An embolic infarct occurs when a particle, or embolus, originates in one part of the body, travels through the bloodstream, and lodges in a blood vessel. This blockage cuts off the blood supply, leading to tissue death (an infarct) from a lack of oxygen.
This is distinct from a thrombotic event, where a blood clot (thrombus) forms directly at the site of the blockage. While both cause tissue damage from reduced blood flow, the origin of the blockage is the primary difference. An embolic infarct happens suddenly when the traveling particle abruptly cuts off circulation.
Formation and Origin of Emboli
Emboli, the particles that cause these infarcts, are most often blood clots (thromboemboli) that form in the heart or large arteries. The most common cause is atrial fibrillation (A-fib), a condition where the heart’s upper chambers beat irregularly. This allows blood to pool and form clots, particularly in a pouch called the left atrial appendage, which can then be pumped from the heart.
Other cardiac issues can also form emboli. After a heart attack, damaged heart muscle can lead to clot formation on the heart’s inner wall. Diseased or artificial heart valves can also be a source for blood clots, as can calcifications on the valves.
Emboli can also originate from major arteries. In atherosclerosis, arteries are narrowed by plaques of fat and cholesterol, and a piece of plaque can break away and travel downstream to cause a blockage. The aorta and the carotid arteries in the neck are common sites for this to occur.
Less frequently, emboli can be made of other materials. Fat emboli can occur after a severe long bone injury releases fat particles from the bone marrow. Air emboli may be introduced during medical procedures or trauma, creating a blocking air bubble. In severe infections like endocarditis, clumps of bacteria and tissue (septic emboli) can break off and circulate.
Affected Organs and Associated Symptoms
The consequences of an embolic infarct depend on where the embolus lodges and which organ’s blood supply is obstructed. While any organ can be affected, some are more common than others, and the symptoms directly relate to the affected area.
The brain is the most frequent site, resulting in an embolic stroke when a clot blocks a cerebral artery. Symptoms appear suddenly and are recalled with the acronym F.A.S.T.: Face drooping, Arm weakness, Speech difficulty, and Time to call emergency services. Other signs include sudden confusion, trouble walking, or loss of balance.
An embolus traveling to the lungs causes a pulmonary embolism. Most of these are blood clots originating from deep vein thrombosis (DVT) in the legs. Symptoms are sudden and include sharp chest pain, shortness of breath, a rapid heart rate, and a cough that may produce bloody sputum.
An embolus blocking an artery to an arm or leg causes acute limb ischemia, a medical emergency. It is characterized by the “6 Ps”:
- Pain
- Pallor (pale skin)
- Pulselessness (no pulse below the blockage)
- Paresthesia (“pins and needles” sensation)
- Paralysis (inability to move the limb)
- Poikilothermia (the limb feels cold)
Other organs can also be affected. An infarct in the spleen or kidneys can cause sudden, sharp pain in the abdomen or flank. A blockage affecting the intestines can lead to mesenteric ischemia, causing severe abdominal pain, nausea, and vomiting.
The Diagnostic Process
Diagnosing an embolic infarct involves confirming tissue damage and identifying the embolus’s source to prevent recurrence. A clinical assessment of symptoms and medical history is the first step; for instance, sudden stroke-like symptoms in a patient with known atrial fibrillation strongly suggests an embolic event.
Imaging studies are important for confirmation. A computed tomography (CT) scan is often performed first for a suspected stroke to rule out bleeding. Magnetic resonance imaging (MRI) provides more detailed images of the tissue damage, while a CT angiogram (CTA) or MR angiogram (MRA) can pinpoint the blockage within the blood vessels.
A cardiac evaluation is necessary to find the source, as the heart is a common origin. An electrocardiogram (ECG or EKG) can detect abnormal rhythms like atrial fibrillation. An echocardiogram (heart ultrasound) is also used to view the heart’s chambers and valves, helping to identify structural problems or clots.
Blood tests are also part of the diagnosis. They can identify underlying conditions that increase clotting risk, such as inherited disorders or markers of inflammation that suggest an infection.
Medical Interventions and Management
Treatment for an embolic infarct is time-sensitive, focusing on restoring blood flow immediately and preventing future events long-term. The approach depends on the blockage’s location and severity, as well as the patient’s health.
In the acute phase, the objective is to remove the blockage and restore circulation. For embolic strokes, this may involve thrombolytic therapy, where clot-busting medications like tissue plasminogen activator (tPA) are given intravenously. For larger clots, a mechanical thrombectomy may be performed, where a catheter is used to physically retrieve the clot.
Long-term prevention focuses on the underlying cause of the embolus. If atrial fibrillation is the culprit, patients are prescribed anticoagulant medications (blood thinners) like warfarin or direct oral anticoagulants (DOACs). These medications reduce the blood’s ability to clot, lowering the risk of another embolus forming.
Managing the source is a continuous process. This may include medications to control heart rate in atrial fibrillation. If atherosclerosis is the problem, this involves managing risk factors like high blood pressure, high cholesterol, and diabetes. For septic emboli, treatment requires antibiotics to clear the infection.