Mechanism
When an arteriovenous fistula is formed involving a major artery like the abdominal 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 typically consist of a relatively normal systolic blood pressure accompanied by decreased diastolic blood pressure, resulting in a wider 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 400–500 mL/min immediately, and 700–1,000 mL/min within 1 month. A brachiocephalic 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 vein increased 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".An arteriovenous fistula can increase preload. AV shunts also decrease the afterload of the heart. This is because the blood bypasses the arterioles which results in a decrease in the total peripheral resistance (TPR). AV shunts increase both the rate and volume of blood returning to the heart. Diagnosis
The diagnosis of this condition can be done via ultrasound

See also
References


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Organ-limited amyloidosis is a category of amyloidosis where the distribution can be associated primarily with a single organ. It is contrasted to systemic amyloidosis, and it can be caused by several different types of amyloid.In almost all of the organ-specific pathologies, there is debate as to whether the amyloid plaques are the causal agent of the disease or instead a downstream consequence of a common idiopathic agent. The associated proteins are indicated in parentheses. Neurological amyloid
Alzheimers disease (Aβ 39-43)
Parkinsons disease (alpha-synuclein)
Huntingtons disease (huntingtin protein)
Transmissible spongiform encephalopathies caused by prion protein (PrP) were sometimes classed as amyloidoses, as one of the four pathological features in diseased tissue is the presence of amyloid plaques. These diseases include;
Creutzfeldt–Jakob disease (PrP in cerebrum)
Kuru (diffuse PrP deposits in brain)
Fatal familial insomnia (PrP in thalamus)
Bovine spongiform encephalopathy (PrP in cerebrum of cows)

Cardiovascular amyloid
Cardiac amyloidosis
Senile cardiac amyloidosis-may cause heart failure

Other
Amylin deposition can occur in the pancreas in some cases of type 2 diabetes mellitus
Cerebral amyloid angiopathy

References


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