Acute arterial embolism

Introduction

Introduction to acute arterial embolism

Arterial embolization refers to a pathological process in which the embolus is detached from the heart or the proximal arterial wall, or enters the artery from the outside, pushed to the distal side by the blood flow, and blocks the blood flow of the artery, causing ischemia or even necrosis of the limb or internal organs. When the artery is embolized, the affected limb has pain, paleness, distant arterial pulsation disappears, cold, numbness and dyskinesia. The disease starts rapidly, and the limbs and even the life are threatened after the onset. Early diagnosis and every second counts must be properly treated. important.

basic knowledge

Sickness ratio: 0.1%

Susceptible people: no specific population

Mode of infection: non-infectious

Complications: swelling, metabolic acidosis, acute renal failure, thrombosis, arteriosclerosis

Pathogen

Cause of acute arterial embolism

Vascular injury (15%):

In particular, there is an increasing trend of iatrogenic injury factors, which are more common in invasive examination and treatment, thrombus on the surface of the catheter, even broken guide wires, catheters, etc., can cause arterial embolism, other extravascular extravascular damage, such as thoracic outlet Syndrome, as well as abnormal neck ribs or first chest rib compression of the subclavian artery, often can produce a wall thrombus, and become the source of embolism of upper extremity arterial embolism, long-term walking can also contusion of the radial artery Coanda thrombosis.

Acute myocardial infarction (30%):

Acute myocardial infarction is also a common cause of arterial embolism. Most of them occur within 6 weeks of myocardial infarction. The mortality rate of arterial embolism after myocardial infarction is as high as 50%. Heparin anticoagulation can reduce the incidence of arterial embolism. Tumor is another source of arterial embolism. About half of ventricular aneurysms have wall thrombosis and 5% are complicated with arterial embolism.

Tumor (6%):

More common in primary or metastatic lung cancer, the prognosis is extremely poor.

Venous thrombosis (5%):

Less common, also known as "paradoxical embolus", is the venous thrombosis that falls through the patent foramen ovale or ventricular septal defect into the arterial system, often accompanied by pulmonary embolism and pulmonary hypertension.

(1) Causes of the disease

The source of emboli has two categories: cardiogenic and non-cardiac:

Cardiogenic

80%90% of peripheral arterial acute embolism is from heart disease, 2/3 is complicated with atrial fibrillation, common heart disease is rheumatic heart disease, coronary heart disease, acute myocardial infarction, cardiomyopathy, congestive heart failure and cardiac prosthetic valve replacement , subacute bacterial endocarditis and cardiac tumors (atrial myxoma).

(1) In the organic heart disease, rheumatic heart disease and coronary heart disease are the most common. The former patients are younger, the ratio of male to female is 1:2; the latter is mostly elderly patients, and the incidence rate of men and women is similar. According to statistics, in the 1960s In the past, rheumatic heart disease was the most common cause of arterial embolism. After the 1960s, coronary heart disease was the main cause. At present, coronary heart disease accounted for more than 70%, and rheumatic heart disease was less than 20%. Atrial fibrillation was a risk factor for peripheral arterial embolism. About 77% of patients with peripheral arterial embolism have atrial fibrillation. According to statistics, chronic atrial fibrillation complicated with acute arterial embolism is 3% to 6% per year, while the incidence of paroxysmal atrial fibrillation and arterial embolism is much lower. Myocardial infarction is also a risk factor for arterial embolism. Studies have shown that long-term anticoagulant therapy [mainly oral warfarin and/or aspirin] can not only effectively reduce the incidence of stroke, but also whether or not it is combined with atrial fibrillation. Reduce the rate of peripheral arterial embolization.

(2) In arrhythmia type heart disease, sick sinus syndrome (SSS) is about 16%, complete atrioventricular block is about 1.3% with arterial embolism, and other rare heart diseases that can be complicated by arterial embolism. In patients with bacterial endocarditis and prosthetic heart valve replacement, lysates of bacterial endocarditis (SBE) often embolize distal arterioles, such as the palm, ankle, and toe, in addition to causing arterial embolism and tissue ischemia. In addition, it also spreads inflammation, which is a serious complication of bacterial endocarditis, the incidence rate is 15% to 35%; after artificial heart valve replacement, 25% of patients will have more than one arterial embolism. And 80% embolization in the brain, 10% of which are fatal, more common in those who fail to adhere to lifelong anticoagulant therapy, partial exfoliation of left atrial myxoma can lead to peripheral arterial embolism, but very rare.

