Pseudoaneurysm

Introduction to pseudoaneurysms Pseudoaneurysm (pseudoaneurysm) can occur in all ages, more common in 20 to 63 years old, there is no significant difference between men and women. It is a pulsatile hematoma formed after the rupture of the arterial wall, and the fiber around the hematoma is wrapped into a pulsatile mass that communicates with the arterial lumen. Because there is no real vascular wall structure, only the hematoma is formed into a tumor wall. Once it is formed, it will gradually increase with repeated rupture or infection. If it is not diagnosed and treated in time, it often leads to massive bleeding and life-threatening. Most of the iatrogenic pseudoaneurysms are more common. basic knowledge The proportion of sickness: 0.03%-0.3% Susceptible people: no specific population Mode of infection: non-infectious Complications: Hypertension Arteriosclerosis

Cause of pseudoaneurysm

Congenital factors (35%)

The arterial wall has three layers of tissue, and the supporting force of the artery is provided by the intermediate muscle layer, which may have congenital defects. Normal blood pressure in the affected artery causes a balloon-like enlargement called a cystic aneurysm. Aneurysms caused by congenital defects almost always occur in the arteries at the base of the brain. They are also called "berry" aneurysms because of their shape and because several aneurysms often gather together.

Infection (15%)

Inflammation, regardless of the cause, can make the arterial wall weak. Most arterial inflammation is caused by diseases such as nodular polyarteritis or bacterial endocarditis (see infective endocarditis).

Disease factor (10%)

The middle part of the muscle wall of the arterial wall slowly deteriorates due to chronic diseases such as atherosclerosis or hypertension. An aneurysm caused by atherosclerosis is likely to be a sausage-shaped enlargement called an aneurysm that develops along a small segment of the artery.

Pathogenesis and pathology

Pseudoaneurysms have been in existence for more than 200 years, but the mechanism of their formation and the cause of rupture have not been fully elucidated. At present, the pathogenesis is that the arteries are caused by certain factors (such as trauma, infection, etc.), and a local hematoma is formed by rupture and hemorrhage, which is then surrounded by surrounding soft tissue, and gradually forms a blood-containing cyst, which is a clot. , blood clots and blood. The wall of the capsule has no three-layer structure of the intima, middle and adventitia of the normal arterial wall, but is composed entirely of fibrous connective tissue. This feature of the wall of the capsule is fundamentally different from the true aneurysm.

Domestic Zheng Yuming and other rabbit rabbit femoral artery successfully replicated the experimental model of femoral pseudoaneurysm in vivo, proposed the basic theory of the cause of traumatic pseudoaneurysm, and divided the formation of early traumatic aneurysm into 4 stages, 1 arterial injury Hematoma formation period (about 3d): Arterial "open type" injury or arterial wall injury and secondary rupture and hemorrhage, forming a localized hematoma. 2 Early stage of formation (4-10d): Arterial rupture and localized hematoma were embolized by blood clots and thrombus, and arterial blood flow could not enter the localized hematoma. 3 formation period (5 ~ 1 ld): blood clots and thrombosis, arterial rupture and localized hematoma, arterial blood flow in the localized hematoma cavity, pulsatile mass, that is, the formation of traumatic pseudoaneurysm. 4 tumor enlargement period (within 30 days): the pulsatile mass increases with the blood flow of the arteries, and increases the pressure on surrounding organs and tissues, causing different clinical symptoms and signs, or due to weak tumor wall, sudden Broken hemorrhage, causing acute arterial bleeding crisis. On the basis of animal models, the domestic hemodynamics of pseudoaneurysm was studied, and the cause of rupture was determined. It is considered that the change of hemodynamics is the enlargement of pseudoaneurysm. The important factor of rupture, that is, the blood flow in the tumor cavity is vortex, the blood flow velocity at the base of the tumor neck is significantly higher than the blood flow velocity in the tumor-bearing artery, and the tangential stress is generated on the tumor wall, and the wall of the force is lack of elasticity. Fiber, the tolerance to tangential stress is poor, and it gradually increases under the action of high-speed blood flow. When it exceeds the tolerance of the tumor wall, it will cause it to rupture. At the same time, the intra-tumor resistance index is higher than that of the tumor-bearing artery. The wall compliance is low, the blood flow resistance is large, and this compliance is negatively related to the tension and the mismatch between the arterial wall and the tumor wall compliance. It is also the cause of the tumor rupture. The infection of the pseudoaneurysm is the tumor cavity. The formation of a thrombus to embolize the distal artery, the surgical operation performed around the lesion to injure the tumor wall, and the use of a high-pressure syringe to push the drug in arteriography is an important cause of tumor rupture.

