Cardiac tamponade: still being newly described.

"Medicine, to produce health, has to examine disease"
--Plutarch c.46-c.119

As clinicians, we are intrigued by unusual cases and challenged by rapid management decisions required by difficult diagnoses. This case presented by Conley et al (1) proves no exception and is remarkable as an uncommon cause of relatively common presentations that occur with metastatic disease to the heart. The authors succinctly review complications of a metastatic process involving several cardiac systems, in this case from Merkel cell carcinoma, emphasizing proper diagnostic and therapeutic decisions.

The causes of pericardial effusion and the involvement of metastatic disease to the pericardium have been well described. (2) One area of recent progress involves the vexing issue of patients who return with recurrent heart failure following pericardiocentesis despite little or no pericardial effusion. Sagrista-Sauleda et al (3) reported 15 patients with clinical cardiac tamponade who were found to have evidence of constrictive pericarditis despite having had successful pericardiocentesis. Of note, 6 of the 15 had a history of neoplasm or radiation to the chest, as did this patient. The diagnosis was not confirmed until cardiac catheterization with measurement of the right atrium, pulmonary artery, pulmonary capillary wedge, and pericardial pressures before and after pericardiocentesis. Despite pericardiocentesis, the right atrium, as well as the right and left ventricular filling pressures, remained elevated and similar in these 15 patients. The visceral pericardium was recognized as the source for the persistently elevated filling pressures. Removal of both the parietal and visceral pericardium could eliminate the "effusive-constrictive" process; however, the decision to pursue pericardiectomy must take into account the high risk of the procedure and the overall prognosis of the patient. (4) Conley et al also correctly emphasized in their patient the use of direct hemodynamic measurements via catheterization to guide management.

In addition to pericardial involvement, the cardiac conduction system is also vulnerable to metastatic invasion. Detection of intracardiac metastatic lesions has been seen in 15% of patients with disseminated neoplasms. (5) The decision to pursue pacemaker therapy in such a patient is not always straightforward. To choose a life-prolonging treatment is a "value decision" with the value of added life possibly at the cost of additional suffering. (6) Decisions such as these are best made with consideration of palliation and respect for the wishes of the patient and family, as was done in this case.

This case of a pericardial effusion secondary to metastatic Merkel cell carcinoma is remarkable both as a first known description of cardiac tamponade and heart block as complications of Merkel cell carcinoma, but also more broadly, as a reminder that tamponade physiology must be considered in new cases even when initial signs and symptoms may be subtle.

References

1. Conley M, Hawkins K, Ririe D. Complete heart block and cardiac tamponade secondary to Merkel cell carcinoma cardiae metastases. South Med J 2006;99:74-78

2. Zayes R, Anguita M, Torres F, et al. Incidence of specific etiology and role of methods for specific etiologic diagnosis of primary acute pericarditis. Am J Cardiol 1995;75:378.

3. Satrista-Sauleda J, Angel J, Sanchez A. Effusive-Constrictive Pericarditis. N Engl J Med 2004;350:469-475.

4. Bonnema DD, O'Brien TX. Pericarditis constrictive-effusive. eMedicine Journal>Medicine>Cardiology, Vol. 6, Number 5, June 22, 2005. Available at: http://www.emedicine.com. Accessed June 22, 2005.

5. Burke A, Virmani R. Tumors metastatic to the heart and pericardium. In Rosai J (ed): Atlas of Tumor Pathology. Washington DC, Armed Forces Institute of Pathology, 1996, pp 195-209.

6. Taylor GJ, Kurent JE. A Clinician's Guide to Palliative Care. Malden, Blackwell Publishing Co. 2003, pp 4-5.

Byron Judson Colley III, MD, and Terrence X. O'Brien, MD

From the Department of Medicine, Medical University of South Carolina and the Office of Research and Development, Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC.

Reprint requests to Dr. Terrence X. O'Brien, Medical University of South Carolina, 135 Rutledge Avenue, Suite 1201, PO Box 250952, Charleston, SC, 29425. Email: [e-mail]

Accepted August 29, 2005.