Acute arterial occlusion

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* Definition

* Pistons

* Thrombosis

* General Medical Attitude to acute ischemia

* Bibliography

Definition

Acute arterial insufficiency, either by an embolism, acute thrombosis or otherwise, is a medical emergency of the first order, along with a ruptured aneurysm or traumatic vascular lesions. Only early diagnosis and treatment can achieve save the affected region.

Etiology

There are two basic causes that can produce acute arterial occlusion of the lower these are: pistons and thrombosis. Less common causes include arterioespasmo, trauma, extrinsic compression and dissecting aortic aneurysm (1).

Plungers

Arterial emboli produce 80% of arterial occlusions of the lower limbs (3) and its frequency is almost twice as high in females than males, often occur especially between 65 to 85 years, is very rare presentation before twenty years (4). When arteries are healthy emboli usually stop at junctions or strictures on the duct as Hunter, but if the arteries are affected by a disease such as arteriosclerosis, these can be stopped at any level (4). Frequently emboli which can produce acute arterial occlusion limbs are:

1.Embolos heart.

2. Atheroemboli.

Pistons heart: The heart is the first source of emboli production, which cause 85% to 95% of arterial occlusions caused by these (3), usually measure more than 5 mm in diameter, so staying in glasses Large diameter as the common femoral artery. Its origin is due to:

Atrial fibrillation.

Myocardial infarction.

Valvular disease.

Atrial fibrillation alone or associated predisposes mural thrombus formation which may lead to emboli peripheral circulation. Transmural myocardial emboli produced after 2 to 3 weeks after the picture produced.

Should investigate the source of the plunger with echocardiography and electrocardiography Holter monitoring.

* Atheroemboli: having a size of less than 5 mm in diameter which are accommodated in small diameter vessels and arteries digital branches arising from an atherosclerotic plaque or thrombus proximal. Often characterized by blue toes and palpable pedal pulses.

Thrombosis

Almost always produced by vascular endothelium prior alterations generally

arteriosclerotic cause (2). The thrombus formation in situ may be favored by different mechanisms:

* Severe arterial stenosis.

* Hyperviscosity, hypercoagulable.

* Low cardiac output.

* Other.

In these cases of arterial thrombosis are a particularly susceptible, which is the superficial femoral artery (2), right at the adductor ring.

Pathophysiology

Produces acute arterial occlusion ischemia anoxic tissues affected arterial segment after which present gangrene (50%), which depends on the site of occlusion, collateral circulation and length of the occlusion. The presence of pain and paresthesia occurs by damage to nerve fibers of the affected area, but the loss of nerve function and paralysis and muscle necrosis indicate imminent (5). Tissue death appears 6-8 hours after embolic phenomenon, but can be changed by the collateral circulation. Thrombosis does not spread beyond the arterial ramifications if the collateral circulation is sufficient, but if this movement is not adequate or there is stasis, were formed venous thrombosis and arterial occlusion distal to the initial.

Clinical Manifestations

It presents six P:

Pain (Pain): It occurs in 75% of patients as the first symptom, but may not be present, this due to adequate collateral circulation, diabetic neuropathy, or has a rapid progression to advanced ischemia with immediate anesthesia.

Paresthesia and paralysis: Paresthesias indicate anoxia of sensory and motor nerve endings. The paralysis speak of necrosis of striated muscle. At the start of ischemia muscles are soft, with time and occurs edema pasty sensation at the site of occlusion, then the necrosis occur muscles become stiff and hard. In this last stage is irreversible ischemic alteration. Yes paresthesia and paralysis are not relieved during 6-8 hours, developed gangrene in the affected limb.

Pale and poikilothermia: reduction of blood flow in an extremity, gives the appearance of pale tip cools. The pale mottled skin that digital pressure indicates irreversible ischemia and blood extravasation due to the dermis by broken capillaries.

Absent peripheral pulses: Indicates arterial occlusion in considering all limb pulses can help us find the height of the obstruction.

* Diagnosis

* The diagnosis is based on:

* Background.

* Clinical.

* Physical exam.

* Doppler.

* Arteriography.

The distinction between embolism and thrombosis can be done only by the presence or absence of underlying etiologies well; coexistence with heart disease or rhythm disorder will think of an embolic etiology (Not forgetting that the phenomena of acute arterial thrombosis are more frequent in patients with generalized atherosclerosis, which in turn have a higher incidence of heart disease). The absence of pulses decreased arterial or arterial pulses in the contralateral limb favor the diagnosis of acute thrombosis. The presence of risk factors for atherosclerosis (snuff, hypercholesterolemia, diabetes, hypertension, etc.), respiratory failure or a history of intermittent claudication make us think of a thrombotic process. The popliteal hiperpulsatilidad in any of the limbs will make us suspect the presence of a popliteal aneurysm caused by its ability thrombosis or embolic ischemic box, especially considering their high frequency of bilaterality (40% of cases).

