Cardiac pacing, 1960-1985: a quarter century of medical and industrial innovation.

Eugene Braunwald1 has compared the intense activity in cardiology between 1950 and 1990 to the systolic phase of the heartbeat. In the present paper, we discuss one important aspect of the broader transformation of cardiovascular medicine: the development of pacemaker technology to treat bradyarrhythmias. (Tachypacing and the implantable cardioverter-defibrillator, innovations of the 1980s, are beyond the scope of this discussion.) We are particularly interested in the sources of innovation in pacing, a field known for rapid shifts in hardware and techniques. After the first pacemaker implants (1958 and 1960), physicians guided technological change in pacing for about a decade. Beginning in the 1970s, pacemaker manufacturers supplanted physicians as the dominant influence on the technology of the field. A new invention ordinarily goes through a period of uncertainty when it is not clear which of several variants will succeed. Eventually a dominant design , a standard version of the technology “synthesized from individual technological innovations introduced independently in prior product variants,” may emerge.2 By the late 1960s, physician-innovators had created a dominant design in pacing; we call it “the reliable pacemaker.” After 1970, device manufacturing firms introduced further innovations, leading to a new dominant design that we will call “the multifunctional pacemaker.” We will use common descriptive labels to refer to specific pacing modes (noncompetitive, AV sequential, etc). At the request of the Inter-Society Commission for Heart Disease Resources, a Pacemaker Study Group (Drs S. Furman, N.P.D. Smyth, and Parsonnet) proposed a standard three-position (later five-position) pacemaker code that has now become part of the language of the field.3 4 We mention the appropriate code when first referring to a particular pacing mode. The code is summarized and the most important pacing modes are diagrammed in Figs 1⇓ and 2⇓. Figure 1. Three-position identification code for characterizing …