A 63 y.o. woman presents with widening of the mediastinum on CXR

She has a complex aortic history with hx of acute type A dissection s/p repair c/b acute on chronic arch dissection and rupture s/p redo sternotomy and total arch replacement with an elephant trunk in (11/5/21), Why is her mediastinum widening?

In this view from March there is a small periaortic hematoma which is much worse on the current film at the top.

Our patient had a type III endoleak in her previous graft.

Type III endoleaks are less common than type II endoleaks with an incidence of 3-4.5%  They are more common in older grafts where 50% would leak after 8 years. As opposed to type I and type II endoleaks, type III are an emergency because they refill the aneursym sac and  cause a nine fold risk of secondary rupture. 

Type I leaks are at the proximal or distal attachment sites.

Type II leads  are caused by retrograde flow through aortic side  vessels into the aneursym sac. They occur in 15% of patients in the first year and can be embolized.  This is the most frequent type of leak.

Type III leads are holes in the stent material

Type IV leaks are porous graft walls, .These rarely occur now with new graft materials.

The stent graft is a tube made of a thin metal mesh covered with a thin polyester fabric or polytetrafluoroethylene (PTFE).  The metal can be on the inside or outside.  The metal in the stent contains nickel in varying amounts and can cause a systemic reaction in those allergic to nickel

Open aortic repair was first introduced in the 1950’s and was used for aortic aneursyms and dissections.  It is still used for individuals with tortuous vessel,  heavy calcifications or insufficient length of the aorta for attachment.  Endovascular repair was first done in 1990  by Parodi.  It has become the procedure of choice for the elderly patient or patient who is a poor surgical risk.

HOWEVER:

The durability of endovascular repair came into question in 2020 with the NICE trial. Guidelines issued at that time in the UK  recommended against endovascular repair for infrarenal aortic aneuryms  based on the high re-intervention rates. Aortic stents  cause a mismatch  in aortic compliance because they stiffen the aorta compared to the native wall of the aorta.  This leads to hypertension, decreased coronary perfusion and increase in pulse wave velocity in the aorta with acceleration of distal atherosclerosis.

 REMEMBERING YOUR EMBRYOLOGY

The aortic structure varies along its length, but stents do not address the variability in physiologic requirements. The proximal aorta arises from the cardiac neural crest as part of the L ventricular outflow tract.   It has a need for elasticity while the distal aorta , beyond the subclavian arises from the mesoderm and is associated with muscular contraction. This has led to consideration of an exostent in those with Marfans and dilation of the proximal aorta to 40-45 mm.  This external aortic root supports (PEARS) prevents further aortic enlargement and avoids stent placement but requires an open procedure. 

type II endoleaks can also lead to rupture of the aneursym sac as shown above; but this occurs rarely.

RANDOM FACT

Nickel, cobalt and iron are all ferromagnetic and stents contain a nickel alloy.  Even though nickel can be affected by a magnetic field  MRI is thought to be safe at field strenghs of 1.5 Tesla or less though image quality may suffer.

Our patient is scheduled for surgery in July.

 Patel R, Sweeting M, Powell J, et al. Endovascular versus open repair of abdominal aortic aneursym in 15 years of follow –up of the UK endovascular aneursym repair trial (EVAR trail  1): a randominsed controlled trial. Lancet 2016;388:2366-2374.

Lal B, Zhou W, Li Z, et al;for the OVER Veterans Affairs Cooperative Study Group. Predictors and outcomes of endoleaks in the Veterans Affair Open Versus Endovascular Repair(OVER) trial of abdominal aortic aneursyms. J Vasc Surg. 2015;62:1394-1404.

Hynes N, Acharya Y, Sultan S. The contemporsry design of endovascular aneurym sent graft materials: PTFE versus polyester. Front Surg. 15 Aug 2022. Sec Vascular surgery (iahttps://doi.org/10.3389/fsurg2022.984727

Kaczynski J, Jaber B, Woolgar J. Rupture of the infrarenal abdominal aortic aneurym(AAA following an endovascular aneursym repair (EVAR) due to an isolated type II endoleak. BMJ Case Reports