Massive Cerebral Infarction Caused by
Paradoxical Embolism: Detection by
Transesophageal Echocardiography
Cyril S. Ofori, MD, LeRoy C. Moore, MD, and George Hepler, RDCS,

Pittsburgh, Pennsylvania
Two days after coronary artery bypass, a 75-year-old woman had sudden dense
left-sided hemiplegia. A transthoraeic echocardiogram showed a suspicious mass in the
right atrium and right ventricle, which was confirmed by transesophageal
echocardiography. Transesophageal echocardiography further demonstrated an
elongated mass across a patent foramen ovale. Deep femoral venous thrombosis and
massive cerebral infarction were also noted by Doppler ultrasonography and head
computed tomographic scanning, respectively. Paradoxical embolization was thought
to be the cause of the stroke. (J AM Soc ECHOCARDIOGR1995;8:563-6.)

A
2"Mthough paradoxical embolism has been a welldescribed entity for more than a century as a complication o f right to left intracardial shunting, the
diagnosis has been largely presumptive in many cases.
The capabilities o f echocardiography, particularly
transesophageal echocardiography, have greatly increased the reliability o f making the diagnosis in the
appropriate clinical setting. The case presented reports a patient w h o had a stroke as a result o f a
paradoxic embolus after coronary artery bypass. The
diagnosis was made by transesophageal echocardi-

ography.
CASE REPORT
A 75-year-old woman with a history of hypertension
was seen with chest pain and subsequently found to have
an inferior wall myocardial infarction. Cardiac catheterization demonstrated triple-vesel disease, and she underwent
five-vessel coronary artery bypass. Two days after surgery,
the patient was noted to have sudden-onset dense left-sided
hemiplegia. An initial head computed tomographic (CT)
scan revealed a probable infarct in the territory of the right
middle cerebral artery.
Transthoracic echocardiography was done the next day,

From the Division of Cardiovascular Disease, the Western Pennsylvania Hospital.
Reprint requests: Cyril S. Ofori, MD, Division of Cardiovascular
Disease, the Western Pennsylvania Hospital, 4800 Friendship
Ave., Pittsburgh, PA 15224.
Copyright 9 1995 by the American Societyof Echocardiography.
0894-7317/95 $3.00 + 0 27/1/62182

and an ill-defined mass was noted in the right atrium and
right ventricle. Transesophageal echocardiography was recommended for better definition of the cardiac mass. With
a Hewlett-Packard 5 MHz, 64-element, rotational-array
omniplane probe (Hewlett-Packard Co., Andover, Mass.),
a large lobulated mass consistent with a thrombus was
noted astride a patent foramen ovale (PFO). Portions were
noted in both atria and both ventricles (Figure 1). The
interatrial sepmm was also noted to bulge toward the left
atrium throughout the cardiac cycle. A tricuspid rcgurgirant velocity of 2.5 m/sec indicated elevated right-sided
pressures. No color flow could be demonstrated across the
interatrial septum with the mass in siva, and no contrast
study was performed.
Repeat head CT scan within 48 hours confirmed a definite large area of infarction in the territory of the right
middle cerebral artery, with significant mass effect and
compression of the lateral ventricles (Figure 2). Doppler
ultrasonography of the lower extremities showed extensive
deep venous thrombosis of the right femoral veins (Figure
3). Her condition continued to deteriorate neurologically
and she had significant respiratory distress necessitating
endotracheal intubation. Because her condition was
deemed terminal, no further studies were performed. She
died on the fourth postoperative day. The family declined
an autopsy. The echocardiographic diagnosis was paradoxical embolization of a large thrombus across a PFO
with a resulting massive cerebra/vascular accident.

DISCUSSION
The advent o f echocardiography and particularly
transesophageal echocardiography has greatly facili563

564

Ofori, Moore, and Hepler

Journal of the AmericanSocieWof Echocardiography
July-August199S

Figure 1 Transesophageal echocardiogram demonstrates thrombus (T) present with right
ventricle (RV), right atrium (RA), across interatrial septum (MS), and into left atrium (LA)
and left ventricle (LV).

Figure 2 CT scan of head demonstrates large area of infarction in right middle cerebral artery
territory with midline shift and compression of lateral ventricles.

Journal of the American Society of Echocardiography

Volume8 Number4

Ofori, Moore, and Hepler

565

Color-flow mapping of right and left femoral veins demonstrates venous thron~bosis
in right femoral vein (RT FV) with marked reduction in flow (flow is shown in blue). Left
femoral vein (LFTFV) appears normal by comparison.
Figure 3

tated the diagnosis of paradoxical embolisml Transesophageal echocardiography allows clearer visualization o f the interatrial septum and, combined with
microbubble contrast studies, is currently the gold
standard for detection of PFO. 1
Four criteria m u s t be met to satisfy the diagnosis

of paradoxical embolism, as first described by
Cohnheim 2 in 1877: (1) venous thrombosis, (2) an
abnormal communication between right and left circulations, (3) evidence of systemic embolization, and
(4) pressure gradient favoring fight to left shunting
at some point during the cardiac cycle. The most

Journal of the AmericanSocietyof Echocardiography

566 Ofori, Moore, and Hepler

definite diagnostic criterion is finding a thrombus
lodged across the intracardiac shunt. 2
The most common intracardiac shunt associated
with presumptive and definite cases of paradoxical
embolus is PFO in 72% of cases. 3 This case satisfies
all the criteria for the diagnosis of paradoxical embolism. Few reports have actually documented definitive diagnosis of impending paradoxical embolus.
In these patients a thrombus across a PFO was diagnosed and confirmed a t s u r g e r y . 4"6
In the absence of fight ventricular systolic hypertension, three mechanisms might be operative in
causing fight to left shunting in patients with PFO.
These include the following: (1) transient spontaneous reversal of left to right atrial pressure differential during the cardiac cycle, (2) sustained elevation
o f right atrial pressure above left atrial pressure induced by respiratory maneuvers, and (3) aberrant
flow redirection across the foramen ovale as a result
of a large right atrial mass. 7
In a study comparing younger adults with stroke
and control subjects, the high prevalence of PFO
suggested paradoxical embolism as a cause, particularly when no other cause was found. The control
group included patients undergoing contrast echocardiography studies before neurosurgical procedures to exclude right to left intracardiac shunting,
which might predispose to air embolism. Peripheral
venous thrombosis was thought to be clinically silent
in about 50% of the cases of stroke. Factors that may
predispose to venous thrombosis such as immobility
after major surgery may be expected to increase the
number of cases, s
In this patient with peripheral venous thrombosis

July-August 1995

and cerebral infarction, transesophageal echocardiography allowed direct visualization of a mass consistent with thrombus crossing a PFO. A pathophysiologic mechanism of paradoxical embolism is
suggested.
We thank the Echocardiography Department for their assistance in preparing this manuscript.

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