<div>The “Airgap” and “Swirling Bubbles” signs in a Patient with
Esophageal Carcinoma</div><div>Tiago Castro Pinto<sup>1</sup>, Tiago Martins<sup>2</sup>,
Daniel Seabra<sup>2</sup>, Nuno Moreno<sup>2</sup></div><div>Afiliations</div><div>Department of Internal Medicine, Hospital Pedro Hispano, Matosinhos,
Portugal</div><div>Department of Cardiology, Hospital Pedro Hispano, Matosinhos, Portugal</div><div>Author Information</div><div>Tiago Castro Pinto, the corresponding author, is a Resident Physician in
Internal Medicine in Pedro Hispano Hospital , Matosinhos, Portugal</div><div>Tiago Martins is a Cardiopneumology Technician in Hospital Pedro Hispano
Hospital, Matosinhos, Portugal</div><div>Daniel Seabra is an Attending Cardiologist in Pedro Hispano Hospital,
Matosinhos, Portugal</div><div>Nuno Moreno is an Attending Cardiologist in Pedro Hispano Hospital,
Matosinhos, Portugal</div><div>Data Availability Statement</div><div>The data presented in the manuscript was extracted from electronic
health records and exam reports, with the informed consent of the
patient, as presented at the end of the manuscript.</div><div>Abstract</div><div>Introduction: Pneumopericardium is a dreaded complication in esophageal
carcinoma.</div><div>Case description: We report a case of a 62 year old patient with past
history of esophageal cancer with spontaneus pneumopericardium, without
hemodynamic compromise. Admission echocardiogram that revealed a
pneumopericadium with the presence of the “swirling bubbles” and the
“air gap” sign. A small esophagopericardial fistula was postulated as
the cause of the pneumopericardium. He underwent esophageal stent
placement with resolution of the pneumopericardium.</div><div>Discussion: Pneumopericardium is usually a sign of marked clinical
deterioration in neoplasia and leads to patients’ death few weeks. Here
we presented a case, in which a more fortunate and unusual outcome
happened.</div><div>Case description</div><div>We present a case of a 62 year old patient, with a past history of
esophageal cancer with pulmonary metastases undergoing palliative
chemotherapy treatment and with 2 palliative esophageal stents.</div><div>Other past medical history included active hepatitis B, arterial
hypertension and dyslipidaemia. He was an ex smoker of 80 pack-year
units).</div><div>He was sent by the outpatient oncology clinic to perform a routine
echocardiogram that revealed a pneumopericadium with the presence of
tiny bright echogenic spots in the pericarial sac</div><div>and the “air gap” sign(<i>figure 1, 2 and 3 and video 2</i> ). There
was no presence of echocardiographic data suggesting hemodynamic
compromise.</div><div>Upon presentation he had no complaints. There was no history of dyspnea,
chest pain, or vomiting. Physical examination was unremarkable. Routine
laboratory investigations, including haemoglobin and HS troponin, were
within normal limits. Electrocardiogram (ECG) showed normal sinus
rhythm, without ST segment alterations.</div><div>He underwent a whole body CT scan that confirmed pneumopericardium,
pneumomediastium and a presence of an oesophageal-pericardial fistula.</div><div>Multidisciplinary discussion followed, in which an upper endoscopy was
agreed, since the fistula was thought to be caused by erosion of tumoral
growth. However, he was started on piperacillin-tazobactam for the high
risk of mediastinitis.</div><div>The exam corroborated the clinical suspicion where a stenosis was
observed in the region of the proximal stent, which was being caused by
tumoral growth. Mediastinum compatible gastrointestinal contrast was
injected between the esophageal stents and the oesophageal wall, and a
small flow fistule was seen. Endoscopic balloon dilation was performed
and a third stent was placed successfully.</div><div>He remained hemodynamically stable and asymptomatic during the whole
stay. A control echocardiogram and CT both revealed a significant
reduction of the pneumopericardium. He was discharged after a 16-day
inpatient stay.No complications have happened since.</div><div>Discussion</div><div>Pneumopericardium is the accumulation of air-fluid level in the
pericardial cavity. It can occur with varied causes such as penetrating
or blunt chest trauma, invasive procedures, pericardium infections and
abnormal communications such as fistula between the pericardium and the
mediastinum, pleura or oesophagus. It has been reported to occur
spontaneously without any underlying etiology in healthy adults.</div><div>At clinical presentation patients are often asymptomatic. When
symptomatic, symptoms tend to correlate with the the extent and the
underlying etiology of the pneumopericardium. The characteristic
