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Background: In infants requiring 3-stage single-ventricle palliation for hypoplastic left heart syndrome, attrition after the Norwood procedure remains significant. The effect of the timing of stage 2 palliation (S2P), a physician-modifiable factor, on long-term survival is not well understood. We hypothesized that an optimal interval between the Norwood and S2P that both minimizes pre-S2P attrition and maximizes post-S2P survival exists and is associated with individual patient characteristics. Methods: The National Institutes of Health/National Heart, Lung, and Blood Institute Pediatric Heart Network Single Ventricle Reconstruction Trial public data set was used. Transplant-free survival (TFS) was modeled from (1) Norwood to S2P and (2) S2P to 3 years by using parametric hazard analysis. Factors associated with death or heart transplantation were determined for each interval. To account for staged procedures, risk-adjusted, 3-year, post-Norwood TFS (the probability of TFS at 3 years given survival to S2P) was calculated using parametric conditional survival analysis. TFS from the Norwood to S2P was first predicted. TFS after S2P to 3 years was then predicted and adjusted for attrition before S2P by multiplying by the estimate of TFS to S2P. The optimal timing of S2P was determined by generating nomograms of risk-adjusted, 3-year, post-Norwood, TFS versus the interval from the Norwood to S2P. Results: Of 547 included patients, 399 survived to S2P (73%). Of the survivors to S2P, 349 (87%) survived to 3-year follow-up. The median interval from the Norwood to S2P was 5.1 (interquartile range, 4.1–6.0) months. The risk-adjusted, 3-year, TFS was 68±7%. A Norwood-S2P interval of 3 to 6 months was associated with greatest 3-year TFS overall and in patients with few risk factors. In patients with multiple risk factors, TFS was severely compromised, regardless of the timing of S2P and most severely when S2P was performed early. No difference in the optimal timing of S2P existed when stratified by shunt type. Conclusions: In infants with few risk factors, progressing to S2P at 3 to 6 months after the Norwood procedure was associated with maximal TFS. Early S2P did not rescue patients with greater risk factor burdens. Instead, referral for heart transplantation may offer their best chance at long-term survival. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT00115934.

Articles, see p 581 and p 589 > Nothing is as powerful as an idea whose time has come. > > —Victor Hugo, Histoire d’un Crime (1852) On November 29, 1944, Dr Alfred Blalock performed the first anastomosis of the subclavian to the pulmonary artery in a child with cyanosis at the Johns Hopkins Hospital in Baltimore. This novel operation was supported by the laboratory work of Vivien Thomas and the encouragement of pediatric cardiologist Helen Taussig. The operation, thereafter called the Blalock-Taussig shunt (BTS), increased pulmonary blood flow (PBF) and relieved symptomatic cyanosis.1 This singular procedure ushered in the modern era of management of the child with complex congenital heart disease and became the foundation for all management strategies that followed. Although the procedure or 1 of its modifications (MBTS) has remained a stalwart for securing a source of pulmonary blood flow for >70 years, an appreciable mortality and morbidity remains.2 As such, alternative management strategies have been suggested and tested in lieu of primary repair.3 In 1991, Coe and Olley4 described a novel transcatheter approach to increase PBF by stenting the arterial duct. Although attractive, initial clinical applications were disappointing.5 However, with improved delivery and stent platforms paralleling an experience with ductal stenting in infants with dual-source PBF, the last decade has seen a number of clinical units apply the technique in single-source …

Hearts with double outlet right ventricle are a heterogeneous group of malformations in which a comprehensive diagnostic approach is required for tailored surgical management. This pictorial essay revisits essential modifiers of clinical and surgical importance in management of the patients with double outlet right ventricle using 3-dimensional volume-rendered endocardial surface images and 3-dimensional print models. Special emphasis is paid to the infundibular morphology, including the size and orientation of the outlet septum, relative to the margin of the ventricular septal defect, and the extent of the muscular infundibulum as an additional modifier of the distance between the ventricular septal defect margin and the arterial valve or valves.

