FIRST DISCOVERY OF CIRCULATION
Records survive that document the accurate per-
ception by Arabic physician Ibn al-Nafis in 1242
of the heart’s chambers and of the closed circula-
tion of the blood. The discovery did not reach
other parts of the world, however, and came to
light only in the 1920s when a medical scholar
uncovered an-Nafis’s medical writings and
drawings.Galenism defined medical knowledge and prac-
tice into the 17th century. In 1628 English physi-
cian William Harvey (1578–1657) published the
document that would become the turning point of
modern Western medicine: Exercitatio Anatomica De
Motu Cordis et Sanguinis in Animalisbus, or in En-
glish, An Anatomical Treatise on the Motion of the
Heart and Blood in Animals. Harvey deduced, cor-
rectly, that the heart pumped the same blood
repeatedly in a closed circuit through the body,
with the arteries carrying oxygenated, bright
blood from the heart and the veins returning
deoxygenated, dark blood to the heart. De Motu
Cordisestablished the basis of cardiovascular struc-
ture and function that still frames understanding
of the heart’s mechanical operation.
Breakthrough Research and Treatment Advances
The most significant breakthrough in cardiology
was the development of the CARDIOPULMONARY
BYPASSmachine, successfully used for the first time
in the 1950s and the cornerstone of cardiovascular
surgery today. Cardiopulmonary bypass makes it
possible for the cardiovascular surgeon to stop the
heart, yet maintain the body’s blood circulation
and oxygenation. Advances in surgery techniques,
technology, and pharmacology in the last decade
of the 20th century made reconstructive opera-
tions for congenital heart malformations, CORO-
NARY ARTERY BYPASS GRAFT(CABG), and even HEART
TRANSPLANTATIONroutine offerings on the slate of
treatment options. Countless people can enjoy
extended, productive lives as a result.
The limited supply of donor hearts for transplan-
tation has focused much technology research on
development of a feasible artificial replacement
heart that could be fully contained within the
chest. In 2001 cardiovascular surgeons implanted
the first of the new generation of total artificial
hearts in a handful of people suffering from end-
stage cardiovascular disease. Other researchers
looked toward assisting, rather than replacing, ail-
ing hearts, resulting in implanted VENTRICULAR ASSIST
DEVICES(VADS) that function in coordination with
the native heart. Some cardiovascular surgeons see
VADs as bridge devices to sustain cardiovascular
function while awaiting a donor heart for trans-
plantation, and others as an end-stage treatment
for people who have complete HEART FAILUREbut are
not candidates for heart transplantation because of
age or other health conditions. Now an approved
treatment option for end-stage heart failure, the
VAD can stay in place for as long as needed.
Cardiovascular surgeons continue to explore
ways to incorporate microsurgery techniques in
operations such as CABG, looking to reduce the
trauma of entering the chest cavity to fully expose
the heart. Minimally invasive endoscopic proce-
dures already permit operations on arteries and
veins, as well as for CABG when only one coro-
nary artery needs replacement. Cardiovascular
surgeons also are beginning to apply minimally
invasive techniques for valve repair and other
operations on the heart.
Breakthroughs in genetics show great promise
for both treatment and prevention of cardiovascu-
lar conditions in the decades ahead. Researchers
have identified numerous genes responsible for
heart conditions such as LONG QT SYNDROME(LQTS),
certain forms of CARDIOMYOPATHY, ATHEROSCLEROSIS,
and some forms of heart failure. Many of these
genes interact with environmental factors such as
diet and level of physical activity, contributing to
rather than outright causing heart disease.
Researchers are exploring ways to use GENE THER-
APYto inactivate destructive genetic influences and
enhance genetic influences that support or
improve cardiovascular function. These influences
likely explain why some people get cardiovascular
diseases and others do not even when their
lifestyles are similar.
Researchers also continue to unravel the mys-
teries of metabolism, gaining increased under-
standing of how exercise and nutrition affect cell
function and how processes such as atherosclero-The Cardiovascular System 7