AJR 2002; 178:1095-1099
© American Roentgen Ray Society
Dependent Pooling
A Contrast-Enhanced Sign of Cardiac Arrest During CT
Po-Pang Tsai1,
Jeon-Hor Chen1,
Jung-Lin Huang2 and
Wu-Chung Shen1
1 Department of Radiology, China Medical College Hospital, No. 2, Yuh-Der Rd.,
Taichung 404, Taiwan.
2 Department of Radiology, Taichung Veterans General Hospital, No. 160, Sect. 3,
Taichung Harbor Rd., Taichung 404, Taiwan.
Received April 23, 2001;
accepted after revision October 25, 2001.
Address correspondence to J.-H. Chen.
Abstract
OBJECTIVE. The purpose of this study is to describe the imaging
features of cardiac arrest that occur during CT.
CONCLUSION. CT features of cardiac arrest are characterized by a
pooling of contrast agent in the dependent parts of the right side of the
body, including the venous system and the right lobe of the liver. If medical
professionals are aware of these specific imaging features, prompt cardiac
resuscitation can be initiated to avoid permanent brain damage and death.
Introduction
Cardiac arrest results in abrupt cessation of cardiac pump function that
may be reversible by prompt intervention but will lead to death in its absence
[1]. Cardiac arrest in a
hospital setting most often follows acute myocardial infarction or is the
result of severe multisystem disease with accompanying hypotension and
associated asystole, bradyarrhythmia, or electromechanical dissociation
[2].
The real incidence of cardiac arrest during CT is unknown. We believe that
the incidence is not rare, especially because CT is playing an increasingly
important role in the diagnosis of disease. When a clinically unstable patient
undergoes CT, appropriate supervision by both visual and cardiopulmonary
monitoring is strongly advocated. In this setting, physicians should be aware
of the dramatic pathophysiologic or hemodynamic changes that might be seen on
CT when appropriate monitoring fails. To our knowledge, the CT features of
cardiac arrest have been described only once in the literature
[3] and not at all in the
English language. In this article, we describe the CT features of cardiac
arrest.
Materials and Methods
During an 18-month period, our review found five patients (one man and four
women, 20-84 years old; mean, 61 years old) at two hospitals who had cardiac
arrest during CT. These two hospitals are 1200- and 1400-bed medical centers.
Each hospital has three CT scanners. The hospitals perform approximately
20,000 and 25,000 CT examinations each year. The medical records and
radiologic studies of these five patients were reviewed. Two patients
presented with acute chest pain, syncope, and acute abdominal pain that had
radiated to their back for several hours. These patients had a widened
mediastinum on chest radiography. One patient had diabetes and was a chronic
alcoholic. He also had sepsis and acute renal failure. The second patient was
a victim of a car crash. She had multiple femoral fractures and was lethargic.
The third patient suffered from acute onset of left limb weakness, fever, and
abdominal pain. Cerebral vascular infarction or hemorrhage was suspected.
An abdominal CT examination was performed on three patients who were
suspected of having an intraabdominal abscess (n = 2) or
intraabdominal bleeding (n = 1). The other two patients were examined
with either chest or abdominal CT to rule out a dissecting aortic aneurysm.
Before the abdominal CT examination, two patients underwent unenhanced CT of
the brain. One of these patients showed extensive right middle cerebral artery
infarction. Of these five patients, two underwent both unenhanced and
contrast-enhanced CT, and the other three underwent contrast-enhanced CT only.
The patient with acute renal failure underwent contrast-enhanced CT because he
had regular hemodialysis.
Two types of CT scanners, the PQ 2000 (Picker International, Cleveland, OH)
and the Twin-Flash (Elscint, Haifa, Israel), were used. For contrast-enhanced
CT, 100 mL of nonionic iodinated contrast agent (Omnipaque [iohexol], 350 mg
I/mL; Nycomed, Oslo, Norway) was injected manually into the superficial vein
of the patient's forearm. The injection time was 90 sec. A CT scan was
obtained cephalocaudally with a collimation of either 8 mm (n = 1) or
10 mm (n = 4). The interslice spacing was 0. The imaging
reconstruction time per slice was 3 sec with the Picker PQ 2000 and 2.5 sec
with the Elscint Twin-Flash. The scanning time varied between 40 and 90 sec
for each set of CT images, depending on the covering range of scanning and the
type of scanner used.
