 8. Atrial switch with baffle stenosis. A 38-year-old woman with transposition of great vessels after initial Mustard (venous switch) operation during early childhood; subsequently, she had SVC obstruction, which was managed with another Mustard repair and placement of a stent in the SVC. She also required RF ablation and ultimately transvenous ICD for multiple episodes of recurrent atrial tachycardia. (A) CTA performed with right arm contrast injection showed significant narrowing of the SVC (red arrows) and IVC (green arrows) baffles at their anastomoses. Note the retrograde opacification of inferior vena cave via the azygous and hemiazygous venous systems. (B) There is significant narrowing of the SVC baffle near its junction with a small-size neo–systemic atrium (red asterisk). (C) The pulmonary venous confluence is connected to the right atrium (yellow arrows). CTA, computed tomography angiography; IVC, inferior vena cava; RF, radio frequency; SVC, superior vena cava. (Color version of figure is available online.)
subsequent traction, right ventricular outflow tract (RVOT) obstruction, and dilation of the neoaortic root.9 In patients with transposition of the great arteries with pulmonary outflow tract obstruction and sufficiently large subaortic ventricular septal defect, a Rastelli operation may be performed, placing a baffle
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in the left ventricle redirecting oxygenated blood to the aorta through the ventricular septal defect and conduit placement between the right ventricle and pulmonary artery.10 Late complications of the Rastelli procedure that may be evaluated with MDCT include conduit calcification and obstruction.11 With
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as the patient's age and potential for future growth, different types of repairs may be performed. Resection of the coarctation and an end-to-end anastomosis is preferable if the anatomy is suitable.12 In patients with long-segment coarctation or older patients with
FIG 9. Aortic coarctation after endovascular stent repair and atrial septal defect, also repaired endovascularly. 3D-MIP CT reconstruction demonstrating appropriately positioned Amplatzer occluder device in atrial septum (arrows). Note the stent across the aortic coarctation. 3D-MIP, 3-dimensional maximum intensity projection; CT, computer tomography.
retrospective ECG gating, the assessment of right ventricular function can also be performed.
Repair of Associated Anomalies Treatment of CHD may require repair of associated anomalies such as intracardiac defects, aortic coarctation, and anomalous coronary arteries. In aortic coarctation, depending on the location, extent, as well FIG 10. A young adult with history of anomalous right coronary artery (RCA) with interarterial course. The patient had a previous saphenous venous bypass to the anomalous artery but had recurrent chest pain. We performed a coronary CTA to evaluate the patency of the graft to the anomalous RCA. (A) Axial oblique thin-section volume rendered reconstruction demonstrating the anomalous origin of the right coronary artery from the left coronary cusp (arrow) taking an interarterial course. AA, ascending aorta; RVOT, right ventricular outflow tract. (B) 3D cut surface volume rendered reconstruction illustrating the patent saphenous graft from the ascending aorta to the right coronary artery. Arrow identifies the graft anastomosis to the native anomalous right coronary artery. RV, right ventricle; PA, pulmonary artery. After the coronary CTA, the etiology of the chest pain was thought to be musculoskeletal in origin. CTA, computed tomography angiography; 3D, 3-dimensional. (Color version of figure is available online.)
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significant atherosclerotic disease, subclavian flap aortoplasty, endovascular stent placement (Fig 9), or patch aortoplasty may be performed.13 Complications may occur and are poorly visualized with echocardiography. MDCT is excellent at assessing these postprocedural complications, including recoarctation as well as pseudoaneurysm formation. Pseudoaneurysm occurs especially after patch aortoplasty with reported incidence between 5% and 38%.14-16 Surgical repair of anomalous coronary arteries with an interarterial course include division and reimplantation of the origin, coronary artery bypass grafting, and unroofing of an intramural segment (Figs 10-12). Unroofing is preferred if the anatomy is suitable. Graft occlusion is frequent in patients treated only with coronary artery bypass, as there is good perfusion through the native vessel in nonstress conditions.