2. Non-cardiac

Non-cardiac arterial embolism is rare, including aneurysms, atherosclerosis with ulcers or stenosis, arterial grafts, vascular injuries, tumors and venous thrombosis.

(1) The wall thrombus of aneurysm is an important source of arterial embolism after heart disease: aneurysms with arterial embolization include abdominal aortic aneurysm, femoral aneurysm, iliac aneurysm and subclavian aneurysm. Aneurysms (25%), subclavian aneurysms (33%) and arterial embolism were the most common.

(2) atherosclerotic stenosis with thrombosis: often occurs in the aorta or iliac artery, the formation of large blood clots, embolization of the arterial diameter is also relatively large, atherosclerotic plaque surface ulcer, cholesterol crystals into Blood circulation can also lead to arterial embolization, embolization of the distal arteries with a diameter of 200-900 m. It is characterized by small embolus and a large number. After embolization, not only the peripheral blood vessels are blocked, but also the cholesterol crystals dissolve into the wall and become inflammatory granulation. Swollen, induce perivascular inflammation, aggravate tissue ischemia, atherosclerosis cholesterol crystal embolism, often occurs after angiography or endovascular treatment, involving the renal artery, retinal artery, lower extremity peripheral artery, etc., showing persistent hypertension, Kidney insufficiency, as well as "blue toe" or limb bleu, there is no effective treatment, drug thrombolysis may be effective.

(two) pathogenesis

Pathological changes caused by acute arterial embolism include local changes (changes in embolized arteries and affected limbs), systemic changes (hemodynamic changes and tissue ischemia, metabolic changes due to hypoxia).

Embolization site

Limb arterial embolization accounted for 70% to 80% of all cases, lower extremity arterial embolization 5 times higher than upper extremity arterial embolization, about 20% of arterial embolization involving cerebrovascular disease, about 10% involving visceral artery, acute arterial embolism prone to arterial bifurcation The femoral artery bifurcation is the most common, accounting for 35% to 50%. The radial artery bifurcation is second. The femoral artery and radial artery embolization is twice as high as that of the aorta and radial artery.

However, arteriosclerotic disease changes the traditional embolization site, arteriosclerosis multi-segment, multi-planar stenosis, so that the thrombus is not confined to the vascular bifurcation, but can also be embolized in the stenosis of the artery.

2. Local changes in arterial embolism

The prognosis of arterial embolization depends largely on the establishment of collateral circulation in the embolization artery. The embolus stays in the bifurcation of the artery, blocks the arterial blood flow and completely blocks the collateral circulation, causing severe ischemia of the limb. The mechanism is more severe limb ischemia:

(1) Arterial thrombus spread, blocking the blood supply of the main trunk and collateral circulation, is the main secondary factor for aggravating ischemia. Early anticoagulant therapy should be actively prevented to prevent the spread of thrombus and protect the collateral circulation of the limb.

(2) local metabolite aggregation, tissue edema, causing compartment syndrome.

(3) Cellular edema, causing severe stenosis and occlusion of small arteries, venules and capillary lumens, aggravating tissue ischemia and venous return disorders.

Ischemic time, ischemic degree, ischemia and reperfusion injury affect capillary wall integrity, ischemia-reperfusion injury causes tissue to release a large number of oxygen free radicals, greatly exceeding the processing capacity of intracellular free radical oxidation system, impairing cell phospholipid membrane The fluid flows to the interstitial space, tissue edema, severe edema reduces local tissue blood flow, aggravates capillary edema of capillary endothelial cells, forms osteofascial compartment syndrome, and is called "no reflow phenomenon", although the main arterial blood is established by measures such as thrombectomy For the peripheral tissues, the blood supply is still insufficient. At this time, the arteries that have been plugged open may form a rapid thrombus. The fasciotomy and decompression can alleviate the compartment syndrome, but it is difficult to relieve small blood vessel obstruction.

3. Systemic changes in arterial embolism

(1) Renal dysfunction: Arterial embolism cases are often accompanied by systemic diseases. After Haimovici reported that blood supply was established, 1/3 of the cases died of metabolic-related complications, and reperfusion injury "triple syndrome": peripheral muscle necrosis, myoglobin Hypertension and myoglobinuria cause acute renal failure. The site of renal injury occurs in the proximal tubule, which may be endothelin-mediated tubular damage. It is thought that oxygen free radical scavenger and alkalized urine are recommended treatments. At present, it is considered that proper expansion is one of the most important treatment methods.

