- Email: [email protected]
Cardiac resynchronization therapy or sequential pacing in failing Mustard?
Available online at www.sciencedirect.com
Journal of Electrocardiology 44 (2011) 285 – 288 www.jecgonline.com
Cardiac resynchronization therapy or sequential pacing in failing Mustard? Giovanni Morani, MD, a,⁎ Giovanni Battista Luciani, MD, b Anna Manica, MD, c Maria Antonia Prioli, MD, a Lorenzo Franceschini, MD, a Ruggero Tomei, MD, a Corrado Vassanelli, MD a a
Division of Cardiology, University of Verona, Verona, Italy Division of Cardiac Surgery, University of Verona, Verona, Italy c U.O. Operativa di Cardiologia, Ospedale Santa Maria del Carmine, Rovereto, Italy Received 13 May 2010 b
Abstract
The atrial switch (Mustard, Senning procedures) was one of the treatments of choice for repair of transposition of the great arteries from the early 1960s to the mid-1980s. A significant proportion of patients with atrial switch develops systemic (right) ventricular failure. A series of surgical therapeutic options exists to manage cardiac failure in this setting, and, more recently proposed, cardiac resynchronization therapy. We describe case report of a 30-year-old woman with congenital heart disease (CHD) and previous Mustard procedure who underwent upgrading from single⁎chamber to dual-chamber pacemaker. The narrower native QRS did not correlate with a better synchrony status nor with a better cardiac output. Functional evaluation confirmed a better performance in DDD mode with short atrioventricular delay and broad QRS. Some echocardiographic and electrocardiographic parameters, such as ejection fraction and QRS duration, well established in adults' heart for selection of candidates to cardiac resynchronization therapy, are much less studied in CHD. Postoperative CHD may provide unique patterns of asynchrony with poorly predictable hemodynamic outcome. © 2011 Elsevier Inc. All rights reserved.
Keywords:
Cardiac resynchronization therapy; Sequential pacing; Mustard
Summary
Case report
The atrial switch (Mustard, Senning procedures) was one of the treatments of choice for repair of transposition of the great arteries (TGAs) from the early 1960s to the mid1980s.1,2 A significant proportion of patients with atrial switch develops systemic (right) ventricular failure late after surgery. A series of therapeutic options exists to manage cardiac failure in this setting, including late arterial switch after left ventricle (LV) retraining (pulmonary artery banding), cardiac transplantation, and, more recently proposed, cardiac resynchronization therapy (CRT). Some echocardiographic and electrocardiographic parameters, such as ejection fraction (EF) and QRS duration, well established in adults' heart for selection of candidates to CRT, are much less studied in congenital heart disease (CHD). Hemodynamic assessment of the systemic right ventricle (RV) is often difficult to establish, and there are no data in literature about relationship between QRS duration and ventricular function in this population.
A 30-year-old woman with previous Mustard procedure for TGA (performed elsewhere) and previous implant of a VVI pacemaker was referred to our center because a routine pacemaker interrogation revealed high impedance values and oversensing phenomenon indicative of damage of the lead. At the age of 4 months, she had undergone Blalock-Hanlon atrial septectomy and, 8 months later, Mustard procedure, with good surgical outcome. Unfortunately, she experienced significant perioperative neurologic anoxic injury, thus requiring continuous support in common daily activities. At age 16 years, single-chamber pacemaker was implanted because of extreme sinus bradycardia (heart rate at rest less than 30 beats per minute [bpm]). Due to the anatomy, the catheter was positioned in the left ventricular apex. The device was then programmed in VVIR mode 50 to 120 bpm. Pacemaker interrogation, on admission, showed a percentage of ventricular pacing of 99%, with an average rate of 70 bpm. Clinically, the patient was unable to perform mild exercise (New York Heart Association [NYHA] class III) and showed exercise hemoglobin desaturation at 6-minute walking test (SpO2 from 90% baseline to 78% after 121
⁎ Corresponding author. Division of Cardiology, Ospedale Civile Maggiore, P.le Stefani 1 37100 Verona Italy. E-mail address: [email protected] 0022-0736/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.jelectrocard.2010.07.010
