This patient, with a known malignancy, presented with nonspecific
abdominal symptoms. These were accompanied by hypotension and tachycardia
which were felt to have been caused by dehydration from poor oral
intake. The patient improved with intravenous rehydration.
The chest radiograph shows multiple
nodular opacities scattered throughout both lungs (Figure 1). These
metastases were noted on a chest CT performed one month earlier
(Figure 3). However, finding one radiographic abnormality should
not distract you from noticing others. A systematic
approach to radiograph interpretation can help to prevent such
an error (see Introduction to Chest Radiology). Her heart is significantly
enlarged (see Figure 4). Cardiac enlargement can be due to either
a dilated cardiomyopathy or a pericardial effusion. Although an
effusion is often described as producing a globular-shaped heart,
it is usually not possible to differentiate a pericardial effusion from
cardiac enlargement on a chest radiograph. An echocardiogram can
readily make this distinction.
A pericardial effusion does not generally cause symptoms unless
it is at elevated pressure and impedes cardiac output, i.e., tamponade.
The diagnosis of cardiac tamponade rests on clinical findings. Beck
(1935) described a triad of signs consisting of (1) systemic hypotension,
(2) elevated systemic venous pressure, and (3) muffled heart sounds. Beck’s triad is typical of
acute tamponade which may be due to abrupt intrapericardial hemorrhage
from penetrating trauma, invasive cardiac procedures, or rupture
of an ascending aortic dissection or myocardial infarction. The
complete triad is rarely present.
When tamponade develops gradually, the presentation is different
and often less dramatic. Dyspnea may
be the predominant symptom. This is believed to be due to lung stiffening
caused by interstitial edema perhaps at a microscopic level since
the chest radiograph generally does not show pulmonary edema. Hypotension
may not be present; the patient may even be hypertensive. Tamponade
thus has a spectrum of presentations ranging from circulatory collapse
to mildly reduced cardiac output with symptoms of dyspnea and chest
or abdominal discomfort.
The characteristic chest radiographic
appearance of tamponade is an enlarged heart with clear lungs.
When a pericardial effusion develops rapidly, as with penetrating
or blunt trauma causing acute hemopericardium, the heart size may
be normal (200 mL of fluid must accumulate before the heart would
appear enlarged). However, most nonhemorrhagic subacute or chronic
pericardial effusions causing tamponade are moderate to large (300–600
Jugular venous distension is a
characteristic clinical finding and is important in distinguishing
tamponade from hypovolemia as a cause of hypotension. However, neck
vein distension might not be present with tamponade when there is
concomitant hypovolemia. Pulsus paradoxicus is
one key to the diagnosis of tamponade, and should be tested whenever
tamponade is suspected. There is an accentuated fall in the systolic
pulse pressure (>10 mm Hg) during inspiration.
Nonetheless, pulsus paradoxicus is not present in one-quarter of patients
with tamponade, particularly patients who are hypotensive.
In this patient, pulsus paradoxicus was not tested, although
it was likely present. The irregular pulse palpated in this patient
(noted in the initial vital signs) was in fact due to disappearance
of the radial pulse during inspiration—the paradoxical pulse described by Kussmaul
in 1873. The pulsus paradoxicus is “paradoxical” not
because of the fall in systolic blood pressure during inspiration
but because the palpated pulse disappears or diminishes despite
the continued presence of auscultated heart sounds.
The EKG showed sinus rhythm with “borderline” low
voltage (QRS amplitude in the limb leads was <5 mm)
suggestive of a pericardial effusion. Electrical
alternans, a more specific sign of tamponade, was not clearly
present. It occurs when there is a very large pericardial effusion
in which the heart swings during cardiac contraction causing a beat-to-beat variation
in the EKG axis (QRS amplitude). An EKG after pericardiocentesis
showed increased voltage (Figure 5).
A. Initial EKG showing low voltage in the limb leads (<5
mm). There is slight beat-to-beat variation in the QRS amplitude
of leads V1, V4 and V5 (electrical alternans). B. EKG after pericardiocentesis and drainage of the pericardial
effusion showing increased QRS amplitude.
This patient’s clinical presentation was initially felt
to be due simply to dehydration; she did improve with rehydration.
However, hypotension due to cardiac tamponade will also temporarily improve
after fluid administration. Hemodynamic compromise would have recurred
had her tamponade not been definitively treated by removing the
pericardial effusion. Her abdominal symptoms remained unexplained
although abdominal discomfort can occur with tamponade (Famularo 2005).
In fact, her poor oral intake and hypovolemia were probably responsible
for unmasking the underlying tamponade.
Echocardiography showed a moderate-size
pericardial effusion (Figure 6). There was diastolic collapse of
the right atrium and right ventricle indicative of tamponade. During
pericardiocentesis, 600 mL of bloody fluid was removed. The systolic
pressure increased from 80 to 110 and heart rate decreased from 120
to 70. The effusion reaccumulated the next day and surgery was performed
to create a pericardial window. Biopsy and cytology showed adenocarcinoma.
Echocardiogram (long axis left parasternal view) showing
a moderate pericardial effusion (1 cm thickness) both anterior and
posterior to the heart (arrows).
The patient was treated with chemotherapy. She did well until
five months later when the pericardial effusion reaccumulated, causing
tamponade. The patient expired during that hospitalization.
Tamponade should be suspected in patients with hypotension or
dyspnea, particularly patients at risk for pericardial effusions
due to cancer, especially breast and lung cancer, uremia, rheumatologic
disorders such as systemic lupus erythematosus or rheumatoid arthritis,
and penetrating or blunt chest trauma. Suggestive clinical signs
should be sought including jugular venous distension and pulsus
paradoxicus, although these are not always present. The chest radiograph
usually shows an enlarged heart. However, small effusions (100–200
mL) may not cause cardiomegaly even though they can cause tamponade
when they accumulate rapidly or when the pericardial membrane is
stiffened from fibrosis.
Echocardiography is the test of
choice to detect a pericardial effusion and can also show signs
indicative of tamponade (right ventricular and right atrial diastolic
collapse). CT can detect a pericardial effusion and might be performed
as the initial test when tamponade is not suspected and other disorders
are being investigated such as pulmonary embolism or aortic dissection.
Treatment consists of emergency pericardiocentesis when there
is hemodynamic compromise. Intravenous fluid administration can
often be used as an initial temporizing measure.