abdominal aortocaval fistula
Introduction
Abdominal aortic vena cava In 1831, James Syne reported for the first time that abdominal aortic aneurysm broke into the inferior vena cava causing aorto-caval fistula (ACF), which is the most common cause of abdominal aortic vena cava. The site of occurrence is mostly at the distal end of the aorta or slightly above the junction of the common iliac vein. basic knowledge The proportion of illness: 0.003% Susceptible people: no special people Mode of infection: non-infectious Complications: pulmonary embolism, blood in the stool
Cause
Abdominal aortic vena cava
(1) Causes of the disease
ACF can be divided into spontaneous (80%), traumatic (15%), and iatrogenic (5%), of which more than 90% of spontaneous ACF is composed of atherosclerotic abdominal aortic aneurysm. Caused by infection, abdominal aortic aneurysm, Marfan syndrome, Ehler-Danlos syndrome and aortic dissection aneurysm combined with ACF.
Abdominal aortic aneurysm with ACF is often larger, with a diameter of more than 6cm, the largest is 13cm. The average is 11cm, because the abdominal aorta and the inferior vena cava are closely adjacent, as the tumor increases, it will be around Tissue (especially inferior vena cava) inflammatory adhesion, with the sustained action of pulsatile pressure, the right a posterior wall of the abdominal aortic aneurysm and the inferior vena cava wall under pressure and necrosis, eventually forming ACF, the site of which occurs more at the distal aorta Or located slightly above the iliac vein junction.
(two) pathogenesis
When ACF is formed, blood is shunted from a high-pressure arterial circulation to a low-pressure intravenous vein, causing the venous pressure to rise, the returning blood volume to increase, the cardiac preload to increase, the myocardial contraction compensatory increase, and the cardiac output and heart rate to increase. Lead to cardiac hypertrophy or even heart enlargement, and finally can form refractory congestive heart failure, the diameter of the pupil >1.5cm will be life-threatening, the risk of coronary heart disease is greater.
On the other hand, due to the decrease of arterial blood flow in the distal end of the tumor, the renal perfusion pressure decreases, which directly causes the glomerular filtration rate to decrease, and further stimulates the renin-angiotensin system, causing the glomerular filtration rate to decrease, and chlorine. Sodium reabsorption increases, and even causes azotemia. Aortic-caval vein shunt will also cause lower limb ischemia, and pelvic organs will be congested due to vena cava hypertension, and lower extremity edema.
The extent of the above-mentioned pathophysiological changes and the rate of progression depend on factors such as pupil size, distance from the heart, size of the sub-flow, and time of pupil formation.
Prevention
Abdominal aortic vena cava prevention
There is no effective preventive measure for this disease. Early detection and early diagnosis are the key to the prevention and treatment of this disease.
Complication
Abdominal aortic vena cava complications Complications, pulmonary embolism, blood in the stool
1. Intravenous hemorrhage caused by elevated venous pressure of blood in the stool and urinary blood may cause rectal bleeding. About 40% of patients have elevated renal venous pressure, and the wall of the bladder wall is congested with gross or microscopic hematuria.
2. Pulmonary embolism is rare in clinical practice. It can cause pulmonary embolism due to the infiltration of the abdominal aortic aneurysm to the pulmonary artery through the pupil, and there is chest pain, difficulty in breathing, blood stasis and so on.
Symptom
Abdominal aortic vena cava symptoms Common symptoms Hypotension Abdominal vascular murmur Acute lower limb ischemic varicose veins No urinary wounds form a stroke... oliguric pulmonary congestion
The patient presented with local manifestations of abdominal aortic aneurysm and hemodynamic changes caused by arteriovenous shunt.
More than 80% of patients have abdominal and/or low back pain, due to necrosis of the tumor wall and pressure on the lumbar sensory nerves. The pain can be released to the groin, testicles and upper thighs. 90% of patients can touch the abdominal pulsation mass. 75% of patients can auscultate continuous vascular murmur in the abdomen, 25% of patients can touch tremor, abdominal back pain, abdominal pulsation mass and continuous vascular murmur are considered to be characteristic changes of abdominal aortic vena cava, if pupillary Small, with a wall thrombus to close the pupil, low blood pressure to reduce the shunt or abdominal aortic aneurysm when the inferior vena cava is completely compressed, can not hear vascular noise.
More than half of the patients fall into high-stroke heart failure with increased flow, tachycardia, diastolic blood pressure, increased pulse pressure and continuous murmur of peripheral arteries, and simultaneous shaking of the head during heartbeat (Musset) Zheng), and there are heart expansion and cardiac hypertrophy, pulmonary congestion, liver and other performance.
Decreased renal arterial pressure reduces renal perfusion pressure, and increased venous pressure can reduce glomerular filtration rate and renal tubular secretion, causing oliguria or anuria, often progressing to renal failure.
Lower extremity arterial blood flow reduction and venous pressure increase can cause acute lower limb ischemia in 1/4 patient, and lower extremity vein and abdominal wall superficial varices, and obvious edema of lower limbs and scrotum, about 60% to 70% The patient can see a pulsatile expansion of the superficial vein of the lower abdominal wall.
Examine
Abdominal aortic vena cava examination
1. Blood tests can be known to increase BUN and Cr.
2. Urine examination can have microscopic or gross hematuria.
3. Fecal occult blood test can be positive.
4. X-ray inspection
(1) Abdominal plain film: It can be seen that the calcification of the tumor wall and the signs of intestinal tube compression are difficult to determine the arteriovenous fistula by the flat piece; the chest plain film can be seen with the enlargement of the heart shadow and the change of pulmonary congestion, suggesting the existence of heart failure. .
(2) aortic angiography: the gold standard for the diagnosis of ACF, can display the location, size, information of abdominal aortic aneurysm and major blood vessel branches, the relationship between abdominal aortic aneurysm and surrounding organs, but renal failure and Hemodynamic instability should not be used.
5. CT and MRI examination of dynamic contrast-enhanced CT scan, its characteristic manifestation is the early development of the inferior vena cava after intravenous injection of contrast medium, which can be equal to the adjacent aorta, and the inferior vena cava dilatation and retroperitoneal pelvic varices can be seen. At the same time, the abdominal aortic aneurysm can be evaluated. The MRA can complete the diagnosis without injecting the contrast agent, and it is also an effective diagnosis method.
6. B-ultrasound can be seen in the abdominal aortic aneurysm and the compressed inferior vena cava and the inferior vena cava in the proximal end of the pupil. Color Doppler ultrasound can directly show abnormal blood flow between the aorta and inferior vena cava.
7. Other examinations of the radionuclide scan can be seen in the early concentrated image of the inferior vena cava; the inferior vena cava pressure and oxygen saturation can be measured by intubation of the femoral vein to the inferior vena cava.
The above examinations are not routine, and if the patient's vital signs are not stable, surgery should be performed as soon as possible.
Diagnosis
Diagnosis and differentiation of abdominal aortic vena cava
In patients with abdominal aortic aneurysm, high-volume heart failure, continuous abdominal vascular murmur, renal failure and lower extremity edema, superficial varices, etc. should be considered in the diagnosis of abdominal aortic vena cava, with the help of B-ultrasound, Auxiliary examinations such as CT can confirm the diagnosis.
