What is Acute Arterial Occlusion (Acute limb ischemia)?
Acute arterial occlusion, also known as acute limb ischemia, is a sudden blockage in an artery. It’s considered a serious emergency for the blood vessels. This blockage can cause a sudden stop in blood flow to a limb and can happen in the arms or legs. When the blood flow to the arms or legs is disrupted, it can lead to severe damage and can threaten both the limb and life of the individual if left untreated. Depending on which artery is affected and the patient’s medical history, the way this issue is diagnosed and treated will vary.
Timing is critical with acute arterial occlusion because if it’s not treated quickly, it can lead to severe tissue damage and loss of the limb, or even life. This medical emergency is also associated with an increase in illness, significant disability, and immediate surgery, especially in patients with high risk.
When a person has acute arterial occlusion, they’ll mostly experience pain in the affected muscle group, typically intensifying with physical activity. The pain a patient feels in the limb when walking is commonly referred to as intermittent claudication. The most common location of such blockage is the distal superficial femoral artery, which results in pain in the calf muscle area.
What Causes Acute Arterial Occlusion (Acute limb ischemia)?
The main cause of sudden blocked blood flow to a limb (acute limb ischemia) is a blood clot that forms in the artery itself. This is most likely to happen in the lower limbs, with people who already have a disease which narrows their arteries (peripheral artery disease or PAD) being at a higher risk. While blood clots can form in the arteries of both the upper and lower extremities, they typically affect the artery on the surface of the thigh.
Patients with a history of PAD tend to already have extra vessels that have grown to bypass the blockage, so symptoms and severity can vary. Other causes of this sudden blocked blood flow include blockages moving from the left side of the heart, the aorta (the main artery leaving the heart), and vessels in the pelvic region, as well as injury from a sharp or blunt force.
Risk Factors and Frequency for Acute Arterial Occlusion (Acute limb ischemia)
Acute limb ischemia, a sudden decrease in limb blood flow, isn’t frequently reported in research, making it hard to know its exact incidence. However, a long-term study conducted in Oxford, England, showed around 22 cases per 100,000 people each year. Acute limb ischemia can affect both older men and women, usually around the age of 75. The risk factors for this condition are age, smoking, diabetes, obesity, lack of physical activity, family history of vascular disease, high cholesterol, and high blood pressure. Non-traumatic limb ischemia is more common in the legs compared to the arms, and it often leads to limb loss.
- The condition often occurs in older adults, with the median age of patients being 75.
- It impacts men and women equally.
- It has many risk factors, including age, smoking, diabetes, obesity, sedentary lifestyle, family history of vascular disease, high cholesterol, and high blood pressure.
- The condition is more common and severe in the lower limbs.
- Atherosclerosis, a related condition, affects approximately 10% of people above 65 in Western countries.
- As the older population is expected to rise by 22% by 2040, diseases like these will pose a significant financial burden on the healthcare system.
- As of 2000, around 5 million people—or 4.3% of the general US population—have Peripheral Artery Disease (PAD), a similar condition. The prevalence of PAD increases with age.
Signs and Symptoms of Acute Arterial Occlusion (Acute limb ischemia)
Acute arterial occlusion, a sudden blockage in the arteries, has a typical pattern of symptoms often referred to as the “six Ps”:
- Pallor: Paleness of the skin
- Pain: Usually localized and lesser when the affected limb is dependent
- Paresthesia: Abnormal sensations such as tingling or prickling
- Paralysis: Temporary or permanent loss of muscle function
- Pulselessness: Absence of detectable pulse in the affected area
- Poikilothermia: Inability to regulate body temperature
These symptoms can appear anywhere below the blockage. Most people initially exhibit pain, pallor, pulselessness, and poikilothermia. The pain often lessens when the affected limb is lowered. As the situation worsens, abnormal sensations take the place of pain, leading eventually to paralysis. People with an occlusion caused by an embolism, a blood clot that has traveled from another part of the body, tend to have sudden onset of these symptoms, which can be severe because the area has not yet developed alternate pathways for blood flow. Remember that these symptoms may develop over hours to days and can either be new or recurring.
Research from Japan has shown an association between low kidney function and the development of arterial blockages. It was found that severe chronic kidney disease increases the risk of this condition.
Testing for Acute Arterial Occlusion (Acute limb ischemia)
When a doctor suspects acute arterial occlusion (a sudden blockage in the arteries), they begin with a physical check-up. This thorough examination measures changes in skin temperature in the suspected blocked area, comparing it to the unaffected side of the body. They also check for adequate blood flow on both sides of the body by manually feeling for pulses and using an arterial Doppler test if a pulse seems weak. Additionally, the doctor evaluates muscle strength and sensation.
If arterial blockage is found, they usually perform a CT angiogram (CTA), which is a special type of X-ray scan that provides detailed pictures of the arteries. However, they also consider how quickly treatment should be started in order to preserve the patient’s life and limb.
