- Email: [email protected]
Which diagnostic modality for adult congenital heart disease?
Journal of Cardiovascular Computed Tomography (2008) 2, 23–25
Editorial
Which diagnostic modality for adult congenital heart disease? KEYWORDS: Cardiac CT; Cardiac MRI; Congenital heart disease; Echocardiography
The population of adults with congenital heart disease (ACHD) is rapidly increasing, as a result of improved outcomes of surgical and catheter-based treatment strategies. Many of these therapeutic procedures are palliative, and clinicians are faced with a growing number of patients with residual complex abnormalities that require further, and often multiple, diagnostic and therapeutic decisions throughout the patient’s lifetime.1 In this issue of the Journal, Cook et al2 have promoted the utility of cardiac computed tomography (CCT) in ACHD. The authors present a retrospective series of 87 patients with a wide range of congenital heart disease that underwent CCT, including 37% with either a permanent pacemaker (PPM) or automatic implantable cardiac defibrillator (AICD). The authors note that 54 patients warranted further consideration for surgical or catheterbased therapy based on the results of the CCT, of which 44% of this subgroup reported no symptoms before the CCT was performed. Because of this finding, the authors conclude that CCT is a valuable adjunctive noninvasive imaging tool in ACHD with significant effect on patient management. Accurate and safe diagnostic tools that complement the clinical assessment are vital in the management of ACHD.3 Traditionally, cardiac catheterization and echocardiography have been the primary diagnostic procedures; however, both techniques have shortcomings. Cardiac catheterization involves radiation exposure, the need for large vessel vascular access with the associated risk of injury, the potential for large iodinated contrast load, and the small but definite risk of serious complications such as arrhythmia, death, stroke, and cardiac perforation. Furthermore, cardiac catheterization may offer inadequate evaluation of frequently encountered diagnostic dilemmas in ACHD, such as severity of pulmonary valve insufficiency, right ventricular size and
function, anatomic suitability for device closure of atrial or ventricular septal defects, and pulmonary baffle obstruction in patients after atrial switch operation. These risks and shortcomings make frequent reassessment by invasive cardiac catheterization impractical. Echocardiography has the advantages of being portable, low cost, readily available, and noninvasive, and it does not involve radiation exposure. Furthermore, echocardiography provides information on hemodynamics and functional status of cardiac chambers, valves, and intracardiac or extracardiac baffles and conduits at rest and with exercise, and it is a safe method for patients that require frequent reassessment.4 Transthoracic echocardiography, transesophageal echocardiography, and more recently intracardiac echocardiography are particularly useful in the evaluation of intracardiac defects and as adjunctive imaging for device closure or cardiac surgery and for the evaluation of prosthetic valve function, suspected bacterial endocarditis, aortic disorders, and subaortic obstruction. The limitations to echocardiography in the evaluation of ACHD are limited transthoracic acoustic windows in patients with prior cardiac surgery or chest wall deformities, in which cases transesophageal echocardiography provides a useful alternative. Echocardiography also is inadequate for the evaluation of the aortic arch, coronary arteries, branch pulmonary arteries, and collateral vessels. Echocardiography is more operator dependent than CT or magnetic resonance imaging (MRI). The use of cardiac MRI and CCT has rapidly increased as noninvasive diagnostic tools for ACHD,5 spearheaded by technologic advances resulting in markedly improved resolution and the potential for functional assessment. Of these two methods for the evaluation of ACHD, cardiac MRI is the more established technique and offers the advantages of being a noninvasive technique that does not require iodin-
1934-5925/$ -see front matter © 2008 Society of Cardiovascular Computed Tomography. All rights reserved. doi:10.1016/j.jcct.2007.12.009
24
Journal of Cardiovascular Computed Tomography, Vol 2, No 1, January/February 2008
