(Circulation. 2000;102:IV-87.)
© 2000 American Heart Association, Inc.
Special Anniversary Issue |
The Past 50 Years of Cardiovascular Surgery
From the Texas Heart Institute at St. Luke’s Episcopal Hospital, Houston, Texas.
Correspondence and reprint requests to Dr Denton A. Cooley, Texas Heart Institute, PO Box 20345, Houston, TX 77225. E-mail dcooley{at}heart.thi.tmc.edu
Key Words: heart diseases • surgery • cardiopulmonary bypass
Cardiovascular surgery has developed so rapidly that it is hard to believe that this specialty is little more than a half-century old. In fact, had it not been for World War II, the emergence of modern cardiac surgery may have been delayed further. In 1943 and 1944, Dwight Harken,1 then a captain in the medical corps, successfully removed foreign bodies from in and around the hearts of >100 soldiers who had been injured in battle. Harken’s work helped overcome the notion that the heart could not be surgically manipulated and, not only did it pave the way for the incredible progress of the last 50 years, it was a catalyst for the event that would mark the dawn of this era: the creation of the first Blalock-Taussig shunt for treating tetralogy of Fallot in 1944.2 The striking results from this procedure, which increased the circulation through the pulmonary arterial system, caused much excitement in the surgical community.
In those early days at the midpoint of the 20th century, many warned about operating on children, particularly those with cardiovascular disease, severe cyanosis, and hypoxia. There was great concern that it would not be possible to anesthetize these young patients safely and to see them through an operation. Helen Taussig believed that one should not try to operate on a child younger than 4 years with tetralogy of Fallot or a child younger than 8 years with an aortic coarctation. Many pediatricians heeded these warnings, and it was with enormous trepidation that the anesthesia staff undertook the first congenital heart operations in very young patients. (In the earliest days of heart surgery, nurse-anesthetists usually administered anesthesia.) However, this did not deter those who believed that successful cardiac surgery could be undertaken in younger patients. By 1959, those at Texas Children’s Hospital had successfully operated on 120 infants with congenital defects.3
Advent of Open Heart Surgery
Until the mid-1950s, most pediatric operations were "palliative" extracardiac procedures performed on the closed heart. The challenge was to operate inside the heart safely and to perform a definitive intracardiac repair. A number of ingenious techniques were proposed for this purpose. For instance, Elton Watkins, a medical student at Harvard, suggested a procedure to Robert Gross that became known as the Gross atrial well.4 They showed that it was possible to operate inside of the beating heart, through a rubber funnel sutured to an incision in the atrial wall, as long as the patient was heparinized. This technique, however, was rather traumatic to the surgeon’s index finger: the only way a surgeon knew when the suture was properly placed was to impale his finger with the needle. That resulted in many painful fingers.
What was definitely needed was a method for interrupting
blood flow during an intracardiac operation. Hypothermia was one of the
early methods tried, either by placing patients in a tub of ice water
or by cooling them with ice packs. Once the patient’s temperature was
lowered to 
26°F, blood flow to the heart could be interrupted
rather easily by placing a snare on the inferior and superior vena
cava. If the repair could be accomplished within 8 or 10 minutes, the
patient was spared cerebral complications. Unfortunately, this
technique had some serious drawbacks, including the possibility of air
embolism, which was one of the greatest problems encountered by the
developers of open heart techniques. In addition, the more complicated
lesions, such as atrioventricular canal and large ventricular septal
defects, could not be repaired at all. Thus, it became increasingly
obvious that more dependable methods were needed.
For over a decade, John Gibbon5 worked to design a device that would provide for the oxygenation and circulation of blood in an extracorporeal circuit. Finally, in 1953, his open heart technique with total cardiopulmonary bypass was tested in 4 patients with congenital heart disease, only one of whom survived. Although Gibbon called a personal halt to the clinical use of his technique, his efforts were a strong stimulus to other investigators.
The first truly successful open heart operations were
performed by C. Walton
Lillehei6 using a
cross-circulation technique; this method had been performed as a
physiological experiment for 50 years before the first trial in a
child. This approach worked very well. One of the parents, usually the
mother, served as the oxygenator. By cross-circulating the parent’s
arterial blood into the recipient and controlling the amount of
venous blood being returned, the surgeon had up to an hour in which to
perform an intracardiac repair. Proponents of this technique soon
determined that the patient could survive if less than full cardiac
output was used and, therefore, only moderate stress was placed on the
donor. Lillehei said that it was the only operation he knew of with a
potential 200% mortality rate, because both the donor and the
recipient could be lost. (In Lillehei’s experience, only 1 donor ever
suffered a serious complication—a stroke that probably resulted from
an air embolism.) With this approach, Lillehei and his team were able
to correct ventricular septal defects and even tetralogy of Fallot.
With the success of this method, he became convinced that open heart
surgery with temporary cardiopulmonary bypass was feasible.
