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The surgical palliation of the functionally univentricular heart: early and late outcomes

Katrien François UGent (2012)
abstract
Patients with functionally univentricular heart form a heterogeneous group of cardiac anomalies, that have in common that only one of the heart chambers is capable of supporting either the systemic or pulmonary circulation. Although these malformations are relatively rare, they account for nearly 9% of all congenital cardiac anomalies. Before any surgical treatment, the single ventricle sustains both the systemic and pulmonary circulations in a parallel circuit, which results in volume overload and chronic arterial desaturation. The current therapeutic approach in children with a functionally univentricular heart starts from birth, and consists of a staged protocol, through a number of consecutive operations, to ultimately result in the Fontan circuit, where both circulations are connected in series again. This results in near normal oxygen saturation and the elimination of volume load to the single ventricle. Symptomatic neonates can present with cardiac failure or cyanosis, depending on the anatomy of the ventricular inlet and outlet, and require palliative surgery to enhance or moderate the pulmonary flow, and relieve any systemic outflow obstruction. The bidirectional cavopulmonary connection, performed at 3-6 months of age, forms the next surgical step, and conducts the venous return from the SVC directly towards the lungs. In the advent of a low pulmonary vascular resistance and a good function of the single ventricle, the Fontan circuit is completed with the total cavopulmonary connection, around 2-3 years of age. Early and late survival are currently excellent in properly selected Fontan candidates. However, early outcome may still be compromised by diastolic dysfunction, elevated pulmonary vascular resistance, and pleural effusions. Late outcome is characterized by subtle, but continuous changes in the various compartments of the circuit, leading to a late Fontan attrition rate. The exact triggers for transition from a compensated to a decompensated state are still poorly understood, and medical therapies aiming at modulation of the pulmonary and systemic vascular resistance, remain limited and suboptimal. This thesis focuses on some aspects of early and late outcome in Fontan patients, in an attempt to optimize or adapt current treatment strategies. In the first part, we investigated the effect of staging the Fontan circulation in comparison to a one-stage approach, on postoperative mortality and morbidity after Fontan completion. We have demonstrated that lowering the age at TCPC, introducing an obligatory hemi-Fontan stage, and shortening the intervals in staged Fontan, had a beneficial impact on early outcome. The staging resulted in preservation of sinus node function, but had no effect on postoperative pleural effusions. Staging the Fontan circulation has become part of our standard protocol. In the second part of the study, we described the results of a prospective randomized trial, to test the impact of the ACE-inhibitor lisinopril on the duration of pleural drainage. Pleural effusions after TCPC remain the most important source of prolonged hospital stay, and are promoted by a complex interplay between inflammatory, hydrostatic and hormonal mechanisms. To study the hormonal component, we choose to investigate the activation of the RAAS by the TCPC, through the serum profiles of aldosteron, renin and ADH. We also investigated the inflammatory component, induced by CPB. We found a significant correlation of CPB and chest tube output duration, and in this regard off-pump or catheter techniques in extracardiac Fontan deserve further study. The hormone profiles all indicated early activation, with a return to baseline after five days. The increased preoperative levels of aldosteron and renin had normalized 6 months later. Pleural drainage correlated with the levels of the study hormones on the first postoperative day, but the administration of lisinopril had no impact on the effusions. We hypothesize that modulating the pulmonary vascular resistance instead of trying to decrease the systemic afterload, is possibly a more useful way to orientate future research. In the third part, we investigated the long-term effects of a Fontan circulation on body growth, by means of a longitudinal study of all single ventricle patients, that completed the Fontan course, and were followed in our center. We found that, already at the time of neonatal surgery, the patients’ weight and height had significantly decreased compared to birth, and this negative trend continued until the BCPA stage. The BCPA signified a turning point for most patients, resulting in a substantial catch-up growth during the pre-TCPC interval. After Fontan completion, only weight continued to improve, but z-scores for height stagnated. The finding that younger age at BCPA was predictive for a better weight gain before TCPC, is important, as this fetches another argument to advance the BCPA stage. Somatic growth was decreased in children treated with an ACE-inhibitor at latest follow-up, compared to Fontan patients without preclinical signs of cardiac failure.
Please use this url to cite or link to this publication:
author
promoter
UGent
organization
year
type
dissertation (monograph)
subject
keyword
univentricular heart, congenital heart disease, Fontan
pages
102 pages
publisher
Ghent University. Faculty of Medicine and Health Sciences
place of publication
Ghent, Belgium
defense location
Gent : UZ (auditorium E)
defense date
2012-01-26 17:30
ISBN
9789461970121
language
English
UGent publication?
yes
classification
D1
additional info
dissertation consists of copyrighted material
copyright statement
I have transferred the copyright for this publication to the publisher
id
2124083
handle
http://hdl.handle.net/1854/LU-2124083
date created
2012-05-31 10:05:49
date last changed
2012-06-01 08:23:55
@phdthesis{2124083,
  abstract     = {Patients with functionally univentricular heart form a heterogeneous group of cardiac anomalies, that have in common that only one of the heart chambers is capable of supporting either the systemic or pulmonary circulation. Although these malformations are relatively rare, they account for nearly  9\% of all congenital cardiac anomalies. 
