Fifteen-year Single Center Experience with the “Giessen Hybrid” Approach for Hypoplastic Left Heart and Variants: Current Strategies and Outcomes
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- Schranz, D., Bauer, A., Reich, B. et al. Pediatr Cardiol (2015) 36: 365. doi:10.1007/s00246-014-1015-2
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Presented is a retrospective outcome study of a 15-year single institutional experience with a contemporary cohort of patients with hypoplastic left heart syndrome and complex that underwent a “Giessen Hybrid” stage I as initial palliation. Hybrid approach consisting of surgical bilateral pulmonary artery banding and percutaneous duct stenting with or without atrial septum manipulation was developed from a rescue approach to a first-line procedure. Comprehensive Aristotle score defined pre-operative condition. Fifteen-year follow-up mortality is reported as occurring within the staged univentricular palliation or before and after biventricular repair. Hybrid stage I was performed in 154 patients; 107 should be treated by single ventricle palliation, 33 by biventricular repair (BVR), 7 received heart transplantation, and 7 were treated by comfort care, respectively. Overall 34 children died. The Aristotle score (mean value 18.2 ± 3) classified for univentricular circulations in newborns did not have statistical impact on the outcome. Two patients died during stage I (1.2 %), and the interstage I mortality was 6.7 %, and stage II mortality 9 %, respectively. Stage III was up to now performed in 57 patients without mortality. At 1 year, the overall unadjusted survival of HLHS and variants was 84 % and following BVR 89 %, respectively. The Fifteen-year survival rate for HLHS and variants was 77 %, with no significant impact of birth weight of less than 2.5 kg. In conclusion, Hybrid stage I fulfilled the criteria of life-saving approach. In our institution, Hybrid procedure replaced Norwood-staged palliation with a considerable mid- and long-term survival rate. Considering interstage mortality close surveillance is mandatory.
KeywordsHypoplastic left heart syndrome Hypoplastic left heart complex Hybrid approach
Hybrid approach expands the surgical options for patients born with hypoplastic left heart syndrome (HLHS) and newborns with multiple left heart obstructions, summarized as hypoplastic left heart complex (HLHC) . Despite significant progress, surgical outcome for high-risk patients with HLHS remains suboptimal [3, 8, 11, 17, 20, 22, 25]. The hybrid palliation lessens the initial operative risk  and is hypothesized to improve in particular neurological survival ; however, the outcome of this sequential approach is unknown. Improved operative outcomes have resulted in the increasing use of the surgical palliation in high-risk patients, but at the expense of considerable morbidity and mortality [5, 6]. The early success with the hybrid approach reported by Akintuerk et al. [1, 2] and Galantowicz et al. [9, 10] have prompted the increasing use of this strategy in order to minimize the deleterious impact of the conventional surgical intervention on high-risk patients [4, 8, 14, 26]. Moreover, aggravating factors as low birth weight and surgical complexity on survival supported the idea that a less extensive neonatal procedure could improve the outcome in these patients [11, 22]. Therefore, we present the overall single institutional 15-year experience with an unselected cohort of HLHS and HLHC patients who underwent a Hybrid procedure as initial palliation providing their mid- and long-term outcome.
Patients and Methods
Patient demographics of HLHS and Variants
Value (n = 121)
Male sex, n (%)
80 (66.1 %)
Low Birth Weight (<2.5 kg)
18 (14.8 %)
9 (7.4 %)
Primary cardiac anatomy
34 (28.1 %)
33 (27.3 %)
6 (5 %)
28 (23.1 %)
Variants of hypoplastic left heart syndrome
20 (16.5 %)
TGA + IAA
DILV + TGA + IAA (hAOA) +MS
Patient demographics of HLHC
Value (n = 33)
Male sex, n (%)
17 (52 %)
Low Birth Weight (<2.5 kg)
10 (30 %)
10 (30 %)
Main primary cardiac anatomy
IAA + VSD + hypoplastic AAO
9 (27 %)
DORV + dTGA + hypoplastic AAO
Aortic stenosis + hypoplastic AAO
Others with HLHC
Main primary cardiac anatomy
Miscellaneous intra-cardiac repairs
Ross-Konno + AOA-reconstruction
Retrospective data collection included variables at admission, operative and postoperative parameters, as well as follow-up information during a 15-year observational period. Risk adjustment was calculated for each patient of the HLHS and variants group A via comprehensive Aristotle score. However, considering that Aristotle comprehensive score is used to classify HLHS in context of a Norwood stage I procedure with a basis score of 14,5 and to adjust for the complexity of the individual patient by taking into account patient specific “procedure-independent” characteristics ; there is currently no value assigned for the Hybrid procedure. However, we calculated for each patient of the HLHS and variants group A via the comprehensive Aristotle score in order to adjust the complexity according to specific patient and procedural characteristics prior to initial hybrid stage I palliation, as a Norwood procedure would have be performed as the usual standard approach.
Data are presented as medians (ranges) or means (±standard deviation) and as absolute counts with percentages where appropriate. Continuous variables were compared using a Mann–Whitney test and Student’s t test. Kaplan–Meier survival curves using single and cumulative end-points for death were stratified by type of initial palliation. Analyses of risk factors for mortality at different time points for the entire cohort and subgroups, as well as logistic regression were performed.