Repair of Combined Anomalies: Tetralogy of Fallot
FIG 11. A 47-year-old man with syncope and exercise-induced transient ventricular tachycardia. During catheter angiography, the right coronary artery (RCA) could not be catheterized, and an anomalous coronary was suspected. (A) The anomalous RCA arising from the left cusp (asterisk) and taking an interarterial course (arrow). Ao, aorta; RVOT, right ventricular outflow tract. (B) An oblique MPR demonstrating mixed plaque (arrow) in the RCA, which was thought to cause a moderate stenosis preoperatively. LV, left ventricle; RV, right ventricle; MPR, multiplanar reconstruction.
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Initial therapy for severe tetralogy of fallot (TOF) is frequently a palliative procedure to increase blood flow to the pulmonary arteries. Definitive repair occurs after any necessary palliative procedures have been performed and involves the closure of the ventricular septal defect and relief of the RVOT obstruction. The latter may be achieved via a valvotomy, resection of the infundibular muscle, RVOT patch, transannular patch, or extracardiac conduit between right ventricle and pulmonary artery.17,18 The role of imaging in patients with TOF after palliative procedures or definitive repair or both includes the determination of any residual defects, assessment of the patency of shunts, status of systemic-pulmonary collaterals, main pulmonary artery and branches (obstruction, distortion from shunts, or aneurysmal dilation), evaluation of RVOT aneurysm, assessment of cardiac function— especially right ventricular function, aortic root measurements, and identification of associated coronary artery anomalies (Figs 13 and 14). Common postoperative complications include residual ventricular septal defect, pulmonic stenosis, pulmonary regurgitation, right ventricular enlargement and dysfunction, tricuspid regurgitation, RVOT aneurysm (related to transannular patch, extensive infundibular muscle resection or ischemic insult), conduit obstruction, and left ventricular dysfunction.19
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FIG 12. The patient in Figure 11 underwent reimplantation of the anomalous right coronary artery (RCA) as well as a right internal mammary graft to the proximal RCA. Shortly after the operation, the patient developed refractory ventricular fibrillation that was felt owing to ischemia. The patient was reopened, and intraoperative probing demonstrated complete occlusion of the mid-RCA. Additional saphenous vein grafts (SVG) were placed to the distal RCA and LAD, and the patient fully recovered. A follow-up CTA was performed 10 months later. (A) Axial oblique MPR illustrating patent RCA origin (arrow) reimplanted on the aorta (Ao). (B) Oblique MPR demonstrating occlusive mixed plaque in the mid–right coronary artery at the previous site of moderate narrowing (arrow). (C) Oblique MPR again illustrating RCA occlusion (arrow) that was adjacent to the first right internal mammary graft anastomosis (not pictured). (D) 3D volume rendered reconstruction showing patent aorta to distal RCA vein graft (arrow). Patent graft to left anterior descending artery is partially imaged (asterisk). Clips from the occluded right internal mammary graft are seen within the center of the image (circle). This case illustrates the importance of evaluating and documenting the presence of atherosclerotic disease in the anomalous artery especially in patients not selectively catheterized during coronary angiography. CTA, computed tomography angiography; LAD, left anterior descending artery; MPR, multiplanar reconstruction. (Color version of figure is available online.)
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FIG 13. Adult with history of repaired tetralogy of Fallot. (A) Axial thin-section 3D volume rendered reconstruction demonstrating main pulmonary artery (MPA) enlargement as well as left greater than right enlargement of the branch pulmonary arteries due to significant, long-standing pulmonary regurgitation. LPA, left pulmonary artery; RPA, right pulmonary artery; AA, ascending aorta; DA, descending aorta. (B) Axial image demonstrating dilation of the right ventricular outflow tract (RVOT) frequently seen in adult postoperative patients with tetralogy of Fallot. LA, left atrium; RA, right atrium. (C) Axial image illustrating right ventricular hypertrophy (RV) and dilated right atrium from chronic pulmonary regurgitation. LV, left ventricle; 3D, 3-dimensional.
Conclusion MDCT is playing an increasingly important role in the postoperative imaging and surveillance of patients with CHD with its unique capabilities to characterize anomalies and complications that may be difficult to evaluate with other techniques. Use of prospective ECG gating
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can lower radiation dose to less than annual background, and MDCT's future role in the assessment and follow-up of these patients will likely increase. This pictorial essay attempts to illustrate the breadth of its applications and will hopefully be educational to those involved in the imaging and care of patients with CHD.