The number of patients with the failing Fontan physiology is increasing. We tested a novel in situ microaxial pump (Impella) to support the failing atrio-pulmonary Fontan circulation in an acute pig model. A Fontan model was established in eight juvenile pigs by connecting the right atrium to the main pulmonary artery after tricuspid valve destruction. The Impella pump was inserted retrograde from the distal main pulmonary artery into the right atrium. Hemodynamics, blood gas, and echocardiographic data were compared among baseline, pure Fontan physiology (10 minutes), and mechanically assisted Fontan physiology (up to 12 hours). The Impella system generated a blood flow of 75-85 ml/kg/minute in six animals, and 55-65 ml/kg/minute in two animals. The mechanically assisted Fontan attained a significantly higher mean blood pressure (39.6 ± 7 vs. 24.7 ± 3.3 mm Hg, p < 0.01), lower central venous pressure (5 ± 2.4 vs. 12.8 ± 1.7 mm Hg, p < 0.01), and higher mixed venous saturation (60.4 ± 10.8 vs. 23.4 ± 8.4 mm Hg, p < 0.01) compared with pure Fontan physiology. Cardiac output and stroke volume were similar during baseline and mechanically assisted Fontan (p = not significant). This acute pig study demonstrated the feasibility of mechanical circulatory support in the failing Fontan physiology. The in situ microaxial pump maintained cardiac output while increasing blood pressure and reducing venous pressure.

We hypothesized that spontaneous inspiratory effort transmitted to the pleural space during airway pressure release ventilation would result in increased lung perfusion after surgery for tetralogy of Fallot or following a cavopulmonary shunt as a consequence of transient decreases in intrapleural pressure.Prospective crossover cohort study.A tertiary care cardiac pediatric intensive care unit.Children after tetralogy of Fallot repair, cavopulmonary shunt, or Fontan operation.Lung perfusion and cardiac output were measured during airway pressure release ventilation and pressure control ventilation with pressure support, both with and without spontaneous ventilation. Oxygen consumption was measured (mass spectrometer) and lung perfusion/cardiac output calculated (Fick equation). Constant levels of CO₂ and mean airway pressure were targeted in all study phases.Twenty patients were enrolled in the study, nine after repair of tetralogy of Fallot and 11 after a cavopulmonary shunt. In the absence of spontaneous ventilation, there were no differences in lung perfusion or any of the measured gas exchange or hemodynamic parameters. In the presence of spontaneous ventilation for all patients, mean pulmonary blood flow increased from 2.4 to 2.9 L·min⁻¹M⁻² (p = .02). Oxygen delivery increased from 594 to 774 mL/min/m² (p = .05) in the patients with tetralogy of Fallot patients and from 473 to 518 L·min⁻¹M⁻² (p = .07) in the cavopulmonary shunt group.Ventilation with airway pressure release ventilation (at comparable mean airway pressure) improves lung perfusion compared with pressure control ventilation in children after tetralogy of Fallot repair and cavopulmonary shunt operations. Although this study focused on tetralogy of Fallot and cavopulmonary shunt operations, the improved cardiopulmonary interactions may be beneficial in other situations in which hemodynamics are impaired by positive pressure ventilation.

Background— Thrombosis, usually considered a serious but rare complication of pediatric cardiac surgery, has not been a major clinical and/or research focus in the past. Methods and Results— We noted 444 thrombi (66% occlusive, 60% symptomatic) in 171 of 1542 surgeries (11%). Factors associated with increased odds of thrombosis were age P =0.002), baseline oxygen saturation P =0.001), previous thrombosis (OR, 2.6; P =0.001), heart transplantation (OR, 4.1; P P =0.01), longer cumulative time with central lines (OR, 1.2 per 5-day equivalent; P P P P =0.02), and partially/fully occluding thrombi (OR, 14.3; P =0.001); indwelling access line in vessel (versus no access line) was associated with lower risk of serious complications (OR, 0.4; P =0.05). Thrombosis was associated with longer intensive care unit (+10.0 days; P P P P =0.002), and reoperation (OR, 2.5; P =0.003); and increased mortality (OR, 5.1; P P P =0.01), older age at surgery (OR, 1.2 per year; P =0.04), higher white blood cell count (OR, 1.1/10 9 cells per 1 mL; P =0.002), and lower fibrinogen (OR, 1.4/g/L; P =0.02) after surgery. Conclusions— Thrombosis affects a high proportion of children undergoing cardiac surgery and is associated with suboptimal outcomes. Increased awareness and effective prevention and detection strategies are needed.

