A case report of successful ex utero intrapartum to resection of a fetal pericardial teratoma: understanding variables affecting management

Introduction

Fetal pericardial teratomas are amongst the least common primary cardiac tumours. Although these tumours are rarely malignant, a major challenge associated with these masses is their ability to rapidly enlarge and accumulate large pericardial effusions. This can result in the rapid evolution of fetal hydrops and fetal demise [1, 2]. It has previously been demonstrated that early intervention is the key to a successful outcome because once hydrops develops the outcome tends to be uniformly fatal [2]. Treatment modalities used for management of a pericardial teratoma include fetal pericardiocentesis, pericardial shunt placement, and open fetal resection. While open fetal resection is the more common and preferred treatment modality, patient-specific factors, especially placental anatomical variations, can make this procedure technically challenging. An ex utero intrapartum treatment to resection (EXIT) approach is a less commonly used method, reported only 3 times in the literature. Two of these resections involved intrapericardial teratomas [2, 3], while one involved a mediastinal teratoma [4]. We report successful management of a large fetal pericardial teratoma using a similar technique, highlighting patient factors that led to selection of this technique and variables that helped decide the procedure’s timing.

Case report

A 29-year-old primigravida was referred for a fetal echocardiogram at 21 weeks’ gestation for a mediastinal mass. The mass was heterogeneous, well circumscribed, cystic in appearance with a concomitant pericardial effusion, and was consistent with an intrapericardial teratoma. It was in the right anterior, superior mediastinum attached to the right atrial free wall and the base of the great arteries. The mass measured 2 × 2 × 2.2 cm at the time of initial diagnosis. At follow-up evaluation in 2 weeks there was a significant increase in the size of the pericardial effusion. She underwent a fetal pericardiocentesis at 24 weeks when 20 ml of clear pericardial fluid was drained. She was closely monitored thereafter using weekly fetal echocardiograms. A fetal magnetic resonance imaging (MRI) was performed close to resection at 33 weeks (Figure 1). We serially monitored the tumour size along with parameters such as combined ventricular output (CVO), umbilical arterial Dopplers, and ductus venosus Dopplers amongst others. Although none of her follow-up scans showed any significant reaccumulating pericardial effusion, the mass continued to enlarge with rapid growth involving both the cystic as well as the solid components of the tumour. At 32.6 weeks’ gestation the mass measured 4 × 5 × 7 cm. The CVO ranged from 382 to 587 ml/kg/min with the lower values noted with advancing gestation, but it always stayed within the normal range throughout pregnancy. Since the pericardiocentesis at 24 weeks, a small persistent right sided pleural effusion was noted, assumed to be oestrogenically induced due to a pleural-pericardial fistula rather than being a marker for hydrops.

Surgical resection

The patient was taken to the operating room at 33 6/7 weeks gestation. A low transverse C section was performed with partial delivery with the fetes still connected to the placenta. A peripheral IV was placed, and a median sternotomy was carried out. The tumour was noted to be large, multicystic, and densely adherent to the right atrium, right ventricle, right ventricular outflow tract, ascending aorta, left sided pericardium, and phrenic nerve. After the mass was resected (Figure 2) the cord was clamped, and the baby was delivered and moved to an adjoining operating table for chest closure. Umbilical catheters were placed, and the patient was intubated and placed on a ventilator. The mediastinum was explored for any residual visible tumour mass. The patient had one episode of supraventricular tachycardia that responded to cardiac compression and cold water. The chest was closed, and the patient was transferred to the neonatal intensive care unit (NICU). The infant remained mechanically ventilated and was extubated on day of life 15. She developed a left diaphragmatic paralysis due to phrenic nerve involvement in the teratoma for which she underwent a left hemidiaphragm plication. The mass was confirmed on biopsy to be a grade 1 immature teratoma.
At one year of follow-up the patient is doing well clinically. There are 2 small residual tumour masses, which due to their location could not be completely excised during surgery. One is located anterior to the aorta at the root of the great vessels and the other along the underside of the aortic arch. These are being monitored using serial axial imaging and serum alpha fetoprotein, a tumour marker. Both of these masses have remained unchanged in size over this time period with normal tumour markers. The patient has not had any recurrent supraventricular tachycardia.

