Long term outcomes of bidirectional glenn and fontan procedures in a tertiary care cardiac centre in south india
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Date
2019-12
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SCTIMST
Abstract
Patients with univentricular or biventricular atrioventricular(AV) connections can be
functionally univentricular, in which the dominant (single) ventricle provides the driving
force to both systemic and pulmonary circulations(1). Irrespective of the anatomic diagnosis,
the restoration of a normal preload, and optimization of afterload to the dominant ventricle
represents the fundamental principle in the management of these complex congenital heart
diseases.
The current staged approach to management involves an early neonatal palliation,
followed by stepwise reduction in preload to the single ventricle(SV)- the creation of a
bidirectional cavopulmonary anastomosis, followed by completion of the Fontan
circulation(2). These palliative surgeries are undertaken to route the systemic venous return
directly to pulmonary arteries (PAs). The bidirectional Glenn (BDG) anastomosis is most
frequently used as the 1st step in a staged palliation in preparation for a later total
cavopulmonary connection(TCPC). The blood from superior vena cava (SVC) is routed to
the pulmonary artery(PA) However, it may also be used in patients with hypoplastic right
ventricle(RV) and selected other lesions, such as Ebstein’s anomaly. It off loads the systemic
ventricle and is a direct source of blood supply to the pulmonary arteries facilitating their
growth. It is most commonly done in late infancy. It may also be performed as the final
palliation in older patients/ in borderline right ventricles/Ebsteins anomaly as part of 1.5
ventricle repair. Most of the patients undergo Fontan procedure on follow up so as to further
off load the systemic ventricle and direct the systemic venous blood totally to the pulmonary
arteries. The surgery involves routing of the blood from inferior vena cava (IVC) to the PA. It
is currently recommended by the age of 1.5 to 4 years. This staged approach gives the
ventricle the time to adapt and help in remodelling following reduction of the volume load.
The intermediate procedure prior to TCPC also helps to address other anatomic and 3
physiologic abnormalities (including atrioventricular valve regurgitation(AVVR), correction
of distorted PA anatomy).
Figure: The relative merits and demerits of BDG and Fontan surgeries
Both the procedures are at the best palliative in nature. There is a large amount of
literature regarding complications encountered on long term follow up of these patients. BDG
helps in offloading systemic ventricle and augments PA growth, however there is
desaturation and almost universal development of pulmonary arteriovenous
malformations(PAVMs)(3). Patients following Fontan surgery have normal saturation but it
is a state of preload deprivation and is fraught with ventricular dysfunction, protein losing
enteropathy (PLE), cirrhosis and arrhythmias in the long run(4). There are limited treatment
options(transplantation) if Fontan failure occurs.
Sree Chitra Tirunal Institute of Medical Sciences and Technology(SCTIMST) is a
tertiary care cardiac centre located in Thiruvananthapuram which caters to patients from
Kerala and the border districts of Tamil Nadu. There is a large cohort of SV patients who
were palliated with these surgeries in our Institute. We aim to report present-day outcomes
following BDG and Fontan procedures in children and young adults with various anomalies
and to examine the risk factors for mortality and morbidity. The ultimate goal is to identify
patients who are at high risk of failure early so that timely interventions may be planned
which may positively influence their survival.
BDG
• Offloading systemic
ventricle
• PA growth
• Demerits
– Desaturation
– PAVMs
FONTAN
• Normal saturation
• Unloads systemic ventricle
further
• Demerits
– Preload deprivation
– Ventricular dysfunction, PLE,
cirrhosis, effusions
– Need for 1 more surgery4
There is scarcity of data regarding the outcomes of BDG from India. It may serve as
the final stage of palliation in a large subgroup of patients where Fontan procedure is delayed
due to lack of resources, economic and social issues. We propose to analyze the long-term
survival, modes of death, and predictors of mortality in a large single-center cohort of
patients treated in SCTIMST with diverse forms of Fontan palliation.