Case Report
Staged Left Ventricular Recruitment and Biventricular Conversion in Hypoplastic Left Heart Syndrome
World Journal for Pediatric and Congenital Heart Surgery 2014, Vol. 5(3) 449-452 ª The Author(s) 2014 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/2150135113519453 pch.sagepub.com
James M. Hammel, MD1, Aswathy Vaikom House, MD2, David A. Danford, MD2, and Shelby Kutty, MD2
Abstract We describe a relatively long left ventricular recruitment pathway consisting of early and serial aortic valvuloplasties and multiple endocardial fibroelastosis resections resulting in successful biventricular conversion of hypoplastic left heart syndrome. Keywords pediatric cardiology, hypoplastic left heart, left ventricular rehabilitation Submitted October 03, 2013; Accepted December 13, 2013.
Case Report Hypoplastic left heart syndrome (HLHS) and its variants with borderline left ventricle (LV) represent a spectrum of different degrees of left heart abnormalities and hypoplasia. A term newborn (birth weight 3.73 kg) presented on the first day of life with murmur and labored breathing. Twodimensional echocardiography (2DE) revealed a hypoplastic LV with mitral and aortic valve hypoplasia. Detailed 2DE after initiation of prostaglandin E1 demonstrated a nonapex-forming LV with a longitudinal dimension of 1.75 cm, and LV enddiastolic volume of 2.41 mL (10.5 mL/m2, z ¼ 5.7). There was severe and extensive endocardial fibroelastosis (EFE) and severely depressed systolic function (LV shortening fraction 15%). The aortic valve was unicuspid with an annular diameter of 0.5 cm (z ¼ 3.5). The mitral valve was nondysplastic and without leaflet fusion but small with annulus diameter of 0.74 cm (z ¼ 3.4). Because the LV appeared somewhat larger than usual for HLHS, cardiac magnetic resonance (CMR) was performed to quantitate LV volume and EFE. The indexed LV end-diastolic volume was 8 mL/m2, and late gadolinium enhancement (LGE) consistent with EFE was present. For EFE scoring, the areas of LGE were manually contoured on each short-axis slice using the QMASS 7.2 software (Medis, Leiden, the Netherlands). The LGE/EFE volume, calculated by adding the planimetered areas of EFE in all short-axis slices, was 4.4 g. The EFE volume expressed as a proportion of total LV myocardium (% scar) was 32%. As the LV size appeared inadequate for initial two-ventricle reconstruction, the patient underwent Norwood operation with Sano modification utilizing cardiopulmonary bypass and cold
blood cardioplegia. The LV EFE was sharply resected, working through the mitral valve, and aortic valvotomy was performed through an oblique aortotomy using a corneal/scleral knife (Alcon Medical, Fort Worth, Texas). The atrial septal communication was closed with glutaraldehyde-fixed autologous pericardial patch leaving a 3.5-mm fenestration that produced a deliberate left atrial (LA) to right atrial (RA) gradient of 4 to 5 mm Hg on intraoperative 2DE. The infant had an uneventful recovery from this operation. The LV dimensions and function were closely observed with serial transthoracic 2DE. Cardiac catheterization at one month of age revealed LA pressure of 8 mm Hg, RA pressure of 4 mm Hg, and indexed pulmonary vascular resistance (PVRi) of 2.7 Wood units.m2. At five months of age, the infant was evaluated for second-stage palliation. Cardiac catheterization demonstrated mean LA pressure of 19, RA pressure of 6, and PVRi of 2.1 Wood units.m2. The patient underwent bidirectional cavopulmonary anastomosis, repeat transmitral LV EFE resection as well as repeat aortic valvotomy. The pulmonary arterial pressures were 12 mm Hg
1 Division of Cardiovascular Surgery, University of Nebraska Medical Center College of Medicine, and Children’s Hospital and Medical Center, Omaha, NE, USA 2 Division of Pediatric Cardiology, University of Nebraska Medical Center College of Medicine, and Children’s Hospital and Medical Center, Omaha, NE, USA
Corresponding Author: Shelby Kutty, University of Nebraska/Creighton University, Children’s Hospital and Medical Center, 8200 Dodge St, Omaha, NE 68114, USA. Email: [email protected]
Downloaded from pch.sagepub.com at UZH Hauptbibliothek / Zentralbibliothek Zürich on December 29, 2014
450
World Journal for Pediatric and Congenital Heart Surgery 5(3)
Abbreviations and Acronyms CMR EFE EF HLHS LA LV LGE PVRi RA 2DE
cardiovascular magnetic resonance endocardial fibroelastosis ejection fraction hypoplastic left heart syndrome left atrial left ventricle late gadolinium enhancement indexed pulmonary vascular resistance right atrial Two-dimensional echocardiography
