foreign the word aneurysm is based off the Greek word aneurysma which means dilation and that makes sense because aneurysms are abnormal dilations in a blood vessel we officially label a bulge and a blood vessel as an aneurysm when the diameter of that bulge is about one and a half times larger than the normal diameter of a blood vessel aneurysms can happen to any blood vessel in your body like the aorta the femoral artery the iliac artery the popliteal artery and the cerebral arteries they can also happen in your veins too but those are less common because blood pressure in veins is much much lower than in arteries there are two major categories of aneurysms true aneurysms and pseudoaneurysms in true aneurysms all the layers of the blood vessel wall dilate together true aneurysms that balloon out symmetrically on all sides of the blood vessel are called fusiform aneurysms whereas asymmetrically shaped aneurysms balloon out only to one side of the blood vessel this asymmetrical shape usually happens because for some reason one side of the blood vessel wall has had to put up with higher blood pressures than the rest of the vessel wall or because the wall was weaker on one side to begin with asymmetrically true aneurysms can be called either saccular or Berry aneurysms you can think of pseudoaneurysms as false aneurysms as in they're not actually aneurysms at all they are caused by a small hole in your blood vessel which allows blood to leak out of the vessel and form a pool of blood that looks like a fusiform or Berry aneurysm depending on where the hole is and how big it is the blood pools because the surrounding tissues act as a wall that contains the blood in one spot arterial aneurysms occur most commonly in the aorta with about 60 percent of true aortic aneurysms happening in the abdominal section of the aorta and about the other 40 percent happening in the thoracic section of all the abdominal aortic aneurysms you can find about 95 percent of them just below the point where the renal arteries Branch off from the abdominal aorta but above the aortic bifurcation that's because there is naturally Less elastin in the walls of this part of the aorta than the rest of the aorta aneurysms are caused by a weakness in the blood vessel wall so anything really anything that causes the wall to weaken can cause an aneurysm when a blood vessel wall weakens it struggles to contain the pressure of the blood pushing against the walls so the diameter of the blood vessel Lumen increases on top of this pressure tension on the blood vessel walls increases as the diameter of the Lumen increases thanks to laplace's law making the aneurysm diameter even bigger creating the cycle of continuous bulging you've likely experienced this when you blow up a balloon the first breath into the balloon is tough but the next several breasts are pretty easy this is why aneurysms usually get bigger over time it's because of this positive feedback loop so what underlying conditions might weaken the wall of blood vessels well one way is if all the layers of those blood vessel walls don't receive oxygen typically the cells of the vessel walls are able to get oxygen from blood as it flows by but in the first section of the aorta where the walls are super thick and muscular in order to handle all that blood pressure coming from the heart they need to have their own set of blood vessels that supply the Tunica Media and the Tunica externa we call these special blood vessels Vasa fazorum and hypertension the vasavesorum can develop hyaline arteriolosclerosis narrowing their Lumen causing ischemia to the aortic wall and we end up with atrophy of the smooth muscle of the tunic a media overall all this weakens the aorta's wall the same thing can happen in blood vessels without Visa visorum if we have a bunch of plaque building up on the Tunica intima thanks to our friendly neighborhood atherosclerosis oxygen just can't penetrate all the vessels of the wall you can see this type of aneurysm often in the abdominal aorta where blood pressure is high and the aorta walls are nourished by passing blood if you think about this it's no wonder than why both aneurysms and atherosclerosis share similar risk factors they're usually people who are male who are over the age of 60 and who have hypertension In Smoke if we look at tertiary syphilis it affects the vasovazorum as syphilis causes inflammation in the Tunica intima of the Vasa vasorum which again are those blood vessels that deliver oxygen to the thick walls of the larger blood vessels and this ultimately leads to a narrower Lumen and restrict blood flow to the vascular walls of the thoracic aorta causing atrophy by the way the name for this Visa visorum inflammation is end arteritis obliterans if you were to look at the Vasa visorum in tertiary syphilis you'd see that inflammation causes fibrosis and scarring on the walls creating this cool to look at but less cool to have tree bark like texture other bacterial infections