286
G. Morani et al. / Journal of Electrocardiology 44 (2011) 285–288
meters and heart rate from 66/min to 72/min). The ECG showed pacemaker-induced rhythm with broad (222 milliseconds) QRS complex right bundle branch block (RBBB) like and a retrograde P wave. Laboratory results revealed only increase in γGT. The chest film on admission showed presence of pacemaker in right pectoral pouch, with a single lead projecting in left ventricular apex and cardiomegaly. The echocardiogram showed the results of Mustard procedure: systemic RV connected with aorta and LV connected with pulmonary artery; pulmonary artery hypertension; and biventricular dysfunction, but predominantly severe systemic RV dysfunction (EF 30%), were present. The patient underwent a procedure of upgrading from single-chamber to dual-chamber pacemaker implantation via subclavian vein, with steroid eluting bipolar screw-in transvenous leads, respectively, positioned in left atrium and on the endocardial surface of left ventricular free wall without complications (Figs. 1 and 2). Device was switched from VVIR to DDDR (with long atrioventricular delay up to 300 milliseconds) to obtain sequential pacing with native QRS complex narrower (110 milliseconds) than before (222 milliseconds). The percentage of ventricular stimulation decreased from 100% to 1% 1 week later. However, after 3 weeks, the NYHA class did not show any improvement and the cycle ergometer stress test confirmed a poor performance. A tissue Doppler imaging evaluation showed, despite a narrow native QRS, a marked intraventricular dyssynchrony (measured as delay between the systolic shortening of the lateral free wall of RV compared with septal wall). With LV pacing, generating an electrically stimulated broad QRS (220 milliseconds), the intraventricular dyssynchrony was unexpectedly reduced and cardiac output (CO) improved. In fact, the echo-Doppler evaluation of CO showed a better result in DDDR mode (with broad stimulated QRS ) than in AAIR mode (data obtained during continuous varying of device setting without changing echocardiographic window; Figs. 3 and 4).
Fig. 2. Left Anerior Oblique view after procedure.
Therefore, the device setting was varied to obtain a stimulated QRS ( DDDR 50-120 bpm with short atrioventricular delay to avoid intrinsic conduction and fusion phenomenon). A subsequent clinical evaluation, 2 weeks later, showed a better functional class (from NHYA 3 to 2) and an appreciable improvement of performance at stress test (Table 1). Improvement of exercise tolerance allowed the patient a relief of symptoms during her daily activity, and so we decided, considering the neurologic status, to postpone the possible upgrading to epicardial biventricular system.
Discussion
Fig. 1. Right Anerior Oblique view after procedure.
The arterial switch operation (Jatene anatomic repair) during the neonatal period is the technique of choice for TGA. However, from the early 1960s to the mid-1980s, the Mustard and Senning procedures (atrial switch) were the standard treatment for TGA.1 In the Mustard procedure, caval venous return is redirected to the LV and pulmonary venous returns to the RV.2 This type of congenital disease, as many other with systemic RV, leads to long-term complication consisting of RV rather than LV failure, as a consequence of chronic volume and pressure overload.3 Right ventricle failure is less studied and poorly understood than LV failure. Clearly, a new surgical option, including late double switch, palliative pulmonary artery banding or even heart transplantation represents a last resort choice. One of the most interesting therapeutic options in CHD with heart failure and in failing Mustard is CRT, a wellestablished therapeutic option in adults with LV failure and broad QRS.4
G. Morani et al. / Journal of Electrocardiology 44 (2011) 285–288
287
Fig. 3. Comparison of Cardiac Output obtained in different pacing mode (DDD versus AAI).
The technical approach generally consists in a hybrid implantation with an endocardial placement of the lead in the left atrium and ventricle and the right chamber stimulation is
generally provided by an epicardial lead placed via thoracotomy. There are some data in the literature supporting the benefit of biventricular pacing, which seems to improve
Fig. 4. Comparison of dyssynchrony (see text for details) in differenct pacing mode (DDDR versus AAIR).