(2) aggregation of metabolites, causing systemic changes, high K, hyperlactemia, myoglobinemia, and elevated cellular enzymes such as SCOT, suggesting that the striated muscle is ischemic, and these accumulations are in ischemia after the blood supply to the limbs is established. Metabolites of the limbs can be suddenly released into the blood circulation of the body, causing severe acidosis, high K and myoglobinuria.

Prevention

Acute arterial embolism prevention

Hyperlipidemia, high blood pressure, smoking, diabetes, obesity and low-density lipoprotein are the predisposing factors of this disease. Therefore, it is also the focus of prevention. Strict control of these risk factors can effectively prevent it. purpose. Play to reduce the incidence of acute arterial embolism.

Complication

Acute arterial embolization complications Complications, swelling, metabolic acidosis, acute renal failure, thrombosis, arteriosclerosis

Complications of acute arterial embolism occur mostly after arterial reconstruction of the limbs with severe ischemia (including thrombectomy and bypass surgery), mainly ischemia-reperfusion injury, obvious swelling of the affected limb, and may be accompanied by osteofascia The manifestations of ventricular syndrome, systemic manifestations of complications including metabolic acidosis, hyperkalemia, cardiopulmonary insufficiency, acute renal failure and other acute arterial embolism, are common vascular surgery emergency, if not treated in time, often lead to Gangrene or physical disability, systemic poisoning and functional failure of vital organs, and even life-threatening.

For patients treated with balloon catheter thrombectomy, the following complications can also be caused:

1 Injury of the arterial intima or even the arterial artery, so the operation should be light, no excessive traction, adjust the pressure inside the capsule at any time, so as not to cause arterial rupture.

2 can cause arterial secondary thrombosis, especially in cases of arteriosclerosis, when part of the arterial intima is removed, the distal section of the intima is often reversed by blood flow, causing stenosis, obstruction or thrombosis, so the ball is taken The capsule should not be too large, and the force should not be too strong.

3Because of the thrombus, the catheter is passed through the embolus, and the thrombus is pulled and removed. Therefore, the thick or relatively thick catheter (compared with the diameter of the artery) cannot be used. Otherwise, not only the embolus but also the embolus can be pushed. To the distal artery, once this occurs, the plug must be removed with a small plug or a distal incision.

4 The catheter is broken or the balloon is detached during operation.

Symptom

Acute arterial embolism symptoms Common symptoms Large arterial blood supply disorders Abdominal pain Limb embolism Peripheral nerve damage Sensory disorder Trauma myocardial infarction "5P" sign High fever severe pain

Acute arterial embolization without collateral circulation compensation, the disease progresses rapidly. Pain, paleness, coldness, numbness, dyskinesia, and weakening and disappearance of arterial pulsations are typical symptoms of acute arterial embolism. The severity of the symptoms depends on the location and extent of embolism, the number of secondary thrombosis, whether there has been an arteriosclerotic disease leading to arterial stenosis, and collateral circulation.

1 pain, pain is often the earliest symptoms, with the buckle gradually extended to the distance. About 20% of patients have the first symptoms to be numb, and the pain is not obvious.

2 skin color and skin temperature change, limb blood circulation disorder, cortical papillary venous plexus blood first empty, the skin is waxy pale. If a small amount of blood accumulates in the blood vessels, scattered small island-like purple spots may appear between the pale skin. Superficial venous fistula, capillaries are slowly filled, and the gastrocnemius muscle is doughy. The ischemia develops further, the muscles can be stiff, and the skin temperature of the affected limbs decreases, which is most obvious in the distal part of the limb. The skin temperature change actually makes the embolization plane lower one joint. At the end of the abdominal aorta embolization, the skin temperature changes about the bilateral thighs and buttocks, the common iliac artery is about the lower thigh, the common femoral artery is about the middle of the thigh, and the radial artery is about the lower part of the lower leg.

3 arterial pulsation weakens or disappears, and proximal arterial pulsation may increase. However, care should be taken to identify the arteries that are transmitted to the distal end of the embolization due to the impulse of the blood. The distal arteries may have conductive pulsations.

4 numbness, dyskinesia: the distal part of the affected limb is a loss zone of the stocking type infection, which is caused by peripheral nerve ischemia. There is a hyposensitivity zone at the proximal end, and there may be a hypersensitivity zone at the proximal end. The affected limb may also have acupuncture-like sensation, weakened muscles, and even paralysis, and a slight degree of sagging of the hands and feet.

Examine

Acute arterial embolization

1. Skin temperature measurement: It can accurately measure the skin temperature and reduce the junction, so as to estimate the site of embolization.

