Case Vignette 2 Continued

A neck MRI/magnetic angiogram study (MRA) and hypercoagulability work-up in the patient was negative. A TEE showed a normal interatrial septum with a PFO, but no atrial septal aneurysm was detected. He was treated with aspirin, and is considering either Coumadin or percutaneous PFO closure in the future is further neurological events occur.

Suggested Work-Up for Source of Embolus

The utility and yield of echocardiography in searching for a presumed cardiac source of embolus will vary with patient's age and comorbidities. Echocardio-graphy is more likely to be useful in younger patients, or those with known predisposing cardiac conditions. In contrast, the workup of most elderly patients with a stroke should start with an imaging modality of the internal carotid arteries (either carotid duplex ultrasound, angiographic computed tomography study, or MRI/MRA).

When is TEE indicated in the workup of stroke? If there is a high suspicion of cardiac source of embolus,

Fig. 12. Transesophageal echocardiography and agitated saline contrast ("bubble") study showing shunting of bubbles from right atrium (RA) to left atrium (LA) via patent foramen ovale (PFO) (A). (B) Shows one popular model of transcatheter closure devices (CardioSEAL®), its appearance during cardiac catherization, and a sketch of its final deployment and anatomical relationship to the interatrial septum. The deployed closure device (C) followed by a repeat "bubble" study confirmed successful closure of the PFO—note the absence of bubbles in the left atrium (D). (Please see companion DVD for corresponding video.)

Interatrial Shunt Device

Fig. 12. Transesophageal echocardiography and agitated saline contrast ("bubble") study showing shunting of bubbles from right atrium (RA) to left atrium (LA) via patent foramen ovale (PFO) (A). (B) Shows one popular model of transcatheter closure devices (CardioSEAL®), its appearance during cardiac catherization, and a sketch of its final deployment and anatomical relationship to the interatrial septum. The deployed closure device (C) followed by a repeat "bubble" study confirmed successful closure of the PFO—note the absence of bubbles in the left atrium (D). (Please see companion DVD for corresponding video.)

and the TTE yields insufficient information to rule out a cardiac source, a TEE is indicated, provided that the results would impact therapy. The sensitivity of TEE has been shown to be superior for left atrial appendage thrombus (nearly 100 vs 39-63% for TTE), ascending aortic atheroma, and vegetations (88-100% sensitivity vs 44-60% for TTE). TEE is better able to evaluate prosthetic valves, particularly mitral valves, which often cause much acoustic shadowing artifact on transthoracic studies. TEE is also more sensitive (89 vs <50% for TTE using contrast) and 100% specific for detecting interatrial septal abnormalities. However, it is only moderately better (11 vs 4% for TTE) for detecting intracardiac masses, and there is no incremental yield in finding intracardiac masses (including thrombi) in patients without cardiovascular disease and a negative TTE.

Class I (definitely proven to be of benefit) American College of Cardiology/American Heart Association guidelines for clinical application of echocardiography in neurological disease include:

1. Patients of any age with abrupt occlusion of a major peripheral or visceral artery.

2. Younger patients (<45 yr) with cerebrovascular events.

3. Older patients (>45 yr) with neurological events, without evidence of cerebrovascular disease or other obvious causes.

4. Patients for whom a clinical therapeutic decision (e.g., anticoagulation) will depend on the results of the echocardiogram.

Class III (definitely proven to be unbeneficial) indications are: patients for whom the result of the echocardio-gram will not impact the approach to diagnosis or therapy.

Chapter 17 / Cardiac Source of Embolus SUGGESTED READING

Amarenco P, Cohen A, Tzourio C, et al. Atherosclerotic disease of the aortic arch and the risk of ischemic stroke. N Engl J Med 1994;331:1474-1479.

Beattie JR, Cohen DJ, Manning WJ, Douglas PS. Role of routine transthoracic echocardiography in evaluation and management of stroke. J Int Med 1998;243:281-291.

Brickner ME. Cardioembolic stroke. Am J Med 1996; 100: 465-474.

Cerebral Embolism Task Force. Cardiogenic brain embolism. The second report of the Cerebral Embolism Task Force. Arch Neurol 1989;46:727-743.

Cheitlin MD, Alpert JS, Armstrong WF, et al. ACC/AHA Guidelines for the Clinical Application of Echocardio-graphy. A report of the American College of Cardiology/ American Heart Association Task Force on Practice Guidelines (Committee on Clinical Application of Echocardiography). Developed in collaboration with the

American Society of Echocardiography. Circulation 1997;95:1686-1744.

Kistler JP, Ropper AH, Heros RC. Therapy of ischemic cerebral vascular disease due to atherothrombosis. N Engl J Med 1984;311: 27-34;100-105.

O'Brien PJ, Thiemann DR, McNamara RL, et al. Usefulness of transesophageal echocardiography in predicting mortality and morbidity in stroke patients without clinically known cardiac sources of embolus. Am J Card 1998;81:1144-1151.

Overell JR, Bone I, Lees KR. Interatrial septal abnormalities and stroke: a meta-analysis of case-control studies. Neurology 2000;55:1172-1179.

The French Study of Aortic Plaques in Stroke Group. Atherosclerotic disease of the aortic arch as a risk factor for recurrent ischemic stroke. New Engl J Med 1996;334:1216-1221.

The Stroke Prevention in Atrial Fibrillation Investigators Committee on Echocardiography. Transesophageal echocardiographic correlates of thromboembolism in high-risk patients with non-valvular atrial fibrillation. Ann Intern Med 1998;128:639-647.

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