288
G. Morani et al. / Journal of Electrocardiology 44 (2011) 285–288
Table 1 Comparison of principal parameters in different pacing mode (AAIR versus DDDR) Electrocardiographic and echocardiographic baseline measurements
AAIR pacing mode 50-120 bpm
DDDR pacing mode 50-120 bpm
QRS duration
110 ms (spontaneous) 106 ms
220 ms (electrically stimulated) 20 ms
1.1 m/s 10-W/min load
1.5 m/s 10-W/min/load
65 bpm 110/70 mm Hg 85%
60 bpm 115/70 mm Hg 88%
91 bpm 120/80 mm Hg 76%
79 bpm 125/80 mm Hg 78%
110 bpm 130/80 mm Hg 68%
102 bpm 130/80 mm Hg 75%
–
110 bpm 140/80 mm Hg 70% II
TDI (delay between systolic shortening of lateral wall of RV and septal wall) CO Cycle ergometer Basal parameters Heart rate (HR) Blood pressure (BP) Oximetry (Spo2) Phase 1 (1 min) HR BP Oximetry (Spo2) Phase 2 (2 min) HR BP Oximetry (Spo2) Phase 3 (3 min) HR BP Oximetry (Spo2) NYHA class
Mustard but may improve cardiac performance. The result is probably an exception rather than a rule, but seems to indicate that an accurate echocardiographic evaluation should be accompanied by a functional evaluation to chose the best pacing mode. A functional evaluation might be the necessary complement to verify the real hemodynamic impact of variations in pacing mode or to assess the hemodynamic outcome of different synchrony status. Conclusion
III
EF and functional status, in many patients with CHD and systemic RV dysfunctioning or heart failure.5-7 Tissue Doppler imaging seems to have greater sensitivity, than QRS duration, to the detection of dyssynchrony in CHD.8 The literature, on the whole, seems to indicate that CRT may be better than conventional single-chamber pacing that, likewise in adult hearts, could cause electromechanical dyssynchrony and worsen prognosis.9,10 However, there are some unresolved issues that may help to explain the unpredictable adverse outcome to CRT observed by some authors.11 The population examined, in above-mentioned studies, is too heterogeneous, comprehending various types of CHD, to have conclusive data about outcome of CRT in CHD. The impact of RBBB on mechanical asynchrony in CHD is not easily comparable with that of LBBB in adult heart disease and M-mode, 2D, Tissue Doppler imaging, well established for structurally normal hearts, might not be equally appropriate for dyssynchrony assessment in patients with systemic RV.12 In our case, the native QRS, incomplete RBBB, was far most narrow than the electrically stimulated complex, but the QRS duration did not correlate with electromechanical synchronization nor provided a better ventricular performance. Our case report highlights the question of the difficult evaluation of electromechanical complexity in CHD and poor reliability of QRS duration as a marker of dyssynchrony, with its inherent problem regarding selection of candidates to CRT. Sequential atrioventricular pacing, exceptionally, not only does not affect negatively exercise capacity in failing
Congenital heart disease involves an heterogeneous population so that data deriving from CRT in heart failure of structurally normal hearts are not totally reliable. Most of available literature consists of observational, retrospective studies, or case reports. There is no randomized study, and the population examined is often small or heterogeneous. The peculiar anatomy and technique of surgical repair often introduce additional changes in cardiac anatomy and hemodynamic load contributing to the development of unique form of asynchrony. Individualized management can guide the operator toward the best possible choice of pacing. A postoperative functional evaluation may be essential to verify the real benefit of the best, theoretical, choice. References 1. Senning A. Surgical correction of transportation of the great vessel. Surgery 1959;45:966. 2. Mustard WT. Successful two-stage correction of transposition of the great vessel. Surgery 1964;55:469. 