Scope and Contents

The collection includes engineering logbooks, drawings, operator manuals, correspondence, photographs, sales brochures and catalogs, biographical information about the engineering staff who worked on the monitor, patents and trademarks, and marketing and sales materials documenting the development of the Holter Monitor, a portable device for continuously monitoring heart activity.

The records document the successful collaboration of an independent inventor and a manufacturing firm to identify problems, develop solutions and bring to market diagnostic technologies. Bruce Del Mar's role as an innovator and collaborator with Holter is especially important, because Del Mar's work spurred the development of an entire diagnostic industry. In addition, the records also chronicle how "Holter technology" was affected by progressive technological innovations in the industry, as vacuum tubes were replaced by transistors, as microprocessors gave way to microchips and circuit boards, and as analog recordings were replaced by digital formats.

Documenting manufacturing developments (highs and lows) and marketing considerations is an important element in better understanding the invention process. Del Mar Avionics was the first to design and manufacture instrumentation for long-term monitoring of the human heart for the medical profession. Today, Holter Monitors continue to be an important diagnostic tool for monitoring the health of the heart.

Series 1, Historical Background, 1951-2010 and undated, consists of biographical materials for Bruce Del Mar, founder of Del Mar Avionics, company histories, copies of the Del Mar Avionics newsletter Pacemaker, employee information, newspaper clippings and ephemera, and photographs of some employees. The employee information contains a 1979 handbook, explaining company policies and the benefits of employment with Del Mar Avionics and a 1951 memo detailing overtime working hours for women, presumably from Douglas Aircraft, where Bruce Del Mar was employed.

Series 2, Del Mar Avionics Engineering, 1958-1976, is divided into three subseries, Subseries 1, Correspondence, 1965-1976; Subseries 2, Reports, 1964-1969; and Subseries 3, Drawings, 1958-1968. The documentation consists primarily of correspondence from the engineering department, 1965 to 1976, related to the development, design, budgeting, testing, and marketing of the Holter Monitor. The majority of the documentation is correspondence and is written by engineering staff members, but also included are quotation requests, trip reports, and technical reports. Correspondence between Holter and Del Mar about the development of the Holter Minotor is in Series 6. The drawings, 1958-1968, include six drawings (22" x 34" or smaller) for Avionics Research Products projects (panel assembly, chassis assembly, and battery chargers for model 602), and Electromation Company (degausser single coil).

Series 3, Patents and Trademarks, 1965-2002 and undated, consists of copies of patents by Norman J. Holter, W.E. Mills, and W.E. Thornton, Cliff Sanctuary. and Isaac Raymond Cherry related to the development of the Holter Monitor. Also included are lists of United States patents issued to Del Mar Avionics employees, as well as lists of registered trademarks and activities for Del Mar Avionics and copies of trademarks issued to the company.

Series 4, Product Literature, 1968-2010 and undated, consists of product literature for Del Mar Avionics products and some of its competitors. The product literature for Del Mar Avionics is arranged chronologically by model number, and the competitor literature is arranged alphabetically. All of the product literature is related to medical instrumentation with the exception of the Hydra Set, a precision load positioner which is the only product Del Mar Avionics sells today.

Series 5, Sales, 1967-1985, consists of price lists, price catalogs (both domestic and international) and sales objectives for medical instrumentation sold by Del Mar Avionics.

Series 6, Holter Monitor Materials, 1958-2005 and undated, is divided into three subseries, Subseries 1, Background Materials, 1958-2005 and undated; Subseries 2, Model 445, 1974-1978; and Subseries 3, Model 660, 1967-1978 and undated, and consists of materials documenting the relationship between Norman J. Holter, an inventor, and Del Mar Avionics.

Holter and Wilford R. Glassock were issued United States Patent 3,215,136 on November 2, 1965 for the Electrocardiographic Means. Dr. Eliot Corday introduced Holter to Bruce Del Mar, founder of the Del Mar Avionics Corporation in Irvine, California. Del Mar engineers developed the "electrocardiocorder" for clinical use, producing a commercially viable monitor which came to be known as the Holter Monitor Test. Further refinements led to the creation of a "minimonitor" in 1968 which was described by Holter as being the "size of a cigarette package." Commercial production of the Holter minimonitor, AVSEP, Jr., began in 1969. The Holter Research Foundation ultimately sold exclusive rights to their patents to Del Mar Engineering Laboratories.

The materials include biographical materials about Norman J. Holter, journal articles about the Holter Monitor, correspondence, engineering notebooks, a licensing agreement, product literature, reports, price lists, catalogs, operating manuals and specific information about the Dynamic Del Mar Avionics ElectroCardioCorder (Model 445), 1977, and the ElectroCardioScanner (Model 660), 1971. Both models were developed by Del Mar's medical device manufacturing staff. The licensing agreement and correspondence detail in chronological order the relationship between Norman Holter and Del Mar Avionics, specifically president Bruce Del Mar, in the rapid commercial marketing and development of Holter's electrocardiorecorder. Although Holter assigned exclusive rights to his patent to Del Mar Avionics, he was involved in the design and development process, albeit from a distance. The engineering staff at Del Mar kept Holter informed, and it is clear that Holter regularly visited the company.

