Thrombolytic therapy: Clot dissolving treatment for opening obstructed arteries and valves. Most commonly used in acute stroke (brain attack) and acute myocardial infarction (heart attack).
Common medications used to dissolve clots are streptokinase, tissue type plasminogen activator and its genetically engineered (recombinant) newer derivatives like tenecteplase and reteplase.
A heart attack usually occurs due to sudden blockage of a blood vessel. Clot dissolving treatment is useful only if given very early after the blockage of the blood vessel.
Stroke can be due to bleeding into a portion of the brain (cerebral hemorrhage) or blockage of a blood vessel to the brain (thrombosis or embolism). Thrombolytic therapy is not given in a stroke due to bleeding. It is given only when the stroke is due to clot formation in a blood vessel.
Now a days, clots in the blood vessels of the heart are rapidly removed mechanically using a procedure known a coronary angioplasty. But it is more expensive and may not be available in small centres. Similarly clots in the blood vessels can also be removed with devices in a process known as mechanical thrombectomy. Though it has not become as popular as coronary angioplasty, it is also gaining momentum with more and more centres offering it for acute stroke patients.
Yet another condition in which clot busting treatment is used is pulmonary embolism. In this condition, clots form in the blood vessels of the legs or tummy and move to the lungs, obstructing the blood vessels there. Person becomes very sick with breathlessness and blood pressure may fall. These clots in the blood vessels of the lung can also be dissolved by thrombolytic therapy.
Mechanical heart valves are another site for clot formation in the heart. Usually those having mechanical heart valves implanted, are placed on lifelong clot prevention medications (anticoagulants). For some reasons if these medications have to be skipped or are forgotten, the clot formation can occur within these mechanical valves. This is a potentially catastrophic condition as the valves can become suddenly blocked and the persons becomes breathless or faints. These clots can also be dissolved by thrombolytic therapy.
Downside of thrombolytic therapy
Any treatment which is aimed at stopping clots or dissolving clots naturally carries a risk of bleeding. Bleeding commonly occurs from the stomach or urinary bladder. Sometimes bleeding into the brain can occur, which can be quite serious. Hence close monitoring for excessive bleeding tendency is needed while giving this form of treatment. Occasionally allergic manifestations can occur to the medicine. This used to be more common with streptokinase, the older medicine of bacterial origin, while it is quite unlikely with the newer medications which are of human origin, made by genetic engineering techniques.