Before scanning, all patients were given large quantities of fluid IV, and
one patient received a blood transfusion. However, their hemodynamic
conditions were still unstable. All patients were hypotensive (112 over 76 to
88 over 45 mm Hg). Three patients were given ventilatory assistance during the
examination. All five patients were carefully evaluated by the supervising
radiologist and the accompanying clinical physician before CT was performed.
Their cardiopulmonary functions, including blood pressure and respiratory
rate, were monitored during the examinations. Patients with both
contrast-enhanced and unenhanced CT images were carefully evaluated between
the two sets of scanning, and there were no changes in their conditions. Three
patients had cardiac arrest immediately after CT. One patient was pulseless at
the time of the chest radiography performed after the CT scan. The other
patient, also with unstable vital signs, had cardiac arrest 15 min after CT.
Vigorous cardiopulmonary resuscitation was performed in these five patients.
Two patients, one with middle cerebral artery infarction and the other with
aortic dissection, died despite resuscitation. Three patients were temporarily
revived but remained comatose. These three patients died several hours (2-5
hr) after the initial cardiopulmonary resuscitation.
CT images of these five patients were retrospectively reviewed by three
independent radiologists, each with considerable experience in abdominal CT.
The positive CT features were then recorded and analyzed.
Results
CT examinations showed type A aortic dissection in two patients and massive
hemoperitoneum in one patient. The CT images of these five patients were
bizarre. The injected contrast agent was distributed mainly in the venous
system. Stasis of contrast agent was found in the right brachiocephalic vein
(n = 2), the right subclavian vein (n = 2), the right
axillary vein (n = 2), and the right scapular vein (n = 1).
Retrograde flow of contrast agent into the left brachiocephalic vein, the left
subclavian vein, the accessory azygous vein, and both sides of the jugular
veins (n = 1) was also noted (Fig.
1A).
View larger version (107K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1A. —Contrast-enhanced CT scans in 84-year-old woman with type I
aortic dissection. Scan at level of thoracic inlet shows stasis of contrast
agent in right subclavian vein and right brachiocephalic vein. Note
regurgitation of contrast agent into left jugular vein (long
arrowhead), left subclavian vein (short arrowhead), and venules
in upper back. Also note enhanced accessory hemiazygous vein in left
prevertebral area.
|
|
CT images in all five patients showed contrast agent collecting in the
dependent portion of the superior vena cava and the inferior vena cava,
forming a blood—contrast level. In one patient, contrast agent
sedimentation was present bilaterally in the common and internal iliac veins.
The external iliac vein was not opacified. The most striking findings were
retrograde flow of contrast agent via the inferior vena cava into the right
hepatic vein, which then densely opacified the venous tributaries and
parenchyma in the right lobe of the liver (n = 5). Opacification of
the right portal vein (n = 4), the left portal vein (n = 3),
the main portal vein (n = 4), and the hepatic artery (n = 1)
was also noted (Fig. 1B).
Contrast agent in the superior portion of the main portal vein in one patient
indicated the possibility of partial thrombosis of the portal vein. The
azygous and hemiazygous veins (n = 4) were found to have contrast
agent pooling from the superior vena cava
(Fig. 1C). Via the inferior
vena cava, contrast agent also migrated to the right renal vein (n =
3), the right renal parenchyma (n = 1), and the right ovarian vein
(n = 1) (Figs. 1D,
1E, and
2). Regurgitation of contrast
agent from the vena cava into the ascending lumbar veins, the posterior
vertebral venous plexus, the posterior intercostal veins, and the dorsal veins
in the back was also discovered in all five patients
(Fig. 3A).