Discussion

While pericardial teratomas are an uncommon primary cardiac tumour, their management presents a dilemma primarily because they have a natural tendency to enlarge rapidly and cause pericardial effusion with rapid evolution of hydrops and fetal demise. The primary variables that guide management decisions include gestational age, maternal comorbidities including structural variations involving the uterus or position of the placenta, size of the tumour, presence of pericardial effusion, compression from the mass causing haemodynamic or airway compromise, and availability of surgical expertise.
Most of these tumours are diagnosed in the second trimester. Once diagnosis is established close follow-up is warranted throughout the remainder of the pregnancy to monitor for evolving hydrops and tumour growth. Based on the experience of Rychik et al. [2] in managing 5 fetuses with this mass, early open fetal resection has been advocated as the primary treatment modality when appropriate surgical expertise is available. In their experience, once hydrops develops the outcome tends to be uniformly fatal. Unfortunately, because most of the parameters typically employed on fetal echocardiography including umbilical and ductus venosus Dopplers may not show any significant abnormalities until after hydrops has set in, fetal combined ventricular output is recommended as a more reliable parameter, abnormalities in which would precede hydropic changes noted on ultrasound. We employed this parameter to closely monitor our patient. We also serially followed the cardiovascular profile score to monitor our patient; this has previously been shown to correlate with mortality in fetuses with cardiac tumours [5].
A common problem with open fetal resection is the elevated risk of preterm delivery with resultant complications of prematurity [6]. Another concern with this approach is the potential problems that one could encounter with cannulation for cardiopulmonary bypass due to the small size of the fetus, should that be required for tumour resection. Additionally, maternal factors such as fibroids or placenta position can make this procedure very technically challenging and may increase maternal morbidity and mortality due to the additional risk it poses, both from a safety standpoint as well as the complications it might create for future childbirth [7]. Transplacental sirolimus has previously been reported in successful management of fetal cardiac rhabdomyomas, but not for pericardial teratomas [8]. Considering all these available options, early fetal resection was considered in our patient; however, the anteriorly positioned placenta and the potential adverse outcomes on subsequent pregnancies made it a suboptimal option. We continued to closely watch for any hydropic changes – the mass was monitored using weekly fetal echocardiography. Special emphasis was placed on combined ventricular output measurements in addition to routine fetal echocardiographic parameters.
An additional advantage of watchful waiting followed by the EXIT procedure, as highlighted in the case report by Agarwal et al., is the opportunity to perform an initial pericardiocentesis in fetuses with pericardial teratomas complicated by massive pericardial effusions, which can cause haemodynamic or airway compromise immediately after delivery. Our patient had a large effusion at the time of presentation, which was successfully drained at 24 weeks of gestation. There was no significant fluid re-accumulation subsequently.
Finally, one of the biggest advantages of the EXIT procedure for a fetus that is well into the third trimester, which would otherwise be delivered and have the tumour resected after birth, is using the uteroplacental circulation to support the fetus while the tumour is being excised. This obviates the need for cardiopulmonary bypass and cannulation. Our patient was able to have an EXIT procedure because the fetus remained haemodynamically stable and did not develop hydrops by the time of surgery. Should this have occurred, the outcome would likely have been quite different and suboptimal with potential problems related to haemodynamic and airway compromise from the mass after delivery, complications related to prematurity, and the critical condition of a hydropic newborn, for which the outcomes tend to be rather dismal.
Based on the experience gained through managing our patient along with reviewing the literature for management of fetuses diagnosed with a pericardial teratoma, we recommend weekly or biweekly fetal echocardiograms for patients diagnosed in the second trimester. We emphasise the use of combined ventricular output monitoring in addition to routine Doppler ultrasound variables. Haemodynamically significant isolated pericardial effusions can be managed by intermittent fetal pericardiocentesis as needed. In the absence of any complicating or contraindicating variables, early fetal surgical resection should still be the preferred modality of management; otherwise, close monitoring with surveillance for hydrops should be performed as pregnancy advances with readiness to perform open fetal resection followed by continuation of pregnancy at the first sign of fetal hydrops. Should there be no development of hydropic changes, pregnancy may be allowed to continue as far along as possible, preferably up to 32 weeks of gestation. At this stage, without contraindicating factors, an EXIT procedure could be the preferred modality for resecting the mass versus delivery of the fetus followed by surgical resection. Such procedures should always be undertaken at a tertiary care centre with appropriate surgical expertise as well as experience in handling these cases. A multidisciplinary team approach involving fetal cardiology, maternal fetal medicine, fetal interventionalists, congenital cardiovascular surgery, and anaesthesia is highly recommended. This is not a procedure that could be easily repeated without all these variables working in conjunction. The primary challenge to devising a standard algorithm is that each case is quite different, with its individual intricacies and nuances. For this reason, an individualised approach should be adopted based on gestational age, tumour characteristics, maternal comorbidities, and other pertinent variables.

Disclosures

Ethical considerations: none.
This research received no external funding.
The authors declare no conflict of interest.

REFERENCES