A stationary blood clot, known as a thrombus, typically forms within a deep vein, most commonly in the legs (deep vein thrombosis). The danger arises when a piece of this clot breaks away, becoming an embolus, and travels through the bloodstream. This dislodged mass moves until it reaches a blood vessel too narrow to pass through, causing a sudden blockage. The location of the blockage determines the resulting medical emergency. Most frequently, the clot travels to the lungs, causing a pulmonary embolism, but it can also reach the brain or other vital organs.
Recognizing Symptoms of Pulmonary Embolism
When a clot dislodges, it travels through the right side of the heart and lodges in the pulmonary arteries, causing a pulmonary embolism (PE). This blockage restricts blood flow to the lung tissue, preventing oxygen uptake. The most prominent symptom is a sudden onset of shortness of breath (dyspnea), which occurs even while resting and worsens quickly with exertion.
The obstruction causes blood pressure to rise in the vessels leading to the lungs. This increased resistance forces the right side of the heart to work harder, leading to strain. A rapid or irregular heartbeat (tachycardia) frequently develops as the heart attempts to compensate and pump blood past the blockage.
A sharp, stabbing chest pain is a hallmark symptom of PE, often described as pleuritic because it feels worse when taking a deep breath, coughing, or bending over. This pain results from the clot blocking a vessel near the outer lining of the lung, irritating the pleura. The severity of the pain requires immediate medical evaluation.
Coughing often accompanies these respiratory symptoms. In some cases, the cough may produce bloody or blood-streaked mucus (hemoptysis). This occurs when lack of blood flow causes localized tissue damage and minor bleeding into the airways.
In severe cases, a large embolus can cause massive obstruction, significantly impairing the heart’s ability to pump blood. This can lead to lightheadedness, dizziness, or a sudden fainting spell (syncope), as the brain temporarily lacks sufficient blood supply. Any combination of these symptoms requires immediate emergency treatment.
Signs of Systemic Embolism in Other Organs
While the lungs are the most common destination, an embolus can travel to the arterial side of circulation, causing blockages in other organs. If the clot travels to the brain, it causes a cerebral embolism, resulting in an ischemic stroke. Stroke symptoms are sudden, unilateral neurological deficits corresponding to the area of the brain deprived of oxygen.
A person may experience abrupt weakness or numbness affecting one side of the body (face, arm, or leg). This is often accompanied by sudden confusion, difficulty speaking, or trouble understanding speech. Vision problems, such as loss of sight in one eye or double vision, can also occur suddenly.
Acute Peripheral Artery Occlusion
A serious complication is an acute peripheral artery occlusion, where the embolus lodges in an artery supplying a limb, usually an arm or leg. Since arteries carry oxygenated blood, a blockage causes immediate and profound ischemia (tissue starvation). This event is characterized by the sudden onset of intense pain in the affected limb.
The limb quickly becomes noticeably pale (pallor) because the flow of oxygenated blood has been interrupted. The affected area will also feel distinctly cool to the touch due to the absence of warm blood circulation. The person may experience severe numbness or a pins-and-needles sensation, and muscles may become weak or paralyzed.
Immediate Emergency Response and Triage
Recognizing severe symptoms of an embolism requires an immediate response. The appropriate action is to immediately call local emergency medical services (such as 911), rather than attempting to drive to the hospital or waiting for symptoms to subside. When speaking with the dispatcher, explicitly state the concern is a potential blood clot, pulmonary embolism, or stroke.
This information allows emergency personnel to begin triaging the situation and activate necessary hospital teams. Upon arrival, medical staff assess the stability of the patient’s heart and lungs. Initial diagnostic tests often involve a blood test to check the D-dimer level, which helps determine the likelihood of a recent thrombotic event.
To confirm a PE diagnosis, the most common test is a CT Pulmonary Angiography (CTPA), which uses dye and X-ray technology to visualize blockages in the lung arteries. For a suspected stroke, a CT scan of the head is performed quickly to rule out bleeding and confirm an ischemic blockage. Treatment often begins immediately with blood-thinning medications (anticoagulants) to stop the clot from growing and prevent new clots.