Devin Chetan

Hybrid Versus Norwood Strategies for Single-Ventricle Palliation

Background— Hybrid and Norwood strategies differ substantially in terms of stage II palliative procedures. We sought to compare these strategies with an emphasis on survival and reintervention after stage II and subsequent Fontan completion. Methods and Results— Of 110 neonates with functionally single-ventricle physiology who underwent stage I palliation between 2004 and 2010, 75 (69%) infants (Norwood, n=43; hybrid, n=32) who subsequently underwent stage II palliation were studied. Survival and reintervention rates after stage II palliation, anatomic and physiologic variables at pre-Fontan assessment, and Fontan outcomes were compared between the groups. Predictors for reintervention were analyzed. Freedom from death/transplant after stage II palliation was equivalent between the groups (Norwood, 80.4% versus hybrid, 85.6% at 3 years, P=0.66). Hybrid patients had a higher pulmonary artery (PA) reintervention rate (P=0.003) and lower Nakata index at pre-Fontan evaluation (P=0.015). Aortic arch and atrioventricular valve reinterventions were not different between the groups. Ventricular end-diastolic pressure, mean PA pressure, and ventricular function were equivalent at pre-Fontan assessment. There were no deaths after Fontan completion in either group (Norwood, n=25, hybrid, n=14). Conclusions— Survival after stage II palliation and subsequent Fontan completion is equivalent between the groups. The hybrid group had a higher PA reintervention rate and smaller PA size. Both strategies achieved adequate physiology for Fontan completion. Evolution of the hybrid strategy requires refinement to provide optimal PA growth.

Left Atrial Decompression During Venoarterial Extracorporeal Membrane Oxygenation for Left Ventricular Failure in Children: Current Strategy and Clinical Outcomes

From 2005 to 2011, 23 of 178 (12.9%) patients with venoarterial (VA) extracorporeal membrane oxygenation (ECMO) had left atrial (LA) decompression to help improve left ventricular (LV) function, LA/LV dilatation, and/or lung edema. LA decompression was achieved with LA cannulation (n = 16), surgically created adjustable atrial septal defect (n = 3), or balloon atrial septostomy (n = 4). Sixteen (70%) patients had LA decompression at the time of ECMO initiation and all had LA decompression within 12 hours of ECMO initiation. ECMO duration was 5.9 ± 4.5 days and 16 (70%) patients were successfully decannulated. Subsequent intensive care unit and hospital survival was achieved in 13 (57%) and 12 (52%) patients, respectively. Earlier timing of LA decompression appeared to be associated with a high probability of weaning from ECMO and reasonable LV functional recovery.

Surgical Palliation Strategy Does Not Affect Interstage Ventricular Dysfunction or Atrioventricular Valve Regurgitation in Children With Hypoplastic Left Heart Syndrome and Variants

Background— All 3 palliation strategies, Norwood, Sano, and Hybrid, currently used for hypoplastic left heart syndrome pose a risk of myocardial injury at different times and through different mechanisms. We sought to compare these strategies to understand longitudinal differences in interstage ventricular dysfunction and their subsequent impact on transplant-free survival and atrioventricular valve regurgitation (AVVR) as well as the relationship between adverse events and ventricular function. Methods and Results— Serial echocardiographic reports and clinical data were reviewed for 138 children with hypoplastic left heart syndrome who underwent stage I surgical palliation (Sano: 11; Norwood: 73; Hybrid: 54) between 2004 and 2011. Stage II palliation was achieved in 92 (67%) patients (Sano: 7; Norwood: 51; Hybrid: 34). Interstage transplant-free survival, ventricular dysfunction, and AVVR were equivalent among palliation strategies. Patients with preserved ventricular function had a higher rate of transplant-free survival and freedom from AVVR, regardless of palliation strategy. Patients who had cardiac arrest, cardiopulmonary resuscitation, or extracorporeal membrane oxygenation (adverse events) experienced more transient and persistent ventricular dysfunction compared to those without adverse events. Surgical palliation strategies were not identified as risk factors for ventricular dysfunction or AVVR. Conclusions— Surgical palliation strategy does not affect mortality, interstage ventricular function, or interstage AVVR in children with hypoplastic left heart syndrome. Therefore, the different timing and mechanisms of myocardial injury among palliation strategies do not affect outcomes. Ventricular dysfunction adversely affects transplant-free survival and atrioventricular valve function. Adverse events are associated with the development of ventricular dysfunction. To improve outcomes, interstage treatment should focus on the preservation of ventricular function.

