Aortic, Hypertensive and Vascular Emergencies

Acute Aortic Syndromes and Ruptured Aneurysms

An aortic dissection occurs when an intimal tear allows blood to enter and separate the layers of the aortic media, creating a false lumen. Dissections are classified anatomically to guide medical and surgical therapy. A Stanford Type A dissection involves the ascending aorta and generally requires emergency surgical repair. In contrast, an uncomplicated Type B dissection is initially managed medically, while complicated or selected high-risk Type B cases may require endovascular repair. Acute aortic dissection often causes abrupt, severe chest, back, or abdominal pain, but the pain is not always described as tearing or ripping, and some patients have little or no pain. While assessing vital signs, an interarm systolic blood pressure difference greater than 20 mmHg or a pulse deficit can raise suspicion for aortic dissection with branch-vessel involvement, but neither finding is diagnostic.

Managing hemodynamics in acute aortic dissection centers on ordered anti-impulse therapy. This therapy generally targets a heart rate of 60 to 80 beats/minute and a systolic blood pressure below 120 mmHg, or the lowest level that maintains organ perfusion. When not contraindicated, an intravenous beta-blocker is generally given before adding a vasodilator to limit reflex tachycardia and aortic shear stress. Think of shear stress like water hammering through a fragile garden hose: slowing the pulse rate first softens each pulse wave, preventing the expanding false lumen from tearing further. Titratable dihydropyridine calcium channel blockers, such as intravenous nicardipine and clevidipine, are used for controlled blood pressure reduction, but the bedside nurse must monitor closely for reflex tachycardia, particularly when treating aortic dissection.

A ruptured abdominal aortic aneurysm presents another catastrophic vascular collapse, causing sudden abdominal or back pain and hypotension. Critical care nurses should note that the classic triad of pain, hypotension, and a pulsatile abdominal mass is present in only a minority of patients. Nurses must also watch for Grey Turner sign, which is flank ecchymosis, and Cullen sign, which is periumbilical ecchymosis; both are late, nonspecific signs of retroperitoneal or intra-abdominal hemorrhage and may occur with aortic rupture. Following endovascular aortic repair, endoleaks occur when blood flows into the aneurysm sac outside the stent graft, requiring vascular surveillance to prevent delayed rupture. After any aortic repair, the nurse must monitor hourly urine output and renal function for early evidence of impaired renal perfusion or acute kidney injury, which may have several causes.