The location of the obstruction is necessary, in order to treatment. In this respect it is very important to study the arterial pulses, which shortage below the lesion. The extent of the ischemic zone not always related to the level of the vascular obstruction, since it depends largely on the collateral circulation.

The Doppler is usually sufficient to provide an accurate diagnosis of the level of damage, but there are specific situations to which one must resort to arteriography (7), these are:

 

* Differential diagnosis difficult between embolism and thrombosis.

* Multiple embolisms.

* Recurrent Stroke.

* Patients previously intervened in the same limb embolism.

* Stroke in patients suspected of preexisting chronic ischemia.

In practice arteriography, images are typical: rough cut of the picture with concave meniscus (convex side up) and poor collateral circulation in case of a stroke, a cut dome shaped (convex down) and irregularity of the rest of the arterial tree with abundant collateral circulation in cases of thrombosis.

Detection of blood hypercoagulable states, is also very important. The study of antithrombin III, fibrinogen, protein C, protein S, polycythemia, etc., will be of great importance as it allows us to establish timely adjunctive medical therapy, in order to prevent further thrombotic occlusive or early failure the blood repermeablilizacin made (4).

Differential Diagnosis

Acute arterial occlusion can be confused with:

* Deep Vein Thrombosis: It differs from acute arterial occlusion is because the rapid onset edema, veins are full, there is no decrease in temperature and palpable distal pulses. In acute arterial occlusion skin is pale, the veins are empty, no pulse, and swelling appears after several hours (3).

* Phlegmasia Cerulea Dolens: Often associated with an absence of pulses and gangrene. This is attributed to spasm of the arteries and the accompanying collapse of arteriolar circulation. The confusion is due to the absence of edema and cyanosis in the initial phase, with the presence of pain and absent pulses. But it appears later stage of venous obstruction symptoms, namely edema and cyanosis (3).

* Low-flow syndrome: Occurs in patients with cardiac decompensation, absent pulses, coldness, and cyanosis, usually affects all four limbs (3).

* Pedrada syndrome: Presents a sharp pain in the back of the calf that appears while driving or with exertion. This syndrome occurs by rupture of intramuscular veins of the calf. Its diagnosis is based on the appearance during exercise, palpation twins level presents a painful area with secondary pasting the presence of hematoma and distal pulses (3).

* Hipersnsibilidad to ergotamine: There is a history of contact with this substance, listed at 2-4 hours after collection, and there is a spasm of the arteries and can sometimes reach thrombosis and gangrene (3).

General Medical Attitude In acute ischemia

The terms of morbidity and mortality of acute ischemia depends on:

Patient’s medical condition.

Severity of ischemia.

People carrying acute ischemia should undergo: a detailed history, with emphasis on vascular and cardiac history should be performed basic laboratory analysis (hematology and biochemistry) an electrocardiogram (10), and chest radiography.

After stabilizing the patient proceeds to general heparinization sodium heparin bolus IV doses of 1 mg / kg body weight, which may be repeated every 3 or 4 hours and transport the patient to a specialist center as quickly as possible. Heparinization is not necessary if the patient is going to intervene in the center. Anticoagulation is performed to prevent proximal and distal propagation of thrombus and prevent venous thrombosis. Additionally all patients at risk of bleeding should not heparinizarce. The pain should be controlled with analgesics, should be administered in cottony protective heel and malleoli. Also keep in mind not to raise the limb as it decreases capillary perfusion and even put in slight decline and apply heat as it may cause damage to skin and subcutaneous tissue (3).

Treatment:

The treatment of acute arterial occlusion, which has been said to be urgent, often presents difficulties, often affect patients with other stigmata of generalized atherosclerosis.

Therapeutic embolic

Arterial embolectomy using the Fogarty catheter embolism cases. Elevated levels of urea, potassium, creatinine, phosphorus, especially CPK and LDH will bypass contraindication and indicate immediate amputation of the limb (5). Do not attempt to restore blood flow in nonviable members as this causes the return of toxic substances such as potassium, lactic acid, etc. (8). The risk of death is high in these cases. Before the surgical procedure should be instituted heparinization, in postoperative Warfarin be administered because prolonged anticoagulation should be since there is a process of cardiac base.

