Chronic arterial occlusion

Chronic arterial occlusion . Chronic ischemia syndrome is the set of symptoms and signs produced by an inadequate arterial supply that has progressively established itself in the extremities.

Summary

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• 1 Etiology
• 2 Clinic
• 3 Physical examination
• 4 Complementary explorations
• 5 Forecast
• 6 Treatment
• 7 Surgical approach
• 8 Sources

Etiology

Without a doubt, the most frequent cause of chronic limb ischemia is atherosclerosis. This disease constitutes today one of the modern plagues, being the morbidity and mortality of the same impressive. It more frequently affects males, with the highest incidence occurring in the sixth and seventh decades of life. Hypertension, hypercholesterolemia, tobacco and diabetes mellitus, among others, are considered risk factors.

Clinic

The most frequent symptom is intermittent claudication, which is defined as the appearance of pain, cramp or numbness in the muscles, which appear with exercise and disappear with rest. The explanation is simple, since with the effort there is a disproportion between the blood that the muscles in activity need and that which can supply the diseased artery. The ischemic muscle hurts, so the patient is forced to stop, and that is when his energy and circulatory needs decrease, the pain disappearing. The patient walks again, to reappear the same pain almost with mathematical precision at a certain distance. Sometimes it can be confused with the so-called pseudoclaudication, due to lumbar spinal canal stenosis,

Claudication is distal to the location of the obstructive lesion. The pain is usually located in the calf, because the occlusions are almost always femoral or femoropopliteal. If the pain refers to the thigh, it will indicate that the occlusion is at the iliac level, and if it is higher, in the thighs or gluteal area, the occlusion is almost certainly bilateral or aortoiliac iliac (Leriche syndrome).

It is striking how difficult it is for these patients to heal their wounds and they become more easily infected. This is explained because a greater blood supply is required in tissue repair than cannot be achieved due to the state of chronic ischemia.

If the disease progresses, the so-called rest pain appears, predominantly at night. In this phase, the patient tells us that he spends his nights awake due to the intense pain that he refers to at the level of the fingers or the foot and that he relieves himself by placing them in a declining position as the perfusion pressure is higher, so these patients sleep sitting with their legs dangling. This pain at rest is indicative of obstruction of a major arterial trunk with very little development of collateral circulation.

The evolution of the disease can be described according to the Fontaine classification in four phases or stages. Critical ischemia would be equivalent to grades III and IV of this classification.

Clinical forms according to their location. Depending on where the level of the lesion is located, we will recognize different clinical pictures:

• Aortoiliac obliteration(Leriche syndrome). Leriche syndrome is understood as the obstructive pathology of the aortoiliac bifurcation. As described by Leriche in the early 1940s, typical symptoms consist of intermittent claudication affecting the calf, thighs, and buttocks and the impossibility of stable erection of the penis due to circulatory failure of the corpora cavernosa. Physical examination highlights the absence of femoral and peripheral pulses, as well as global atrophy of the two lower limbs, along with pallor and coldness of the legs and feet. This clinical form is of early presentation (between the ages of 35 and 55), being the most frequent cause of claudication in young adults.
• Femoropopliteal obliteration. This location is the most frequent, representing more than half of the cases. The most frequent site of atherosclerotic occlusion in the lower extremities is at the level of the superficial femoral artery inside the Hunter canal. Its clinical translation is given by the typical intermittent calf claudication. Physical examination revealed a normal femoral pulse, but the pulses were not palpated or decreased at the level of the popliteal artery, posterior tibia, and pedia (MIR 99-00, 259).
• Tibioperoneal or distal obliteration. It is more frequent in the elderly, diabetics and thromboangiitis obliterans. The clinical translation consists of claudication of the foot. The absence of pulses is at the level of the trunks below the popliteal artery. The prognosis is poor as there is little chance of establishing a good collateral circle.

Physical exploration

Anamnesis and physical examination are extremely important to establish the diagnosis of limb ischemia in many cases and to assess its severity and topography.

The most important maneuver on physical examination is palpation of arterial pulses. Pulsatility is examined in all accessible places: in the lower extremity at the level of the groin for the common femoral, behind the knee for the popliteal, on the dorsum of the foot for the pedia and in the internal retromaleolar region for the posterior tibial . The absence or decrease in intensity of any of these pulses will make us think of an arterial condition. For the upper extremity we will explore the subclavian in the retroclavicular region, in the axilla the axillary, in the humeral fold the humeral and distally the radial and ulnar. The integrity of the circulation of the palmar arches, the ulnar and radial arteries is determined by the Allen maneuver. To carry it out, the radial artery is compressed with uniform intensity, while the patient rhythmically opens and closes the hand. In general, a slight and transitory decrease in flow is observed, apparent in the form of a pink coloration of the skin (patent ulnar artery and palmar arch). In the event of occlusion of the ulnar artery or the palmar arch, intense diffuse pallor of the hand appears on its internal face, which does not disappear until after the radial artery is no longer compressed.