Pseudoaneurysm prevention

The occurrence of pseudoaneurysm is related to factors such as irregular puncture technique, improper postoperative compression, premature activity, application of anticoagulant drugs, excessive arterial fistula, and hypertension.

The following precautions are recommended for probable factors:

1. Proficiency in puncture technique and standardization of femoral artery puncture;

2, effective and effective femoral artery compression to stop bleeding, the intensity and time of oppression should be sufficient;

3. Strict lower limb braking and bed rest;

4. Appropriate application of anticoagulant and use of small arterial sheath as much as possible;

5. Actively control blood pressure. Avoid a sudden increase in abdominal pressure.

Pseudoaneurysm complications Complications, hypertension, arteriosclerosis

Untreated pseudoaneurysms may have adverse consequences such as vascular rupture, thromboembolism, compression of peripheral nerve tissue, skin and subcutaneous tissue necrosis, and significant blood loss.

Pseudoaneurysm symptoms common symptoms pulsatile mass localization signs local tenderness vascular murmur persistent pain tracheal shift dysphagia

Most pseudoaneurysms have progressive pain, and there are dilatational and pulsatile masses. In the lumps, squeaky vascular murmurs can be heard. When combined with arteriovenous fistula, they are persistent rumbling murmurs, compression and resistance. The murmur is weakened or disappears immediately when the blood flow is broken. According to the different parts of the pseudoaneurysm, there are special clinical manifestations: pseudoaneurysm located in the deep femoral artery, there may be obvious swelling and pulsating pain in the upper thigh; posterior peritoneal leave caused by rupture of abdominal aortic aneurysm Aneurysm, mainly characterized by sudden low back pain; pseudoaneurysm located in the intracranial or wrist, due to space constraints, the surrounding compression symptoms are more prominent, manifested as focal symptoms and local signs; vertebral artery The pseudoaneurysm at the beginning may cause difficulty in swallowing, tracheal displacement, wheezing, etc. due to its compression of surrounding tissue.

In addition, the thoracic aorta broke the esophagus, and the abdominal aorta broke the intestinal tube and caused the corresponding symptoms. Infectious pseudoaneurysms are usually accompanied by systemic and local inflammatory reactions, including: fever, fatigue and redness, swelling, heat, tenderness, and the pulsation of the mass may not be easily affected by swelling of the surrounding soft tissue.

Pseudoaneurysm examination

Pseudoaneurysm has characteristic changes in imaging such as CT, MPd, Doppler ultrasound and arterial digital subtraction angiography (IADSA). The common feature is the mass inside the pseudoaneurysm and the flow of blood. Among them, Doppler ultrasonography and IADSA have a diagnostic significance.

