Vascular disorders

I) Aneurysms: An aneurysm is an abnormal dilation of a blood vessel. It is seen most commonly in the abdominal aorta. It can be commonly, saccular, fusiform or cylindrical.

Characteristics of common aneurysms

Dissecting Aneurysms: It is vessel dilation that occurs from the formation of a vessel wall hematoma due to a tear in typically, the tunica intima. There is no true aneurysm formation. Older age, hypertension, pregnancy, coarctation of aorta, trauma, any condition causing cystic medial necrosis like Marfan syndrome etc are common causes of dissecting aneurysms. It is most common in the ascending aorta. The hematoma collects in the tunica media. It may extend into aortic branches and abdominal aorta. It can be classified as Type A or proximal , where the dissection starts in the ascending aorta and may extend into the descending aorta; and type B or distal which begins in the descending aorta near the origin of the subclavian artery. Type A is managed surgically while type B can be medically managed. Patients present with excruciating, tearing pain in the anterior or posterior chest, AR if aortic valve is involved, STEMI from coronary artery involvement (don’t give anticoagulants in AMI from dissection), cardiac tamponade, shock, weakened pulses, organ ischemia like abdominal ischemia, stroke, retroperitoneal hemorrhage, collapse and death. X ray shows widened mediastinum and double aortic contour.

II) Peripheral arterial disease or arteriosclerosis obliterans: Peripheral vascular or arterial disease is the presence of systemic atherosclerosis in arteries distal to the arch of the aorta. Sometimes it may occur from embolisation. Risk factors are age older than 60 years, smoking, hypertension, DM, hyperhomocysteinemia, elevated CRP, elevated lipoprotein A, insulin resistance, chronic renal insufficiency and dyslipidemia. It presents with pain in the legs called intermittent claudication with physical activity such as walking, that gets better with rest, pain in buttocks, hips, thigh or calf. If the pain is confined to the calf, the superficial femoral artery is the likely site; if in the thigh and calf, the iliofemoral segment; if in the buttock and distally, the aortoiliac segment is involved. Examination will show muscle atrophy, loss of hair with smooth, shiny skin on the affected area, decreased or absent pulses in the feet, non-healing leg ulcers, cold or numb toes. Ulcers have a punched-out appearance, with a gray or yellow fibrotic base and undermined edges. Erectile dysfunction may occur either alone or as part of Leriche syndrome, which is caused by atherosclerotic stenosis of the abdominal aorta at it’s bifurcation into iliac arteries. In advanced disease, livedo reticularis may be seen. There is an increased risk of CAD.

ABI or ankle-brachial index is calculated as the ratio of systolic pressure in the ankle to brachial pressure, in the supine position. Normal ratio is greater than 1. The presence of an ABI less than 0.9 is consistent with PVD. In severe disease, ABI is < 0.5. Pressure is measured by doppler ultrasound at the brachial artery and posterior tibial artery. Arteriography is the gold standard for diagnosis.

III) Arteriovenous fistula: It is an abnormal connection between an artery and vein without intervening capillaries. They may be congenital or acquired. Congenital fistulas may be seen in Osler-Weber-Rendu syndrome or hereditary hemorrhagic telangiectasias. Acquired causes are penetrating trauma, cardiac catheterization or medically created for dialysis. They may appear as purplish, bulging vessels; local swelling. Larger AV fistulas are symptomatic causing hypotension, high output heart failure, fatigue, diversion of blood flow causing ischemic symptoms in the local area supplied. It predisposes to thromboembolism and internal bleeding. A machinery murmur may be heard over the fistula.