Changes in skin coloration and determination of venous filling time are also important. These changes can be seen spontaneously or caused by raising the limb to be scanned. Thus, if there is a lack of irrigation, a cadaveric pallor will appear on the plantar surface of the affected foot, and in a declining position, a flush secondary to reactive hyperemia.

The auscultation of the vessels must always be carried out, since a stenotic lesion may be the cause of a systolic murmur.

In the presence of chronic ischemia, the affected limb can appear on cold and pale examination compared to the contralateral one, and in advanced stages, atrophy of the skin, hair loss and thickening and fragility of the toenails can be observed.

The location of the ulcers is a good key to make the differential diagnosis with venous stasis ulcers. Arteriosclerosis ulcers usually occur on the distal parts of the fingers, around the nail bed, or on bony prominences, such as the metatarsal heads, heel, or malleoli.

In contrast, there is almost never an ulceration due to venous insufficiency below the level of the malleolus and although they are sometimes painful, they are never as painful as the arterial ones. When an acute arterial occlusion progresses to gangrene, it is usually “wet,” with edema, bullae, and purplish coloration. In the event that the chronic progresses gradually to severe ischemia, what will occur will be a characteristic mummification: “dry gangrene.”

Complementary explorations

Although the diagnosis of arterial occlusive disease is almost always made through a medical history and physical examination, certain non-invasive techniques can be very useful for the objective assessment of the severity of the disease. These include the Doppler technique, segmental pressure measurements, plethysmography, and stress testing on a treadmill (with pressure drop and recovery time being proportional to the degree of disease).

• Ultrasonography allows the visualization of the path of the vessels by means of two-dimensional ultrasound and the analysis of flow velocities by the wave obtained using the Doppler technique. In the presence of a stenosis, the proximal velocity increases proportionally to the degree of obstruction.
• The Doppler allows to study the flow of the different vessels by recording the pulse wave and determining its pressure, being a bloodless and fast method. For the study of blood pressure, the cuff of a sphygmomanometer is placed immediately above the point to be explored and the transducer is used as if it were a stethoscope to record blood flow. Normally, the blood pressures in the legs and arms are very similar and, if anything, somewhat higher in the ankle. In patients without arterial disease, the ratio or index of ankle / arm pressure (ITB) is 1 or higher. A BTI less than 0.9 is a diagnosis of peripheral arterial disease. In the presence of claudication, the blood pressure in the leg decreases and this ratio is usually between 0.9 and 0.4. A ratio <0, 4 corresponds to severe ischemia with rest pain and tissue loss. Patients with arteries calcified from DM or kidney failure sometimes have relatively non-compressible arteries that lead to falsely elevated ITB values.
• Arteriography consists of recording the radiological image of the arteries after administration of a contrast. As it is an invasive exploration, it should not be used as a routine test, but it is a very valuable diagnostic method for the surgeon to plan the surgical strategy, and therefore it is carried out before a possible revascularization intervention.
• Angiography obtained by NMR has a high quality and its sensitivity and specificity is very similar to that of conventional angiography. It is likely that as its accessibility increases, it may be the technique of choice in most patients.

Forecast

Patients with intermittent claudication can remain stable for long periods of time. Their survival is limited by the presence of atherosclerotic disease at other levels: 50% may have coronary heart disease and up to 30% have cerebral atherosclerosis. Survival at 5 years is 70%. Revascularization surgery is required in approximately 10% of patients, and 5% ultimately undergo amputation. These figures are much higher in patients who continue smoking and in diabetics (in whom an amputation rate of up to 20% can be reached).

Most of the deaths are a consequence of the sequelae of vascular atherosclerotic disease elsewhere and, especially in the coronary and cerebral circulation (between 20-30% of patients with peripheral artery disease have lesions in the cervical arteries and 40 -60% in the coronary arteries).

Treatment

We must start from the basis that arteriosclerosis is a disease for which there is no specific treatment, but there are a number of factors that favor or worsen it. As it is a progressive disease, treatment must be aimed at preventing such progression. It is advisable to restrict fats and products rich in cholesterol, avoid obesity, normalize the glycemia of diabetic patients, control blood pressure and give up smoking. The latter is the most important initial measure, since it can increase the claudication distance up to double and condition the results of any other treatment.

In patients with intermittent claudication, walking until the onset of pain and then resting should be recommended, since exercise stimulates the formation of collateral circulation.

Foot hygiene will be extremely superior to normal. A minimal injury or infection, which would be insignificant in a healthy person, in the arteriosclerosis can have serious consequences. Compression, such as elastic stockings, should be avoided as they reduce blood flow. The footwear must be wide, thus avoiding pressure on the bony prominences. In patients with ischemia at rest, they can improve perfusion and pain by keeping the limb slightly lower in bed than the rest of the body.

Regarding pharmacological treatment, current data indicates that therapy with peripheral vasodilators is not effective in this disease, since a “theft” phenomenon can occur in diseased arteries.

