Page 66 - Critical Care Notes

4223_Tab02_045-106 29/08/14 10:00 AM Page 60

CV

Aortic Dissection
Aortic dissection is a tear (without hematoma or an intramural hematoma) in
the aortic wall that causes a longitudinal separation between the intima and
adventitia layers resulting in diversion of blood flow from its normal arterial
pathway. Aortic dissection requires emergency surgery.
Pathophysiology
Tear in aorta intima → blood flows into subintimal region → pulsatile pressure
creates a false channel between intimal and medial layers of aorta → intimal
and medial layer is separated → circulatory volume decreases → channel
expands and creates either an expanding mass or a hematoma (from blood
coagulating) → lumen narrows and obstructs blood flow, cardiac output
decreases → results in end-organ failure, also diverted blood can pool around
heart, resulting in cardiac tamponade.
Clinical Presentation

Consider acute phase if diagnosed within first 2 wk of onset of pain.
Presenting Symptoms
■ Mimics inferior wall MI
■ Standard type A aortic dissection: severe chest pain, sometimes sharp
■ Standard type B dissection: sudden, severe chest pain radiating to the back;
described as “ripping or tearing” pain
■ Pain can shift to the abdomen
■ Increasing restlessness (sign of extending dissection)
■ Decrease in urine output
■ Anxiety: “feeling of doom”
■ Fainting or dizziness
■ Clammy skin
■ Nausea and vomiting
■ Pallor
■ Tachycardia, shortness of breath, orthopnea
■ Altered mental status and CVA-type symptoms
Diagnostic Tests
■ Chest x-ray: shows widening mediastinum
■ ECG
■ Transthoracic echocardiogram
60