OBJECTIVES Cardiopulmonary bypass in infants results in a hypermetabolic response. Energy requirements of these patients have not been well studied. We assessed energy expenditure and caloric and protein intake during the first 3 days following the Norwood procedure. DESIGN Clinical investigation. SETTING Children's hospital. PATIENTS Seventeen infants (15 boys, age 4-92 days, median 7 days). INTERVENTIONS VO2 and VCO2 were continuously measured using respiratory mass spectrometry in 17 infants for the first 72 hrs following the Norwood procedure. The respiratory quotient was determined as VCO2/VO2. Energy expenditure was calculated using the modified Weir equation. Measurements were collected at 2- to 4-hr intervals. The mean values in the first 8 hrs, hours 8-32, hours 32-56, and the last 16 hrs were used as representative values for postoperative days 0, 1, 2, and 3. Total caloric and protein intakes were recorded for each day. MEASUREMENTS AND MAIN RESULTS Energy expenditure, VO2, and VCO2 were initially high; declined rapidly during the first 8 hrs; and were maintained relatively stable in the following hours (p < .0001). Respiratory quotient showed a significant linear increase over the 72 hrs (p = .002). Energy expenditure on days 0, 1, 2, and 3 was 43 +/- 11, 39 +/- 8, 39 +/- 8, and 41 +/- 6 kcal/kg/day, respectively. Total caloric intake was 3 +/- 1, 14 +/- 5, 31 +/- 16, and 51 +/- 16 kcal/kg/day. Protein intake was 0, 0.2 +/- 0.2, 0.6 +/- 0.5, and 0.9 +/- 0.5 g/kg/day on days 0, 1, 2, and 3, respectively. CONCLUSIONS Infants exhibit a hypermetabolic response immediately following the Norwood procedure. Caloric and protein intake was inadequate to meet energy expenditure during the first 2 days after surgery. Further studies are warranted to examine the effects of caloric and protein supplementation on postoperative outcomes in infants after cardiopulmonary bypass.

Objective: We hypothesized that intraoperative coronary Doppler profiles after button implantation would help predict survival and morbidity after arterial switch. Methods: Children (N=319) undergoing arterial switch (2000-2012; TGA 190, TGA-VSD 95, TGA-VSD-PS 10, Taussig-Bing 14, others 10) underwent intraoperative echocardiographic assessment of coronary buttons. Studies were blindly reviewed to delineate Doppler gradient, peak flow velocity, velocity-time integral (VTI) and late diastolic flow reversal, which were explored as predictors of death, ICU morbidity and need for late coronary revision via parametric risk-adjusted regression and bootstrap reliability. Results: Outcomes included: death=9 (3%), ECMO=13 (4%), surgical coronary revision=9 (3%). Higher left button Doppler values were predictors of chest open duration, post-op JET, need for revision or ECMO. Mean left button gradient was the most reliable - table. Right button Doppler values were not strong predictors of morbidity. Higher left Doppler gradients confer disproportionate impact - figure. Mean gradient ≥ 1.5 had late revision risk 27%, versus 1.6% for < 1.5 ( P =.0016). Intraoperative strategies to improve button geometry included release of fascia (16, 5%) or button revision (9, 3%). Such strategies reduced gradients, velocities and VTI ( P between .004 and .03 ). Left Doppler values retained their predictive value even in 296 (93%) children who had no such coronary manipulation - table. Conclusions: Aiming for mean left coronary gradient < 1.5-2 and peak