ated contrast administration or radiation exposure. Additionally, MRI has good temporal resolution that allows for accurate analysis of cardiac chamber size and function, provides valuable functional and physiologic information, such as flow assessment (by phase contrast imaging), and allows for tissue characterization, identifying myocardial fibrosis (by delayed enhanced imaging) or edema (by T2 imaging). Limitations to the widespread use of MRI include long acquisition times requiring prolonged monitoring and a high level of patient cooperation and the possible need for general anesthesia or sedation in claustrophobic patients. MRI is generally contraindicated in patients with PPM or AICD. The evaluation of coronary artery disease by MRI is limited by difficult acquisitions and limited resolution. Finally, there are recent concerns with the safety of gadolinium in patients with chronic renal insufficiency. Nevertheless, cardiac MRI has become the standard diagnostic method for certain adult congenital heart disorders, such as patients with severe residual pulmonary insufficiency statuspost surgical repair for tetralogy of Fallot or arrhythmogenic right ventricular dysplasia. As shown in this issue of the Journal, CCT is now emerging as an alternative to cardiac MRI for the evaluation of ACHD, because it offers faster acquisition time with improved patient monitoring and less need for anesthesia or sedation. Its inherent high-spatial resolution offers evaluation of cardiac chambers size and function, conduits, baffles, aortic arch, great vessels, and pulmonary arteries and veins. The possibility of performing electrocardiographic-gated studies provides for precise evaluation of coronary artery anatomy, which is likely its greatest strength as a noninvasive imaging technique.6 Furthermore, CCT allows the evaluation of surrounding structures, such as the lungs, mediastinum, and chest wall. The main limitation of CT is the use of ionizing radiation. Careful consideration needs to be given to the associated cancer risk,7 which is additive with subsequent studies. When frequent reassessment is required, then the use of CCT is limited. There are other disadvantages to CCT, such as the use of iodinated contrast, lack of physiologic information, and difficulty in performing gated studies in patients with fast heart rates or arrhythmias. Thus, in our opinion, the use of CCT should be a carefully considered option in ACHD primarily when the use of alternative noninvasive options such as echocardiography or cardiac MRI cannot be performed. In our opinion, some patients described by Cook et al2 would be more suitably and safely evaluated by nonradiation techniques. For example, cardiac MRI is a preferred method in the evaluation of pulmonary regurgitation and right ventricular volumes and function, in the evaluation of branch pulmonary stenosis potentially requiring stent placement. Transesophageal echocardiography provides an accurate method for the evaluation of atrial septal defect rims before decision making for device closure. However, in several cases described by Cook et al2 CCT was probably performed primarily to evaluate the coronary arteries in the decision making for future procedures (surgery versus cath-
eter laboratory intervention), in which case additional anatomic information from other cardiac structures was provided during the examination, presumably at no additional risk (eg, additional contrast or radiation exposure). A team approach of specialists with particular interest and knowledge in adult and pediatric congenital heart disease, including clinical and interventional cardiologists, echocardiographers, and radiologists, is required for adequate selection of patients considered for a CCT. At the current time, CCT has an important role as a diagnostic tool in ACHD patients with PPM or AICD or any other contraindicated metal implant in the body, and in those patients unable to tolerate a prolonged MRI study with contraindications for sedation or general anesthesia. CCT is also indicated and accurate when the evaluation of coronary artery anatomy and disease is required because of implications in the planning of surgical and catheter-based procedures. Beyond these indications, taking into consideration the risk of radiation and contrast exposure in young adults that may require frequent reassessment, the clinician needs to determine the indications for CCT as a first-line diagnostic procedure to answer clinical questions that other noninvasive tests cannot. As with any new diagnostic technique that becomes available for clinical use, there is need to define the role of CCT in the management of ACHD, with careful consideration of risk and benefits relative to more-established techniques such as echocardiography and cardiac MRI. Several questions need to be answered before CCT gains widespread use in ACHD: Does CCT have the potential to answer the clinical question? Will the results of the examination affect management? Are there alternative tests that may give the same answers without radiation exposure? To what degree can the radiation exposure be reduced? Is electrocardiographic gating necessary or could the clinical question be answered with a non-gated CCT? Welldesigned research studies are needed to answer these questions. Ignacio Inglessis, MD Adult Congenital Heart Disease Program MassGeneral Hospital Boston, MA, USA Suhny Abbara, MD Department of Radiology MassGeneral Hospital Boston, MA, USA Michael de Moor, MD* Pediatric Cardiology Division MassGeneral Hospital for Children 175 Cambridge Street, Boston, MA 01778, USA E-mail address: [email protected]
References 1. Warnes CA. The adult with congenital heart disease: born to be bad? J Am Coll Cardiol. 2005;46:1– 8.
