2. Palliative surgery
2.1 B-T shunt
Dr. Alfred Blalock created the B-T shunt operation in 1948 with the
support of pediatric cardiologist Helen B Taussig and surgical
technician Vivien Thomas. For patients with pulmonary obstruction,
pulmonary dysplasia, and severe hypoxia, the B-T shunt operation can be
performed to improve pulmonary circulation and promote pulmonary
vascular development. After 6 months of age, pulmonary vascular
resistance and PA development may be evaluated to determine the
feasibility of a bidirectional Glenn operation.10
2.2 PA banding
For patients with restricted pulmonary circulation, a pulmonary loop
surgery should be performed within 2 - 3 months to protect the pulmonary
vascular bed and prevent the development of pulmonary
hypertension.11 If the PA pressure is satisfactorily
reduced, a bidirectional Glenn operation may be performed after 6 months
of age.12
2.3 Norwood Operation
Dr. Norwood developed a series of operations to treat fetuses with
hypoplastic left heart syndrome (HLHS) and achieved appreciable
outcomes. Since then, Norwood’s operation has been widely adopted with
great success worldwide.13 Norwood’s techniqueis one
of the effective treatments for HLHS and left ventricular outflow tract
obstruction complicated by SV. The Norwood operation contains three
phases: phase I consists of palliative care with Norwood-type surgery in
the neonatal period, phase II consists of a Glenn operation, and phase
III consists of a full lumen operation.15
2.4 Glenn Operation
Dr. Glenn performed the first superior vena cava-right PA anastomosis
for tricuspid regurgitation in 1958.15 The
bidirectional Glenn operation is a form of bidirectional superior vena
cava pulmonary anastomosis, in which the proximal end of the superior
vena cava is cut off, sutured, and closed, and the distal end has an
end-to-side anastomosis with the right PA. If the left superior vena
cava persists, the left superior vena cava and the left PA should be
anastomosed at the same time. The Glenn operation is an important part
of the series of palliative operations for SV treatment. It has been
reported that the bidirectional Glenn operationfacilitates long-term
remission in patients with a single functioning
ventricle.16
2.5 Fontan Operation
It has been nearly 50 years since Dr. Fontan first described the Fontan
operation in 1971.17 The traditional Fontan operation
is performed by connecting the right atrium to the PA, suturing the
tricuspid valve, and directly draining the vena cava blood to the lung.
At present, the traditional Fontan operation is rarely used. A modified
Fontan operation that consists of caval-pulmonary anastomosis was
introduced and involves the intracardiac tunnel, intracardiac duct, and
extracardiac total lumen-PA connection. At present, the most common
clinical application of this technique is the extracardiac conduit of
total cavopulmonary connection (ECTCPC). This
surgical approach reduces the need
for anoperation in the right atrium, avoids high right atrial pressure,
and eventually reduces the incidence of early and mid-term arrhythmia
after other surgical procedures.18 The Fontan cycle is
characterized by increased vena cava pressure, decreased non-pulsating
pulmonary blood flow, decreased ventricular preload, and increased
postload.19 However, in the long run, the Fontan
circulation is a non-physiological state, in which patients’ tolerance
to exercise and hemodynamic response are compromised, which can lead to
various complications and affect the long-term
prognosis.20 Broad Fontan circulatory failure can be
classified into three categories: ventricular dysfunction, systemic
complications of Fontan physiology (such as plastic bronchitis and
protein-loss bowel disease), and chronic Fontan circulatory
failure.21 Additional complications associated with
Fontan surgery include an increased risk of stroke, protein-loss bowel
disease, and arrhythmia without survival
improvements.16 Despite these potential complications,
the Fontan series of operations is still a common and effective method
for SV treatment. When the Fontan series of operations and medical
treatments are ineffective, the only choice for SV treatment is heart
transplantation.