auscultation sound is the mill wheel murmur “bruit de moulin” heard as
a succession splash and shaking movement of the heart within pericardial
cavity.</div><div>However, it can be relatively easy diagnosed with TTE. The latter has
two pathognomic signs: “The air gap sign”(<i>figure 1, 2 and 3 and
video 2</i> ) traducing a cyclic disappearance of the cardiac shape during
systole coinciding with a cycling appearance of air within the
pericardium and “The swirling bubbles sign”(<i>figure 4 and video 1
and 3)</i> , in diastole, representing the presence of an air-fluid
interface with continuous churning movements in pericardial cavity due
to heart activity. The latter is revealed in echocardiography by several
small bright echogenic spots evoking micro air bubbles in the
pericardial sac. Chest CT can quickly confirm the diagnosis if in doubt,
and it offers further information about its’ possible etiology and
mechanisms.</div><div>Pneumopericardium can present and evolve in different manners. Usually,
if asymptomatic and without hemodynamic compromise, it can have a benign
course. However, it can be life threatening if cardiac tamponade is
present.</div><div>Comparing with current literature[1-6], cases of pneumopericardium
have variable prognosis. In the setting of an esophago-pericardial
fistula, it may resolve with therapy directed to the condition
responsible for the fistula formation and scarring by second intention,
but it is still a dreaded situation. In our case, the fistula and the
pneumopericardium resolved after stent placement, and possible infection
was treated early with piperacillin. Liao et al[5] reports a similar
case where after, a perdicardiocentesis because of cardiac tamponade, an
esophageal stent placement, leading to the resolution of the fistula.</div><div>We believe that what may possibly have led to the pneumopericardium was
the fact that the large volume pericardiocentesis performed one week
before, opened a latent communication canal due to a rapid decrease in
pericardial pressure.</div><div>The same fistula that was present between the esophagus and the
pericardium in pericardial space allowed the air to enter and exit
throughout the cardiac and respiratory cycle without significantly
increasing pericardial pressure. Hence, there was no hemodynamic
impairment or clinical signs of cardiac tamponade with our patient.
Miller et al[1] also reports a patient where a esophagopericardial
fistula with pyopneumopericardium could not be ruled on first contrast
imaging, but minuscule one was later revealed in meglutamine diatriozate
radiographic contrast study.</div><div>The treatment of pneumopericardium is also dependent on its
presentation. Patients with hemodynamic instability require emergent
pericardiocentesis[1, 2, 5, 7]. Watchful waiting may be considered
if asymptomatic and hemodynamically stable, as it happened to our
patient and with Caselli et al[3] and Durães-Campos et al[6], as
it can resolve spontaneously or by treatment of the underlying
condition[8].</div><div>Although most pericardiocenteses undergo successfully, the underlying
condition that creates pneumopericardium usually is a sign of marked
clinical deterioration in neoplasia and leads to patients’ death few
weeks. Here we presented a case, in which a more fortunate and unusual
outcome happened.</div><div>Bibliography</div><div>1. Miller WL, O.M.e.a., Pyopneupericardium Attirubuted to an
Esophagopericardial Fistula: Report of a Survivor and Review of the
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esophagopericardial fistula: Treatment with a coated expandable metal
stent. Gastrointestinal Endoscopy, 2000. <b>52</b> (5): p. 689-691.</div><div>Figure legends</div><div>Figure 1: M mode, showing the “airgap” phenomenon, as denoted by the
orange arrows.</div><div>Figure 2: Modified subcostal view in diastole evidencing
pneumopericardium (yellow arrow) and the “airgap” phenomenon (orange
arrow and orange line). LV=Left Ventricle, RV=Right Ventricle, PC=
Pericardial Cavity</div><div>Figure 3: Modified subcostal view in systole evidencing
pneumopericardium (yellow arrow) and the Airgap phenomenon (orange arrow
and orange line), as evidenced by the increase in length of the orange
line and the disappearance of the RV. LV= Left Ventricle, RV=Right
Ventricle, PC= Pericardial Cavity</div><div>Figure 4: multi-angle view (Apical 2 chamber left and short axis view
right) showing air in the PC. LV= Left Ventricle, RV=Right Ventricle,
PC= Pericardial Cavity</div><div>Video 1: “Swirling bubbles” sign in multi-angle view</div><div>Video 2: “Airgap” sign in modified subcostal view</div><div>Video 3: “Swirling bubbles” sign in apical 2 chamber view</div>