Arteriovenous fistula
That day i saw a pt haf fistula in hand n thr is pulse there..
finally i've found out what's that actually..
That is Arteiovenous(AV) fistula...
=> is an abnormal passage btw an artery and a vein. It may be congenital or surgical created for haemodialysis pt(renal failure), or acquired due to pathologic process such as trauma or an erosion of arteriole aneurysm
Patients with end stage renal failure are treated with hemodialysis. In dialysis, blood is withdrawn from an artery or vein, purified, and returned to a vein. The volume of blood is too great for veins to handle, so a vein must be enlarged. An artery and vein, usually in the arm above or below the elbow, are sewn together, to create a fistula, and arterial pressure eventually enlarges the vein. The enlarged vein can accommodate a cannula or large needle.
Physiology
finally i've found out what's that actually..
That is Arteiovenous(AV) fistula...
=> is an abnormal passage btw an artery and a vein. It may be congenital or surgical created for haemodialysis pt(renal failure), or acquired due to pathologic process such as trauma or an erosion of arteriole aneurysm
Patients with end stage renal failure are treated with hemodialysis. In dialysis, blood is withdrawn from an artery or vein, purified, and returned to a vein. The volume of blood is too great for veins to handle, so a vein must be enlarged. An artery and vein, usually in the arm above or below the elbow, are sewn together, to create a fistula, and arterial pressure eventually enlarges the vein. The enlarged vein can accommodate a cannula or large needle.
Physiology
When an arteriovenous fistula is formed involving a major artery like theabdominal aorta, it can lead to a large decrease in peripheral resistance. This lowered peripheral resistance causes the heart to increase cardiac output to maintain proper blood flow to all tissues. The physical manifestations of this would be a relatively normal systolic blood pressurewith a decreased diastolic blood pressure resulting in a wide (large) pulse pressure.
Normal blood flow in the brachial artery is 85 to 110 milliliters per minute (mL/min). After the creation of a fistula, the blood flow increases to 400 to 500 mL/min immediately, and 700 to 1,000 mL/min within 1 month. A bracheocephalic fistula above the elbow has a greater flow rate than a radiocephalic fistula at the wrist. Both the artery and the vein dilate and elongate in response to the greater blood flow and shear stress, but the vein dilates more and becomes "arterialized". In one study, the cephalic veinincreased from 2.3 mm to 6.3 mm diameter after 2 months. When the vein is large enough to allow cannulation, the fistula is defined as "mature." [1]
From wikipedia..
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