Introduction: Postoperative thrombosis in children undergoing cardiac surgery with cardiopulmonary bypass (CPB) is a frequent, under-diagnosed and clinically detrimental complication. Methods: Pediatric patients were prospectively enrolled before surgery with CPB in an observational cohort study. Children Results: Of 400 enrolled patients (54% males, 55% Conclusions: Given the poor performance of relying on clinical suspicion for detecting post-operative thrombosis, children

Introduction: Infants with severe tetralogy of Fallot (TOF) may undergo: 1) early primary surgical repair (EARLY) or 2) early catheter palliation (CATH) prior to delayed surgical repair. We compared these two strategies to 3) usual elective single stage TOF repair (USUAL). Methods: We studied 453 TOF repairs (2000-2012, excluding BT shunts). USUAL strategy at our institution is repair ≥3 months. Risk adjusted hazard analysis compared freedom from surgical or catheter reintervention. Somatic size, branch PA size and RV systolic pressure were modeled using 2543 echo reports via mixed model regression. Results: Table: group characteristics for USUAL (383), EARLY (42) and CATH (28). CATH involved: RVOT stent=18, RVOT balloon=9, ductal stent=1. Risk adjusted freedom from surgical reoperation was 88%, 87% and 85% for USUAL, EARLY and CATH respectively, at 10 years. EARLY and CATH had similar reoperation rates, except for very young children ( Risk adjusted freedom from catheter reintervention was higher for EARLY (76%) and especially so for CATH (53%) at 10 years, versus USUAL (83%; Figure). Somatic growth and progression of RVSP (37-40mmHg) was similar among groups at 8 years. EARLY (P=.02) and CATH (P=.09) tend to have smaller bPAs initially. The CATH group tend to remain smaller in the long-term, whereas growth in EARLY matches USUAL. Conclusions: Early primary repair at very young ages comes with a cost of increased late surgical reoperation. Early transcatheter palliation tends to come with a cost of increased late transcatheter intervention - possibly related to slower branch PA growth.

Objectives: The interdigitating technique in aortic arch reconstruction in hypoplastic left heart syndrome and variants (HLHS) is very effective to minimize the recoarctation rate. Little is known on the aortic arch’s growth characteristics and the resulting clinical impact. Methods: 139 patients with HLHS underwent staged palliation between 2007 and 2014. 72 patients who underwent Norwood arch reconstruction with the interdigitating technique were included. Dimensions of the ascending aorta (AA), transverse arch (TA), isthmus (IA) and descending aorta (DA) in pre-stage II (P1, n=50) and pre-Fontan (P2, n=21) angiograms were measured and geometry and growth characteristics of the aortic arches were analyzed. Correlations between the aortic dimensions and clinical outcomes were assessed. Results: There were significant increases in diameters in all segments between P1 and P2 (p < .0005). The z-scores in AA, TA and IA were unchanged between P1 and P2 (p = .931/.425/.121), but increased significantly in DA at P2 (p = .039). The percent increase in diameters were comparable among 4 segments (mean, 146% in IA, 144 in DA, p=.648). There were correlations in dimensions and z-scores between P1 and P2 in AA (p = .029/.013) and TA (p = .001/ < .0005), but no correlations were found in IA (p = .140/.747) and DA (p = .075/.432). The most significant tapering in the arch dimension occurred between TA and IA in both time points (P1, 67.3% vs. P2, 61.1%, p=.303). The reverse coarctation index (TA/IA ratio) at P1 (r = .381, p = .042), but not coarctation index (CoAI, IA/DA ratio) at P1 (p = .774) had a significant correlation with post-stage II ventricular function. Balloon dilatation for recoarctation was needed in 2 (2.7%) patients prior to stage II palliation. CoAI at P1 was a predictor for ventricular dysfunction at latest follow-up (p=.017). Conclusions: Aortic arch growth after interdigitating reconstruction in HLHS is substantial and relatively constant. The isthmus growth is proportional to other segments. Overall reintervention rate for recoarctation is exceptionally low. CoAI prior to stage II palliation may be associated with long-term ventricular function.