Longevity and Durability of Atrioventricular Valve Repair in Single-Ventricle Patients

BACKGROUND The durability of atrioventricular valve (AVV) repair and risk factors for recurrent AVV regurgitation (AVVR) and reintervention in single-ventricle patients are not well defined. METHODS Among 66 single-ventricle patients who underwent AVV repair between 1998 and 2011, 58 hospital survivors (88%) were retrospectively reviewed. Freedom from recurrent AVVR and reintervention were analyzed with Kaplan-Meier analysis. Predictors for recurrent AVVR, ventricular dysfunction, and reintervention were analyzed using regression analysis. RESULTS Significant (more than mild+) AVVR developed in 47 patients (81%) during mean follow-up of 37 months (range, 0.2 to 103 months). Freedom from significant AVVR was 23.8% at 1 year and 16.9% at 5 years. Reintervention was performed in 12 patients (26%) at a mean of 24 months (range, 2 to 64 months) after the initial repair. Freedom from reintervention was 92.3% at 1 year and 75.3% at 5 years. There were 11 late deaths (19%). Predictors for recurrent AVVR included repair at stage II (p=0.020) and cardiopulmonary bypass time (p=0.014). Predictors for reintervention included valvuloplasty as a repair technique (p=0.013), cardiopulmonary bypass time (p=0.002), aortic cross-clamp time (p=0.003), and significant residual intraoperative AVVR (p=0.012). Intraoperative ventricular dysfunction (p<0.001), aortic cross-clamp time (p=0.005), and cleft as the mechanism of regurgitation (p=0.023) predicted postrepair ventricular dysfunction. CONCLUSIONS Although significant AVVR developed in most patients within 1 year of repair, the need for repeat valve repair is relatively low if ventricular function is preserved. Ventricular function after repair did not predict late survival but was related to the longevity of AVV competence and subsequent risk for reintervention.

Evolution of Technology, Establishment of Program, and Clinical Outcomes in Pediatric Extracorporeal Membrane Oxygenation: The “SickKids” Experience

Technological development has had a tremendous impact on the management of patients who require extracorporeal membrane oxygenation (ECMO). Team development and education are a vital component of a successful extracorporeal life support (ECLS) Program to reduce complications and subsequently improve clinical outcomes. We sought to review the evolution in technology, importance of team development and training, and report our experience at The Hospital for Sick Children, Toronto. There were a total of 576 ECMO runs in 534 patients (42 repeat ECMO runs) between January 1988 and June 2012. The use of ECMO for cardiac disease has increased in the last decade due to an expanded indication for ECMO in patients with single-ventricle physiology. Cardiac ECMO still remains a challenge in terms of survival (177/392, 45%). Although development of an ECLS program and team education facilitated extracorporeal cardiopulmonary resuscitation, clinical outcomes were not satisfactory (survival, 33%). The most common complications were hemorrhagic (13.8%), followed by renal (10.6%) and pulmonary dysfunction (6.9%). Advances in technology made management during ECMO safer, and the mechanical complications related to the ECMO system were 6.1%, including circuit changes due to thrombus formation, cannula repositioning, or optimization of size.

