Clinical implication
As is known to all, pregnancy is a risk factor for
AD15. Previous studies have reported a higher
incidence rate of TAAD in pregnancy than TBAD4, 12.
However, recent data indicates an increasing trend in the occurrence of
TBAD, especially in women with pregnancy3. Consistent
with this, all five pregnant patients with AD admitted to our hospital
were Stanford type B in the past two years. In our study, advanced in
maternal age, preeclampsia and cesarean delivery may be contributing
risk factors of TBAD, which is consistent with literature
reports16, 17. It is recommended that patients with
high risks for aortic dissection should receive transthoracic ultrasound
every 4-6 weeks of pregnancy as part of routine prenatal
examination18, and should be given more attention to
the occurrence of AD.
Early identification and diagnosis of AD are crucial for treatment.
However, the diagnosis of AD in pregnancy is challenging. The symptoms
vary among patients, especially in those with TBAD, and are easily
confused with physiological discomfort and other diseases during
pregnancy19. Given the rarity of AD, it is easily
misdiagnosed. CTA has high sensitivity and specificity in the detection
of dissection20. However, patients may refuse to
undergo CTA due to concerns about the impact of radiation on the fetus.
In fact, fetal radiation doses delivered by CT examinations are
generally below the consensus levels for negligible risk (< 50
mGy)21. In addition, although iodinated contrast
agents typically traverse the placenta, the use of contrast agents in
pregnancy is considered relatively safe22.
Transthoracic echocardiography (TTE) is recommended as a preliminary
screening method for pregnant women complicated with AD because of its
high safety and technical popularity12, 23. However,
only lesions near the aortic root can be detected by transthoracic
echocardiography, and missed diagnosis may occur in the diagnosis of
TBAD24. In our study, all five patients were diagnosed
TBAD timely through CTA. Notably, not all the patients had no signs of
TBAD in transthoracic echocardiography. Since cardiac Magnetic Resonance
imaging (MRI) is time-consuming, we did not choose MRI before treatment.
Based on our experience, CTA is the optimal examination for pregnant
patients with suspected TBAD. It can not only quickly detect the
existence of dissection, but also clarify the type and extent of the
lesion. Moreover, CTA can show the iliac artery tortuosity and
pathological changes, which is essential for selecting safest surgical
approaches25.
Complicated TBAD with malperfusion or rupture is considered a medical
emergency and requires surgery management26. In the
endovascular era, new technologies are constantly emerging. TEVAR has
been shown to have lower mortality and morbidity compared with open
aortic repair in patients with TBAD 27, 28. Currently,
there are limited reports on the application of TEVAR in pregnant
patients with TBAD. The timing of TEVAR and cesarean section is also
controversial. Considering the negative impact of cardiac surgery on
fetus, a cesarean section was recommended before any surgical
intervention with the mother19, 29. Shu et al.,
reported two cases of TBAD in late pregnancy, who were successfully
treated through TEVAR11. They suggested that for the
late third trimester of pregnancy (beyond 37 weeks gestational age),
emergency intervention on the aorta should be before delivery if
accompanied by the complication11. In our study, the
first case experienced dissection rupture during cesarean section and
died unexpectedly. On the contrary, the following four patients who
underwent TEVAR before cesarean section survived following successful
treatment. Thus, we think that for patients with complicated TBAD in the
third trimester, there is a risk of dissection rupture during delivery.
This may be because of the cessation of placental circulation and an
increase in cardiac blood volume after fetal delivery. Given this,
performing TEVAR first may be a wise choice. Even though, this treatment
method is still challenging as TEVAR may become complex in patients with
late pregnancy. Due to the compression of the uterus, the stent-graft
delivery system is difficult to pass through the iliac artery. One
patient in our study experienced rupture of right iliac artery because
of above reason. Moreover, the amount of radiation was limited for the
safety of the fetus. Thus, TEVAR during pregnancy requires experienced
and skilled cardiac surgeons to ensure the safety and short duration of
the surgery.
Due to the small numbers reported globally, there is a lack of recorded
long-term outcomes for pregnant patients with TBAD who were treated by
TEVAR. The outcomes are satisfying in our series. Despite complications,
such as internal leakage, iliac artery rupture, and progression to TAAD,
which occurred during the treatment process, patients successfully
completed TEVAR and survived. Moreover, no major late complication was
detected, and a recovery of cardiac function was observed at last
follow-up. Another concern for applying TEVAR in pregnancy is the safety
of the fetus. It was reported that the total radiation dose during
endovascular therapy and one year after surgery is lower than 50
mGy30, which is within the safe range for the fetus.
In addition, except for the death of one neonate with preoperative fetal
distress died, three neonates survived TEVAR without any complications.
It is undeniable that brief neonatal asphyxia has occurred and may
worsen if the surgical time is extended. Besides trying to control the
duration of surgery, other methods to ensure the safety of newborns
should be explored.