Machines in Our Hearts: The Cardiac Pacemaker, the Implantable Defibrillator, and American Health Care (review)

Kirk Jeffrey, professor of history at Carleton College, may have obtained his Ph.D. from Stanford with a thesis on middle-class family life in three American cities in the early 19th century, but one suspects he must also have taken an M.D., although his curriculum vitae denies this. Dr. Jeffrey—the appellation fully applies to him despite the reticence of many Ph.D.'s in the humanities to use the title—knows more about cardiac arrhythmias and their treatment than many physicians. His technique in researching and writing Machines in Our Hearts may be historical, but his knowledge includes medical as well as electronic and business expertise.

Cardiac arrhythmias are the bumps in the night, those unsettling sensations in the chest that healthy people notice when their minds are not otherwise occupied. Although usually of no clinical significance, arrhythmias can cause trouble particularly when the heart rate is dangerously slow or rapid, producing symptoms of significant distress or even death. Effective treatment of these conditions, like that of so many illnesses, is an accomplishment of the second half of the 20th century, and it is this extraordinary story of clinical success that Jeffrey tells in this fine book.

Although the heart is fundamentally an organ that pumps blood through the body, its action is coordinated by a complex electrophysiological system that can malfunction and produce abnormal heart rhythms, either slow (bradyarrhythmias) or rapid (tachyarrhythmias). Bradyarrhythmias are often caused by disruption of the normal sequence of cardiac activation whereby the heart rate, established in the sinus node, a collection of specialized cells in the right atrium, cannot pass through to the ventricles where the principal pumping action of the heart is performed. This condition is known as heart, or atrioventricular, block, and in its most severe form it can prevent the heart from beating faster than about 35 beats per minute.When the heart affected by heart block beats even slower, the patient may faint or die. The treatment for this condition, as many non-physicians know, is a pacemaker, a device that replaces the function of the sinus node and restores a normal heart rate responsive to the demands of the body's activity. In most cases, once one has a pacemaker for this condition, survival returns to its predicted length before the development of the block. Before pacemakers, about half of patients with heart block died within a year after diagnosis.

Although pacemakers had been studied previously, it was in the 1950s that their application to patients was first demonstrated. As knowledge and experience grew, the capabilities and versatility of pacemakers increased as their size and weight decreased. Today, the typical patient quickly becomes unaware of its presence as the device performs its vital functions. Reaching the excellence of today's units, however, took years, money, and the efforts of many talented people with medical, electronic, and business skills. Jeffrey describes this process comprehensively and clearly. Since he explains most of the medical and electronic terms he uses, the book can be understood by readers without specialized knowledge. Doctors, scientists, businessmen, and the general reader with an interest in medical developments will find the stories intriguing to read and rewarding to study.

Although Jeffrey emphasizes the pacemaker story—nine of the 11 chapters feature this subject—he also explains the development and function of implantable cardioverter-defibrillators in his clearly written Chapter 10. These are lifesaving devices for patients who develop dangerous tachyarrhythmias. Many of the current models of cardioverter-defibrillators also include pacing functions, so they can treat the effects of slow arrhythmias as well.

Jeffrey reviews the extraordinary life and career of Dr. Michel Mirowski (1924-1990), who was principally responsible for the implantable defibrillator. Born in Warsaw, Mirowski escaped the Holocaust by...