Before any surgical treatment, the single ventricle sustains both the systemic and pulmonary circulations in a parallel circuit, which results in volume overload and chronic arterial desaturation.
The current therapeutic approach in children with a functionally univentricular heart starts from birth, and consists of a staged protocol, through a number of consecutive operations, to ultimately result in the Fontan circuit, where both circulations are connected in series again. This results in near normal oxygen saturation and the elimination of volume load to the single ventricle. 
Symptomatic neonates can present with cardiac failure or cyanosis, depending on the anatomy of the ventricular inlet and outlet, and require palliative surgery to enhance or moderate the pulmonary flow, and relieve any systemic outflow obstruction. The bidirectional cavopulmonary connection, performed at 3-6 months of age, forms the next surgical step, and conducts the venous return from the SVC directly towards the lungs. In the advent of a low pulmonary vascular resistance and a good function of the single ventricle, the Fontan circuit is completed with the total cavopulmonary connection, around 2-3 years of age. 
Early and late survival are currently excellent in properly selected Fontan candidates. However, early outcome may still be compromised by diastolic dysfunction, elevated pulmonary vascular resistance, and pleural effusions. Late outcome is characterized by subtle, but continuous changes in the various compartments of the circuit, leading to a late Fontan attrition rate. The exact triggers for transition from a compensated to a decompensated state are still poorly understood, and medical therapies aiming at modulation of the pulmonary and systemic vascular resistance, remain limited and suboptimal.
This thesis focuses on some aspects of early and late outcome in Fontan patients, in an attempt to optimize or adapt current treatment strategies.
In the first part, we investigated the effect of staging the Fontan circulation in comparison to a one-stage approach, on postoperative mortality and morbidity after Fontan completion. We have demonstrated that lowering the age at TCPC, introducing an obligatory hemi-Fontan stage, and shortening the intervals in staged Fontan, had a beneficial impact on early outcome. The staging resulted in preservation of sinus node function, but had no effect on postoperative pleural effusions. Staging the Fontan circulation has become part of our standard protocol. 
In the second part of the study, we described the results of a prospective randomized trial, to test the impact of the ACE-inhibitor lisinopril on the duration of pleural drainage. Pleural effusions after TCPC remain the most important source of prolonged hospital stay, and are promoted by a complex interplay between inflammatory, hydrostatic and hormonal mechanisms. To study the hormonal component, we choose to investigate the activation of the RAAS by the TCPC,  through the serum profiles of aldosteron, renin and ADH. We also investigated the inflammatory component, induced by CPB. We found a significant correlation of CPB and chest tube output duration, and in this regard off-pump or catheter techniques in extracardiac Fontan deserve further study. The hormone profiles all indicated early activation, with a return to baseline after five days. The increased preoperative levels of aldosteron and renin had normalized 6 months later. Pleural drainage correlated with the levels of the study hormones on the first postoperative day, but the administration of lisinopril had no impact on the effusions. We hypothesize that modulating the pulmonary vascular resistance instead of trying to decrease the systemic afterload, is possibly a more useful way to orientate future research.
In the third part, we investigated the long-term effects of a Fontan circulation on body growth, by means of a longitudinal study of all single ventricle patients, that completed the Fontan course, and were  followed in our center. We found that, already at the time of neonatal surgery, the patients{\textquoteright} weight and height had significantly decreased compared to birth, and this negative trend continued until the BCPA stage. The BCPA signified a turning point for most patients, resulting in a substantial catch-up growth during the pre-TCPC interval. After Fontan completion, only weight continued to improve, but z-scores for height stagnated. The finding that younger age at BCPA was predictive for a better weight gain before TCPC, is important, as this fetches another argument to advance the BCPA stage. Somatic growth was decreased in children treated with an ACE-inhibitor at latest follow-up, compared to Fontan patients without preclinical signs of cardiac failure.},
  author       = {Fran\c{c}ois, Katrien},
  isbn         = {9789461970121},
  keyword      = {univentricular heart,congenital heart disease,Fontan},
  language     = {eng},
  pages        = {102},
  publisher    = {Ghent University. Faculty of Medicine and Health Sciences},
  school       = {Ghent University},
  title        = {The surgical palliation of the functionally univentricular heart: early and late outcomes},
  year         = {2012},
}

Chicago
FRANCOIS, KATRIEN. 2012. “The Surgical Palliation of the Functionally Univentricular Heart: Early and Late Outcomes”. Ghent, Belgium: Ghent University. Faculty of Medicine and Health Sciences.
APA
FRANCOIS, KATRIEN. (2012). The surgical palliation of the functionally univentricular heart: early and late outcomes. Ghent University. Faculty of Medicine and Health Sciences, Ghent, Belgium.
Vancouver
1.
FRANCOIS K. The surgical palliation of the functionally univentricular heart: early and late outcomes. [Ghent, Belgium]: Ghent University. Faculty of Medicine and Health Sciences; 2012.
MLA
FRANCOIS, KATRIEN. “The Surgical Palliation of the Functionally Univentricular Heart: Early and Late Outcomes.” 2012 : n. pag. Print.