3. Piran S, Veldtman G, Siu S, Webb GD, Liu PP. Heart failure and ventricular dysfunction in patients with single or systemic right ventricles. Circulation 2002;105:1189. 4. Dubin AM, Janousek J, Rhee E, et al. Resynchronization therapy in pediatric and congenital heart disease patients. An international multicenter study. J Am Coll Cardiol 2005;46:2277. 5. Janousek J, Tomek V, Chaloupecky V, et al. Cardiac resynchronization therapy: a novel adjunct to the treatment and prevention of systemic right ventricular failure. J Am Coll Cardiol 2004;44:1927. 6. Zimmermann FJ, Starr JP, Koenig PR, Smith P, Hijazi ZM, Bacha EA. Acute hemodynamic benefit of multisite ventricular pacing after congenital heart surgery. Ann Thorac Surg 2003;75:1775. 7. Dubin AM, Feinstein JA, Reddy VM, Hanley FL, Van Hare GF, Rosenthal DN. Electrical resynchronization. A novel therapy for the failing right ventricle. Circulation 2003;107:2287. 8. Pham PP, Balaji S, Shen I, Ungerleider R, Li X, Sahn DJ. Impact of conventional versus biventricular pacing on hemodynamics and tissue Doppler imaging indexes of resynchronization postoperatively in children with congenital heart disease. J Am Coll Cardiol 2005;46:2284. 9. Tantengco MV, Thomas RL, Karpawich PP. Left ventricular dysfunction after long-term right ventricular apical pacing in the young. J Am Coll Cardiol 2001;37:2093. 10. Kindermann M, Hennen B, Jung J, Jeisel J, Bohm M, Frohlig G. Biventricular versus conventional right ventricular stimulation for patients with standard pacing indication and left ventricular dysfunction (HOBIPACE). J Am Coll Cardiol 2006;47:1927. 11. Kiesewetter C, Michael K, Morgan J, Veldtman G. Left ventricular dysfunction after cardiac resynchronization therapy in congenital heart disease patients with a failing systemic right ventricle. PACE 2008; 31:159. 12. Diller GP, Okonko D, Uebing A, Yen Ho S, Gatzoulis MA. Cardiac resynchronization therapy for adult congenital heart disease patients with a systemic right ventricle: analysis of feasibility and review of early experience. Europace 2006;8:267.
Journal of Electrocardiology 44 (2011) 285 – 288 www.jecgonline.com
Cardiac resynchronization therapy or sequential pacing in failing Mustard? Giovanni Morani, MD, a,⁎ Giovanni Battista Luciani, MD, b Anna Manica, MD, c Maria Antonia Prioli, MD, a Lorenzo Franceschini, MD, a Ruggero Tomei, MD, a Corrado Vassanelli, MD a a
Division of Cardiology, University of Verona, Verona, Italy Division of Cardiac Surgery, University of Verona, Verona, Italy c U.O. Operativa di Cardiologia, Ospedale Santa Maria del Carmine, Rovereto, Italy Received 13 May 2010 b
Abstract
The atrial switch (Mustard, Senning procedures) was one of the treatments of choice for repair of transposition of the great arteries from the early 1960s to the mid-1980s. A significant proportion of patients with atrial switch develops systemic (right) ventricular failure. A series of surgical therapeutic options exists to manage cardiac failure in this setting, and, more recently proposed, cardiac resynchronization therapy. We describe case report of a 30-year-old woman with congenital heart disease (CHD) and previous Mustard procedure who underwent upgrading from single⁎chamber to dual-chamber pacemaker. The narrower native QRS did not correlate with a better synchrony status nor with a better cardiac output. Functional evaluation confirmed a better performance in DDD mode with short atrioventricular delay and broad QRS. Some echocardiographic and electrocardiographic parameters, such as ejection fraction and QRS duration, well established in adults' heart for selection of candidates to cardiac resynchronization therapy, are much less studied in CHD. Postoperative CHD may provide unique patterns of asynchrony with poorly predictable hemodynamic outcome. © 2011 Elsevier Inc. All rights reserved.