Introduction: Development of atrioventricular valve regurgitation (AVVR) with or without ventricular dysfunction (VD) often occurs during the first 6 months of life and has a significant impact on outcomes for single-ventricle patients. Yet, it is not well known whether AVVR causes VD or vice versa. Thus, we sought to identify the timing and causal relationship between AVVR and VD. Methods: Among 156 consecutive single-ventricle patients who had staged palliation (2005- 2012), 28 who had AVV repair at the time of stage II (n=24, 86%) or inter-stage (n=4, 14%) were reviewed. Diagnosis included HLHS in 17 (61%) patients, tricuspid atresia in 2 (7%), and others in 9 (32%). Ventricular morphology was left-dominant in 6 (21%) patients and right-dominant in 22 (79%). AVV morphology included mitral in 6 (21%) patients, tricuspid in 18 (64%), and common in 4 (14%). Serial echocardiograms were reviewed to identify the timing of development of AVVR and/or VD. Results: After stage I palliation, ventricular end-diastolic dimension (VEDD) z-score significantly increased from 4.01 to 5.69 (p Conclusions: Ventricular dilation occurred immediately after stage I palliation and continued until stage II palliation. Secondary annular dilation occurred inter-stage and this further triggered the development of AVVR. Tangible ventricular dysfunction was not seen before AVV repair, however, important ventricular dysfunction was unmasked after volume unloading surgery. Heart failure management and early intervention to significant AVVR may reduce the incidence of ventricular dysfunction following AVV repair.

Introduction: Preoperative antithrombin (AT) deficiency is common in infants undergoing cardiac surgery with cardiopulmonary bypass (CPB), and is associated with heparin resistance, difficulties achieving optimal intraoperative anticoagulation and post-operative thrombosis. Methods: We performed a pilot randomized trial of pooled human AT supplementation for children Results: We randomized 18 subjects; 17 completed the study (9 controls, 8 AT). Mean preoperative AT level was similar between groups (Control: 0.65±0.10 vs. AT: 0.68±0.15 U/mL, p=0.66). AT group subjects had higher AT than controls immediately after start of CPB (Control: 0.44±0.10 vs. AT: 1.15±0.20 U/mL, p Conclusions: AT supplementation to treat preoperative AT deficiency in young children is associated with decreased heparin resistance, improved anticoagulation and decreased thrombogenecity. Safety profile regarding bleeding and infections appears favorable. Equipoise exists for a larger definitive outcome trial.

Introduction: Late outcome of repaired TOF is driven by the impact of residual lesions. We shifted strategy from liberal transannular patch (TAP) use to aggressive valve and annulus preservation (AP) hypothesizing that for equivalent anatomy, AP would leave a mixed stenosis regurgitation lesion that would lead to a healthier right ventricle (RV). Methods: Between 1996 and 2002, 185 children underwent TOF repair (median age 7.7 m). A regression equation for predicting annulus preservation, in the AP group, was derived from preoperative anatomic parameters and applied to all. Patients were identified (n=107) that could have had either AP or TAP on the basis of anatomical equivalency (subgroup validation with propensity matching) with 52 having a TAP and 55 having AP. These are the primary study group. Results: Cardiac MRI at mean age 13.1±2.3 yrs (TAP n=28, AP n=23) showed AP was associated with significantly lower indexed RV end diastolic vol (AP: 120±29; TAP: 181±35 mL - Fig. 1), RV end systolic vol (AP: 57±23; TAP: 95±25 mL), RV stroke volume (AP: 64±15; TAP: 86±15 mL), MPA regurgitant fraction (AP: 28±11; TAP: 45±9 %), all p Conclusion: This is the first long-term follow-up study demonstrating that, for equivalent anatomy, an aggressive AP strategy leads to a lower reoperative incidence, less pulmonary insufficiency, smaller indexed RV volumes and better LV function as compared to a standard TAP. Surgical strategy directly impacts ventricular health and should be reflected in practice.