Among the different types of oxygenators being investigated,
the one devised by one of Lillehei’s younger colleagues, Richard
DeWall,7A proved the
most practical
(Figure 1
). DeWall and his colleagues devised a simple
bubble diffusion system, with a helical coil for defoaming the blood by
means of a silicone antifoam substance. With this mechanical oxygenator
and a pump in the circuit, open heart surgery finally became a reality.
Many more complicated defects, such as tetralogy of Fallot, ventricular
and atrial septal defects, and other intricate lesions, became amenable
to surgical correction. Using the more complex Gibbon-type apparatus
(Figure 2), John Kirklin at the Mayo Clinic also
demonstrated that open repair of complicated defects could be
accomplished with low
risk.8 Soon
thereafter, our team at the Texas Heart Institute also adopted the
DeWall-Lillehei device, which allowed us to establish an open heart
program in 1955. We modified the DeWall device, however, by building a
vertical stainless steel model that was easier to assemble and use
(Figure 3). By the end of 1956, using this device and a
roller pump (Figures 4 and 5), we had performed >100 open heart
procedures, more than any other group in the
world,9 including the
first repair of a postinfarction ventricular septal
defect10
(Figure 6).
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One of the major problems associated with those early
procedures was the need to prime the extracorporeal system with blood.
Depending on the complexity of the system, up to 14 U of blood had to
be collected on the morning of surgery, and the blood had to be freshly
heparinized and kept at body temperature
(Figure 7). With some of the larger extracorporeal
systems, the operation could not be performed until 8 or 10 o’clock at
night because it was difficult to collect so much blood. Eventually, we
showed that blood could be stored overnight and that it could be
citrated. Nonetheless, cardiac surgeons had become slaves of the blood
bank with respect to the scheduling of open heart
operations.
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A major breakthrough came when Nazih Zudhi and colleagues11 demonstrated that priming the extracorporeal circuit with blood was not only unnecessary, but potentially hazardous. Our team next promoted and popularized the concept of hemodilution with 5% dextrose solution12 and, although we had many critics, the critics were proved wrong. In this technique, which is used almost universally today, a disposable oxygenator primed with 5% dextrose was used with normothermia. For the first time, open heart surgery became practical. It also became safer because, when 6 or 8 U of blood are mixed together in an extracorporeal circuit, patients end the procedure with more transfused blood than their original volume. Also, because each unit of blood had some basic incompatibility with the others, some patients developed homologous blood syndrome, which contributed to various postoperative complications. With the introduction of a non–blood-priming technique, these concerns became relatively unimportant.
With these simplified techniques, surgeons were quickly able to extend their use of open heart surgery and to repair almost every type of intracardiac abnormality.
Valvular Repair and Replacement
The earliest intracardiac operations had been performed
for rheumatic heart disease and mitral stenosis. Several surgeons,
including Lord
Brock,13 Charles
Bailey,14 and Dwight
Harken and
colleagues,15 had
shown that the stenotic mitral valve could be manipulated in a
technique called "finger-fracture" valvuloplasty. However, those
who performed such procedures realized that, in many instances, they
were not really accomplishing much. Even with a knife on the fingertip,
this technique was not very effective. In 1954, the treatment of mitral
valve stenosis was revolutionized with the advent of the mechanical
dilator, a relatively simple device that was designed and first used by
Charles Dubost.16
The dilator had 2 parallel blades that could be passed into the atrium
and into the valve
(Figure 8). Dilating the valve mechanically proved more
effective than pulling it open manually. Today, cardiologists are using
balloons, introduced through catheters in leg veins, for the same
purpose. The approach seems to work well as a palliative
measure.
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Heart valve repair gave rise to a whole new field of possibilities, as well as a number of ingenious devices and techniques. In 1952, Hufnagel and Harvey17 introduced a valve that they had placed in a patient’s descending aorta to treat aortic regurgitation. Unfortunately, the silicone-type ball (methacrylate) was very resonant; if the patient opened his or her mouth, the clicking of the ball could be heard across a large room. Nevertheless, this valve did partially relieve aortic regurgitation by reducing left ventricular load by about one-third to one-half.
The real breakthrough was total valve replacement, which was
introduced almost simultaneously by 2 surgeons: Dwight
Harken,18 who used a
double-caged, ball-and-seat prosthesis, and Albert
Starr,19 who used a
caged ball-and-seat valve. Both models incorporated a silastic ball
within a metal cage. With the introduction of the ball-and-seat valve,
surgeons could finally definitively treat aortic valve and mitral valve
disease. Years of trial and error, however, were necessary before
consistently durable, reliable valves would become available. Many of
the pioneers of cardiac surgery worked to develop reliable prostheses,
and they gave their names to the products that they developed: Smeloff,
Magovern, Cromie, Braunwald, DeBakey, Barnard, Beall, Cross,
Jones, Conrad, Kay, Starr, Taber, Cooley, Lillehei, Wada, Stuckey,
Pierce, Behrendt, Morrow, Williams, Bjork, Gott, Emery, and Nicoloff,
among others
(Figure 9).
