Dr. MEYER. It is usually in millimeters, and if one wishes to do any research on this, if you have this accurately measured and put down into retrievable form, in due course, this is going to cause a tremendous advance in the reading of electrocardiograms.

Senator NELSON. Well, it reduces his time-if you say it takes 10 to 15 minutes for the doctor to do the measurements and evaluate an ordinary one, how much time is this going to save him?

Dr. MEYER. I would think it would save him 50 percent, 60 percent of the time he spends actually on that tracing, and he would then look at that tracing for 4 or 5 minutes instead of 8 to 10 minutes.

Senator NELSON. Then a cardiologist in a medical center could, in effect, in servicing the whole surrounding countryside for many miles, could double the number of diagnoses that he could make per day? Is that what you are saying?

Dr. MEYER. Yes, sir; or he would be free or freer to discuss with the referring physician the implication of this particular tracing to the patient, and he would then have the opportunity to talk and to teach the person who is transmitting the EKG.

Mr. CALLAHAN. Mr. Chairman, we also have Dr. Caceres of the U.S. Public Health Service, speaking from the Medical Systems Development Laboratory here in Washington, will be describing his program to us by Telelecture in a moment. He is on the line now. If you wish, I am sure Dr. Caceres will be able to give you more information on this subject.

Senator NELSON. Proceed. Any time the questioning interferes with the mechanical presentation of something you planned here, just interrupt Senator Hatfield or me.

Mr. CALLAHAN. Yes, sir.

I believe the discussion as a result of your questions has brought out the additional comment that I was about to make. Therefore, I would like at this point to introduce to the committee, Dr. Cesar A. Caceres of the U.S. Public Health Service, who is directing this program.

Dr. Caceres, are you on the line with us now?

STATEMENT OF DR. CESAR A. CACERES, CHIEF, MEDICAL SYSTEMS DEVELOPMENT LABORATORY, HEART DISEASE CONTROL PROGRAM, NATIONAL CENTER FOR CHRONIC DISEASE CONTROL, PUBLIC HEALTH SERVICE, U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE, WASHINGTON, D.C.

Dr. CACERES. Yes; I am.

Mr. CALLAHAN. Would you go ahead and make your presentation? Dr. CACERES. In a very short time there will be more human beings alive at one time than have populated the world since the beginning of man.

The need to provide for this sudden huge population growth creates new medical problems. Entirely new concepts of medical analysis and treatment-not merely improvements of existing ones-must be de

veloped to maintain the quality of medical care needed for the rapidly increasing mass of human beings.

In routine physical examinations and in the diagnosis and treatment of heart disease, physicians in the United States spend part of their scarce time analyzing some 50 million electrocardiograms per year, for example, as one of the things they have to do.

These tests and many more can now be done on a mass scalequickly, reliably, and inexpensively-by automated systems using computers.

Just as automation in a thousand industries has jumped up production while saving time and money and conserving manpower, it can now be used in medical care. To be of greatest effectiveness, automation requires extensive communication facilities.

Automation is a giant step in the battle against heart disease, with its annual mortality in the United States alone of well over 700,000against stroke, with an annual mortality of approximately 200,000— against other killer diseases of the cardiovascular and cardiopulmonary systems.

The growing number of physical and laboratory tests required by our increasing and aging population, the shortage of physicians and other health personnel, and our awareness of the need for raising the quality of medical practice for all our citizens, force us to utilize the precision and rapidity of computers and communications systems. These systems can be tools in medical practice to help us keep up and not fall behind in our vital battle to preserve the health of our people. Delegation of routine duties to automated systems is an ideal way in which the physician can find more time for development and exercise of higher professional skills and to provide leadership to the medical teams required in today's concept of comprehensive health

care.

Since a computer system can increase the effective use of the physician's time, he can concentrate more on his needs for further education to maintain awareness of day-by-day scientific advances.

The computer can, for example, relieve the heart station physician, the industrial physician, and the physician in group or hospital practice, of the tedium of reviewing predominantly normal electrocardiograms. The physician-time thus saved can be reflected in better care of patients.

