Friday, August 05, 2005

Abhishek - Interventional Radiology

Hi all,

My last week was pretty hectic and eventful with my journey to Ithaca to make my devices work. I was in Ithaca for 4 days last week and was working on making the strain gauges work for my project in the Urology department. I have one working strain guage probe and have brought it along with me to New York city. I will be performing an experiment coming Monday. I will keep you all updated.

Interventional Radiology -

Dr. Frayer introduced me to Dr. Sullivan at Interventional Radiology. I observed 2 procedures being performed - Cardiac Catheter replacement and blod clot removal in a graft.

The procedure is performed with X-ray imaging which aids the surgeon to locate the catheter being inserted inside the patient. The X-ray machine is the semicircular machine seen in the image above and the surgeon switches on/off the x-ray with a switch using his feet.

Lead aprons are worn in the Operation room for protection from X-rays. These aprons are very heavy and be quite a weight to bear when one has to stand in the OR for more than 3 hours. The patient is usually under light sedation and has a numbing agent introduced which numbs the portion of the body where the catheter is being inserted. The catheter replacement is a routine procedure for the surgeons and the only obstacles they face is the catheter coiling up inside the vein.

The other surgery that I observed, blod clot removal in a graft, was pretty tricky and required 2 surgeons to do the job. The patient had a graft placed in his left arm which connected the artery to a vein. This graft was used for Haemodialysis and was working fine for 4 years for the patient. But recently it stopped working and he was brought to Interventional Radiology to get it fixed. The surgeons at the start of the procedure did not know that it was a clot. They at first observed the graft in the left arm using Ultrasound. They introduced a catheter close to the graft and using ultrasound imaging were able to get the catheter inside the artery and drove the catheter in. The x-rays were switched on and the catheter was observed as it moved into the artery. At one position the catheter was no longer able to move and coiled up. The surgeons after taking a lot images came to the conclusion that it was a blod clot. To remove the clot the surgeons contemplated using Heparin which is an anticoagulant but then ruled it out. This was because Heparin once introduced in the blood stream would go everywhere and remove blood clots formed to protect a previous surgical scar on the heart. The other option was to use an equipment called AngioJet Rheolytic Thrombectomy System. The AngioJet Rheolytic Thrombectomy System consists of a single-use catheter, single-use pump set, and multi-use drive unit. Thrombectomy is accomplished with the introduction of a pressurized saline jet stream through the directed orifices in the catheter distal tip. The jets generate a localized low pressure zone via the Bernoulli effect, which entrains and macerates thrombus. The saline and clot particles are then sucked back into the exhaust lumen of the catheter and out of the body for disposal. Treatment with the device takes about one minute. The surgeon informed the patient of the use of the equipment and also the complications (heart failure etc.) which may arise with its use. The surgeons inserted the catheter and flushed the blood clot using the saline jet.

The surgery on the whole was very interesting. The surgery gave me a feel of the kind of user interface the surgeons are familiar/comfortable with. I have learnt one thing that I will always remember when I design instruments/devices in the future - keep everything simple and ready to use. Its not that the surgeons don't understand how it works but its the simple fact that in the OR there is no time.


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