Treatment of diseased tissues by various therapies is of vital importance in the medical community. Visualization of the treatment site is preferred; however, medical advances have provided improved methods, such as cardiac catheterization, which permits a physician to perform a medical procedure on the heart without ever directly observing the treatment site.
Cardiac catheterization includes the use of a catheter, which delivers, for example, a fiber optic cable to the treatment site. Transmission of electromagnetic energy, such as laser light, through the fiber optic cable can then be used to coagulate blood vessels or cauterize tissue via photothermal treatment. It has been found desirable to utilize photothermal treatment for a variety of diseases, including heart disease and ischemic portions of the heart muscle. Photothermal treatment involves the delivery of optical energy to the desired site and the conversion of the optical energy into thermal energy.
Photothermal treatment of tissue has certain drawbacks associated with the positioning of the catheter and the fiber optic cable. For example, the heat that is generated can cause blood in the artery, vein, or atrium to coagulate and/or form a thrombosis. This misdirected energy may also prevent the treatment site from receiving what is believed to be the appropriate dose of therapeutic energy. These drawbacks are often associated with not being able to directly or indirectly visualize the treatment site.
Generally, the catheter is visualized by use of X-rays. The opacity of the catheter and its components, in comparison to the relative transparency of body tissues and fluids, permits the physician to determine the approximate location of the catheter. This method allows for some uncertainty in the exact placement of the fiber optic cable and catheter and does not inform the physician when the catheter is in contact with tissue. Alternatively, viewing the catheter endoscopically can monitor positioning of the fiber optic cable inside a patient. However, blood and other body fluids can obstruct the view of the physician, which can lead to imprecise positioning of the catheter. Either method does not allow the physician to always predict when the distal end of the catheter is in contact with the site that requires treatment.
A need therefor exists for a method and apparatus, which overcomes and circumvents the above-identified problems. In particular, there is a need for phototherapy systems that can optimize contact and/or control the delivery of phototherapy such that radiation is delivered only when a satisfactory degree of contact is achieved.