Introduction: Heparin-based anticoagulation in children is challenging as they have a high prevalence of heparin resistance. Antithrombin, one of the main natural anticoagulant inhibitors that potentiate heparin anticoagulation activity, might be a critical component of heparin response and anticoagulation effectiveness. Objectives: Determine the impact of antithrombin levels on anticoagulation (heparin sensitivity and effectiveness) during cardiopulmonary bypass (CPB) in children Methods: Secondary analysis of a randomized controlled trial of individualized vs weight based heparin management in 90 infants Results: As expected, older patients had higher blood antithrombin levels (relative increase of 16±6% for patients >6 months old vs. those Conclusions: Low antithrombin level is associated with resistance to heparin and decreased anticoagulation activity, ultimately leading to lower ability to suppress thrombin generation during CPB. Antithrombin supplementation may potentially individualize and improve anticoagulation.

Introduction: We introduced the NASA “threat and error model” to our surgical unit; all admissions are considered “flights”, which should pass through stepwise de-escalations in risk. Hypothesis: Errors significantly influence risk de-escalation and contribute to poor outcomes. Methods: Patient flights (524) were tracked real-time for threats, errors and unintended states (figure). Expected risk de-escalation was: wean from mechanical support, sternal closure, extubation, ICU discharge and discharge home. Data were accrued via performance personnel, bedside data, reporting mechanisms and staff interviews. Infographics of flights were openly discussed weekly. Results: In 12% (64/524) of flights, the child failed to de-escalate sequentially through expected risk levels; unintended increments instead occurred. Failed de-escalations were highly associated with errors (426; 257 flights), however seemingly benign (P The most dangerous errors were “apical” errors typically (84%) occurring in the OR which led to cycles of propagating unintended states (n=110): these had 43% (47/110) rate of failed de-escalation (vs 4%, P Conclusions: Deaths and brain injury almost always occur from propagating error cycles that originate in the OR and are often amplified by additional ICU errors. Improvements in threat management, error detection/rescue and vigilance at times of failed de-escalation will translate into improved outcomes.

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.

Background— The objective was to determine if intraoperative pulmonary artery (PA) flow studies after complete unifocalization correlate with postrepair hemodynamics for pulmonary atresia (PA), ventricular septal defects (VSD), and major aortopulmonary collaterals. Methods and Results— Twenty patients (median age, 8 months; weight, 7.9 kg) underwent unifocalization between 2003 and 2008. A functional PA flow study was achieved by cannulating the unifocalized central PA before intracardiac repair and increasing flow incrementally to 2.5 L/min per m 2 . Mean PA pressure (mPAP) was measured. The intent was to close the VSD for a mPAP of P =0.0027) and RVSP/systemic systolic pressure (ρ=0.67; P =0.0063). Total neopulmonary artery index had a nonsignificant negative correlation with RVSP (ρ=−0.42; P =0.079). Total incorporated pulmonary segments and pulmonary segment artery ratio were not correlated. Flow study mPAP had the highest accuracy in predicting successful VSD closure: area under the receiver-operator curve (0.83) versus total neopulmonary artery index (0.42), pulmonary segments (0.35), and pulmonary segment artery ratio (0.33). Conclusions— The intraoperative pulmonary flow study predicted postoperative physiology significantly better than did standard anatomic measures. Conventional measures should be used with caution when determining the possibility for complete repair.

