Blood clot formation, or “thrombosis,” is a basis of a number of serious diseases, such as ischemic stroke, myocardial infarction (heart attack), and deep vein thrombosis (DVT). Blood clots, or “thrombi,” form inside blood vessels and obstruct the flow of blood through the circulatory system, thereby depriving tissue and organs of oxygen. In the case of a stroke, for instance, when blood flow to the brain is obstructed for longer than a few seconds, brain cells can die and permanent neurological damage can result.
Thrombi can be treated (reduced or eliminated) by inducing thrombolysis. Thrombolysis is the dissolving, or “lysis,” of a thrombus. Thrombolysis can sometimes be induced pharmacologically, such as by administering a tissue plasminogen activator drug (tPA), the most common thrombolytic agent. Thrombolytic agents (commonly called “clot-busting drugs”) can be administered via an intravenous line or using a catheter to deliver them proximally to the thrombus. However, thrombolysis by administration of clot-busting drugs has its limitations. For example, to be successful, the clot-busting drugs should be administered within three (3) hours of an acute ischemic stroke, and preferably within two (2) hours. Further, patients who use blood-thinning medications, and certain other medications, are usually not candidates for pharmacological thrombolysis. And of those patients receiving the treatment, it is unsuccessful in dissolving thrombi in approximately 25% of patients.
In view of the limitations of pharmacologically induced thrombolysis, various medical devices for surgically removing thrombi have been developed. The procedure for surgically removing thrombi is generally known as a “thrombectomy.” In thrombectomy treatments, a catheter system is typically used to deliver a device to the thrombus. The device can be, for example, an aspiration catheter. Aspiration catheters can perform a thrombectomy by suctioning the thrombus out of the blood vessel. Other thrombectomy procedures use a mechanical device to physically entangle with a thrombus, and to remove the thrombus as the device is removed from the blood vessel. Various types of mechanical devices, such as wires, corkscrew-like coils, bristles, and baskets have been employed to entangle with thrombi.
Some traditional thrombectomy devices can cause damage to blood vessel walls. In addition, some traditional thrombectomy devices can be prone to generating thrombotic fragments that become emboli when they travel within the bloodstream. Emboli can become lodged in arteries, veins, arterioles, and capillaries, and can block the blood supply to vital organs such as the brain or heart. Emboli in the bloodstream can be life-threatening. In the case of DVT treatment, dislodged thromboemboli can travel to the lungs, resulting in a pulmonary embolism, which can be fatal.