Embolus in transit.

Abstract: A patient who presented with recurrent syncopal episodes was discovered to have a right-sided heart mass, which was revealed as an embolus in transit resulting in a lethal pulmonary embolic event. The initial focus of etiology on tumor rather than thrombus was misleading. A higher index of suspicion of thrombus in right heart mass may help future patients receive more directed therapy.

Key Words: cardiac mass, emboli in transit, pulmonary embolus, saddle embolus

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Cardiac masses can include tumor, vegetation, thrombus, or artifact. Right-sided heart masses are most often renal cell or uterine carcinoma, atrial or ventricular myxoma, or migrant thrombi. (1) Such migrant thrombi, often termed emboli in transit, have subtle distinguishing characteristics that are essential in consideration of treatment modality.

Atrial fibrillation or heart failure can often lead to left atrial or left ventricular dilation and predisposition to thrombus formation. Formation of thrombi in the right heart is much less frequent. These thrombi are more often embolized venous thrombi that have become entrapped in the valves and trabeculations of the right atrium and ventricle, thus appearing as a cardiac mass on an echocardiogram. (1) The mass is often pleomorphic and may demonstrate mobility during the imaging studies. (2)

Acute pulmonary embolus often arises from lower-extremity deep vein thrombosis and may be unsuspected clinically, delaying treatment. Pulmonary emboli result in 50,000 to 100,000 preventable deaths yearly. (3) Indeed, the mortality rate for emboli in transit, specifically, may reach 50%. (4) It is estimated that 33% of emboli in transit initially detected by echocardiography will proceed to full pulmonary embolism within 24 hours. (5) In cases of pulmonary embolism with rapid deterioration and death, it is common to find large emboli obstructing the main pulmonary artery or the bifurcation of the pulmonary artery. (3)

Discussion

Pulmonary embolus can present with sudden onset of dyspnea, pleuritic chest pain, hypoxia, and circulatory failure. (6) In massive pulmonary embolism, sudden hypotension, severe hypoxemia, and cardiac arrest may be found. (3) Patients at risk of deep vein thrombosis include those with heart failure, immobility, malignancy, or postoperative state. Treatment should be initiated with heparin, sometimes before any definitive diagnosis.

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Embolus in transit was first diagnosed by two-dimensional echocardiography in 1981. (7) Although transthoracic echocardiographic images can demonstrate cardiac masses, a transesophageal echocardiogram has significantly higher resolution and thus superior sensitivity for differentiation. (1) Emboli in transit often demonstrate a decreased acoustic density in comparison to normal myocardium or myxoma. (7) These emboli may manifest symptomatically as dyspnea and syncopal episodes, and may even present on auscultation as ejection murmur or a 0diastolic "tumor plop." (8)

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As stated previously, one-third of emboli in transit will proceed to pulmonary embolus within 24 hours. (5) Although thrombolytic therapy should be strongly considered preemptively, the fibrinolytic effects of heparin may not be rapid enough. (2) Embolectomy may be the appropriate intervention. (3) As both thrombolytic therapy and embolectomy carry the risk of further embolic events, filter systems should also be considered. (2)

Our experience in this case serves as a reminder of the possibility of discovering an embolus in transit, and perhaps will help increase suspicion of this potentially lethal circumstance. The 3-month-long period of symptoms preceding the patient's admission served as a distraction from this diagnosis, as an embolus would be expected to complete its journey within 24 hours. This, along with the echocardiographic images showing involvement of the inferior vena cava, right atrium, and right ventricle, led us instead toward an initial belief that the mass was a tumor in origin. Although our intervention was swift, if we had initially suspected a cardiac embolus rather than a tumor mass, immediate emergent intervention might have made a difference in the outcome.

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Key Points

* Emboli in transit will often proceed to pulmonary embolus within 24 hours of presentation.

* Physicians should maintain a high level of suspicion for emboli in transit with right-sided heart masses.

* Emboli in transit may be better differentiated by transesophageal echocardiography.

* Treatment modalities for emboli in transit include thrombolytic therapy and embolectomy.

Practice without thought is blind;

Thought without practice is empty.

--Kwame Nkrumah

Acknowledgments

We thank the Departments of Family Medicine and Internal Medicine at the Texas Tech Health Sciences Center for providing funding for supplies and materials and the Texas Tech Department of Medical Photography for their assistance in the preparation of the figures. We also thank Margaret Vugrin for her help with compiling the references.

From the Departments of Family Medicine, Cardiology, and Nuclear Medicine, Texas Tech Health Sciences Center, Lubbock, TX.

Reprint requests to Gary Meyerrose, MD, 3601 4th Street, Lubbock, TX 79430.

