(Doctors only)

 Ischemic stroke prevention: why we do the things we do 

Investigations

Transthoracic echocardiogram (TTE) (order with ‘‘bubble study’’)

– To assess for embolic source (anterior wall or apical akinesis, clot, valvular disease, large PFO).

– Low ejection fraction (20–30% is generally agreed upon as a cutoff) significantly increases thromboembolic risk due to stasis, and also should trigger further specific cardiac evaluation and treatment.

Transesophageal echocardiogram (TEE) (order with ‘‘bubble study’’)

– To assess for embolic source not seen well on TTE (aortic atheroma, PFO, atrial septal aneurysm, spontaneous echo contrast, left atrial appendage clot).

– If a PFO is found, we often will also do a screen for hypercoagulable states, a bilateral lower extremity ultrasound, and MRvenogram of the pelvis to look for venous thrombosis.

Carotid ultrasound (CUS)

 – To assess for internal carotid artery stenosis or occlusion.

 – Shows you direction of vertebral artery flow.

-You might not need it if you have a good-quality normal MRA or CTA of the extracranial circulation. CUS can be used to confirm a stenosis seen on MRA or CTA. If these non-invasive tests are concordant, it may not be necessary to do an invasive DSA to determine candidacy for endovascular or surgical treatment of a carotid stenosis.

Transcranial Doppler (with or without bubble study)

 – To monitor clot presence and lysis in the acute setting.

– To confirm intracranial stenosis/occlusion of major arteries seen on MRA or CTA.

– Emboli detection/monitoring.

– Look for PFO by injecting microbubbles. TCD with ‘‘bubble study’’ is the most sensitive and least expensive/invasive way to screen for right to left shunting.

– Hemodynamic reserve (breath holding index, vasomotor reactivity).

– Evaluate collateral flow patterns.

Digital subtraction angiography (DSA)

– Gold standard for determining degree of stenosis.

– Only way to definitively delineate and follow aneurysms or AVMs, dissection, vasculitis, or other arteriopathies.

.- If a PFO is found, we often will also do a screen for hypercoagulable states, a bilateral lower extremity ultrasound, and MRvenogram of the pelvis to look for venous thrombosis.