2. Ultrasound examination: Doppler ultrasound can measure the arterial blood flow, can more accurately make the embolization positioning, and can provide the blood supply insufficient baseline, easy to compare preoperative and postoperative, to understand the revascularization and monitor the vascular revascularization Wait.

3. Arterial angiography: angiography is the most accurate method for embolization. Most patients can make a diagnosis based on clinical symptoms and signs and Doppler ultrasound. There is only doubt in diagnosis, or whether the artery must be known after thrombectomy. An angiography is performed immediately.

After the diagnosis is confirmed, chest X-ray, electrocardiogram, cardiac X-ray and echocardiography are performed to find out whether there is arrhythmia and recent myocardial infarction, so as to further identify the cause of arterial embolization, so as to timely treat and control the cause.

Laboratory tests are an important reference for assessing the degree of ischemia and the necessary basis for surgical preparation.

1. Blood routine: Hemoglobin can be increased after a few hours of limb ischemia, and white blood cells can be as high as 20×109/L. When DIC occurs, the number of platelets decreases sharply.

2. Blood biochemistry: blood urea nitrogen and creatinine increased after limb ischemia, ischemia continued to develop, and muscle creatine phosphatase increased sharply after muscle necrosis.

3. Blood gas analysis: may have the performance of systemic acidosis.

4. Doppler ultrasound segmental pressure measurement: to determine the severity of limb arterial ischemia, in addition to auscultation of arterial pulsation, venous return sounds also need to be carefully listened to, most severe limb ischemia cases of arteriovenous ultrasound auscultation are silent, / The sputum index is <0.3 and the sacral blood pressure is lower than 30 mmHg (4 kPa). The segmental pressure measurement includes knees, knees and high thighs. For example, the blood pressure of the adjacent plane is 30 mmHg, indicating proximal occlusion.

5. Color ultrasound (color ultrasound): accurately locate the site of limb arterial embolization, measure the arterial diameter, blood flow velocity and resistance index and other indicators, determine the severity of limb ischemia and indirectly determine the collateral circulation.

Two-dimensional audio-visual features: conventional ultrasound in the lumen of the lower extremity arterial obstruction section sees the hypoechoic to moderate echo of the parenchymal mass, the lumen disappears, especially the femoral artery or radial artery is most obvious, at the same time, due to arterial obstruction, blood flow can not Passing but impacting the obstruction, resulting in an increase in the overall beat amplitude of the artery at the obstruction, showing a "jumping".

Color Doppler flow imaging features: the color flow signal of the obstructed segment is interrupted or disappeared, and the blood flow of the distal arterie can also disappear; sometimes the thrombus can be found in the veins accompanying it, and the surrounding tissue is thickened and sounded. Increased degree, such as incomplete occlusion after embolization to form a narrow, color Doppler shows that the flow channel is thinner, the color is colorful mosaic.

6. Arteriography: For the gold standard for the diagnosis of limb ischemia, angiography can show the embolization site, whether there is multiple embolism, and collateral compensatory condition, one side lower extremity arterial embolization or upper extremity arterial embolization, can be through the health side Arterial catheter angiography; embolization of the abdominal aortic bifurcation, the intubation of the radial artery to the descending aorta; embolization of the distal femoral artery, can be punctured by the ipsilateral femoral artery.

The main signs of angiography are: 1 sudden interruption of the contrast from the contrast agent to the embolization, the section is a cup-shaped depression, indicating that the embolus completely blocks the arterial cavity, and the filling of the arterial cavity in the 2 arterial lumen indicates that the arterial cavity is not completely blocked, 3 embolization The upper and lower side supports are displayed on the plane.

For patients with acute lower extremity ischemia of unknown cause, the angiography is recommended for the conditional angiography. The reason of arterial angiography is to determine the cause of limb arterial ischemia. Acute arterial embolization can often achieve perfect curative effect. Acute thrombosis based on arteriosclerosis The effect of simple thrombectomy is poor, and preoperative arterial angiography is important for identifying the cause of ischemia.

Diagnosis

Diagnosis and diagnosis of acute arterial embolism

diagnosis

1. Qualitative diagnosis

Sudden signs of severe limb ischemia occur in the patient, and the corresponding arterial pulsation disappears, that is, there is a "5P" sign, accompanied by organic heart disease, arteriosclerosis, especially with atrial fibrillation, recent myocardial infarction or abdominal aorta The patient with the tumor can be diagnosed clearly.

2. Positioning diagnosis

The position of the embolus can be blocked by: 1 the location of the initial pain; 2 the plane of normal pulse disappearance, the plane of skin temperature and other changes; 3 non-invasive examination (such as Doppler ultrasound); 4 range of limb circulation disorders 5 emboli are easy to stay at the arterial bifurcation and other characteristics to determine.

