Preoperative Evaluation:
Despite continuous improvements in diagnostic techniques and refinements
in management strategies, surgical mortality for Type-A dissection
patients remains high, and is mostly influenced by the patient’s
clinical status at presentation. 8 Without surgical
intervention, the mortality of type-A dissection has been reported to be
approximately 1 to 2% per hour after symptom onset, with up to 90% of
patients dying within 30days 5. Time is therefore of
paramount importance. A high degree of clinical suspicion for Type-A
dissection should be maintained for any patient who presents with sharp
chest or back pain, pulse deficit or waxing and waning of peripheral
pulses, and any hemodynamic instability.9
Once suspected, imaging options such as computed tomography (CT),
transthoracic and/or transesophageal echocardiography (TEE), and
magnetic resonance imaging can be utilized for confirmation.10, 11 Definition of anatomic details are important to
achieve true lumen cannulation when establishing cardiopulmonary bypass.
A multislice ECG-gated CT angiography will best define the anatomic
details about true and false lumens, extent of dissection, and status of
the intimal-medial flap.12 However, if hemodynamic
instability precludes definitive CT imaging, intra-operative TEE may
provide relevant details about the anatomy. Intra-operative
echocardiographic guidance should always be available to confirm true
lumen cannulation. 13 14