Imagine a submarine holding a team of scientists and physicians reduced to the size off red blood cells and then injected into a patient’s body in order to perform lifesaving brain surgery. This was the story told in the motion picture Fantastic Voyage in 1966. It offered first time views of what areas of the human body would look like if one were reduced to the microscopic level. Sounds farfetched, yes, but to some extent, aspects of this scenario are happening now in the medical field. Specially designed bacteria loaded with chemotherapeutic agents are guided by magnetic fields to tumors in hard to reach areas within the body.
In vascular surgery, many procedures inside the body are now accomplished without incisions, utilizing specially designed wires, long thin catheters and devices to treat blocked arteries and veins. A challenge has always been real time visualization of the area being treated with imaging. The mainstay of imaging has traditionally been x-ray, in which a fluoroscopic camera provides images of blood vessels. This technique is limited, however, by exposure of both the patient and surgical team to radiation, of which long term exposure has been linked to various types of cancer. Another limitation of fluoroscopy is the requirement for an iodine-based contrast agent to be injected into the blood vessel. This agent is notorious for harming kidney function in patients with some level of renal disease at the start. Additionally, the images provided by fluoroscopy, although quite accurate, are only obtained as a two-dimensional view. Finally, details of blood vessel wall anatomy is not available with fluoroscopy.
A newer technology, intravascular ultrasound, or IVUS has addressed the traditional limitations of x-ray, and is becoming more widely utilized in treatment of both the peripheral arteries and veins as well as the coronary arteries of the heart. IVUS uses ultrasound energy only and contains no radiation whatsoever and no kidney toxic agent is required to visualize the blood vessels. IVUS is able to provide a 3-dimensional view of blood vessels unlike any other imaging modality, and delivers a detailed view of the blood vessel wall anatomy. More and more, IVUS is assisting vascular surgeons and cardiologists in treating blood vessels and the heart in a less harmful, more informative manner. Here’s an example:
Recently, I cared for a patient with heaviness and pain in both legs. My assessment was that she probably had a condition in which a large pelvic vein (the iliac vein) was being compressed by the overlying iliac artery, thereby preventing normal return of blood from the leg and causing her symptoms. An x-ray (venogram) of her left iliac vein clearly showed the compression, but the right side appeared normal. Intravascular ultrasound confirmed the suspected compression on the left, and surprisingly, also revealed right sided compression. Both sides were treated with stents and the patient’s symptoms completely resolved in both legs.
While it would be exciting to travel through the bloodstream and view the wonders within, I, like the crew in Fantastic Voyage would need to contend with the attacking killer antibodies. I’m just thankful that I can see what’s happening from the safety of the operating room!