Keywords:
Cardiac resynchronization therapy; Sequential pacing; Mustard
Summary
Case report
The atrial switch (Mustard, Senning procedures) was one of the treatments of choice for repair of transposition of the great arteries (TGAs) from the early 1960s to the mid1980s.1,2 A significant proportion of patients with atrial switch develops systemic (right) ventricular failure late after surgery. A series of therapeutic options exists to manage cardiac failure in this setting, including late arterial switch after left ventricle (LV) retraining (pulmonary artery banding), cardiac transplantation, and, more recently proposed, cardiac resynchronization therapy (CRT). Some echocardiographic and electrocardiographic parameters, such as ejection fraction (EF) and QRS duration, well established in adults' heart for selection of candidates to CRT, are much less studied in congenital heart disease (CHD). Hemodynamic assessment of the systemic right ventricle (RV) is often difficult to establish, and there are no data in literature about relationship between QRS duration and ventricular function in this population.
A 30-year-old woman with previous Mustard procedure for TGA (performed elsewhere) and previous implant of a VVI pacemaker was referred to our center because a routine pacemaker interrogation revealed high impedance values and oversensing phenomenon indicative of damage of the lead. At the age of 4 months, she had undergone Blalock-Hanlon atrial septectomy and, 8 months later, Mustard procedure, with good surgical outcome. Unfortunately, she experienced significant perioperative neurologic anoxic injury, thus requiring continuous support in common daily activities. At age 16 years, single-chamber pacemaker was implanted because of extreme sinus bradycardia (heart rate at rest less than 30 beats per minute [bpm]). Due to the anatomy, the catheter was positioned in the left ventricular apex. The device was then programmed in VVIR mode 50 to 120 bpm. Pacemaker interrogation, on admission, showed a percentage of ventricular pacing of 99%, with an average rate of 70 bpm. Clinically, the patient was unable to perform mild exercise (New York Heart Association [NYHA] class III) and showed exercise hemoglobin desaturation at 6-minute walking test (SpO2 from 90% baseline to 78% after 121
⁎ Corresponding author. Division of Cardiology, Ospedale Civile Maggiore, P.le Stefani 1 37100 Verona Italy. E-mail address: [email protected] 0022-0736/$ – see front matter © 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.jelectrocard.2010.07.010
286
G. Morani et al. / Journal of Electrocardiology 44 (2011) 285–288
meters and heart rate from 66/min to 72/min). The ECG showed pacemaker-induced rhythm with broad (222 milliseconds) QRS complex right bundle branch block (RBBB) like and a retrograde P wave. Laboratory results revealed only increase in γGT. The chest film on admission showed presence of pacemaker in right pectoral pouch, with a single lead projecting in left ventricular apex and cardiomegaly. The echocardiogram showed the results of Mustard procedure: systemic RV connected with aorta and LV connected with pulmonary artery; pulmonary artery hypertension; and biventricular dysfunction, but predominantly severe systemic RV dysfunction (EF 30%), were present. The patient underwent a procedure of upgrading from single-chamber to dual-chamber pacemaker implantation via subclavian vein, with steroid eluting bipolar screw-in transvenous leads, respectively, positioned in left atrium and on the endocardial surface of left ventricular free wall without complications (Figs. 1 and 2). Device was switched from VVIR to DDDR (with long atrioventricular delay up to 300 milliseconds) to obtain sequential pacing with native QRS complex narrower (110 milliseconds) than before (222 milliseconds). The percentage of ventricular stimulation decreased from 100% to 1% 1 week later. However, after 3 weeks, the NYHA class did not show any improvement and the cycle ergometer stress test confirmed a poor performance. A tissue Doppler imaging evaluation showed, despite a narrow native QRS, a marked intraventricular dyssynchrony (measured as delay between the systolic shortening of the lateral free wall of RV compared with septal wall). With LV pacing, generating an electrically stimulated broad QRS (220 milliseconds), the intraventricular dyssynchrony was unexpectedly reduced and cardiac output (CO) improved. In fact, the echo-Doppler evaluation of CO showed a better result in DDDR mode (with broad stimulated QRS ) than in AAIR mode (data obtained during continuous varying of device setting without changing echocardiographic window; Figs. 3 and 4).
Fig. 2. Left Anerior Oblique view after procedure.
