Treatment of AAA/Dissecting Aneurysms
Recently, the Medical Director of our Air Ambulance Program asked me about the use of Beta Blockers and other “sheer force” reducing medications for the treatment of Abdominal Aortic Aneurysms. It was his belief, that in Abdominal Aneurysms that were “dissecting”, these medicine would be of benefit.
My belief is that there is a difference between the pathophysiology of a dissecting aortic arch/aortic aneurysm that with your run of the mill AAA.
Case presentation
Recently we had a case where a patient was being transferred via helicopter. The nurses/medics on-board requested Beta Blockers and Nitroglycerin (IV) or perhaps Nitroprusside to reduce BP and “shear forces”. I declined stating that a rupturing or [potential rupturing AAA generally required monitoring for a precipitous drop in blood pressure, wherein the treatment would be fluids, blood and hopefully >>(before the event) surgical intervention. I explained my rationale. There appeared to be some question, but my orders were heeded. Within in 5 minutes the BP dropped from 180 – 190 systolic to 70 – 80 systolic. The patient landed, alert with BP of about 90. He made it to the OR and is doing fine.
So, what is the answer. If it is a known dissecting aortic aneurysm, regardless of location, do we use “shear force” reducing agents. Or, it is a suspected AAA, do we just do as I did?
Please respond ASAP and with references, if possible. I looked through Rosen and others and their is never a mention of “shear force” reducing medicines in AAA. There is always mention of these agents in dissecting thoracic aneurysms.
As I know, symptoms and physiopathology of dissecting thoracic aneurysms and AAAs are quite different. First of all, the anatomical lesion in background is different (dissection is not disruption). Second, patients with dissecting thoracic aneurysm are usually hypertensive while ruptured (or little leaked) AAAs produce a typical hemorrhagic shock. The rationale for hypotensive drugs in thoracic aortic dissections is to reduce heart work and distal resistances and to avoid progression of the dissection’s edge. I can’t see any indication to give hypotensive drugs to a patient already hypotensive because of his hypovolemia. Some works have been published about a role of beta-blockers in reducing size increase of AAAs, but they are not conclusive and a possible role of these drugs in emergency cases was not proposed.
B blockers are used for dissecting aneurysms. It has never been recommended in ruptured aneurysms. Some people have recommended B blockers in aneurysms to try and decrease growth rate, but this has never taken off.