Inglessis et al
Which diagnostic modality for ACHD?
2. Cook SC, Dyke PC 2nd, Raman SV. Management of adults with congenital heart disease with cardiovascular CT. J Cardiovasc Comput Tomogr. 2008;2:12–22. 3. Kaemmerer H, Stern H, Fratz S, Prokop M, Schwaiger M, Hess J. Imaging in adults with congenital heart disease. Thorac Cardiovasc Surg. 2000;48:328 –35. 4. Hirsch R, Kilner PJ, Connelly MS, Redington A, St John Sutton MG, Somerville J. Diagnosis in adolescents and adults with congenital heart disease. Prospective assessment of individual and combined roles of magnetic resonance imaging and transesophageal echocardiography. Circulation. 1994;90:2937–51.
25 5. Samyn MM. A review of the complementary information available with cardiac magnetic resonance imaging and multislice computed tomography (CT) during the study of congenital heart disease. Int J Cardiovasc Imaging. 2004;20:569 –78. 6. Nicol ED, Gatzoulis M, Padley SP, Rubens M. Assessment of adult congenital heart disease with multi-detector computed tomography: beyond coronary lumenography. Clin Radiol. 2007;62: 518 –27. 7. Einstein AJ, Henzlova MJ, Rajagopalan S. Estimating risk of cancer associated with radiation exposure from 64-slice computed tomography coronary angiography. JAMA. 2007;18;298:317–23.
Editorial
Which diagnostic modality for adult congenital heart disease? KEYWORDS: Cardiac CT; Cardiac MRI; Congenital heart disease; Echocardiography
The population of adults with congenital heart disease (ACHD) is rapidly increasing, as a result of improved outcomes of surgical and catheter-based treatment strategies. Many of these therapeutic procedures are palliative, and clinicians are faced with a growing number of patients with residual complex abnormalities that require further, and often multiple, diagnostic and therapeutic decisions throughout the patient’s lifetime.1 In this issue of the Journal, Cook et al2 have promoted the utility of cardiac computed tomography (CCT) in ACHD. The authors present a retrospective series of 87 patients with a wide range of congenital heart disease that underwent CCT, including 37% with either a permanent pacemaker (PPM) or automatic implantable cardiac defibrillator (AICD). The authors note that 54 patients warranted further consideration for surgical or catheterbased therapy based on the results of the CCT, of which 44% of this subgroup reported no symptoms before the CCT was performed. Because of this finding, the authors conclude that CCT is a valuable adjunctive noninvasive imaging tool in ACHD with significant effect on patient management. Accurate and safe diagnostic tools that complement the clinical assessment are vital in the management of ACHD.3 Traditionally, cardiac catheterization and echocardiography have been the primary diagnostic procedures; however, both techniques have shortcomings. Cardiac catheterization involves radiation exposure, the need for large vessel vascular access with the associated risk of injury, the potential for large iodinated contrast load, and the small but definite risk of serious complications such as arrhythmia, death, stroke, and cardiac perforation. Furthermore, cardiac catheterization may offer inadequate evaluation of frequently encountered diagnostic dilemmas in ACHD, such as severity of pulmonary valve insufficiency, right ventricular size and
function, anatomic suitability for device closure of atrial or ventricular septal defects, and pulmonary baffle obstruction in patients after atrial switch operation. These risks and shortcomings make frequent reassessment by invasive cardiac catheterization impractical. Echocardiography has the advantages of being portable, low cost, readily available, and noninvasive, and it does not involve radiation exposure. Furthermore, echocardiography provides information on hemodynamics and functional status of cardiac chambers, valves, and intracardiac or extracardiac baffles and conduits at rest and with exercise, and it is a safe method for patients that require frequent reassessment.4 Transthoracic echocardiography, transesophageal echocardiography, and more recently intracardiac echocardiography are particularly useful in the evaluation