An infarct represents an area of tissue death that occurs due to an insufficient blood supply. This serious medical event signifies that cells in a particular region have been deprived of the oxygen and nutrients necessary for their survival. When blood flow is severely reduced or completely interrupted, the affected tissue cannot function properly and ultimately dies.
How an Infarct Develops
An infarct begins with a condition known as ischemia, which is a restriction in blood supply to tissues, causing a shortage of oxygen and glucose. Ischemia can arise from a blockage within a blood vessel, such as a blood clot (thrombus) forming locally or an embolus traveling from elsewhere in the body and lodging in a vessel. Severe narrowing of a blood vessel channel can also lead to this insufficient blood flow. The duration and severity of this blood flow interruption determine the extent of tissue damage. While ischemia refers to the reduced blood flow, an infarct specifically describes the resulting area of dead tissue.
Common Sites and Warning Signs
Infarcts can occur in various parts of the body, with the heart and brain being common sites. A myocardial infarction, often referred to as a heart attack, occurs when blood flow to a section of the heart muscle is interrupted. This can cause chest pain or discomfort, often described as pressure or squeezing, which may radiate to the left arm, jaw, neck, back, or upper abdomen. Other indications can include shortness of breath, sweating, nausea, lightheadedness, or an overwhelming feeling of anxiety.
A cerebral infarction, also known as an ischemic stroke, involves an area of necrotic tissue in the brain. Symptoms typically appear suddenly and can include sudden numbness or weakness on one side of the face, arm, or leg. Individuals might also experience sudden confusion, difficulty speaking or understanding speech, trouble seeing in one or both eyes, or a sudden loss of balance or coordination. The specific symptoms depend on the brain region affected and the extent of the damage.
What Happens to Affected Tissue
Once an infarct occurs, they cannot regenerate. The body initiates a repair process to address the damaged area. Initially, inflammatory cells are attracted to the injury site to clear away the dead tissue. Scar tissue, primarily composed of collagen, then forms. This scar tissue is not functionally equivalent to the original tissue; for instance, scar tissue in the heart muscle is non-contractile and does not contribute to the heart’s pumping action. The formation of this non-functional scar tissue can impair the overall function of the affected organ, with the degree of impairment depending on the infarct’s size and location.
Detecting an Infarct
Medical professionals identify an infarct and assess tissue damage using imaging techniques like computed tomography (CT) scans and magnetic resonance imaging (MRI). These scans can visualize areas of dead tissue and highlight regions where blood flow has been compromised. MRI, particularly diffusion-weighted imaging, is recognized for its accuracy in detecting early ischemic changes within minutes to hours of onset. Blood tests are also used to detect specific biomarkers that are released into the bloodstream when tissue damage occurs, such as cardiac enzymes for myocardial infarction. For cerebral infarcts, while no single blood test is currently definitive for diagnosis, biomarkers like S100B or glial fibrillary acidic protein (GFAP) can indicate brain injury and inflammation. Timely and accurate diagnosis through these methods allows for appropriate medical intervention.