Explosion Of Knowledge
Researchers in the eighteenth and nineteenth centuries developed effective treatment for some types of heart disease and greatly expanded their diagnostic knowledge. One important finding was the discovery that the purple foxglove plant contained a substance that was an effective medicine for some types of heart disease.
In 1775, William Withering (1741-1799), a British physician and botanist, was called to evaluate a folk remedy for dropsy, a serious condition involving an accumulation of fluid in the body that can affect the heart, the liver, and other organs. The remedy had 20 or more herbs, and Withering determined that foxglove was the active ingredient. Using his poor patients to test the remedy, Withering found the drug to be helpful in dropsy and in heart disease.
Contemporary physicians use foxglove, now called digitalis, to boost the strength of heart contractions and to lower the heart rate. It is often used in cases of congestive heart failure but can be used for other types of heart disease as well. Withering realized the potential danger in using too much foxglove and warned in 1785 that too much of the medicine could cause illness and death. Nevertheless, the medicine was used in excessive quantities by his contemporaries, leading to the death of patients and the eventual shunning of the medication. By the end of the eighteenth century, foxglove was no longer used widely for heart disease. The medication was reintroduced at the end of the nineteenth century, when its therapeutic properties were reassessed.
Other eighteenth century findings found more immediate acceptance, such as the discovery by Austrian Joseph Leopold Auenbrugger (1722-1809) that one could detect heart disease by tapping the chest in different places. A skilled examiner can use this technique (called percussion) to detect areas in the heart or lungs which have too much fluid.
Another advance which changed medicine was the invention of the stethoscope by René-Théophile-Hyacinthe Laënnec (1781-1826). Earlier physicians, such as Harvey, described the sounds of the heart. In 1816, Laënnec realized he could amplify those sounds. He first created a paper cylinder and then began using a wooden instrument. Laënnec used the stethoscope to expand knowledge about the heart, diagnosing narrowed valves and heart murmurs. The stethoscope enabled physicians to diagnose heart disease earlier in its course. The device also showed physicians that heart disease was not invariably fatal.
During the first half of the nineteenth century, physicians learned to distinguish between different types of heart murmur and the different types of valve damage they suggested. British physician James Hope conducted extensive experiments in which he used the poison curare to conduct surgery to examine the heart and other organs in animals. This experimentation led Hope to draw and describe, in 1839, two widely seen problems of the mitral valve, which is located between the left atrium and the left ventricle. Mitral valve incompetence occurs when the valve does not fit tightly, while mitral valve stenosis takes place when the valves do not open properly.
Another important finding about the heart was made in 1838, when Italian physicist Carlo Matteucci discovered that the heart muscle generates electricity. This electrical force enables the healthy heart to beat steadily and regulate its own activity. This finding cleared the way for electronic measurement of the heart, a technological advance which remains central to contemporary diagnosis of heart problems. The electrocardiogram was developed by William Einthoven (1860-1927), a German professor of physiology. Einthoven's electrocardiogram, which he first described in 1903, documented contraction and relaxation of different parts of the heart.
The death from heart disease of a young woman in labor motivated physician James Mackenzie (1835-1925) to begin an exhaustive study of heart disease early in his career. Mackenzie monitored the hearts of pregnant women and others using a polygraph he developed to detect and document the pulse in the neck. Through careful observation of patients over many years, Mackenzie realized that patients with certain types of irregular, extra heart beats were normal and could live normal lives. This contradicted contemporary wisdom, which advised the confinement of children and adults with abnormal heart beats. Mackenzie's 1908 textbook on heart disease also described auricular fibrillation (now known as atrial fibrillation), a type of irregular heart beat characterized by the ineffectual movement of the auricles, or atrial heart muscles, which can result in heart failure.