• The pentoxifylline(a methylxanthine) acts on microcirculation decreasing blood viscosity and increasing flexibility of RBCs, leading to increased running distance, but consistent improvement is not observed in many studies.
• Cilostazol is a phosphodiesterase inhibitor, therefore it increases cAMP levels and has an antiplatelet and vasodilator effect. Increases the distance to claudication more effectively than pentoxifylline. Their biggest problem is that their safety in heart failure patients is unknown, in which other phosphodiesterase inhibitor drugs have been shown to increase mortality.
• Antiplatelet medication ( aspirinand especially clopidogrel ) reduces the risk of adverse cardiovascular events. Anticoagulant therapy is used in the treatment of exacerbations (due to thrombosis or embolism ) of chronic ischemia and in cases of special thrombogenicity (MIR 96-97F, 55).
• Statins reduce the incidence of intermittent claudication and improve the duration of effort until the appearance of claudication, in addition to its enormous cardiovascular benefits.
• If the patient has ischemic heart disease,beta-blockers should be administered (they do not adversely affect the ability to walk or the symptoms in people with mild to moderate peripheral arterial disease) since they are cardioprotective. They are especially indicated before, during and after lower limb revascularization surgery since they improve the prognosis and decrease the incidence of intra and postoperative infarction. ACE inhibitors are also recommended to reduce cardiovascular morbidity and mortality.

Surgical approach

Revascularization surgery is usually reserved for patients with progressive, severe or disabling symptoms and ischemia at rest, and for individuals who, due to their occupation, must be asymptomatic as long as they do not respond to previous hygienic-dietary and pharmacological measures. Guided by the Fontaine classification, degrees IIb (disabling claudication), III (ischemic pain at rest) and IV (trophic lesions) would be operated. The surgery aims to restore the truncal arterial flow to the ischemic areas, either by acting directly on the occlusive lesion (unblocking by thromboendarterectomy) or bypassing them by an anatomical or extra-anatomical bypass.

Entre las intervenciones no operatorias está la angioplastia percutánea transluminal. Esta técnica permite la dilatación de lesiones aisladas mediante el inflado de un balón en el área estenótica, utilizándose con frecuencia las denominadas prótesis endoluminales (stents), que son sistemas de material expandible que se colocan vía percutánea, permitiendo que, una vez realizada la dilatación, la arteria mantenga su diámetro. La implantación de stent en estas lesiones obtiene una mayor tasa de permeabilidad a largo plazo. Esta técnica es de elección en caso de estenosis u oclusiones cortas (<10 cm) en arterias de mediano o gran calibre, sobre todo en la ilíaca, en donde se consiguen índices de permeabilidad a largo plazo del 90%. Los índices de permeabilidad en la arteria femoral superficial y en las arterias poplíteas son menores.

The most frequently used surgical approach is to perform a by-pass, to solve the deficit of contribution to the distal areas to obstructive lesions. In proximal injuries, the most frequent use is dacron grafts. If the injury is located in the infrarenal abdominal aorta or in the iliac artery and is extensive, the procedure of choice is the aortofemoral or aortoiliac graft, generally with a dacron graft. In case the lesion was bilateral, a Y graft is applied, bifurcating both common iliac or femoral bones.

A variant of the by-passes is made by extra-anatomical grafts. These techniques arise from the need to search for a valid therapeutic alternative to complex surgery in high-risk patients or when the usual revascularization techniques present difficulties. It consists of the implantation of a graft, either axilobifemoral or femoral-femoral, at the subcutaneous level, without entering the thoracic or abdominal cavity. They achieve excellent revascularization in exchange for minimal morbidity and mortality, these techniques being indicated in patients at high risk for serious associated disease and advanced age, or in those patients with low life expectancy (MIR 98-99F, 65; MIR 96- 97, 187).

The usual surgical treatment for femoropopliteal and distal disease is bypass. Venous grafting, generally at the expense of autologous saphenous vein in situ and inverse grafts, is usually preferred to prosthetics (dacron and PTFE), since the former has greater long-term patency (60-70% permeability to 5 years, compared to 30% of infrapopliteal grafts with PTFE). In short, for most surgeons, the material of choice in cases of very distal occlusions or requiring anastomosis below the knee , is the patient’s own internal saphenous vein (MIR 97-98, 123; MIR 95-96 , 175).

The surgical technique of thromboendarterectomy consists of the extraction of occlusive thrombi after the artery has been opened together with the intima of the artery. The indications for this technique lie in short, segmental occlusions, especially in carotid territory, and in lesions that are short or confined to the primitive iliac or iliofemoral axis. Endarterectomy has the advantage that it is a more physiological technique, since it conserves the proper artery, increasing its caliber and respecting the collateral circulation routes and avoiding the placement of an artificial prosthesis.

Another form of surgical treatment is lumbar sympathectomy to produce vasodilation. This technique is widely questioned today for the limited benefits it provides, since although it can increase the flow in the skin , it does not increase it in the muscles. Today it is mainly reserved for patients with rest pain without the possibility of direct arterial surgery (MIR 95-96, 170).