intraoperatively despite the deliberate elevation in LA pressure (due to the restrictive atrial septal patch) in the preceding months. The recovery was uneventful after surgery. The LV volume was observed again to increase (17, 20, and 24 mL/ m2, respectively, on serial CMR at 4, 6, and 12 months) and LV systolic function that was initially depressed returned to normal (ejection fraction 67%) by 12 months of age. The atrial septal communication closed spontaneously at about 18 months of age. Pulmonary blood flow remained adequate through the bidirectional cavopulmonary circulation based on clinical status and systemic oxygen saturations. Scoring of EFE on serial short-axis CMR images of the LV is shown in Figure 1. At 23 months of age, cardiac catheterization was performed to evaluate for conversion to biventricular circulation. The mean pulmonary artery pressure was 15 mm Hg, LV end-diastolic pressure was 17 mm Hg, RA mean pressure was 5 mm Hg, and PVRi was 2.5 Wood units.m2, but the LV was found to be very sensitive to volume changes, suggestive of continued restrictive physiology. Therefore, an interval procedure consisting of resection (third time) of EFE and aortic valvotomy was performed and a right ventricle to pulmonary artery nonvalved conduit was added to increase LV volume load. Systemic arterial oxygen saturations (%) rose to mid 90’s after the procedure. At 33 months of age, CMR demonstrated increase in the LV end-diastolic volume to 48 mL/m2. At this time, the patient underwent conversion to biventricular circulation. The Damus-Kaye-Stansel neoaortic arch was taken down, the pulmonary root was reanastomosed to the pulmonary bifurcation and the cavopulmonary anastomosis was taken down. The patient was extubated in the operating room after surgery and was discharged on the sixth postoperative day. Figure 2 shows parasternal long-axis 2DE images demonstrating LV growth. The patient is presently thriving at 4.3 years of age, 20 months after biventricular conversion. Left ventricular function remains hyperdynamic (ejection fraction [EF] 70%) by 2DE, and the patient has excellent exercise tolerance.
Comment Different strategies for recruitment and conversion to biventricular circulation have been reported for the borderline LV.1-6 For example, in a case reported by Moon-Grady et al, fetal and postnatal balloon aortic valvuloplasty and early postnatal hybrid stage I palliation were performed as the initial steps of LV
Figure 1. Manual contouring of the endocardial border (inner circle; red line) and epicardial border (outer circle; green line) was performed for volumetric and functional quantification of the LV and calculation of EFE burden. Panels A, B, C and, D show images at birth, 6, 12, and 22 months, respectively. Note the large and confluent area of EFE (shaded area) with high signal intensity of late gadolinium enhancement. The percentage of EFE and ventricular mass is expressed. LV indicates left ventricle; LGE, late gadolinium enhancement; EFE, endocardial fibroelastosis.
rehabilitation.2 This was followed by surgical takedown of the hybrid and conversion to biventricular circulation by adding Ross-Konno procedure and aortic arch reconstruction to the EFE resection.2 In the present case, without fetal intervention a complete aortic valvotomy in the newborn period led to successful LV recruitment. In selected patients with potential for LV growth, surgical valvotomy by direct visualization offers both a precise valvotomy and the opportunity to excise EFE tissue.3 The staged LV recruitment approach described in this case allowed for repeat surgical aortic valvuloplasty, giving time for improved transaortic flow, annular growth, and potentially aortic leaflet growth. Although aortic incompetence is less likely to be a significant issue prior to biventricular conversion (immediate performance of this valve is not required), avoiding residual aortic stenosis may help reduce EFE burden or EFE recurrence. Importantly, Ross operation was avoided in this patient although the aortic valve was initially inadequate. A Ross operation would have committed the patient to future right ventricle to pulmonary artery conduit replacements and would have risked late neoaortic root dilation with autograft valve dysfunction. We created a deliberately restrictive atrial communication at the initial neonatal palliation procedure to foster LV growth by increasing LV filling pressure. A transseptal gradient of 5 mm Hg (as in our case) following initial surgery is considered appropriate in this setting.1 Our case demonstrates that uncomplicated recovery from the Norwood-Sano procedure is possible with a deliberately elevated LA pressure. Balloon dilation
Downloaded from pch.sagepub.com at UZH Hauptbibliothek / Zentralbibliothek Zürich on December 29, 2014
Hammel et al
451
Figure 2. Two-dimensional echocardiographic images in parasternal long axis demonstrating growth of the LV. Panels A, B, and C show images at 1 month, 8 months, and 23 months (between surgical steps), and panel D shows image at 34 months (after biventricular repair). LV indicates left ventricle; RV, right ventricle; LA, left atrium; AO, aorta.
