Infrared Imaging and Open Heart Surgery

Infrared Imaging and Open Heart Surgery

By Wayne Ruddock, Advanced Infrared Resources, 177451 Bastanchury Rd, Suite 100D Yorba Linda, CA, Ph 250-579-2141

Introduction:
The study of temperature has been associated with health and the human body as far back as the 1st century BC. At that time the Greek philosopher Hypocrites, who is considered the father of medicine, used the sense of touch in relation to skin surface temperature anomalies to determine the "health" of
his patients, and to assist in the diagnosis of disease. Even in today's modern world an elevated body temperature or a "fever" is often a key which aides in both diagnosis and treatment planning.

Infrared Imaging:
All objects above absolute zero, -459 F, give off infrared radiated energy as the result of the acceleration and deceleration of charged atomic particles at the surface of an object. This radiated energy is directly related to the temperature of the object. The higher the temperature, the higher the kinetic molecular energy, leading to increased molecular motion, which results in an increased level of infrared radiated energy. Infrared imaging can be defined as the detection and measurement of this radiated energy, with the information being displayed and stored for both real time and post collection analysis. In the beginnings of this technology in the early 1960's, this information was displayed on a black and white CRT and captured using black and white film. Today this information can be displayed in color or gray scale on a CRT or LCD display and can be digitally stored and then analyzed at a later time using powerful computer programs. Infrared Imaging Systems are currently available in 3 common wavelength bands. Cameras known as long wave systems detect radiated energy in the wavelength band between 8 and 14 microns. These systems are typically uncooled systems using a Focal Plane Array detector set up which gives high resolution gray scale or color images. These type of systems are the most commonly used cameras in industrial infrared applications. A second type of camera generally known as a short wave system detects energy in the 2 - 6 micron bandwidth. Today, the majority of these cameras require cooling, using either liquid nitrogen or a sterling cycle cooler to accomplish this task. The detector array is cooled to -196 Celsius, giving the cameras excellent thermal resolution. A new addition to the infrared imaging camera field in the last few years has been the Near IR system. The main use of this camera, which detects energy in approximately the .9 - 1.7 micron bandwidth, is in the telecommunications industry.

Infrared Imaging and Open Heart Surgery Today:
Infrared imaging in the past, has been confined mainly to the evaluation of external skin temperatures in a variety of applications. These uses have met with success in a number of publicized situations. For many years, Dr. Ernest M. Feiler, MD, has been working on a technique to prove the value of infrared imaging in open heart surgery. Dr. Feiler has patented this initiative and is currently involved in case studies, which are proving the effectiveness of this technique. Today, infrared imaging is proving its ability to assist the surgeon in making real time decisions during the open heart surgery procedure. It gives valuable information during the operation by showing the change in temperature
patterns on the heart as various procedures are performed. Dr. Feiler has indicated that the three main areas infrared imaging can be of assistance to the surgeon are as follows:

1. The use of infrared imaging in open heart surgery demonstrates unsuspected areas of inadequate myocardial perfusion, due to obstruction of the tiny branch arteries that do not show up on coronary arteriography, generally associated with adjacent myocardial infarction, diabetes mellitus, or old age. The goal is to correct this inadequate perfusion, when identified by infrared imaging during the operation, by the use of procedures such as of TransMyocardial Laser Revascularization, (TMLR).
2. In cases of multiple obstructions in one coronary artery, infrared imaging will show if a graft placed distal to one of the obstructions supplies the other parts of the artery as well, by antegrade or retrograde flow past the obstructions, and therefore produces adequate myocardial perfusion as seen by comparison of the myocardial perfusion in each area. By using infrared imaging to see this, the surgeon can then determine if further grafting into that artery is necessary.
3. Infrared imaging can demonstrate if there is partial sharing of perfusion beds between an artery whose graft has been completed graft and another artery that is being approached, due to the development of collateral vessels, or detour routes. This is suspected when the perfusion fluid of one artery flows out when another artery is opened, which then requires a graft to keep it from closing. Now, one can discover this, before the artery is opened, utilizing the line profile function on the infrared imaging instrument, and confirm it by comparison of the relative perfusion of the myocardium surrounding each artery. "Competitive Grafting", of necessity, decreases the flow through both grafts, thereby endangering the survival of both grafts. The AIR-MED system is a specifically designed package that allows high resolution of the relatively small chest cavity area, worked on during the open heart surgical procedure. This area is viewed from a remote position that in no way interferes with the surgical procedures. As this technique is non contact and non invasive, there is no adverse effects or dangers involved in the employment of this technology. The infrared imager currently being employed in this set of tests makes use of a Raytheon 320 X 240 Focal Plane Array (FPA) with an uncooled Barium Strontium Titanate (BST) detector. This is the least expensive of the three systems available to hospitals and surgeons interested in exploring the use of infrared imaging in open heart surgery. The second system that will be tested, will also be a 320 X 240 focal plane array but it will use a camera with an uncooled, microbolometer detector. This detector senses energy in approximately the 8 - 14 micron range. This system is capable of higher spatial resolution.
The most powerful system in this series, uses a sterling cycle, cooled, Indium Antimonide FPA with a 320 X 256 pixel array. This camera is a short wave camera, detecting infrared energy in the 3 - 5 micron bandwidth.

Summary:
Infrared imaging can play an important role in open heart surgery by supplying the surgeon with real time information that can assist in the ongoing decision making process that takes place during the procedure. The information supplied by the infrared camera is unavailable pre-operatively.