OBJECTIVE: We hypothesized mean pulmonary artery (PA) pressure obtained from an intraoperative pulmonary flow study would better predict the ability to close the ventricular septal defect (VSD) and better predict postoperative right ventricular systolic pressure (RSVP) than classic anatomical parameters after complete uniforcalization in patients with pulmonary atresia, VSD, and major aortopulmonary collaterals. METHODS: Sixteen consecutive patients (median, 11 mo, range 2 mo – 16 yrs) underwent one-stage (75%) or staged (25%) uniforcalization between 1/03 and 8/07. Intraoperative functional pulmonary blood flow study was achieved by inserting an arterial cannula in a reconstructed central PA. Flow was increased to 2.5 L/min/m2 while measuring PA pressure. RVSP and systemic systolic pressure (SBP) were recorded after VSD closure. Total neopulmonary artery index (TNPAI) (MAPCA + native PA index), total incorporated pulmonary vascular segments, and pulmonary segment artery ratio (PSAR) (ratio of incorporated segment to 18) were analyzed. Spearman rank correlation and area under the receiver operator characteristics curve (ROC-AUC) were used. RESULTS: The mean PA pressure on flow study was 21.8+/−6.2 mmHg (range, 11–31). Three patients had a pressure of > 30 mmHg. The VSD was closed in 14 (87%). One patient with flow study mean PA pressure of 25 mmHg had suprasystemic RVSP and underwent intraoperative VSD fenestration. One with a flow study mean PA pressure of 30 mmHg had a prospective fenestrated VSD patch placed. There is a weak negative correlation between TNPAI and the flow study PA pressure (rho=−0.4, p=0.12). The flow study mean PA pressure was correlated with post-repair RVSP (rho=0.72, p=0.0027), and with RVSP/SBP ratio (rho=0.67, p=0.0063). TNPAI, total incorporated segments, and PSAR were not correlated with the postoperative RVSP or RVSP/SBP ratio. Flow study mean PA pressure had the highest sensitivity in predicting VSD closure: ROC-AUC (0.82) vs. TNPAI (0.46), pulmonary segment (0.64), and PSAR (0.64). CONCLUSIONS: Intraoperative pulmonary flow study predicted the ability of VSD closure better than total incorporated segments, TNPAI, and PSAR. Flow study mean PA pressure highly correlated with postoperative RVSP and RVSP/SBP ratio.

We appreciate the contribution of Dr Schranz and colleagues to the development of the hybrid procedure for single ventricle palliation and their insightful comments regarding our recent article.1 The hybrid procedure with bilateral pulmonary banding and arterial duct stenting was designed as a minimally invasive alternative to a Norwood procedure. By avoiding cardiopulmonary bypass and the consequent ischemia-reperfusion injury and systemic inflammatory response, we hypothesized that we would find minimally altered systemic hemodynamic and oxygen transport status as compared with the well-documented hemodynamic derangements associated with the Norwood procedure.2 We evaluated the hybrid strategy through analysis of dispassionate and objective data and, to our knowledge, our study represents the only published hemodynamic assessment of this strategy. As noted in our article, the patterns of hemodynamic alterations after hybrid procedures were more complex than might have been anticipated. Although the data are precise, Dr Schranz and colleagues appear to be concerned that these data may not accurately represent all hybrid procedures. Our intuition (without data) would suggest that this may be so and, consequently, we will endeavor to obtain another dataset in the future to determine whether the early position of this cohort on our learning curve was an important modulator of …

Background— Creation of a bi-directional cavopulmonary shunt after the Norwood procedure for hypoplastic left heart syndrome is delayed to allow pulmonary vascular resistance to fall with maturation of the pulmonary vascular bed. We hypothesized that unfractionated heparin (UFH) and low molecular weight heparin (LMWH), which promote angiogenesis and inhibit smooth muscle cell growth, could accelerate this process. Methods and Results— Fifty-six newborn rabbits were randomly selected to receive UFH 225U/kg (n=12), LMWH 1 mg/kg (n=14), LMWH 10 mg/kg (n=16), or saline (n=14) by subcutaneous injection every 12 hours for 14 days. Treatment with heparin reduced mean pulmonary artery (PA) pressure by 12% to 16% relative to controls [9.0±0.2 (UFH), 9.4±0.1 (LMWH 1 mg/kg), 9.2±0.2 (LMWH 10 mg/kg) versus 10.7±0.2 mm Hg (saline), P =0.0001]. Lower PA pressures were associated with reduced alveolar:arterial ratio consistent with enhanced pulmonary angiogenesis in heparin treated animals [8±1 (UFH), 13±2 (LMWH 1 mg/kg), 12±2 (LMWH 10 mg/kg) versus 23±5 (saline), P Conclusions— These results indicate that both UFH and LMWH are effective at accelerating pulmonary vascular maturation in newborn rabbits. This raises the possibility that administration of heparin to children after the Norwood procedure might allow for earlier conversion to a bi-directional cavopulmonary shunt.