Therefore, the device setting was varied to obtain a stimulated QRS ( DDDR 50-120 bpm with short atrioventricular delay to avoid intrinsic conduction and fusion phenomenon). A subsequent clinical evaluation, 2 weeks later, showed a better functional class (from NHYA 3 to 2) and an appreciable improvement of performance at stress test (Table 1). Improvement of exercise tolerance allowed the patient a relief of symptoms during her daily activity, and so we decided, considering the neurologic status, to postpone the possible upgrading to epicardial biventricular system.
Discussion
Fig. 1. Right Anerior Oblique view after procedure.
The arterial switch operation (Jatene anatomic repair) during the neonatal period is the technique of choice for TGA. However, from the early 1960s to the mid-1980s, the Mustard and Senning procedures (atrial switch) were the standard treatment for TGA.1 In the Mustard procedure, caval venous return is redirected to the LV and pulmonary venous returns to the RV.2 This type of congenital disease, as many other with systemic RV, leads to long-term complication consisting of RV rather than LV failure, as a consequence of chronic volume and pressure overload.3 Right ventricle failure is less studied and poorly understood than LV failure. Clearly, a new surgical option, including late double switch, palliative pulmonary artery banding or even heart transplantation represents a last resort choice. One of the most interesting therapeutic options in CHD with heart failure and in failing Mustard is CRT, a wellestablished therapeutic option in adults with LV failure and broad QRS.4
G. Morani et al. / Journal of Electrocardiology 44 (2011) 285–288
287
Fig. 3. Comparison of Cardiac Output obtained in different pacing mode (DDD versus AAI).
The technical approach generally consists in a hybrid implantation with an endocardial placement of the lead in the left atrium and ventricle and the right chamber stimulation is
generally provided by an epicardial lead placed via thoracotomy. There are some data in the literature supporting the benefit of biventricular pacing, which seems to improve
Fig. 4. Comparison of dyssynchrony (see text for details) in differenct pacing mode (DDDR versus AAIR).
288
G. Morani et al. / Journal of Electrocardiology 44 (2011) 285–288
Table 1 Comparison of principal parameters in different pacing mode (AAIR versus DDDR) Electrocardiographic and echocardiographic baseline measurements
AAIR pacing mode 50-120 bpm
DDDR pacing mode 50-120 bpm
QRS duration
110 ms (spontaneous) 106 ms
220 ms (electrically stimulated) 20 ms
1.1 m/s 10-W/min load
1.5 m/s 10-W/min/load
65 bpm 110/70 mm Hg 85%
60 bpm 115/70 mm Hg 88%
91 bpm 120/80 mm Hg 76%
79 bpm 125/80 mm Hg 78%
110 bpm 130/80 mm Hg 68%
102 bpm 130/80 mm Hg 75%
–
110 bpm 140/80 mm Hg 70% II
TDI (delay between systolic shortening of lateral wall of RV and septal wall) CO Cycle ergometer Basal parameters Heart rate (HR) Blood pressure (BP) Oximetry (Spo2) Phase 1 (1 min) HR BP Oximetry (Spo2) Phase 2 (2 min) HR BP Oximetry (Spo2) Phase 3 (3 min) HR BP Oximetry (Spo2) NYHA class
Mustard but may improve cardiac performance. The result is probably an exception rather than a rule, but seems to indicate that an accurate echocardiographic evaluation should be accompanied by a functional evaluation to chose the best pacing mode. A functional evaluation might be the necessary complement to verify the real hemodynamic impact of variations in pacing mode or to assess the hemodynamic outcome of different synchrony status. Conclusion
III