of intracardiac defects and as adjunctive imaging for device closure or cardiac surgery and for the evaluation of prosthetic valve function, suspected bacterial endocarditis, aortic disorders, and subaortic obstruction. The limitations to echocardiography in the evaluation of ACHD are limited transthoracic acoustic windows in patients with prior cardiac surgery or chest wall deformities, in which cases transesophageal echocardiography provides a useful alternative. Echocardiography also is inadequate for the evaluation of the aortic arch, coronary arteries, branch pulmonary arteries, and collateral vessels. Echocardiography is more operator dependent than CT or magnetic resonance imaging (MRI). The use of cardiac MRI and CCT has rapidly increased as noninvasive diagnostic tools for ACHD,5 spearheaded by technologic advances resulting in markedly improved resolution and the potential for functional assessment. Of these two methods for the evaluation of ACHD, cardiac MRI is the more established technique and offers the advantages of being a noninvasive technique that does not require iodin-
1934-5925/$ -see front matter © 2008 Society of Cardiovascular Computed Tomography. All rights reserved. doi:10.1016/j.jcct.2007.12.009
24
Journal of Cardiovascular Computed Tomography, Vol 2, No 1, January/February 2008
ated contrast administration or radiation exposure. Additionally, MRI has good temporal resolution that allows for accurate analysis of cardiac chamber size and function, provides valuable functional and physiologic information, such as flow assessment (by phase contrast imaging), and allows for tissue characterization, identifying myocardial fibrosis (by delayed enhanced imaging) or edema (by T2 imaging). Limitations to the widespread use of MRI include long acquisition times requiring prolonged monitoring and a high level of patient cooperation and the possible need for general anesthesia or sedation in claustrophobic patients. MRI is generally contraindicated in patients with PPM or AICD. The evaluation of coronary artery disease by MRI is limited by difficult acquisitions and limited resolution. Finally, there are recent concerns with the safety of gadolinium in patients with chronic renal insufficiency. Nevertheless, cardiac MRI has become the standard diagnostic method for certain adult congenital heart disorders, such as patients with severe residual pulmonary insufficiency statuspost surgical repair for tetralogy of Fallot or arrhythmogenic right ventricular dysplasia. As shown in this issue of the Journal, CCT is now emerging as an alternative to cardiac MRI for the evaluation of ACHD, because it offers faster acquisition time with improved patient monitoring and less need for anesthesia or sedation. Its inherent high-spatial resolution offers evaluation of cardiac chambers size and function, conduits, baffles, aortic arch, great vessels, and pulmonary arteries and veins. The possibility of performing electrocardiographic-gated studies provides for precise evaluation of coronary artery anatomy, which is likely its greatest strength as a noninvasive imaging technique.6 Furthermore, CCT allows the evaluation of surrounding structures, such as the lungs, mediastinum, and chest wall. The main limitation of CT is the use of ionizing radiation. Careful consideration needs to be given to the associated cancer risk,7 which is additive with subsequent studies. When frequent reassessment is required, then the use of CCT is limited. There are other disadvantages to CCT, such as the use of iodinated contrast, lack of physiologic information, and difficulty in performing gated studies in patients with fast heart rates or arrhythmias. Thus, in our opinion, the use of CCT should be a carefully considered option in ACHD primarily when the use of alternative noninvasive options such as echocardiography or cardiac MRI cannot be performed. In our opinion, some patients described by Cook et al2 would be more suitably and safely evaluated by nonradiation techniques. For example, cardiac MRI is a preferred method in the evaluation of pulmonary regurgitation and right ventricular volumes and function, in the evaluation of branch pulmonary stenosis potentially requiring stent placement. Transesophageal echocardiography provides an accurate method for the evaluation of atrial septal defect rims before decision making for device closure. However, in several cases described by Cook et al2 CCT was probably performed primarily to evaluate the coronary arteries in the decision making for future procedures (surgery versus cath-