3. Degree diagnosis

According to clinical signs and examination results, acute arterial embolization can be divided into three categories:

(1) mild ischemia: such patients have severe intermittent claudication, and the resting pain is mild. From the onset to the treatment, there are often several days. In addition to the pale limbs and the decrease in skin temperature, there are no movement and sensory disturbances. There is no secondary thrombus in the distal end of the arterial occlusion, and the collateral circulation is abundant. Such patients may have more time to do the corresponding examination and preoperative preparation. According to the specific condition, anticoagulant thrombolysis is considered. treatment.

(2) Moderate ischemia: Most of the clinical patients are of this type, the resting pain is obvious but can be tolerated, and there are mild sensory disturbances, such as decreased sensitivity to light touch, but no movement disorder, and need to actively perform surgery before surgery. Prepare and timely take the plug.

(3) severe ischemia: loss of sensory and motor function of the affected limb, stiff gastrocnemius, purple spots or blisters on the skin, often requiring amputation to save lives. Some scholars have pointed out that patients with severe ischemia, such as arterial thrombectomy, The mortality rate is as high as 50% to 75%. If the patient's general condition allows, no renal insufficiency, only limb sensation and motor dysfunction but no muscle stiffness, osteofascial compartment syndrome and skin purpura, etc., Fogarty catheter thrombectomy It is safe and effective for most patients, but most of the patients often have sequelae of nerve damage such as numbness and foot drop.

Differential diagnosis

1. Acute arterial thrombosis: Most of the atherosclerosis is secondary to thrombosis, resulting in acute arterial ischemia. The main points of differential diagnosis are: 1 The onset is not as fast as the arterial embolism, the limb is pale, and the chilly plane is blurred. 2 Previous history of chronic arterial ischemia, such as intermittent claudication and dystrophic changes caused by insufficient arterial blood supply, 3 angiography showed extensive atherosclerosis, uneven arterial wall, irregular distortion, segmental stenosis or Occlusion, there have been more manifestations of collateral formation, and concurrent with arterial occlusion.

2. Acute iliac-femoral vein thrombosis: severe acute iliac-femoral vein thrombosis, such as femoral bruising, extreme swelling of the limbs on the arteries and strong arterial spasm, can cause arterial blood supply disorders and distal arterial pulsation disappear, However, the clinical manifestations of deep swelling of the lower extremities, compensatory dilation of superficial veins, normal or slightly elevated skin temperature are characteristic of deep vein thrombosis, which can be distinguished from arterial embolism. Doppler auscultation can clearly detect the sound of arterial pulsation. The / index is usually >0.5.

3. Decreased cardiac output: acute myocardial infarction, congestive heart failure, sepsis, dehydration and severe trauma, etc., can significantly reduce cardiac blood output, increase vasopressin secretion, systemic vasoconstriction, and extremity vascular perfusion Reduced, cold limbs, even skin spots, arterial pulsation weak or disappear, but in addition to the manifestations of the heart itself, limbs and cold, etc. should also involve the limbs, in anti-shock, blood volume recovery, cardiac primary disease is effectively controlled Afterwards, the hypoperfusion of the limb arteries is also relieved.

4. Dissection aneurysm: less common, aortic dissection aneurysm involving one or both of the radial artery, can lead to acute ischemia of the lower extremity arteries, usually the symptoms of dissection aneurysms are more prominent, patients with high blood pressure, severe back or Chest pain and other symptoms.

5. Radial artery or femoral aneurysm: acute thrombotic aneurysm, endovascular thrombosis leads to occlusion of the lumen, pulsation and pulsatile mass in the corresponding anatomical site, double-color ultrasound can confirm aneurysm and intraluminal thrombosis.

6. Femoral bruising: It is a special and serious type of acute thrombosis of deep veins of the lower extremities. The limbs are extremely swollen, cyanosis, superficial vein dilatation, and the dorsal and posterior tibial arteries cannot be beaten, but the limbs are still warm.

7. Intimal endometrial separation: Intimal detachment of the arteries causes intracavitary pseudosinus compression of the arterial lumen, which may be accompanied by distal arterial embolization, but these patients often have chest and back pain, a history of long-term hypertension, and auscultation with murmurs. The chest radiograph has a mediastinum widening to help diagnose.

In addition, peripheral aneurysm thrombosis, popliteal entrapment syndrome and ergotintoxication may cause intermittent claudication, severe ischemic symptoms need to be noted.

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