of the atrial communication was not needed to relieve LA hypertension at any time during follow-up. Furthermore, atrial septal restriction did not appear to complicate recovery from the superior cavopulmonary anastomosis procedure nor did it produce an unacceptably high PVRi. In contrast to the strategy described by Moon-Grady et al,2 we performed EFE resection in combination with the Norwood-Sano procedure. Others have reported that LV rehabilitation during the neonatal period can be challenging due to the difficulty of EFE resection and mitral valve repair through a small mitral valve orifice.4 In our experience, EFE resection can be performed safely in the newborn period working through a hypoplastic mitral valve, and early resection is potentially beneficial to promote LV recruitment and increase LV volume. We believe that volume development of the LV cannot be as effective until the EFE that restricts LV filling is removed; the earlier this can occur, the better. Mitral valve injury and mitral regurgitation are potential problems with early EFE resection; however, if the regurgitation created was minimal, it would not be necessarily a great harm as long as the LV is able to eject at a systemic pressure. Moreover, the recovery of LV diastolic function with early EFE resection could help reduce LA and pulmonary pressures. The present case also highlights the utility of repeat resection of EFE in subsequent surgeries. These repeat resections were tolerated well, and there was progressive reduction in EFE burden and increase in LV volume. In locations of previously resected EFE, the EFE layer was qualitatively thinner and
more elastic than the initial layer. We speculate that the myocardium immediately beneath the EFE layer is probably less healthy compared to normal myocardium, and some of it presumably undergoes fibrosis. In addition, the subendocardial capillary distribution is abnormal in these locations, probably subjecting the remaining myocardium to greater risk. These observations on EFE in previously resected areas are similar to the description by Emani et al.4 On follow-up of our case after biventricular repair, minimal EFE was seen in the basal septal aspect of the LV. Our patient did not have mitral valve dysplasia. Poor mitral valve mobility would have complicated management, and a different strategy with surgical mitral valvuloplasties or multiple mitral leaflet augmentations would have been required. Mitral stenosis may be a greater threat to the success of LV recruitment than mitral regurgitation, provided LV systolic pressure can be maintained at systemic levels. We use serial CMR to monitor the progress of LV recruitment. The LV response seen after EFE resection in this case is noteworthy. The greatest increase in left heart dimensions was noted following the bidirectional cavopulmonary anastomosis procedure, and this is consistent with the observations of others.1 In HLHS variants, an LV end-diastolic volume 30 mL/m2 was associated with successful conversion, while the minimum was 22 mL/m2 in an atrioventricular septal defect group who underwent successful conversion.1,5 With each EFE resection, change in EF was noted in our case; therefore, onestep resection may not produce optimal LV recruitment. If the
Downloaded from pch.sagepub.com at UZH Hauptbibliothek / Zentralbibliothek Zürich on December 29, 2014
452
World Journal for Pediatric and Congenital Heart Surgery 5(3)
early course of LV recruitment is satisfactory, and the patient is progressing well along the path of eventual biventricular circulation, the bidirectional cavopulmonary anastomosis could be avoided but replacing the Sano conduit with a larger restrictive valved conduit may be necessary. In conclusion, a CMR-guided relatively long LV recruitment pathway with early and serial aortic valvuloplasties, and multiple EFE resections enabled successful biventricular conversion in this patient with HLHS. This approach is limited to a small subset of patients with HLHS, and absence of mitral dysplasia in our case allowed EFE resection at the neonatal operation. Despite the extremely favorable outcome in this carefully selected case, the results of a more general application of these methods to the problem of LV hypoplasia remain uncertain at best. Therefore, longer follow-up and larger experience are required to determine the ultimate impact of this strategy, particularly its effects on LV growth and performance in the long term. Choice of surgical strategy will depend on careful analysis of the relative merits and risks of the Fontan palliation versus LV recruitment. Acknowledgments The authors thank Ling Li, MD, PhD, for her assistance with the preparation of the figures.
Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.
References 1. Emani SM, del Nido PJ. Strategies to maintain biventricular circulation in patients with high-risk anatomy. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2013;16(1): 37-42. 2. Moon-Grady AJ, Moore P, Azakie A. Ross-Konno and endocardial fibroelastosis resection after hybrid stage I palliation in infancy: successful staged left-ventricular rehabilitation and conversion to biventricular circulation after fetal diagnosis of aortic stenosis. Pediatr Cardiol. 2011;32(2): 211-214. 3. Hammel JM, Duncan KF, Danford DA, Kutty S. Two-stage biventricular rehabilitation for critical aortic stenosis with severe left ventricular dysfunction. Eur J Cardiothorac Surg. 2013;43(1): 143-148. 4. Emani SM, Bacha EA, McElhinney DB, et al. Primary left ventricular rehabilitation is effective in maintaining two-ventricle physiology in the borderline left heart. J Thorac Cardiovasc Surg. 2009;138(6): 1276-1282. 5. Nathan M, Liu H, Pigula FA, et al. Biventricular conversion after single-ventricle palliation in unbalanced atrioventricular canal defects. Ann Thorac Surg. 2013;95(6): 2086-2095. 6. Alsoufi B, Karamlou T, McCrindle BW, Caldarone CA. Management options in neonates and infants with critical left ventricular outflow tract obstruction. Eur J Cardiothorac Surg. 2007;31(6): 1013-1021.
Downloaded from pch.sagepub.com at UZH Hauptbibliothek / Zentralbibliothek Zürich on December 29, 2014
Staged Left Ventricular Recruitment and Biventricular Conversion in Hypoplastic Left Heart Syndrome
World Journal for Pediatric and Congenital Heart Surgery 2014, Vol. 5(3) 449-452 ª The Author(s) 2014 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/2150135113519453 pch.sagepub.com
James M. Hammel, MD1, Aswathy Vaikom House, MD2, David A. Danford, MD2, and Shelby Kutty, MD2
Abstract We describe a relatively long left ventricular recruitment pathway consisting of early and serial aortic valvuloplasties and multiple endocardial fibroelastosis resections resulting in successful biventricular conversion of hypoplastic left heart syndrome. Keywords pediatric cardiology, hypoplastic left heart, left ventricular rehabilitation Submitted October 03, 2013; Accepted December 13, 2013.
Case Report Hypoplastic left heart syndrome (HLHS) and its variants with borderline left ventricle (LV) represent a spectrum of different degrees of left heart abnormalities and hypoplasia. A term newborn (birth weight 3.73 kg) presented on the first day of life with murmur and labored breathing. Twodimensional echocardiography (2DE) revealed a hypoplastic LV with mitral and aortic valve hypoplasia. Detailed 2DE after initiation of prostaglandin E1 demonstrated a nonapex-forming LV with a longitudinal dimension of 1.75 cm, and LV enddiastolic volume of 2.41 mL (10.5 mL/m2, z ¼ 5.7). There was severe and extensive endocardial fibroelastosis (EFE) and severely depressed systolic function (LV shortening fraction 15%). The aortic valve was unicuspid with an annular diameter of 0.5 cm (z ¼ 3.5). The mitral valve was nondysplastic and without leaflet fusion but small with annulus diameter of 0.74 cm (z ¼ 3.4). Because the LV appeared somewhat larger than usual for HLHS, cardiac magnetic resonance (CMR) was performed to quantitate LV volume and EFE. The indexed LV end-diastolic volume was 8 mL/m2, and late gadolinium enhancement (LGE) consistent with EFE was present. For EFE scoring, the areas of LGE were manually contoured on each short-axis slice using the QMASS 7.2 software (Medis, Leiden, the Netherlands). The LGE/EFE volume, calculated by adding the planimetered areas of EFE in all short-axis slices, was 4.4 g. The EFE volume expressed as a proportion of total LV myocardium (% scar) was 32%. As the LV size appeared inadequate for initial two-ventricle reconstruction, the patient underwent Norwood operation with Sano modification utilizing cardiopulmonary bypass and cold