View larger version (115K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1B. —Contrast-enhanced CT scans in 84-year-old woman with type I
aortic dissection. Scan at level of hepatic hilum reveals densely opacified
parenchyma in right lobe of liver due to retrograde flow from inferior vena
cava. Note unusual opacification of right portal vein (arrow), main
portal vein, and hepatic artery (arrowhead).
|
|
View larger version (101K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1C. —Contrast-enhanced CT scans in 84-year-old woman with type I
aortic dissection. Scan at level of ascending aorta shows type A aortic
dissection. Note sedimentation of contrast agent in azygous (large
arrowhead) and hemiazygous (small arrowhead) veins. Pulmonary
artery is densely opacified, but aorta is faintly enhanced.
|
|
View larger version (110K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1D. —Contrast-enhanced CT scans in 84-year-old woman with type I
aortic dissection. Scan at level of renal hilum shows stasis of contrast agent
in dependent portion of inferior vena cava and regurgitation into right renal
vein (arrowhead). Note densely opacified vessels in right lobe of
liver and faintly enhanced aorta.
|
|
View larger version (103K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1E. —Contrast-enhanced CT scans in 84-year-old woman with type I
aortic dissection. Scan at lower level of abdomen shows contrast agent in
dependent portion of both aorta and inferior vena cava. Note unusual
opacification of right ovarian vein (arrowhead).
|
|
View larger version (104K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2. —20-year-old woman injured in car crash. Contrast-enhanced CT
scan at level of kidney shows contrast material pooling in right renal
parenchyma. Note small caliber abdominal aorta and blood—contrast level
in inferior vena cava.
|
|
View larger version (85K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3A. —Contrast-enhanced CT scans in 77-year-old woman with
dissecting aortic aneurysm. Scan at level of ascending aorta shows dense
opacification of azygous vein (arrowhead) and abundant venous plexus
in back area. Dissected aorta is not enhanced.
|
|
CT images in one patient showed regurgitation of contrast agent from the
right atrium into the coronary sinus and the great cardiac vein (Figs.
3B and
3C). The heart chambers and the
aorta did not enhance well. Two patients did not have opacification of the
cardiac chambers or the aorta (Figs.
3A and
4). One patient had
enhancement of the right side of the heart and the pulmonary artery only (Fig.
3A,3B,3C).
The other two patients had small amounts of contrast agent in the four cardiac
chambers, the pulmonary vessels, and the aorta (Fig.
1A,1B,1C,1D,1E).
CT images in one patient also showed a blood—contrast level in the lower
abdominal aorta (Fig. 1E). CT
images in another patient showed a small caliber of the abdominal aorta
(Fig. 2), a finding associated
with shock and hypotension. No evidence was seen of collapse of the aorta or
the inferior vena cava in the other four patients. The other abdominal organs
and vessels were not opacified in these five patients. Anteroposterior
radiography of the chest obtained immediately after CT in one patient clearly
showed the stasis of contrast agent in the dependent regions previously
described (Fig. 5).
View larger version (93K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3B. —Contrast-enhanced CT scans in 77-year-old woman with
dissecting aortic aneurysm. Scan at level of heart shows enhancement of right
ventricle and superior vena cava. Left heart chambers are not opacified. Note
enhanced great cardiac vein (arrowhead) and hemiazygous vein.
|
|
View larger version (100K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3C. —Contrast-enhanced CT scans in 77-year-old woman with
dissecting aortic aneurysm. Scan 2 cm caudal to B shows opacification
of right ventricle, right atrium, right hepatic veins, and vena cava. Note
regurgitation of contrast agent into coronary sinus (arrowhead).
|
|
View larger version (103K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4. —75-year-old woman with right middle cerebral artery
infarction and suspected intraabdominal abscess formation. Contrast-enhanced
CT scan at level of heart shows no enhancement of cardiac chambers. Contrast
agent deposits in dependent portion of superior vena cava. Note unusual
enhancement of azygous and hemiazygous veins.
|
|
View larger version (114K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 5. —49-year-old man with sepsis and suspected intraabdominal
infection. Anteroposterior radiograph of chest obtained after CT shows stasis
of contrast agent in dependent portions of right side of body, including right
subclavian vein, vena cava, right hepatic veins, right renal vein, bilateral
posterior intercostal veins, ascending lumbar vein, azygous vein, and abundant
venous plexus in upper chest and neck areas.
|
|
Discussion
CT is a popular diagnostic tool. Before performing CT, and then during the
scanning, the supervising radiologist should ensure that the patient is
clinically stable. In some instances, when the need for the CT examination is
sufficiently great, radiologists may need to consider whether to perform CT on
a patient who is clinically unstable. However, in such situations, effective
visual and cardiopulmonary monitoring should be performed before, during, and
after the CT examination because of the possibility of a dramatic change in
the patient's condition in a short time. It is therefore the physician's
responsibility to intervene immediately. The characteristic CT features of
cardiac arrest presented in this article afford important hemodynamic
information to the supervising physicians in addition to their direct visual
observation and cardiopulmonary monitoring.