The engineering notebooks relate to the models 445 and 660. The notebooks were maintained by engineering staff members D. Anderson, N. Mohammedi, Ray Cherry and Fike. The notebooks are handwritten, although in some instances memos and other information have been inserted. For example, N. Mohammedi's notebook documenting Model 445 contains black-and-white prints, magnetic tape samples, and recorder tape (EKG graph paper) samples with data from the monitor. The notebooks are bound and paginated, and individual pages are stamped sequentially.

Series 7, Slides, circa 1990s, consists of color slides used for presentations by Del Mar Avionics staff to discuss and promote the marketing of the Holter Monitor.

Arrangement

The collection is arranged into seven series.

Subseries 1, Correspondence, 1965-1976

Subseries 2, Reports, 1964-1969

Subseries 3, Drawings, 1958-1968

Subseries 1, Del Mar Avionics, 1968-2010 and undated

Subseries 2, Competitors, 1974 and undated

Subseries 1, Background Materials, 1958-2005

Subseries 2, Model 445, 1974-1978

Subseries 3, Model 660, 1967-1978 and undated

Biographical / Historical

Norman Jefferis "Jeff" Holter (1914-1983) was born in Helena, Montana, to a prominent Montana pioneering family. After attending public schools in Helena, he earned master's degrees in chemistry from the University of Southern California (1938) and physics from the University of California, Los Angeles (1940). During these years Holter also organized Applied Micro Sciences, a scientific photography business, and began working with Dr. Joseph A. Gengerelli of UCLA on nerve stimulation in frogs and brain stimulation in rats. Holter's interest in studying electrical activity in humans in their daily activities without touching them, spawned his lifelong pursuit to develop the Holter Monitor.

During World War Two, Holter served as a senior physicist for the U.S. Navy's Bureau of Ships, conducting research into the behavior of ocean waves in preparation for wartime amphibious operations. After the war, in 1946, Holter headed a staff of oceanographic engineers at Bikini Atoll during Operation Crossroads, the first postwar atomic bomb tests, measuring wave actions and underwater disturbances caused by the explosions.

Because of demands of his family's business affairs, Holter returned to Helena in 1947 to continue his research activities. In 1947 he formed the Holter Research Foundation, with a laboratory originally located in the rear of the Holter Hardware Company building. From 1956 to 1971 the laboratory facilities were located in the Great Northern Railroad depot building in Helena. The foundation was initially funded by Holter and other members of his family, but in 1952 Holter began to receive grants from the National Institutes of Health (NIH).

Holter continued his collaboration with Dr. Gengerelli of UCLA in attempting to transmit information, primarily brain waves, by radio. Holter turned his attention from the brain to the heart because the heart's greater voltage made the electronics easier, and because heart disease was far more prevalent than cerebral disease. Holter's introduction to Dr. Paul Dudley White (1886-1973), a renowned physician and cardiologist, helped convince him to focus his research on recording electrical activity from the heart. Holter's goal was to radio broadcast and record the more obvious electrophysiological phenomena occurring in humans while carrying on their normal activities, rather than having to lie quietly on a couch.

The first broadcast of a radioelectrocardiogram (RECG) took place circa 1947 and required eighty to eighty-five pounds of equipment, which Holter worn on his back while riding a stationary bicycle. This was not practical and in no way could be worn by a patient. The initial transmitter and receiver required that the subject remain in the general area of the laboratory, so a portable and lighter RECG receiver-recorder had to be developed.

Next, Holter created a briefcase-like device that could be carried by a patient. By using very thin magnetic recording tape, twenty-four hours of RECG could be captured on a reel five inches in diameter. The initial method of examining the voluminous records from the tape recordings developed by Holter was called Audio-Visual Superimposed ECG Presentation (AVSEP). AVSEP made it possible to examine twenty-four hours of RECGs in twenty minutes, with signals being presented visually on an oscilloscope and audibly through a speaker.

With the development of transistors, radioelectrocardiography was made obsolete, and it became possible for the amplifier, tape recorder, temperature-control circuits, motor speed control circuits, and batteries to be placed in a single unit small enough for a coat pocket or purse. In 1952, Holter succeeded in creating a small unit that weighed 1 kilogram. Wilford R. Glassock, a senior engineer working with Holter, traveled to Cedars of Lebanon Hospital (now Cedars-Sinai Hospital of Los Angeles) in 1962 to demonstrate the Holter monitor system and discuss making it more practical. At Cedars, Dr. Eliot Corday observed the practicality of the system and not only embraced the technology, but collaborated with Holter's team and was an early promoter of the technology to both industry and physicians. Holter and Glassock were issued US Patent 3,215,136 on November 2, 1965 for the Electrocardiographic Means.

