Keywords
Cardiac arrest - computed tomography - contrast pooling - CT contrast media
Introduction
Following intravenous contrast injection during an multidetector computed tomography
(MDCT) examination of stable patients, triphasic timeline technique is performed routinely.
Accordingly, the early arterial phase demonstrates arterial tree of the desired area,
based on the placement of the bolus tracking region of interest. However, in patients
with cardiac arrest or impending cardiac failure, opacification of hepatic veins and
layering of contrast medium in the inferior vena cava and renal veins has been described
in the literature. We present a case of hemodynamically stable patient in whom extensive
reflux of contrast medium into the hepatic, renal, and spinal veins was observed in
addition to a densely opacified inferior vena cava.
Case Report
An 80-year-female patient presented with signs and symptoms of acute left ventricular
dysfunction and severe pulmonary edema 1 month ago which was managed by mechanical
ventilation and decongestant therapy and discharged from the hospital after full recovery.
She returned to emergency room with history of pain in the left iliac fossa and burning
micturition for 1 week, vomiting and watery stools since 4 days, and shortness of
breath since 1 day. There was no history of hypertension or diabetes. On examination,
patient was conscious and breathless (NYHA class IV). Pitting edema of both lower
limbs was noted. Her blood pressure was 130/80 mm Hg. She had tachypnea (97/mnt) and
breathing at a rate of 29/min. Basal crepitations and pansystolic murmur were appreciated
on auscultation. ECG showed V1 to V5 ST segment elevation. Chest radiography revealed
cardiomegaly. Echocardiography demonstrated diameters of aorta and left atrium 33
and 40 mm, respectively. Left ventricular end diastolic diameter was 54 mm and end
systolic diameter was 38 mm. Posterior wall measured 9 mm with an ejection fraction
of 20%. Pressure in the right ventricle was 36 mm Hg. Dilated left ventricle with
akinesia of distal septum, apex, and apicolateral segment were noted. Moderate mitral,
aortic, tricuspid, and pulmonary regurgitation were observed. Both atria did not show
any abnormality. Her oxygen saturation, serum electrolytes, and arterial blood gases
were noncontributory. Diagnosis of severe left ventricular dysfunction associated
with pulmonary edema was considered. Ultrasonography of abdomen revealed prominent
inferior vena cava and peripherally calcified round mass lesion in left suprarenal
region. Pleural effusion was noted on both sides. After obtaining informed consent,
contrast enhanced CT Scan (GE Revolution 16 slice) was performed using nonionic iodinated
contrast medium (Omnipaque 350 mgI/ml) at a rate of 4 ml/s into the right femoral
vein because of unavailable veins in the upper extremities. Severe reflux of contrast
medium was noted into the hepatic, renal, and spinal veins while right atrium and
inferior vena cava were opacified densely, indicating severely raised pressure in
the right atrium [Figure 1] and [Figure 2]. Her vital conditions were stable during and immediately after the CT scanning.
She was treated by diuretics, bronchodilator nebulization therapy and broad spectrum
antibiotics for 1 week. Inotropes were not used during the treatment. Her breathlessness
gradually improved and was free of symptoms at the time of discharge from the hospital
on the 6th day of admission. At home, the patient suddenly became unconsciousness
and succumbed.
Figure 1 (A-C): (A) Contrast enhanced CT of abdomen. Most cranial A B axial section demonstrates
uniformly enhancing cardiac chambers. (B) Axial image shows densely filled hepatic
segment of inferior vena cava. Branching hepatic veins are also seen due to retrograde
reflux. (C) Axial view demonstrates significant reflux into both renal veins from
the inferior vena cava
Figure 2 (A and B): (A) CT scan of abdomen with contrast enhancement. A. Sagittal reformatted image demonstrates
severe reflux into inferior vena cava, iliac and epidural veins. Regurgitation into
renal veins is appreciated. (B) Axial view shows reflux into iliac and epidural veins
on both sides
Discussion
Velocity of flow of fluid particles (blood) in concentric laminae varies progressively
from zero to maximal near to the wall in the axial stream without mixing in the lumen.
From Reynolds’s formula, it is assumed that all venous flow is laminar unlike in a
turbulent flow where thorough mixing occurs.[1],[2],[3] During contrast-enhanced MDCT examination for routine indications, triphasic bolus
tracking technique is performed to demonstrate arterial tree effectively in the early
arterial phase. It is widely known that severely increased right ventricular pressure
and acute right heart failure impede the forward flow of contrast medium, resulting
in reflux into inferior vena cava, the path of least resistance. Intense enhancement
of abdominal veins is accompanied by faint opacification of abdominal aorta and arteries.
In hemodynamically stable patients, even mixing of cardiac output does not affect
the differential specific gravities of blood and injected contrast medium at the clinical
rate of delivery. In the event of severely impaired cardiac function with cessation
of cardiac pulsations and electrical activity, layering and stagnation of contrast
medium in the dependent portion of inferior vena cava and abdominal veins are observed.[4],[5] Besides the inferior vena cava, hepatic veins and renal veins are also visualized
densely. Reflux into the portal, lumbar, and iliac veins is also described.[6],[7] Cardiogenic shock following acute myocardial infarction and acute dissection of
aorta were described to result in dependent venous contrast pooling and hypostasis
in two different patients who were alive during the CT examination and died within
hours.[8] Dependent contrast pooling has been recognized as a sign of cardiac arrest.[9],[10] Constrictive pericarditis and ischemic cardiomyopathy also may result in acute cardiac
failure causing venous contrast pooling on CT examination. Route of injection via
the femoral vein is not a contributory factor for the gross reflux observed in our
patient as venography through femoral vein for many other indications does not result
in retrograde flow into the tributaries. Even a direct selective catheter delivery
of contrast medium into renal vein osteum against the antegrade flow does not opacify
the renal vein. It requires sufficiently high injection pressure to delineate the
main renal vein. Also vena cavography does not show the spinal veins. Even in the
case of venacaval obstruction, injected contrast medium finds the antegrade direction
through collateral pathways, but not towards end organs such as kidneys or spinal
cord. According to the reviewed literature, this phenomenon is observed during terminal
event such as cardiac arrest or acute heart failure just before death, but not in
patients with stable vital parameters as in our patient who lived for a week following
the examination.
Conclusion
The patient described here had stable vital signs during the CT scanning and for the
next 7 days. Reflux of contrast medium into the inferior vena cava, hepatic, renal,
and lumbar epidural veins otherwise observed on MDCT examination in patients with
cardiac arrest or acute right heart failure as a terminal event is described in this
surviving patient, a novel feature not described in the literature.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms.
In the form the patient(s) has/have given his/her/their consent for his/her/their
images and other clinical information to be reported in the journal. The patients
understand that their names and initials will not be published and due efforts will
be made to conceal their identity, but anonymity cannot be guaranteed.
