Acute Arterial Occlusion
Acute arterial occlusion is a medical emergency that directly threatens certain tissues or organs. The most important aspect of a sudden arterial closure is the lack of oxygen in the affected tissues, because the majority of them are able to survive for only a limited period of time.
The most frequent cause is arterial occlusion by a blood clot. The blood clot may be either formed at the site of the closure (in such case the blood clot is referred to as “thrombus”) because of the atherosclerosis or it is formed elsewhere and brought to the site of closure by the blood flow (in such case we call the blood clot as “embolus”). The emboli may occur in a frequent arrhythmia known as atrial fibrillation and septic emboli may accompany the infective endocarditis. However, there are even much rarer causes of arterial closure such as the Raynaud’s phenomenon, aortic dissection (that can occlude large arteries branching from aorta), traumatic obstruction of arteries in severe injuries and closure Buerger’s disease.
The symptoms depend on the specific type of occluded artery and the affected organ. Sudden closure of a coronary artery may cause acute heart attack, occlusion of a brain artery causes ischemic stroke, and closure of arteries supplying the intestines may lead to dangerous vascular ileus. Very specific issue is a sudden occlusion of arteries of the lower extremities and I would like to dedicate the rest of this article to this topic.
If there is a sudden blockage of an artery of the lower limb (whether due to a thrombus or embolus), it is a medical emergency which may cause irreversible damage to the affected extremity. The condition manifests by pain and pallor of the affected limb. Acute sharp pain is a symptom typical for most arterial occlusions and it can be considered a positive sign, because what hurts, that is still alive. In addition, the limb is cold and when palpated, there is no pulse. The affection of local nerves disrupts the sensitivity and in more severe cases, it may cause the muscle paralysis.
The diagnosis is based on patient’s symptoms and on the outcome of physical examination. It is very important to know, if the patient has a peripheral arterial disease (PAD) in his personal history. If the patient suffered from symptoms of PAD, the probable cause of the acute arterial occlusion is local thrombosis in narrowed arteries. When the acute arterial occlusion occurred in previously healthy patient, it is more likely caused by a blood clot embolism.
The physical examination should focus on the lower extremities and differences between them – their color, temperature and pulse palpation. Any asymmetry is suspicious.
More precise information about the location of the occlusion can give us the arterial duplex ultrasound and angiography. The angiography is a great examination method that can not only visualize the closure, but also become a therapeutic option (see below).
In a total arterial occlusion, the situation should be solved within hours as there is a high risk of necrosis of the extremity.
The patient is usually administered anticoagulants (typically heparin) and strong painkillers. Further approach depends on the individual case. The situation may be solved conservatively by administration of special substances dissolving the thrombus (thrombolysis). However, these drugs may have many side-effects including increased risk of internal bleeding.
Invasive, endovascular approach (i.e. non-surgical solution) includes puncture of the affected artery and aspiration of the blood clots by a special device. We refer it to as the percutaneous aspiration thromboembolectomy.
Surgical treatment focuses on creating access into the affected artery and mechanical removal of the blood clots by various tools (for example embolectomy by Fogarty catheter).
The affected limb may be also treated by therapeutic angiography with extension of the occluded space with a special balloon followed by a stent implantation, which keeps the blood vessel open. In acute conditions, however, the other above-mentioned methods are more preferred.
In case that the affected extremity is no longer viable, the surgeons must perform its amputation. When the limb is saved (or successfully amputated), it is advisable to look for the reason of arterial closure and solve it, if possible.