As articles describing the foundation's invention of these devices began to appear in the professional literature, there was considerable demand from doctors and hospitals for the equipment. Dr. Corday introduced Holter to Bruce Del Mar, founder of the Del Mar Avionics Corporation in Irvine, California. Del Mar engineers developed the "electrocardiocorder" for clinical use, producing a commercially viable monitor which came to be known as the Holter Monitor Test. Further refinements led to the creation of a "minimonitor" in 1968, which was described by Holter as being the "size of a cigarette package." Commercial production of the Holter minimonitor, AVSEP, Jr., began in 1969. The Holter Research Foundation ultimately sold exclusive rights to their patents to Del Mar Engineering Laboratories.

Later known as Del Mar Avionics, a team of engineers diverted their attention from successful manufacturing of military weapons training devices to focus on improving the speed and accuracy of computerized ECG analysis and they became the acknowledged leader in Holter monitoring technology for over 40 years. In 1969, because of the increased amount of required paper work and red tape, Holter canceled the grant funding his foundation had been receiving from NIH. He was also in constant conflict with the Internal Revenue Service over the foundation's non-profit status, rights to patents, and commercial production of equipment. The foundation continued to maintain a laboratory and conduct varied scientific work, but on a much smaller scale. The Holter Research Foundation, Inc. was dissolved in 1985, two years after Holter's death.

Del Mar Avionics was founded on January 9, 1952, as Del Mar Engineering Laboratories in Los Angeles, California by Bruce Del Mar, who led the development of aircraft cabin pressurization systems. Del Mar was born in Pasadena, California in 1913. An engineer, inventor, entrepreneur and businessman, Del Mar graduated from the University of California, Berkeley (1937) with a Bachelor of Science degree. Del Mar worked for Douglas Aircraft (1933-1951) as a research engineer on many projects before founding Del Mar Engineering Laboratories. In 1938, Del Mar married Mary Van Ness. The couple had two daughters, Patrica Jean Parsons and Marna Belle Schnabel.

In 1958, Del Mar formed a wholly-owned subsidiary, Electromation Inc., which manufactured tape recording and communication equipment. He later established, Aeroplastics Corporation to manufacture plastic products and Avionics Research Products Corporation to develop and produce biomedical instrumentation. By the mid-1960s, the company had become a leading U.S. Defense Department prime contractor in the development and production of aerial tow target systems for weapons training and instrumented ground targets for scoring air-to-ground automatic weapons delivery. It also produced helicopter target drones and helicopter flight trainers for the U.S. Army.

In 1961, the company entered the growing medical instrumentation market with the development of the first long-term ambulatory monitoring systems.

In 1965, the company introduced the Hydra Set Load Positioner that controls the precise vertical positioning of loads up to 300 tons (272,000 kg) in increments as small as 0.001 inch (0.025mm). This unique product, mounted between the load and the crane (or hoist), permits precise mating and de-mating of critical components, thus eliminating unforeseen damage to valuable loads. Hydra Set Load Positioners are in use worldwide in the aerospace, military/commercial aviation, nuclear and fossil fuel power generating industries and in various industrial applications. In 1975, the company, then re-named Del Mar Avionics, moved to its current location in Irvine, California.

Related Materials

Project Bionics Artificial Organ Documentation Collection [videotapes], 2002 (AC0841) documents the invention and development of artificial internal organs through oral history interviews with scientists and others involved.

The James A. E. Halkett and Sigmund A. Wesolowski, M.D., Papers, 1948-1951 (AC0200) documents Halkett and Wesolowski's experiments on an early mechanical heart. Halkett and Wesolow(ski) materials show the process of technological innovation through laboratory protocols.

The George Edward Burch Papers, 1984-1986 (AC0316) documents Burch's pioneering work in clinical cardiology and research through technical notes, diagrams, and correspondence regarding laboratory work on the "2-pump heart model," 1984-1986.

Wilson Greatbatch Innovative Lives Presentation, 1996 (AC0601) documents the invention of the implantable cardiac pacemaker in 1958.

The Ronald J. Leonard Papers, circa 1980-1997 (AC1109) documents Leonard's development of pumps and oxygenators used in cardio-pulmonary bypass surgery.

The Division of Medicine and Science (now Division of Medicine and Science) holds two monitors: the Dynamic and the Del Mar Avionics ElectroCardioCorder (Model 445), 1977 and the ElectroCardioScanner (Model 660), 1971. Both were developed by Del Mar's Medical Device Manufacturing staff. See accession #: 2011.0196.

Holter Family papers, 1861-1968

Includes documentation about the Holter Research Foundation, Inc.

Holter Research Foundation, Inc. records, 1914-1985

The Holter Research Foundation, Inc. was a private, non-profit, scientific research foundation started in Helena, Montana, in 1947 by Norman J. "Jeff" Holter. Records (1914-1985) include correspondence, financial records, laboratory records, subject files, photographs, etc. Also included are subgroups for N.J. Holter; his work in the U.S. Navy on bombs and waves; his work as assistant chancellor at University of California, San Diego; and the Society of Nuclear Medicine.