blood cardioplegia. The LV EFE was sharply resected, working through the mitral valve, and aortic valvotomy was performed through an oblique aortotomy using a corneal/scleral knife (Alcon Medical, Fort Worth, Texas). The atrial septal communication was closed with glutaraldehyde-fixed autologous pericardial patch leaving a 3.5-mm fenestration that produced a deliberate left atrial (LA) to right atrial (RA) gradient of 4 to 5 mm Hg on intraoperative 2DE. The infant had an uneventful recovery from this operation. The LV dimensions and function were closely observed with serial transthoracic 2DE. Cardiac catheterization at one month of age revealed LA pressure of 8 mm Hg, RA pressure of 4 mm Hg, and indexed pulmonary vascular resistance (PVRi) of 2.7 Wood units.m2. At five months of age, the infant was evaluated for second-stage palliation. Cardiac catheterization demonstrated mean LA pressure of 19, RA pressure of 6, and PVRi of 2.1 Wood units.m2. The patient underwent bidirectional cavopulmonary anastomosis, repeat transmitral LV EFE resection as well as repeat aortic valvotomy. The pulmonary arterial pressures were 12 mm Hg
1 Division of Cardiovascular Surgery, University of Nebraska Medical Center College of Medicine, and Children’s Hospital and Medical Center, Omaha, NE, USA 2 Division of Pediatric Cardiology, University of Nebraska Medical Center College of Medicine, and Children’s Hospital and Medical Center, Omaha, NE, USA
Corresponding Author: Shelby Kutty, University of Nebraska/Creighton University, Children’s Hospital and Medical Center, 8200 Dodge St, Omaha, NE 68114, USA. Email: [email protected]
Downloaded from pch.sagepub.com at UZH Hauptbibliothek / Zentralbibliothek Zürich on December 29, 2014
450
World Journal for Pediatric and Congenital Heart Surgery 5(3)
Abbreviations and Acronyms CMR EFE EF HLHS LA LV LGE PVRi RA 2DE
cardiovascular magnetic resonance endocardial fibroelastosis ejection fraction hypoplastic left heart syndrome left atrial left ventricle late gadolinium enhancement indexed pulmonary vascular resistance right atrial Two-dimensional echocardiography
intraoperatively despite the deliberate elevation in LA pressure (due to the restrictive atrial septal patch) in the preceding months. The recovery was uneventful after surgery. The LV volume was observed again to increase (17, 20, and 24 mL/ m2, respectively, on serial CMR at 4, 6, and 12 months) and LV systolic function that was initially depressed returned to normal (ejection fraction 67%) by 12 months of age. The atrial septal communication closed spontaneously at about 18 months of age. Pulmonary blood flow remained adequate through the bidirectional cavopulmonary circulation based on clinical status and systemic oxygen saturations. Scoring of EFE on serial short-axis CMR images of the LV is shown in Figure 1. At 23 months of age, cardiac catheterization was performed to evaluate for conversion to biventricular circulation. The mean pulmonary artery pressure was 15 mm Hg, LV end-diastolic pressure was 17 mm Hg, RA mean pressure was 5 mm Hg, and PVRi was 2.5 Wood units.m2, but the LV was found to be very sensitive to volume changes, suggestive of continued restrictive physiology. Therefore, an interval procedure consisting of resection (third time) of EFE and aortic valvotomy was performed and a right ventricle to pulmonary artery nonvalved conduit was added to increase LV volume load. Systemic arterial oxygen saturations (%) rose to mid 90’s after the procedure. At 33 months of age, CMR demonstrated increase in the LV end-diastolic volume to 48 mL/m2. At this time, the patient underwent conversion to biventricular circulation. The Damus-Kaye-Stansel neoaortic arch was taken down, the pulmonary root was reanastomosed to the pulmonary bifurcation and the cavopulmonary anastomosis was taken down. The patient was extubated in the operating room after surgery and was discharged on the sixth postoperative day. Figure 2 shows parasternal long-axis 2DE images demonstrating LV growth. The patient is presently thriving at 4.3 years of age, 20 months after biventricular conversion. Left ventricular function remains hyperdynamic (ejection fraction [EF] 70%) by 2DE, and the patient has excellent exercise tolerance.