The digital computer in this way can help solve today's problem of the shortage of medical manpower.

To make this major advance, research and demonstrations have been conducted the past several years in the use of computers and modern electronic systems to interpret electrocardiograms and other medical signals.

System Development

Several steps were necessary to develop a functional system. First, a new electronic instrument was engineered to take an electrocardiogram. The unit, which can be operated by any EKG technician, is called a data acquisition console. Slide No. 1 shows an example of this. (The illustration referred to follows:)

Dr. CACERES. It is similar to conventional electrocardiograph machines. The technician connects the leads in the usual manner. The console unit is essentially a tape recorder plus a conventional EKG machine.

The data acquisition unit provides many unique features-in addition to the standard tracing. Among these features is a system for coding to identify the EKG and to identify the patient and record certain of his physical characteristics, such as age, sex, height, and weight. An automatic timer is provided to meter standard lengths of recording. A side panel provides for the electrocardiogram and additional physiological inputs such as electroencephalography, phonocardiography, and spirometry. The unit is operated in the same manner as ordinary EKG machines.

The patient and lead-identification codes are recorded both on the visible tracing and on analog magnetic tape, which can serve as the input to the computer system.

In the second slide, we see an example of a service being provided today. The signal or the magnetic tape recording of the electrocardiogram or other signal can be fed through a telephone from Hartford by use of data-telephone systems, which sends the signal to the computer center, however distant. The slide shows you the diagrammatic presentation of what we are doing. There, the individual in bed, in the out-patient department or the emergency ward, can have an electrocardiogram recorded by telephone. This can be sent to the Public Health Service field station in Washington, D.C., where the telephone data is received and, if necessary, re-recorded on analog magnetic tape. This tape is fed into an analog-to-digital converter. (The illustration referred to follows:)

Dr. CACERES. This device samples the continuous EKG waveform 500 times per second. Each sample is thus tagged so that a computer program can identify the peaks and valleys of the wave complex. A method to determine the amplitudes and durations of the P, Q, R, S, and T waves, as used in present-day electrocardiography, has been programed into many thousand individual instructions.

Each lead is monitored for several seconds. Within 15 seconds after the computer has recognized the waveforms of all the leads, it associates the values and can print out an interpretation, such as the physician would receive from an electrocardiographer.

Storage of the processed data for later retrieval for comparison, followup, or statistical analysis can also be made from the processed data stored on digital magnetic tape. Within a few seconds, results can be fully processed and returned to the physician or to the hospital. High-speed teletype machines and printers, which make out reports for delivery by wire, can also serve in situations where rapid screening of large numbers of people is necessary.

With this routine processing system, the Public Health Service has established less than 1 percent error in the computer system. This is far less than any human system can possibly produce. There is a high agreement between cardiologists and computer interpretations. Moreover the computer helps the physician avoid missing any significant data.

The field trials conducted by the heart disease control program have been highly successful. Forty thousand electrocardiograms were processed in the first year of routine operation, using only one-third of the system's capability. For example, computer-analyzed electrocardiograms have been routinely employed for the past 2 years at the Hartford Hospital.

Records are processed in the evening and are available routinely at the hospital the following morning.

Two-step exercise tests and continuous recordings will be analyzed, as well. Our computer system is being programed for these, to take advantage of the information obtained through post-exercise electrocardiography.

In the future computer analysis programs will also utilize other physiological data, such as the respiratory test, blood vessel volume changes, brain waves, and heart sounds.

The computer system of the future can make complete electrocardiography service available full time in nursing homes, where the EKG can be recorded on tape for transmission to a computer center or in a patient's home while he is on home care.

With the increasing sophistication of telephone technology, signals can be transmitted through specialized analog data-telephone transmitters. A small, portable electrocardiograph machine used with a telephone interface developed by Bell Telephone employs any conventional telephone in transmitting the cardiographic signal. By simply dialing a special number, the sender can transmit the signal to a predetermined computer center for recording and analysis.

We have successfully transmitted electrocardiograms from France to Washington, D.C., for computer analysis and immediate return, using telephone, RCA communications, and satellite transmission.