In most cases, as patients experiencing acute limb ischemia (a sudden lack of blood flow to a limb) end up in the emergency room, an immediate vascular surgery consultation is arranged. The intensity of the ischemia is further evaluated via a physical exam, using a classification system known as the Rutherford classification. Identifying the cause of the blockage is very important. For example, a patient who suddenly experiences symptoms and has a history of irregular heartbeats (atrial fibrillation) is more likely to have a blockage due to an embolism (a blood clot or other substance that has traveled to the arteries). On the other hand, a patient with a history of Peripheral Artery Disease (PAD) and claudication (cramping pain in the leg) is more likely to have a blood clot for a blockage (thrombotic source).
Treatment Options for Acute Arterial Occlusion (Acute limb ischemia)
If someone has a severe blockage of blood flow to a limb, which might threaten the survival of the limb, they need to be seen urgently by a surgeon who specializes in blood vessels. The goal of the surgery in these cases is to restore the flow of blood to the affected limb. This can be achieved using different methods such as bypass surgery, endarterectomy (removing plaque from the artery wall), or embolectomy (removing a clot).
The outcomes for these methods can vary greatly. They mainly depend on how long the limb has been without proper blood flow and how extensive the blockage in the blood vessel is. There’s also an option of a catheter-directed thrombolysis (CDT) which involves a specially trained doctor, called an interventional radiologist, using a thin tube to deliver clot-busting drugs to the site of the blockage. This method is generally used for patients who still have a good chance of saving their limb.
If a patient arrives with severe loss of function in the limb, lack of pain, and no detectable pulses, it’s usually taken as a sign that the damage is irreversible and amputation would be needed.
Surgical treatments are typically used in more severe cases, or if non-surgical treatments do not work. The options include traditional open surgery to bypass the blockage or less invasive endovascular therapies. The latter include inserting a stent (a tiny mesh tube) to keep the artery open, or inflating a small balloon within the artery to squeeze the blockage to the side (angioplasty), or cutting away the plaque (atherectomy).
While traditional open surgery was common two decades ago, the less invasive endovascular procedures have become more popular recently.
While awaiting evaluation for surgery or CDT, initial treatment should include giving fluid, managing pain and administering a drug called unfractionated heparin. This drug works to prevent the clot from getting bigger. The goal of this drug is to increase a certain lab value (partial thromboplastin time) by 2.0 to 2.5 times its normal range.
After successful treatment to restore blood flow, the patient must be closely monitored. If a limb is without adequate blood flow for more than 4 hours, it can lead to a condition called compartment syndrome which is a medical emergency. Therefore, the limb needs to be checked every hour for signs of nerve and blood vessel function.
What else can Acute Arterial Occlusion (Acute limb ischemia) be?
When someone has sudden blockage of an artery, known as acute arterial occlusion, it can seem like many different health issues. If a person is experiencing pain and other symptoms similar to those of poor blood flow, doctors might consider several conditions:
- Arterial embolus (a blockage caused by a traveling blood clot)
- Acute arterial thrombosis (a blood clot forms inside an artery)
- Aortic dissection (a tear in the wall of the aorta)
- Chronic exertional compartment syndrome (an exercise-induced muscle and nerve condition)
- Chronic venous insufficiency (poor blood flow in the veins, usually the legs)
- Degenerative disk disease (wear and tear of spinal disks)
- Osteoarthritis (joint inflammation causing pain and stiffness)
- Spinal stenosis (narrowing of spaces within the spine)
- Thromboangiitis obliterans (a rare disease of small/medium-sized blood vessels)
- Varicose vein surgery (a surgical procedure might give similar symptoms)
It’s critical for doctors to ponder and rule out all these possibilities by carrying out the appropriate tests to make sure they diagnose the issue correctly.
What to expect with Acute Arterial Occlusion (Acute limb ischemia)
A study on patients suffering from arterial occlusive disease (a condition where the arteries become blocked) found that two-thirds of the patients needed surgery right at the start of their hospital stay due to ongoing severe lack of blood supply. Although the death rate due to sudden blood clot was lower, there was a 35% risk of having a major limb removed. The study suggests that in cases of sudden arterial blockage due to a blood clot, reconstructing the blood vessels shouldn’t be delayed.
Possible Complications When Diagnosed with Acute Arterial Occlusion (Acute limb ischemia)
Here are some complications that can happen due to acute arterial occlusion, a sudden stoppage of blood flow in an artery:
- Compartment syndrome, a serious condition caused by increased pressure in a muscle compartment
- Amputation
- Necrosis and gangrene, both of which involve death of body tissue
- Bleeding
- Stroke, a condition that affects the brain
- Myocardial infarction, also known as a heart attack
- Death
Recovery from Acute Arterial Occlusion (Acute limb ischemia)
After receiving treatment for a severely restricted blood flow to a limb, these patients must be watched closely in the Intensive Care Unit (ICU). If the patient has peripheral vascular disorder or irregular heart rhythms, they may need to take aspirin or a blood-thinning medication. It’s important to find out why the limb wasn’t getting enough blood to ensure it doesn’t happen again. Since many of these patients might be weak or fragile, physical therapy should take an active role in helping them regain their strength and functionality.
Preventing Acute Arterial Occlusion (Acute limb ischemia)
It’s good practice to inform patients about potential risk factors and provide guidance on how to control them. Here are some steps patients can take to avoid experiencing serious health problems related to poor blood flow:
- Quit smoking
- Keep high blood pressure under control
- Manage diabetes effectively
- Keep a healthy body weight
- Take prescribed medications as directed