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FIG 14. A 39-year-old man with history of tetralogy of Fallot after complete repair and tricuspid valve replacement. The patient had undergone conventional coronary angiography for ventricular tachycardia that suggested a coronary artery anomaly and had an ICD placed. The anomalous coronary anatomy could not be adequately characterized with conventional angiography and a coronary CTA was performed. (A) Axial MIP demonstrates both the left anterior descending artery (LAD) and the right coronary artery (RCA) arising from the right coronary cusp (asterisk). The right coronary cusp was abnormally rotated presumably owing to the patient's altered anatomy and right-sided chamber enlargement. The RCA took the normal course in the right atrioventricular groove. The LAD took a prepulmonic course (benign) and further traveled along the anterior interventricular septum. The diminutive left circumflex (not pictured) also arose from the right coronary cusp and took a retroaortic course to the left atrioventricular groove (also a benign course). Coronary CTA allowed us to define this unusual but benign coronary artery anomaly that could not be adequately characterized with catheter angiography. A prepulmonic LAD, although intrinsically benign, is an important anomaly in patients with TOF as unintentional iatrogenic injury during a right ventricular outflow tract repair can occur. RVOT, right ventricular outflow tract; Ao, aorta; PA, pulmonary artery. (B) Is a volume rendered axial CTA image demonstrating narrowing of the right ventricular outflow tract (circle) with poststenotic dilatation. CTA, computed tomography angiography; MIP, maximum intensity projection.
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6. Fredenburg TB, Johnson TR, Cohen MD, et al. The Fontan procedure: Anatomy, complications, and manifestations of failure. Radiographics 2011;31(2):453-63. 7. Bardo DM, Frankel DG, Applegate KE, et al. Hypoplastic left heart syndrome. Radiographics 2001;21:705-17. 8. Freedom RM, Lock J, Bricker JT. Pediatric cardiology and cardiovascular surgery: 1950-2000. Circulation 2000;102 (20 suppl 4):IV58-68. 9. Wernovsky G, Mayer JE Jr, Jonas RA, et al. Factors influencing early and late outcome of the arterial switch operation for transposition of the great arteries. J Thorac Cardiovasc Surg 1995;109:289-301. 10. Rastelli GC. A new approach to anatomic repair of transposition of the great arteries. Mayo Clin Proc 1969; 44:1-12. 11. Kreutzer C, De Vive J, Oppido G, et al. Twenty-five-year experience with Rastelli repair for transposition of the great arteries. J Thorac Cardiovasc Surg 2000;120:211-23. 12. Crafoord C. Classics in thoracic surgery: Correction of aortic coarctation. Ann Thorac Surg 1980;30:300-2.
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13. Vossschulte K. Plastic surgery of the isthmus in aortic isthmus stenosis. Thoraxchirurgie 1957;4:443-50 [in German]. 14. Aebert H, Laas J, Bednarski P, et al. High incidence of aneurysm formation following patch plasty repair of coarctation. Eur J Cardiothorac Surg 1993;7:200-4. 15. Ala-Kulju K, Heikkinen L. Aneurysms after patch graft aortoplasty for coarctation of the aorta: Long-term results of surgical management. Ann Thorac Surg 1989;47: 853-6. 16. Clarkson PM, Brandt PW, Barratt-Boyes BG, et al. Prosthetic repair of coarctation of the aorta with particular reference to
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Dacron onlay patch grafts and late aneurysm formation. Am J Cardiol 1985;56:342-6. 17. Fraser CD Jr, McKenzie ED, Cooley DA. Tetralogy of Fallot: Surgical management individualized to the patient. Ann Thorac Surg 2001;71:1556-61. 18. Starnes VA, Luciani GB, Latter DA, et al. Current surgical management of tetralogy of Fallot. Ann Thorac Surg 1994; 58:211-5. 19. Aeba R, Katogi T, Kashima I, et al. Left atrial appendage insertion for right ventricular outflow tract reconstruction. Ann Thorac Surg 2001;71:501-5.
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