Impact of Norwood versus hybrid palliation on cardiac size and function in hypoplastic left heart syndrome

Objective The hybrid approach for hypoplastic left heart syndrome (HLHS) could theoretically result in better preservation of right ventricular (RV) function then the Norwood procedure. The aim of this study was to compare echocardiographic indices of RV size and function in patients after Norwood and hybrid throughout all stages of palliation. Methods 76 HLHS patients (42 Norwood, 34 hybrid) were retrospectively studied. Echocardiography was obtained before stage I, before and after stage II, and before and after Fontan. Median follow-up was 4.9 years (range 1.1–8.5). Results Baseline characteristics before stage I were similar. Hybrid patients demonstrated a significant decrease in RV fractional area change (FAC) between baseline and pre-stage II (36±9% vs 27±6%; p<0.01); Norwood patients remained stable (32±10% vs 32±7%; p=0.21). At pre-stage II, moderate/severe tricuspid valve (TV) regurgitation was found in nine Norwood (33%) and four hybrid (18%) patients (p=0.19). After stage II, the difference in FAC became insignificant (29±7% vs 25±8%, p=0.08) and moderate/severe TV regurgitation (TR) was found in 13 Norwood (48%) and four hybrid patients (19%) (p=0.18). At pre-Fontan, RV FAC was similar after Norwood and hybrid (34±5% vs 33±6%, p=0.69), which remained unchanged after Fontan. After Fontan, one Norwood and one hybrid patient had moderate TR. RV and TV size were similar for both groups at each time point. Conclusions Patients after Norwood and hybrid procedures had equivalent indices of RV size, and systolic and diastolic function throughout all stages of palliation. Small differences in individual RV and TV indices are likely to be explained by differences in physiology or surgical timing rather than by intrinsic differences in myocardial and valve function.

Persistent fenestration may be a marker for physiologic intolerance after Fontan completion

BACKGROUND We sought to evaluate the medium-term implications of fenestration status. METHODS Between 1994 and 2012, 326 patients received an extracardiac Fontan (hospital mortality n = 6, 1.8%). A fenestration was routinely created (n = 306, 94%) unless there was technical difficulty. Three hundred patients discharged with an open fenestration were included. The primary end points were death and Fontan failure. Secondary outcomes were Fontan complications such as venovenous collaterals, protein-losing enteropathy, pacemaker requirement, and arrhythmias. RESULTS The fenestration was closed in 260 patients: 185 as a catheter intervention (62%) and 75 (25%) spontaneously. Forty patients (13%) had the fenestration open at a median follow-up period of 5.05 years. Of these patients, catheter-based closure failed in 10 (3%). There was no statistically significant difference in pre-Fontan hemodynamic parameters, such as pulmonary artery pressure and pulmonary vascular resistance between the patients with open fenestration and the ones with closed fenestration. Patients with an open fenestration had significantly more late deaths (P < .001), Fontan failure (P = .021), and Fontan complications (P = .011) compared with those with a closed fenestration. Multivariable Cox regression revealed open fenestration (P < .001) and indeterminate ventricular morphology (P = .002) as risk factors for death/Fontan failure, and ventricular dysfunction (P = .014) and open fenestration (P = .009) as risk factors for Fontan complications. CONCLUSIONS Persistent fenestration was a marker for physiologic intolerance as noted by increased rates of mortality and a higher incidence of Fontan failure/complications. The specificity of pre-Fontan physiologic data for fenestration status may not have the fidelity needed for long-term care and thus, the consequences of decision making regarding fenestration status may not be determined until well after the operation.

Geometry and growth of the reconstructed aorta in patients with hypoplastic left heart syndrome and variants

Objective: The interdigitating technique in aortic arch reconstruction in hypoplastic left heart syndrome and variants (HLHS) reduces the recoarctation rate. Little is known on aortic arch growth characteristics and resulting clinical impact. Methods: A total of 139 patients with HLHS underwent staged palliation between 2007 and 2014; 73 patients underwent arch reconstruction. Dimensions of ascending aorta, transverse arch, interdigitating anastomosis, and descending aorta in pre‐stage II and pre‐Fontan angiograms were measured. Aortic arch dimensions were analyzed. Ventricular and atrioventricular valve function were assessed. Results: Diameters increased in all segments between pre‐stage II and pre‐Fontan (P < .0005). The z scores remained unchanged in all segments but the descending aorta that was significantly larger pre‐Fontan (P = .039). Dimensions and z scores between pre‐stage II and pre‐Fontan correlated in proximal segments, but not at and distal to the interdigitating anastomosis. Pronounced tapering occurred between the transverse arch and the interdigitating anastomosis. Arch intervention of any type was performed in 7 (9.6%), and intervention for recoarctation in 3 (4.1%) patients. Conclusions: The aortic arch after reconstruction with the interdigitating technique differs from normal. Growth was proportional with no further geometrical distortion. Recoarctation and reintervention rate is low. Further improvement may be achieved by optimizing patch configuration and material.

