Live from Chennai

Published : Jul 04, 2003 00:00 IST

Dr. Mathew Samuel Kalarickal during India's first live transmission of a surgical procedure, from Apollo Hospitals, Chennai. - BY SPECIAL ARRANGEMENT

Dr. Mathew Samuel Kalarickal during India's first live transmission of a surgical procedure, from Apollo Hospitals, Chennai. - BY SPECIAL ARRANGEMENT

For the first time ever, two complex surgical procedures done in Chennai are presented live to a global audience.

ON May 22, over 2,000 interventional cardiology professionals from all over the world watched live from Paris two surgeons perform two complex procedures at Chennai's Apollo Hospitals. The programme, part of the EuroPCR conference, a prestigious annual event where interventional cardiologists, vascular surgeons, radiologists, nurses, technicians and healthcare professionals dealing with interventional cardiology learn current techniques through live demonstrations from around the globe, marked two firsts. One, for the first time ever, a country from the Asia-Pacific region was invited to demonstrate its expertise at the conference. Two, the surgical procedures performed by the teams led by Dr. Mathew Samuel Kalarickal, director, interventional cardiology and cardiac catheterisation laboratories, Apollo Hospitals, Chennai, and Dr. Upendra Kaul of Batra Hospital, New Delhi, used the latest-generation sirolimus-eluting stent (stainless steel mesh tube placed to keep the artery open) for the first time in a live demonstration to a global audience, though they have been using the stents on their patients for the past one year.

The two surgical procedures, performed simultaneously, were complex and took nearly four hours to complete. Said Dr. Kalarickal: "The cases were very difficult and we had to change strategies several times." EuroPCR session chairperson John Marker, who was very happy with the demonstrations, said: "The cases beamed from India were excellent and we learnt a lot from them."

The main difficulty, according to Dr. Kalarickal, was that both the patients had undergone bypass surgery some years ago. "Worse, the blocks had recurred with a vengeance," he said. According to Dr. Upendra Kaul, the blocks, thickened with calcium deposits, were worse than what they had been before the earlier surgery, and that made it extremely difficult to insert a balloon into the narrow artery. "This forced us to change strategies continuously," he said.

From strategies involving the use of the balloon, the cut-balloon, and multiple wires, to the drilling of the artery, the two teams tried it all. What is important is that the patients were saved, and the world saw it happen.

Recalled Dr. Upendra Kaul: "Changing techniques was not easy. The entire hardware had to be changed. The paramedical staff had to be on their toes. Though we were prepared for the different strategies, we did not know until we opened up the patients as to which strategy we would use."

The doctors used the bifurcation balloon technique, the latest in interventional cardiology, and various other strategies to prevent the distal embolisation of clots in the grafts that were facing occlusion, apart from some complex artery diseases. Said Dr. Kalarickal: "Luckily, everything went off well and the sirolimus-eluting stents were successfully inserted into the patients."

STENTS have revolutionised the treatment of coronary artery disease. However, in over 30 per cent of the patients, the stent becomes partially blocked owing to the re-narrowing of the treated arterial segment. This process, known as restenosis, is caused by the cellular proliferation and growth of the innermost layer of the vessel wall inside the stent, which reduces the vessel diameter and causes blocks in the arteries.

So drug-eluting stents were developed. These stents, which deliver a drug to prevent restenosis, have ushered in a new era in interventional cardiology. A number of drug-eluting stents, releasing different types of drugs, are being clinically evaluated in hospitals and medical centres around the world. Cordis Corporation, a subsidiary of Johnson and Johnson Limited and a pioneer in the development and manufacture of interventional medicine, came out with the Chypher sirolimus-eluting stents.

The sirolimus-eluting stent is essentially designed to prevent re-narrowing within the stent (in-stent restenosis). The stainless steel stent has a thin coating of the sirolimus drug on its surfaces. The drug is located within a polymer (plastic) coating. The stent provides structural support to the artery, and the drug is slowly released into the artery wall around the stent.

Sirolimus belongs to a category of cytostatic drugs known as cell-cycle inhibitors. This drug limits the overgrowth of the normal tissue by blocking cell-cycle progression. The sirolimus cytostatic mechanism stops cell division early in the cell cycle while simultaneously blocking the inflammatory process in the vessel wall. By acting early in the cell cycle, sirolimus stops cell division without killing the cells, thereby reducing the risk of tissue damage.

The sirolimus-eluting stent, one of the first drug-eluting stents to be commercially released, combines a unique antiproliferative agent, sirolimus, a naturally occurring substance that blocks the neointimal proliferation process without killing the cells and allows natural healing of the vessel.

The sirolimus-eluting stents achieve unprecedented reduction in restenosis rates and enable the use of long, adjoining, multiple or overlapping stents without the risk of local tissue toxicity.

Sirolimus was first isolated in 1975 from a soil micro-organism, Streptomyces hygroscopius, found in Easter Island. The purified crystalline sirolimus was found to be active against several strains of yeast and filamentous fungi. Thus, it was first classified as an anti-fungal antibiotic. Later, through in vitro and in vivo vascular models, it was proved that sirolimus had powerful anti-proliferative and immunosuppressant properties. Hence it was considered an effective agent for the prevention of restenosis in angioplasty models.

According to Dr. Kalarickal, randomised, double-bind, multi-centre clinical studies using sirolimus-eluting stents show a 100 per cent reduction in in-stent restenosis for three years and late lumen loss (there is generally a late lumen loss of 0.8 mm when bare stents are used). Since August 2001, clinical trials of the sirolimus-eluting stent are being conducted at over 50 centres in the United States, apart from several other centres in different parts of the world.

According to Dr. Erick Schampaert, principal investigator at Hospital Sacre-Coeur de Montreal, Canada, who studied the sirolimus stent on 100 patients, including 24 diabetics and those with long lesions and small vessels, the sirolimus-eluting stent provides exceptional treatment option to a broad range of patients.

According to Dr. Jean Fajadet, principal investigator at Clinique Posteur, Toulouse, France, who studied the sirolimus stent on 238 patients, there were no restenosis, percutaneous target lesion revascularisation, thrombosis or cardiac deaths after one year of the procedure.

With over 40 clinical trials, the sirolimus stent remains the most studied drug-eluting stent. It has the largest body of publicly available clinical evidence. It received the European CE Marl approval in April 2002, and obtained the USFDA approval in April 2003. It is now available in more than 60 countries.

While the sirolimus-eluting stent has marked a turning point in the history of interventional cardiology as it reduces restenosis in 90 per cent of all in-stent procedures, it is three times (Rs.1.5 lakhs) costlier than conventional stents. But, says Dr. Kalarickal: "The cost is bound to come down with economies of scale as its usage increases."

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