can also cause aneurysms which we label as mycotic aneurysms the bacteria from an infection somewhere else in the body can break off from the main infection and travel around in the blood usually these embolic bacteria will get stuck in the intracranial arteries viscal arteries or the arteries feeding the arms and legs there the bacteria enter and weaken the blood vessel walls leading to you guessed it in aneurysm some of the bacteria that commonly cause mycotic aneurysms are and these can be tricky to pronounce so bear with me bacteroids fragilis pseudomonas aruginosa and anything in the salmonella species you'll also see mycotic aneurysms are a complication of infective endocarditis but it's not limited to just bacteria infections from the fungi aspergillus candida and mucor are also a common cause of mycotic aneurysms genetic disorders affecting your body's ability to properly form connective tissues like fibrillin or collagen also weakens the blood vessel walls so people with Marfan Syndrome have weakened blood vessel walls because the elastic properties found within fibrillin is impaired and people with ehlers-danlos syndrome are more likely to develop aneurysms because their ability to form collagen proteins is disrupted alrighty then so intact aneurysms are usually okay and don't cause any symptoms I say usually because the bulging blood vessel can compress organs or vessels around it so if an aneurysm compresses a major vein like the inferior or superior vena cavae it could decrease the amount of blood returning to the heart usually though the big worry with aneurysms is the possibility that they might explode or more like rupture but it's more fun to say explode when an aneurysm ruptures it's like having a water main break blood is spewing out of the hole in the blood vessels and less blood is Flowing Downstream to the cells that need it which causes ischemia in that Downstream tissue in thoracic aneurysm specifically a very serious complication can occur if the aneurysm is right above the aortic valve as the aneurysm dilates it pulls on the walls around the aortic valve preventing the aortic valve from closing properly and allowing blood from within the aorta to flow back into the ventricle during ventricular diastole this particular condition is called aortic insufficiency and can also cause a high-pitched brassy-like cough because the left recurrent laryngeal nerve which wraps around the aorta is stretched by that expanding diameter of the aorta I don't have an audio clip for that brassy cough sound but it's pretty distinct when you hear it moving on to the brain If an aneurysm ruptures in the brain blood will pull into the subarachnoid space putting pressure on the brain tissue and irritating the meninges causing symptoms like a very sudden and intense headache and the inability for someone to flex their neck forward another point on this list of terrible things aneurysms can cause is blood clots as blood flows past the aneurysm some of the blood might pull over into the extra Lumen space caused by the aneurysm itself this Blood isn't being pushed along the blood vessel as quickly as the rest of the blood and when blood stays still for too long it likes to clot given enough time the blood clot might become so big it blocks off the entire blood vessel causing tissue ischemia or it could break into smaller pieces called emboli and get wedged into the small blood vessels also causing ischemia as an aside it's kind of nifty that the clotting property of blood is really useful to stop blood from leaking out of blood vessels but it also happens to be really really deadly if it stops the blood from moving altogether honestly blood coagulation could be the plot for like the third installment of the speed movies okay back on track abdominal aortic aneurysms sometimes have signs and symptoms and sometimes they don't even if the aneurysm has ruptured really severe pain in the Left Flank which includes the abdomen chest lower back as well as the groin a pulsating mass that is in time with the heartbeat somewhere in this painful region and hypotension occur in about 50 percent of aneurysms that have ruptured and are considered the classic signs of abdominal aortic aneurysm thoracic aorta aneurysms usually don't have any symptoms although sometimes they can cause severe chest back and abdominal pain aneurysms can be asymptomatic and are sometimes diagnosed accidentally when an individual gets an Imaging study for another reason usually they're seen best on an ultrasound CT scan or MRI if an aneurysm is present and large enough to cause risk to an individual it can be treated surgically alright as a quick recap aneurysms are blood-filled bulges that form in weakened areas of the blood vessel walls left untreated aneurysms can burst causing uncontrolled internal bleeding or excessive blood clotting based on the size and location of an aneurysm surgical treatment may be 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