1. Ultrasound real-time gray-scale ultrasound shows that pseudoaneurysm is a cystic mass adjacent to the artery. Spectrum Doppler ultrasound shows systolic and diastolic continuous blood flow in the tumor cavity, between the tumor cavity and the artery. The intra-channel exploration and reciprocating sign spectrum (ie, high-speed systolic blood flow from the inside of the artery and into the pseudoaneurysm cavity and slower diastolic blood flow from the pseudoaneurysm cavity). Color Doppler ultrasound can detect the color flow signal of turbulence or eddy current in the tumor cavity. Domestic history Shuixin et al. describe the color Doppler performance of pseudoaneurysm in each stage according to animal experiments. Stage I: Color Doppler shows blood flow signals in the arteries. The tumors are in liquid dark areas or dark areas with weak spots, accompanied by slight flutter. Stage II: The arterial blood flow signal is visible, the arterial rupture is unclear, the outline of the tumor is clear, the internal echo is different, and no eddy current phenomenon is observed. That is, the side of the tumor is a flowing red signal, and the opposite side is a flowing blue signal. Stage III: Color Doppler imaging shows the characteristic manifestation of pseudoaneurysm, ie to-and froimaging. The tumor is clear, the wall is smooth, and eddy currents appear inside. Stage IV: in addition to the tumor The increase is almost the same as the formation period.

2. The central area of the CT scan is an equal signal or a low signal, and the CT shows contrast agent spillage into the tumor cavity. The central part of the area has a high density of shadows, and can be associated with thrombosis, the tumor wall is not strengthened, and the peripheral hematoma of the tumor is high density.

3. MRI shows that it is a cystic structure. The WI and T2WI showed a mixed signal and a high signal-based mass. The airflow signs were visible. Because the freely diluted MHb in the pseudo-aneurysm thrombus showed high signal on all weighted images, MR was on the tumor. The diagnosis of internal thrombosis is of special significance. For small aneurysms <2mm in diameter, with thrombosis and vasospasm, angiography may not show the presence of an aneurysm. At this time, MR can be characterized by high intracellular MHb signal and hemosiderin black ring. Helps diagnose ".

4, IADsA manifested as arterial damage and contrast agent spillover into the tumor cavity, because it can directly show the location, size, morphology, tumor cavity and peripheral vascular changes of the pseudoaneurysm, it is of guiding significance for the correct choice of treatment options and treatment methods . The angiography showed that the shape of the tumor cavity was mostly round and elliptical, followed by lobulated and other shapes. The tumor is mostly located on one side of the damaged artery, and the damaged artery and the tumor cavity filled with the contrast agent resemble the melon with the vine. The density of the tumor cavity can be uniform or uneven, and it can also be seen as a layered or spiral shape. The size of the tumor and the tumor cavity is related to the location of the tumor. The diameter of the tumor is relatively large, such as the armpit, elbow, abdomen, etc., which can fluctuate between 1 and 10 cm. On the contrary, the soft tissue is strong. The size of the tumor is small, such as the palm of the hand.

Diagnosis and diagnosis of pseudoaneurysm

According to the physical examination, pulsatile mass with tremor, murmur and vascular murmur, color Doppler ultrasound, angiography, CT and MRI features, and the diagnosis of pseudoaneurysm is generally not difficult. Traumatic pseudoaneurysms generally have a clear history of trauma. The disease can occur for a long time or even years after trauma. Any mass that appears in the original injured part should be considered first. Infectious pseudoaneurysm masks the signs of pulsatile mass due to inflammatory swelling and may be misdiagnosed as soft tissue edema. Therefore, auxiliary inspection is more important. The incidence of rupture of pseudoaneurysm and the mortality rate are extremely high. Therefore, it must be detected early and treated promptly. Be wary of the following:

1, combined infection, inflammatory edema of the tumor wall.

2. The distal end of the tumor-bearing artery is embolized, and the pressure in the tumor cavity is increased.

3, the tumor suddenly suffered from excessive pressure (such as physical examination, B-ultrasound, angiography).

Domestic studies have suggested that early diagnosis of pseudoaneurysm tends to rupture:

1, more than one month after the injury, the pain in the lesions increased, local and systemic temperature increased.

2, pulsatile mass increased significantly in a short period of time, increased tension, soft tissue around the mass of red tissue, wound infection increased, increased secretions, or bloody fluid exudation.

3. At the same time as the pulsatile mass increases, symptoms of adjacent neurological damage appear. 4 The distal arterial pulse of the limb was weakened earlier, and the skin temperature was lower than that of the contralateral side.

Differential diagnosis

Different from true aneurysms and dissecting aneurysms.

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