Comment Different strategies for recruitment and conversion to biventricular circulation have been reported for the borderline LV.1-6 For example, in a case reported by Moon-Grady et al, fetal and postnatal balloon aortic valvuloplasty and early postnatal hybrid stage I palliation were performed as the initial steps of LV
Figure 1. Manual contouring of the endocardial border (inner circle; red line) and epicardial border (outer circle; green line) was performed for volumetric and functional quantification of the LV and calculation of EFE burden. Panels A, B, C and, D show images at birth, 6, 12, and 22 months, respectively. Note the large and confluent area of EFE (shaded area) with high signal intensity of late gadolinium enhancement. The percentage of EFE and ventricular mass is expressed. LV indicates left ventricle; LGE, late gadolinium enhancement; EFE, endocardial fibroelastosis.
rehabilitation.2 This was followed by surgical takedown of the hybrid and conversion to biventricular circulation by adding Ross-Konno procedure and aortic arch reconstruction to the EFE resection.2 In the present case, without fetal intervention a complete aortic valvotomy in the newborn period led to successful LV recruitment. In selected patients with potential for LV growth, surgical valvotomy by direct visualization offers both a precise valvotomy and the opportunity to excise EFE tissue.3 The staged LV recruitment approach described in this case allowed for repeat surgical aortic valvuloplasty, giving time for improved transaortic flow, annular growth, and potentially aortic leaflet growth. Although aortic incompetence is less likely to be a significant issue prior to biventricular conversion (immediate performance of this valve is not required), avoiding residual aortic stenosis may help reduce EFE burden or EFE recurrence. Importantly, Ross operation was avoided in this patient although the aortic valve was initially inadequate. A Ross operation would have committed the patient to future right ventricle to pulmonary artery conduit replacements and would have risked late neoaortic root dilation with autograft valve dysfunction. We created a deliberately restrictive atrial communication at the initial neonatal palliation procedure to foster LV growth by increasing LV filling pressure. A transseptal gradient of 5 mm Hg (as in our case) following initial surgery is considered appropriate in this setting.1 Our case demonstrates that uncomplicated recovery from the Norwood-Sano procedure is possible with a deliberately elevated LA pressure. Balloon dilation
Downloaded from pch.sagepub.com at UZH Hauptbibliothek / Zentralbibliothek Zürich on December 29, 2014
Hammel et al
451
Figure 2. Two-dimensional echocardiographic images in parasternal long axis demonstrating growth of the LV. Panels A, B, and C show images at 1 month, 8 months, and 23 months (between surgical steps), and panel D shows image at 34 months (after biventricular repair). LV indicates left ventricle; RV, right ventricle; LA, left atrium; AO, aorta.
