Stent stunts

An improved version of a device that keeps blood vessels inflated -after cholesterol deposits have been ballooned out of them - has been developed by European cardiologists

Published: Sunday 31 March 1996

-- (Credit: Rustam Vania)DEPOSITS of cholesterol left untreated in one's blood vessels could mean death. There is also a chance that if the blood vessel is cleared by angioplasty, it would collapse at the post-operative stage. Angioplasty is a procedure wherein a tube having a balloon at its tip is guided to the obstructed heart vessel through an artery in the groin. Once at the site, the balloon is inflated to squash the deposits of cholesterol that obstruct th~ vessel. The device, known as ste.rtt, which has been in use since 1987 to keep the vessel bloated after the blockage is removed, suffers from a serious shortcoming: it leads to severe bleeding at the cleared site which means that a clot would form ~nd block the channel again, at exactly the same spot. Now, a modified version developed by a team of EurQpeancardiologists led by Patrick W Semiys ofErasmus University in Rotterdam in the Netherlands, promises to reduce the complications plaguing the previous one.

Stent is a flexible mesh metal cylinder that acts as a scaffolding, If required, it is placed over a tube (after angioplasty has been performed) and is guided into the constricted area. The balloon inflates and locks the stent in place. As a result, the artery is held open by the rigid support that the stent provides. To overcome the risk ofseri- ous bleeding associated with the stents, Serruys' group te'amed up With a Swedish company Carmeda, to develop I an anti-clotting drug coating for the Palmaz-Schatz stent, manufactured by Johnson & Johnson. Coated with heparin (a natural arid standard antico- agulant), the new modified device eliin- inates the need for a patient to take injections of heparin or other similar drugs. Earlier in the case of the ~ncoated stents, bleeding was severe enough to cause blood clots at the site; sometimes requiring transfusions or leading to car- diac strokes as well. Anticoagulants were needed to prevent the formation of blood clots that block the artery at the site of angioplasty. But now, along With the new hepariri-coated stent, patients take two drugs, aspirin and ticlopidine, which are usually safer than,anti- clotting drugs.

In a study conducted in four phases involving 51 patients, the heparin stent , was inserted and the condition of the subjects monitored. Significantly, the scientists found that with the new stent, bleeding complications requiring trans- fusions or surgery fell steadily from 7.9 percent in the first phase to zero in the fourth phase. The length of the hospital stay was reduced from seven days in tl}e first stage to three days in the last stage. J'he incidence of restenosis or a new blockage, was 13 per cent compared with 30 per cent during a follow-up of the patients treated with balloon angio- plasty. Hailing the new stent as 'a major advance in treating heart disease, doctors feel that heart surgery is in for a revolution because of this drug-coated device.

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