Case report
The patient was a 34-year-old woman (weight, 38.3 kg; height, 150 cm;
BSA, 1.29) who had been diagnosed at birth with tetralogy of Fallot on
the basis of severe cyanosis. The original m-BT shunt on the left was
performed at the age of 2 years. During outpatient follow-up, the
patient fell down the stairs and suffered a cervical spinal injury.
Recently, however, cyanosis has progressed rapidly during physical
movement, and we decided to treat her with surgery. The patient’s
physical activities of daily living had decreased significantly, and
there was concern about pulmonary artery hypoplasia; therefore, it was
thought that the patient would not tolerate radical surgery.
Preoperative contrast-enhanced computed tomography (CT) revealed
stenosis of the subclavian artery at the anastomosis to the pulmonary
artery and complete occlusion of the right ventricular outflow tract.
(Figure 1 a) In surgery, dissection was performed through a midline
incision approach as usual, and after establishing an artificial
heart-lung machine with ascending aortic blood supply and right atrial
debridement, a short circuit was created from the ascending aorta to the
main pulmonary artery using a 6 mm artificial vessel. (Figure 2) The
patient was easily weaned from cardiopulmonary bypass and had a good
course of postoperative ICU management. The patient was weaned from the
ventilator on the first postoperative day, and subsequent rehabilitation
progressed smoothly despite the paralysis. Postoperatively, her SpO2
increased to 80% and her preoperative symptoms, such as decreased SpO2
with light exertion, improved. Postoperative contrast-enhanced CT showed
that blood flow to the shunt and pulmonary artery was maintained.
(Figure 1 b)
Discussion
The BT shunt was originally designed and performed to improve cyanosis
in the tetralogy of Fallot, but it is not curative, and the pulmonary
artery blood flow rate decreases as the body grows. In fact, the
survival rate at 25 years after surgery of patients with tetralogy of
Fallot who underwent palliative surgery only is approximately 50%.
[2] There have been almost no case reports of palliative central
shunting in adulthood, [3] and we report here another case in which
cyanosis was improved in adulthood after central shunting.
The concerns in this case were the development of postoperative
congestive heart failure and hypercapnic lung injury. [4] Shunt
reduces blood flow to the body and increases pulmonary blood flow,
thereby increasing Qp/Qs as a surgical procedure. Although it is
difficult to accurately evaluate preoperatively whether the patient’s
heart tolerates congestive heart failure, the 6 mm artificial vessel
used in this study did not progress to heart failure due to low blood
flow, although the postoperative lungs showed temporary lung damage due
to high pulmonary blood flow.
The second concern is the patency of artificial blood vessels. In
general, there are many reports on the patency of artificial vessels in
FP bypass, but there are no reports on the patency of the central shunts
in adulthood. The shorter distance of the artificial vessel and its
higher blood flow rate in this procedure may be expected to result in a
higher patency rate than that of FP bypass; however, this has not been
clearly confirmed.
Central shunting was effective in improving SpO2 in adult patients;
however, there are many uncertainties regarding postoperative
hemodynamics.