The likely cause of cardiac arrest in these five patients was either an
unstable general physical condition or acute hemodynamic events that occured
during the CT rather than as a result of a reaction to the contrast medium.
The bizarre CT features of cardiac arrest in these patients are impressive and
are not fully understood. Hemodynamically, when cardiac arrest occurs, blood
flow slows. Both arterial and venous pressures drop dramatically to
undetectable levels. The normal pressure gradients between different vascular
systems, including arteriovenous and venovenous, are lost. Hence, the
distribution of the injected contrast agent at this time is determined partly
by the manually pushed pressure and partly by the hydrostatic pressure of the
contrast agent. Therefore, most of the contrast agent is found in the superior
vena cava, the inferior vena cava, and the dependent parts of the body,
including the organs and vessels. Another reason for the distribution of
contrast agent might be the force of the artificial ventilation that moves the
contrast material to the right side of the heart and down the venous side to
the inferior vena cava.
The unusual opacification of the portal vein and the hepatic artery cannot
be fully explained by the reasons previously mentioned. Except for one patient
with slight enhancement of the superior mesenteric vein, none of the patients
showed opacification of the celiac artery, superior mesenteric artery,
superior mesenteric vein, or splenic vein. Therefore, the contrast agent in
these two vessels most likely came from the right lobe of the liver, which was
filled with contrast material, by reverse flow via sinusoid communication.
Because the portal vein and hepatic artery are more anteriorly located than
the inferior vena cava and the right lobe of the liver, it is unknown why the
contrast agent regurgitated into the portal vein and the hepatic artery.
CT features in one patient showed blood—contrast levels in the lower
abdominal aorta; and in two patients, no opacification of the heart or the
aorta was present, suggesting a weakly pumping heart. Four of the five
patients underwent unenhanced CT of the abdomen or the brain, but these CT
images did not disclose any evidence related to cardiac arrest.
In conclusion, although only five patients were included in this study, and
the CT examinations were confined to the chest and the abdomen, the CT
features were characteristic of cardiac arrest. The injected contrast agent
provides little, if any, opacification of the heart chambers and the aorta.
Rather, the contrast material sinks to the dependent portions of the right
side of the body, mainly in the venous system and the right lobe of the liver.
The bizarre imaging findings are likely the result of the altered hemodynamic
distribution of contrast material which, because it is heavier than blood, is
more likely to sink in a patient whose heart has failed. All medical
professionals should be aware of these findings so that the CT examination can
be aborted immediately. This would allow cardiopulmonary resuscitation to be
instituted, if necessary, to preclude permanent brain or other significant
damage.
References
-
Myerburg RJ, Castellanos A. Cardiac arrest and sudden cardiac
death. In: Braunwald E, ed. Heart disease: a textbook of
cardiovascular medicine. Philadelphia: Saunders,
1997: 742-756
-
Nieman JT. Cardiopulmonary resuscitation. N Engl J
Med 1992;327:1075
-1080[Medline]
-
Stoger A, Munsterer B, Schinnerl A. Acute heart arrest in spiral CT
[in German]. Rofo Fortschr Geb Rontgenstr Neuen Bildgeb
Verfahr 2000;172:490
-491[Medline]
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
|
|
 
K. L. WININGER
Chest Compressions: Biomechanics and Injury
Radiol. Technol.,
March 1, 2007;
78(4):
269 - 274.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
C. Roth, M. Sneider, N. Bogot, M. Todd, and P. Cronin
Dependent venous contrast pooling and layering: a sign of imminent cardiogenic shock.
Am. J. Roentgenol.,
April 1, 2006;
186(4):
1116 - 1119.
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