Thrombolytic therapy

Thrombolytic therapy is most effective when administered within two weeks of thrombosis. The treatment starts with aspirin or heparin, which diminishes the formation of thrombus around the catheter. The catheter for treatment such as it is positioned proximal to the occlusion, this followed an arteriogram is performed diagnosis. The catheter must be inserted into the thrombus for successful treatment. During the first 4 hours is given 4000 IU / min of urokinase, urokinase 2000UI/min followed up for 48 hours (9). Arteriograms are repeated at regular intervals to establish the efficiency of clot lysis. Treatment was discontinued within 48 hours if lysis is satisfactory. Thrombolytic agents can lyse thrombi inaccessible to surgical methods such as the distal tibial vessels.

Amputation-free survival in patients treated with urokinase is 71.8% at 6 months and 65% per year, while in patients undergoing amputation-free survival was 74.8% at 6 months and of 69.9% per year (11).

Percutaneous Angioplasty deep

The deep femoral artery is necessary to maintain the viability of the limb when severe occlusive arterial disease affecting member. This provides the main blood supply to the tissues of the thigh and also the most important collateral vessel bypass for superficial femoral artery occluded or blocked (12).

Endovascular stent graft

In femoropopliteal occlusions both angioplasty and stents have poor long-term results, so the classic bypass remains the treatment of choice in large femoropopliteal obstructions. The saphenous vein bypass is provided that better results, but not recommended in femoropopliteal lesions located above the knee, and to save coronary bypass vein (13).

The intraoperative use of an endograft is a surgical repertoio extension, especially when combined with conventional techniques recanalization. Because preserving the saphenous vein and minimizes tissue trauma, this attempt can be an alternative to femoropopliteal bypass with synthetic graft above the knee (13).

Management risks

Bleeding hidden disease, gastrointestinal bleeding and brain, in these cases, treatment should be discontinued and correct bleeding in surgical or pharmaceutical form. Complications arise if the decreases fibrinogen 100mg/dl. Simple thrombectomy or angioplasty thromboendarterectomy if more severe and extensive thrombosis (6). Arteriospasm If the cause is not recommended test medical treatment with vasodilators, as these to alleviate vasospasm may aggravate the flow diversion ischemia of the affected areas to areas of normal vascularity, and allow the extension of the thrombus within small arteries and arterioles, previously protected by vasospasm.

REFERENCES

Schwartz. S, et al; PRINCIPLES OF SURGERY: Seventh Edition, Vol I, pp, 1017-1024, McGraw – Hill Interamericana, 2000.

Veith. F, Hobson. R, Williams. R, Wilson. S; Vascular Surgery Principles and Practice: Second Edition, McGraw-Hill, 1994

J. Fernandez Alvarez Julin Gutirrez J. Menndez M. Herrero; acute ischemia of the extremities; Hospital Central de Asturias.

Cowboy F. Uriach L. acute ischemia; 1994.

Sabiston. SURGERY, 2000

Scribner R. W. Brown Tawes R.; DECISION MAKING IN VASCULAR SURGERY, BC Decker Inc. Toronto – Philadelphia. 1987.

Lazar G. Michael M. Keith O. Gerald Z. Keith L.; ESSENTIALS OF SURGERY STIENTIFIC Principles and Practice.; Publisher Lippincott – Raven, Washington Square – Philadelphia. 1997.

Hardy. SURGERY; Editorial Medica Panamericana, Argentina 1985.

J. Davis Sheldon G.; SURGERY A PROBLEM – salving APPROACH, Second Edition, Vol II; Edition Mosby, St. Louis – Missouri. 1995.

J. Hoch T. Kennell M. Hollister Sproat I, et al.; COMPARISON OF TREATMENT PLANS FOR LOWER EXTREMITY ARTERIAL MADE WITH occlusive disease Electrocardiography – TRIGGERED TWO – DIMENSIONAL TIME – OF – FLIGHT Magnetic Resonance Angiography Angiography AND DIGITAL SUBTRACTION., In: The American Journal of Surgery, Vol 178 August 1999.

Aldo Tabares.; COMPARISON OF VASCULAR SURGERY WITH RECOMBINANT Urokinase AS INITIAL TREATMENT FOR ACUTE OCCLUSION OF THE LEGS., In: New England Journal of Medicine, Vol 338. pp: 1105-1111. 1998.

J. Silva Ramee S. White Ch Et al.; Percutaneous PROFUNDAPLASTY IN THE TREATMENT OF LOWER EXTREMITY Ischemia: RESULTS OF LONG – TERM SURVEILLANCE.; Journal of Endovascular Therapy: Vol 8, No. 1, pp. 75-82.

Bauermeister G.; ENDOVASCULAR STENT-GRAFTING IN THE TREATMENT OF SUPERFICIAL FEMORAL ARTERY occlusive disease., In: Journal of Endovascular Therapy: Vol 8, No. 3, pp. 315-320.

Dr. Diego De La Torre Villagmez Bladimir

RURAL MEDICAL

ECUADOR – QUITO