eter laboratory intervention), in which case additional anatomic information from other cardiac structures was provided during the examination, presumably at no additional risk (eg, additional contrast or radiation exposure). A team approach of specialists with particular interest and knowledge in adult and pediatric congenital heart disease, including clinical and interventional cardiologists, echocardiographers, and radiologists, is required for adequate selection of patients considered for a CCT. At the current time, CCT has an important role as a diagnostic tool in ACHD patients with PPM or AICD or any other contraindicated metal implant in the body, and in those patients unable to tolerate a prolonged MRI study with contraindications for sedation or general anesthesia. CCT is also indicated and accurate when the evaluation of coronary artery anatomy and disease is required because of implications in the planning of surgical and catheter-based procedures. Beyond these indications, taking into consideration the risk of radiation and contrast exposure in young adults that may require frequent reassessment, the clinician needs to determine the indications for CCT as a first-line diagnostic procedure to answer clinical questions that other noninvasive tests cannot. As with any new diagnostic technique that becomes available for clinical use, there is need to define the role of CCT in the management of ACHD, with careful consideration of risk and benefits relative to more-established techniques such as echocardiography and cardiac MRI. Several questions need to be answered before CCT gains widespread use in ACHD: Does CCT have the potential to answer the clinical question? Will the results of the examination affect management? Are there alternative tests that may give the same answers without radiation exposure? To what degree can the radiation exposure be reduced? Is electrocardiographic gating necessary or could the clinical question be answered with a non-gated CCT? Welldesigned research studies are needed to answer these questions. Ignacio Inglessis, MD Adult Congenital Heart Disease Program MassGeneral Hospital Boston, MA, USA Suhny Abbara, MD Department of Radiology MassGeneral Hospital Boston, MA, USA Michael de Moor, MD* Pediatric Cardiology Division MassGeneral Hospital for Children 175 Cambridge Street, Boston, MA 01778, USA E-mail address: [email protected]
References 1. Warnes CA. The adult with congenital heart disease: born to be bad? J Am Coll Cardiol. 2005;46:1– 8.
Inglessis et al
Which diagnostic modality for ACHD?
2. Cook SC, Dyke PC 2nd, Raman SV. Management of adults with congenital heart disease with cardiovascular CT. J Cardiovasc Comput Tomogr. 2008;2:12–22. 3. Kaemmerer H, Stern H, Fratz S, Prokop M, Schwaiger M, Hess J. Imaging in adults with congenital heart disease. Thorac Cardiovasc Surg. 2000;48:328 –35. 4. Hirsch R, Kilner PJ, Connelly MS, Redington A, St John Sutton MG, Somerville J. Diagnosis in adolescents and adults with congenital heart disease. Prospective assessment of individual and combined roles of magnetic resonance imaging and transesophageal echocardiography. Circulation. 1994;90:2937–51.
25 5. Samyn MM. A review of the complementary information available with cardiac magnetic resonance imaging and multislice computed tomography (CT) during the study of congenital heart disease. Int J Cardiovasc Imaging. 2004;20:569 –78. 6. Nicol ED, Gatzoulis M, Padley SP, Rubens M. Assessment of adult congenital heart disease with multi-detector computed tomography: beyond coronary lumenography. Clin Radiol. 2007;62: 518 –27. 7. Einstein AJ, Henzlova MJ, Rajagopalan S. Estimating risk of cancer associated with radiation exposure from 64-slice computed tomography coronary angiography. JAMA. 2007;18;298:317–23.