of the atrial communication was not needed to relieve LA hypertension at any time during follow-up. Furthermore, atrial septal restriction did not appear to complicate recovery from the superior cavopulmonary anastomosis procedure nor did it produce an unacceptably high PVRi. In contrast to the strategy described by Moon-Grady et al,2 we performed EFE resection in combination with the Norwood-Sano procedure. Others have reported that LV rehabilitation during the neonatal period can be challenging due to the difficulty of EFE resection and mitral valve repair through a small mitral valve orifice.4 In our experience, EFE resection can be performed safely in the newborn period working through a hypoplastic mitral valve, and early resection is potentially beneficial to promote LV recruitment and increase LV volume. We believe that volume development of the LV cannot be as effective until the EFE that restricts LV filling is removed; the earlier this can occur, the better. Mitral valve injury and mitral regurgitation are potential problems with early EFE resection; however, if the regurgitation created was minimal, it would not be necessarily a great harm as long as the LV is able to eject at a systemic pressure. Moreover, the recovery of LV diastolic function with early EFE resection could help reduce LA and pulmonary pressures. The present case also highlights the utility of repeat resection of EFE in subsequent surgeries. These repeat resections were tolerated well, and there was progressive reduction in EFE burden and increase in LV volume. In locations of previously resected EFE, the EFE layer was qualitatively thinner and
more elastic than the initial layer. We speculate that the myocardium immediately beneath the EFE layer is probably less healthy compared to normal myocardium, and some of it presumably undergoes fibrosis. In addition, the subendocardial capillary distribution is abnormal in these locations, probably subjecting the remaining myocardium to greater risk. These observations on EFE in previously resected areas are similar to the description by Emani et al.4 On follow-up of our case after biventricular repair, minimal EFE was seen in the basal septal aspect of the LV. Our patient did not have mitral valve dysplasia. Poor mitral valve mobility would have complicated management, and a different strategy with surgical mitral valvuloplasties or multiple mitral leaflet augmentations would have been required. Mitral stenosis may be a greater threat to the success of LV recruitment than mitral regurgitation, provided LV systolic pressure can be maintained at systemic levels. We use serial CMR to monitor the progress of LV recruitment. The LV response seen after EFE resection in this case is noteworthy. The greatest increase in left heart dimensions was noted following the bidirectional cavopulmonary anastomosis procedure, and this is consistent with the observations of others.1 In HLHS variants, an LV end-diastolic volume 30 mL/m2 was associated with successful conversion, while the minimum was 22 mL/m2 in an atrioventricular septal defect group who underwent successful conversion.1,5 With each EFE resection, change in EF was noted in our case; therefore, onestep resection may not produce optimal LV recruitment. If the
Downloaded from pch.sagepub.com at UZH Hauptbibliothek / Zentralbibliothek Zürich on December 29, 2014
452
World Journal for Pediatric and Congenital Heart Surgery 5(3)
early course of LV recruitment is satisfactory, and the patient is progressing well along the path of eventual biventricular circulation, the bidirectional cavopulmonary anastomosis could be avoided but replacing the Sano conduit with a larger restrictive valved conduit may be necessary. In conclusion, a CMR-guided relatively long LV recruitment pathway with early and serial aortic valvuloplasties, and multiple EFE resections enabled successful biventricular conversion in this patient with HLHS. This approach is limited to a small subset of patients with HLHS, and absence of mitral dysplasia in our case allowed EFE resection at the neonatal operation. Despite the extremely favorable outcome in this carefully selected case, the results of a more general application of these methods to the problem of LV hypoplasia remain uncertain at best. Therefore, longer follow-up and larger experience are required to determine the ultimate impact of this strategy, particularly its effects on LV growth and performance in the long term. Choice of surgical strategy will depend on careful analysis of the relative merits and risks of the Fontan palliation versus LV recruitment. Acknowledgments The authors thank Ling Li, MD, PhD, for her assistance with the preparation of the figures.
Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.
References 1. Emani SM, del Nido PJ. Strategies to maintain biventricular circulation in patients with high-risk anatomy. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu. 2013;16(1): 37-42. 2. Moon-Grady AJ, Moore P, Azakie A. Ross-Konno and endocardial fibroelastosis resection after hybrid stage I palliation in infancy: successful staged left-ventricular rehabilitation and conversion to biventricular circulation after fetal diagnosis of aortic stenosis. Pediatr Cardiol. 2011;32(2): 211-214. 3. Hammel JM, Duncan KF, Danford DA, Kutty S. Two-stage biventricular rehabilitation for critical aortic stenosis with severe left ventricular dysfunction. Eur J Cardiothorac Surg. 2013;43(1): 143-148. 4. Emani SM, Bacha EA, McElhinney DB, et al. Primary left ventricular rehabilitation is effective in maintaining two-ventricle physiology in the borderline left heart. J Thorac Cardiovasc Surg. 2009;138(6): 1276-1282. 5. Nathan M, Liu H, Pigula FA, et al. Biventricular conversion after single-ventricle palliation in unbalanced atrioventricular canal defects. Ann Thorac Surg. 2013;95(6): 2086-2095. 6. Alsoufi B, Karamlou T, McCrindle BW, Caldarone CA. Management options in neonates and infants with critical left ventricular outflow tract obstruction. Eur J Cardiothorac Surg. 2007;31(6): 1013-1021.
Downloaded from pch.sagepub.com at UZH Hauptbibliothek / Zentralbibliothek Zürich on December 29, 2014