Hybrid Stage I and Interstage I
The 15-year single center experience with the hybrid stage I was focused on the outcome of all stages of univentricular palliation and corrective biventricular surgery, respectively. Considering our local setting, the hybrid stage I approach fulfilled all attributes of a highly effective therapeutic tool to treat neonates with duct-dependent systemic blood flow even in patients with a high Aristotle score. Therefore, the retrospective analysis was not intended to compare the “Giessen-Hybrid” with classical Norwood or Sano palliation or differently performed Hybrid procedures. However, 15 years ago, our institutional outcome with the classical Norwood procedure was comparable with outcome data reported by Ashburn et al.  in the year of 2003. They reported that only 28 % of neonates undergoing classical Norwood procedure reached a stage III-Fontan completion. Based on our institutional results with the classical Norwood procedure at this point in time and the already published “Hybrid” idea from Gibbs et al. , in June 1998, the Hybrid stage I program in Giessen was started. The first patient, who is still living in a good clinical condition, was referred as a newborn in an acute cardiovascular failure because of a postnatal pulmonary run-off. High urgency bPAB saved his life. After clinical stabilization, the duct was stented by a technique, which had been already established to palliate neonates selected for HTX . He was also the first worldwide, who received a successful comprehensive stage II, followed by Fontan completion. Our initial hybrid series was published in 2002 . Based on the promising initial experiences, the hybrid approach developed to our first choice procedure for all newborns with HLHS and variants. Since 2001, bPAB and percutaneous duct stenting were also used for a small group of newborns with HLHC with the goal to avoid neonatal Norwood procedure or to delay a high-risk surgical approach together with expanding surgical options in later infancy without compromising the survival of neonatal patients but still keeping the option for a uni-or biventricular circulation . A demanding controversy, however, exists in the management of this subset of patients with borderline small left heart, e.g. HLHC. In our institution lastly, the decision for hybrid versus “traditional” surgical approach was performed on our surgeon’s risk adjustment . The criteria for cross-over from postnatal univentricular to two ventricle approach 6–8 months later is based on the inflow and outflow characteristics of the grown-up left ventricle obtained by echocardiographic and additional magnetic resonance imaging data. However, the results of BVR remains in some patients questionable, as has been demonstrated in these two patients, in whom the diastolic dysfunction of the left ventricle resulted in unacceptable pulmonary hypertension with consecutive need for HTX and single ventricle re-palliation, respectively. The detailed analysis of all, lastly biventricular-repaired patients and its further discussion are presented elsewhere .
The first larger series of Hybrid transcatheter-surgical palliation as a basis for univentricular or biventricular repair was published in 2007 . Until now risk factors as low birth weight, high Aristotle score or aortic atresia did not statistically influence the15-year outcome data. Procedural mortality by the “Giessen Hybrid” stage I approach remained rare. Following the first and until now unique surgical death during hybrid stage I approach, we encounter that meticulous surgery and minimized circulatory compromise by anesthesiological efforts play a key role for successful Hybrid stage I. Therefore, duct stenting and atrial septum manipulations including stenting were performed in the vast majority of patients extubated, only sedated and breathing spontaneously. Innovative self-expandable stents CE-certified for duct and coarctation stenting in neonates with HLHS further optimized the interventional approach [18, 23]. Considering the morphologic variability of the ductal-aortic junction, the high incidence for atrial septum manipulation as well as the occasional presence of an aortic coarctation, we favor the percutaneous approach after surgical bPAB. Meanwhile, the term “Hybrid approach” is used for diverse procedures [9, 10, 14, 26]. Therefore, our outcome analysis should not be generalized to other described hybrid methods. The data of the Pediatric Heart Network report  showed a one-year transplant-free survival of 64 versus 74 % for the Norwood and Sano cohorts, respectively. The rate of serious adverse events was up to 46 %, representing a significant morbidity. Initial hybrid treatment, including patients with a high Aristotle score is highly effective in case of prostaglandin resistant duct obstruction, pulmonary run off, or restrictive/intact atrial septum [21, 23, 24]. In addition, the Hybrid stage I approach allows postnatal resuscitation even with the option of later compassionate therapy based on the parent’s decision-making. However, the therapeutic objective is to achieve a long-term prospect for patients, which is worth living after staged procedures finalized by Fontan completion or after biventricular repair. The Achilles’ heel of the hybrid approach was the interstage I period, the fate of the left pulmonary artery after comprehensive stage II, and the diastolic dysfunction in two patients directed from univentricular strategy to BVR. Based on the growing body of literature, that the brain of newborns with HLHS develops with some delay, thereby being more vulnerable to injury from open-heart surgery , the authors are convinced, that in principle the hybrid approach allows for a normal neurological outcome, and can stand the comparison with the Norwood palliation. Currently, a prospective study considering this topic is ongoing, and the results of the first almost twenty analyzed patients are promising. However, without considering the Aristotle score at admission, normal somatic and neurological outcome can only be achieved, if there is no negative impact of the surgical-interventional strategy per se. The interstage deaths and also the need for HTX between the initial procedures and even after comprehensive stage II demonstrate these vulnerable periods. The observation of late, post stage II deaths in two , and the need for HTX in additional three patients demonstrate even more that not all surviving patients have the chance for transplant-free outcome. The same is true after Fontan completion and even in patients after BVR. Although the presented data are reporting about 15-year experience with the hybrid approach, the median observation period is still to short to reach a conclusion, which neonates really benefit from the hybrid procedure in terms of the long-term outcome.
The retrospective design of this study precluded the assessment of risk factors not entered in the model. Complete data of known risk factors for mortality, such as prenatal diagnosis, were not available for many patients and were not included in the analysis. We also identified a high level of correlation between some of the variables, which may have confounded the multivariable analysis and prevented us from identifying independent associations between variables and the outcome measures. Finally, the duration of follow-up is currently limited to a median of 5.3 years.
It remains to be seen whether these encouraging results are reflected in improved longer-term outcome for these patients. The ongoing prospective neurological follow-up data collection will tell us if this strategy might have additional beneficial aspects for most patients born with HLHS.
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