EF and functional status, in many patients with CHD and systemic RV dysfunctioning or heart failure.5-7 Tissue Doppler imaging seems to have greater sensitivity, than QRS duration, to the detection of dyssynchrony in CHD.8 The literature, on the whole, seems to indicate that CRT may be better than conventional single-chamber pacing that, likewise in adult hearts, could cause electromechanical dyssynchrony and worsen prognosis.9,10 However, there are some unresolved issues that may help to explain the unpredictable adverse outcome to CRT observed by some authors.11 The population examined, in above-mentioned studies, is too heterogeneous, comprehending various types of CHD, to have conclusive data about outcome of CRT in CHD. The impact of RBBB on mechanical asynchrony in CHD is not easily comparable with that of LBBB in adult heart disease and M-mode, 2D, Tissue Doppler imaging, well established for structurally normal hearts, might not be equally appropriate for dyssynchrony assessment in patients with systemic RV.12 In our case, the native QRS, incomplete RBBB, was far most narrow than the electrically stimulated complex, but the QRS duration did not correlate with electromechanical synchronization nor provided a better ventricular performance. Our case report highlights the question of the difficult evaluation of electromechanical complexity in CHD and poor reliability of QRS duration as a marker of dyssynchrony, with its inherent problem regarding selection of candidates to CRT. Sequential atrioventricular pacing, exceptionally, not only does not affect negatively exercise capacity in failing
Congenital heart disease involves an heterogeneous population so that data deriving from CRT in heart failure of structurally normal hearts are not totally reliable. Most of available literature consists of observational, retrospective studies, or case reports. There is no randomized study, and the population examined is often small or heterogeneous. The peculiar anatomy and technique of surgical repair often introduce additional changes in cardiac anatomy and hemodynamic load contributing to the development of unique form of asynchrony. Individualized management can guide the operator toward the best possible choice of pacing. A postoperative functional evaluation may be essential to verify the real benefit of the best, theoretical, choice. References 1. Senning A. Surgical correction of transportation of the great vessel. Surgery 1959;45:966. 2. Mustard WT. Successful two-stage correction of transposition of the great vessel. Surgery 1964;55:469. 3. Piran S, Veldtman G, Siu S, Webb GD, Liu PP. Heart failure and ventricular dysfunction in patients with single or systemic right ventricles. Circulation 2002;105:1189. 4. Dubin AM, Janousek J, Rhee E, et al. Resynchronization therapy in pediatric and congenital heart disease patients. An international multicenter study. J Am Coll Cardiol 2005;46:2277. 5. Janousek J, Tomek V, Chaloupecky V, et al. Cardiac resynchronization therapy: a novel adjunct to the treatment and prevention of systemic right ventricular failure. J Am Coll Cardiol 2004;44:1927. 6. Zimmermann FJ, Starr JP, Koenig PR, Smith P, Hijazi ZM, Bacha EA. Acute hemodynamic benefit of multisite ventricular pacing after congenital heart surgery. Ann Thorac Surg 2003;75:1775. 7. Dubin AM, Feinstein JA, Reddy VM, Hanley FL, Van Hare GF, Rosenthal DN. Electrical resynchronization. A novel therapy for the failing right ventricle. Circulation 2003;107:2287. 8. Pham PP, Balaji S, Shen I, Ungerleider R, Li X, Sahn DJ. Impact of conventional versus biventricular pacing on hemodynamics and tissue Doppler imaging indexes of resynchronization postoperatively in children with congenital heart disease. J Am Coll Cardiol 2005;46:2284. 9. Tantengco MV, Thomas RL, Karpawich PP. Left ventricular dysfunction after long-term right ventricular apical pacing in the young. J Am Coll Cardiol 2001;37:2093. 10. Kindermann M, Hennen B, Jung J, Jeisel J, Bohm M, Frohlig G. Biventricular versus conventional right ventricular stimulation for patients with standard pacing indication and left ventricular dysfunction (HOBIPACE). J Am Coll Cardiol 2006;47:1927. 11. Kiesewetter C, Michael K, Morgan J, Veldtman G. Left ventricular dysfunction after cardiac resynchronization therapy in congenital heart disease patients with a failing systemic right ventricle. PACE 2008; 31:159. 12. Diller GP, Okonko D, Uebing A, Yen Ho S, Gatzoulis MA. Cardiac resynchronization therapy for adult congenital heart disease patients with a systemic right ventricle: analysis of feasibility and review of early experience. Europace 2006;8:267.