The Natural and Surgically Modified History of Anomalous Pulmonary Veins From the Left Lung

BACKGROUND Reconstruction of anomalous left pulmonary veins (ALPV) requires an anastomosis at a nonanatomic position, posing the potential risk of pulmonary vein obstruction (PVO). METHODS The 514 patients who were diagnosed with a pulmonary vein abnormality from 1990 to 2010 were reviewed. Thirty-eight patients (7.4%; median age, 1.4 years; interquartile range, 0.1 to 5.7 years) were identified. ALPV was diagnosed as an isolated anomaly in 23 (61%) or as part of mixed total anomalous pulmonary venous drainage in 15 (39%). Patients were divided into 3 groups (group 1: partial ALPV, treated; group 2: total ALPV, treated; or group 3: partial ALPV, untreated). Freedom from poor clinical (death/reoperation) and functional (any PVO, mean pressure gradient > 3 mm Hg) outcomes were analyzed. RESULTS Repair in 30 ALPV patients (79%) was performed with direct anastomosis to the left atrium (n = 26 [68%]) or by sutureless repair (n = 4 [11%]). Two deaths occurred in group 2 (heart failure and PVO). The 4 reoperations in group 2 were prompted by PVO and occurred within 6 months of the initial repair. There was a nonsignificant trend of lower freedom from poor outcomes in group 2 (74.6%) vs group 1 (100%) at 10 years (p = 0.105). There was no difference in the incidence of any left PVO among the groups (p = 0.381). Severe left PVO did not develop in group 3 (n = 8 [21%]). CONCLUSIONS Total ALPV carries a high risk of early PVO. Thus, the optimal surgical approach remains elusive. Untreated partial ALPV remained unobstructed during midterm follow-up. Therefore, surgical treatment may not be necessary in patients with partial ALPV.

Is Restrictive Atrial Septal Defect a Risk in Partial Anomalous Pulmonary Venous Drainage Repair

BACKGROUND The creation or enlargement of an atrial septal defect (ASD) in partial anomalous pulmonary venous drainage (PAPVD) repair may pose a risk of postoperative pulmonary vein stenosis (PVS), superior vena cava stenosis (SVCS), and atrial rhythm disturbances. METHODS 155 children who underwent repair of right PAPVD between 1990 and 2010 were reviewed. PVS and SVCS were defined by mean gradients on echocardiography: mild=3 to 5 mm Hg; severe=6 mm Hg or higher. Postoperative cardiac rhythms were categorized as sinus, transient nonsinus, and persistent nonsinus rhythms. Outcomes were compared between patients who underwent the creation or superior enlargement of an ASD (group A) and those who did not (group B). RESULTS There was no early or late death. Freedom from any PVS at 15 years after operation was lower in group A than in group B (76.1% vs 96.5%, p=0.002), and no differences were found in freedom from severe PVS (p=0.103), any SVCS (p=0.419), or severe SVCS (p=0.373). Group A patients had more PVS-related reoperations (p=0.022). Nineteen patients had nonsinus rhythm, and 4 patients experienced first-degree atrioventricular block, but no significant difference was found between the groups. Cox regression revealed the creation or superior enlargement of an ASD as a predictor for postoperative PVS (p=0.032). A case-match analysis confirmed a higher risk of PVS in patients with the creation or superior enlargement of an ASD (p=0.018). CONCLUSIONS Late outcomes after repair of PAPVD are excellent. The subgroup that requires creation or superior enlargement of an ASD in repair of a right PAPVD is at a higher risk of late PVS and a subsequent increase in PVS-related reoperation. The presence of restrictive ASD did not increase SVCS, sinus node, or atrial conduction dysfunction.