Accepted October 30, 2002.

Copyright [c] 2003 by The Southern Medical Association 0038-4348/03/9611-1158

References

1. Otto CM. Textbook of Clinical Echocardiography. Philadelphia. W.B. Saunders Co., 2000, ed 2, pp 354-366.

2. Farfel Z, Shechter M, Vered Z, et al. Review of echocardiographically diagnosed right heart entrapment of pulmonary emboli-in-transit with emphasis on management. Am Heart J 1987:113:171-178.

3. Goldman L, Bennett JC (eds). Cecil Textbook of Medicine. Philadelphia. W.B. Saunders Co., 2000, ed 21, pp 442-448.

4. Proano M. Oh JK, Frye RL, et al. Successful treatment of pulmonary embolism and associated mobile right atrial thrombus with use of a central thrombolytic infusion. Mayo Clin Proc 1988;63:1181-1185.

5. European Working Group on Echocardiography. The European Cooperative Study on the clinical significance of right heart thrombi. Eur Heart J 1989;10:1046-1059.

6. Murray JF, Nadel JA (eds). Textbook of Respiratory Medicine. Philadelphia, W.B. Saunders Co., 2000, ed 3, pp 1507-1508.

7. Armstrong WF, Feigenbaum H, Dillon JC. Echocardiographic detection of right atrial thromboembolism. Chest 1985;87:801-806.

8. Thompson R. Slack JD, Taliercio CP, et al. Embolus in transit. Clin Cardiol 1992;15:923-926.

RELATED ARTICLE: Case Report

A 74-year-old white man presented to the emergency department with the complaint of increasing number of syncopal events during the past several months. He had recently undergone corpectomy for cervical stenosis in the month before his presentation. The syncopal episodes, as well as episodes of what the patient described as chest tightness and shortness of breath, had occurred intermittently without apparent provocation for the past 6 months. The patient's medical history was significant only for cervical stenosis and tobacco use.

Workup in the emergency department included a normal complete blood cell count and chemistry panel, normal sinus electrocardiogram, negative chest x-ray, negative head computed tomographic scan, and a urinalysis with evidence of urinary tract infection and volume contraction. Physical examination was unremarkable with the exception of a systolic ejection murmur and moderate pitting edema to the lower extremities.

The patient was subsequently admitted for further evaluation of the syncopal episodes, orthopnea, and edema, and for treatment of the urinary tract infection and volume contraction. He was started on IV fluid hydration and an IV antibiotic on the night of admission. An echocardiogram with two-dimensional Doppler was obtained the next morning and revealed a mass that appeared to involve the inferior vena cava and right atrium. The mass was seen to intermittently cross the tricuspid valve and prolapse into the right ventricle (Figs. 1 and 2).

On discovery of the mass, computed tomographic scans of the chest and abdomen as well as a cardiothoracic surgical consultation, were obtained. However, shortly thereafter, the patient developed chest pain and became acutely short of breath. Computed tomographic scan of the chest revealed several large intraluminal filling defects in the right and left proximal pulmonary arteries, as well as in some of the smaller branches. These findings were thought to represent multiple pulmonary emboli. He recovered somewhat with oxygen therapy and was transferred immediately to the cardiac intensive care unit, where the patient went into cardiopulmonary arrest. He was resuscitated and appeared stable on both ventilatory and pressure support. A second echocardiogram obtained during and immediately after resuscitation revealed the absence of the right atrial mass and the appearance of a small right ventricular mass (Fig. 3). Clinically, it was thought that the cardiac mass had embolized to the lungs. While arrangements were being made to proceed with a transesophageal echocardiogram and emergent surgical intervention, the patient suffered another cardiopulmonary arrest, and resuscitative efforts were unsuccessful. Consent for autopsy was later obtained from the family.

On autopsy, there were no abnormalities of the kidneys, ruling out renal cell carcinoma. Furthermore, the inferior vena cava was clear of any mass or residual thrombus. On examination of the heart, the anatomy was again without abnormality. No mass, residual thrombus, or damage existed within the heart. Dissection of the pulmonary artery, however, yielded the suspected embolus. A large, well-formed thrombus was discovered, doubled and wrapped on itself and completely blocking the bifurcation of the pulmonary artery, which represents the classic presentation of saddle embolus (Fig. 4). Finally, examination of the lower extremities revealed large residual thrombi in the popliteal veins bilaterally (Fig. 5).

Jodie Dejecacion, MD, Deanne Veselka, MD, Michael Ragain, MD, Leigh Ann Jenkins, MD, and Gary Meyerrose, MD