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Even in cardiac surgery, techniques and procedures lose and gain fashion. For example, today’s surgeons are now using homograft valves in an increasing number of cases. In earlier years, homografts never had the popularity that their mechanical counterparts did, in part because of the problems of supply and demand and of storage and preservation. Some, however, continued to use homografts, especially Donald Ross20 and Brian Barratt-Boyes,21 who were largely responsible for their development.
Even before valve prostheses became available, Ross22 conceived the idea of implanting a patient’s own pulmonary valve as an autograft into the aortic annulus; he then replaced the pulmonary valve with a homograft or some other kind of valve. Today, there is renewed interest in the Ross procedure, and surgeons are even considering the use of mitral homografts to mimic normal function and eliminate the need for anticoagulation. Nevertheless, the natural valve should be retained whenever possible.
Coronary Revascularization
Patients with coronary artery disease comprise another group that challenged early cardiac surgeons. Originally, the only option was to modify or palliate this condition. Early operations were designed to stimulate intercoronary anastomoses by producing a granulomatous response in the pericardium and epicardium. To achieve this goal, powdered asbestos, talc, silica, or phenol was insufflated into the pericardial space. Other approaches included abrading the epicardium, ligating the internal mammary artery or coronary vein, arterializing the coronary sinus, or grafting vascular tissue into the epicardium.
A major breakthrough occurred with the advent of coronary arteriography, which allowed surgeons to visualize the coronary lesion for the first time. This breakthrough was brought about fortuitously in 1958 by Sones and Shirey,23 who were attempting to perform a left ventriculogram in a patient and inadvertently injected a contrast agent into the patient’s coronary circulation. Sones was terrified that the patient would not survive because, at that time, coronary injection was mistakenly considered dangerous. Sones subsequently designed and successfully used a specialized coronary catheter for selective coronary angiography.
Once surgeons could see where a coronary blockage was located, they could proceed with revascularization by means of a bypass graft technique. With cardiopulmonary bypass and cardioplegic arrest, surgeons were able to construct coronary bypass grafts in a quiet, bloodless field, originally by using saphenous vein grafts and later by including the internal mammary artery. The first coronary bypass was performed by Edward Garrett and colleagues24 in 1964, when they encountered difficulties while performing an endarterectomy and were forced to bypass the left anterior descending artery. Much of the pioneering work in the area of coronary bypass was done by René Favaloro and Donald Effler and colleagues,25 who were the first to report the procedure, and by Dudley Johnson and Derward Lepley and colleagues,26 beginning in late 1968. The procedure soon became the world’s most frequently performed cardiac operation.
After the introduction of percutaneous transluminal coronary angioplasty by Andreas Gruentzig and colleagues,27 the use of interventional techniques increased, and the number of surgical revascularization procedures began to decline. At the Texas Heart Institute and at most other heart centers, patients with coronary artery disease now undergo more interventional procedures than direct surgical operations. However, the pendulum may swing the other way again. The results of simple beating-heart surgery are so satisfactory that surgeons can almost offer patients the same degree of comfort, and perhaps a better life expectancy, by performing an internal mammary artery bypass in a minimally invasive procedure rather than by an interventional procedure.
Many surgeons today are reverting to operating on the
beating heart. Because coronary artery bypass grafting is done on the
surface of the heart, cardiopulmonary bypass is not absolutely
essential. Moreover, the extracorporeal circuit (particularly the
oxygenators and suction devices) can induce a whole-body inflammatory
response and other postoperative complications, which are eliminated by
beating-heart surgery. One of the most difficult problems in developing
this technique has been in finding methods to stabilize the arteries
during grafting. New devices are being developed, however, to make such
procedures safer and more reliable
(Figure 10).
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Despite the success of conventional myocardial revascularization techniques, some patients are not suitable candidates for these therapies, so researchers have continued to look for new options. Surgeons have begun to use lasers to perform a procedure called transmyocardial laser revascularization. The laser creates new channels through which oxygenated blood can enter the myocardium from the intracavitary region.28 Controversy exists, however, regarding the mechanism of transmyocardial laser revascularization and the likelihood of the channels’ remaining patent. Whatever its mechanism, this technique may stimulate angiogenesis, thereby revascularizing the ischemic myocardium. Thus far, it remains unclear whether the promising results are related to subjective factors or to actual myocardial revascularization.
Aneurysm Repair
Aneurysm surgery has evolved in a fashion similar to coronary surgery, in that various indirect methods were used for some years until excision was undertaken and, later, repair became standard. In 1951, at the annual meeting of the Southern Surgical Society, Cooley and DeBakey became the first to recommend direct surgical removal of aortic aneurysms. Synthetic vascular grafts were not yet available, so the early operations were performed mainly on sacciform aneurysms, many of which of were luetic in origin. After fabric vascular grafts became available in the late 1950s, the goal became to restore circulation without excision of the lesion.
Cardiac Support and Replacement
Probably the most exciting event in heart surgery occurred in 1967, when a South African surgeon named Christiaan Barnard29 performed the first human heart transplant. The operation was only temporarily successful, but it was an important historic event. Although Barnard was roundly criticized at the time by ethicists and religious groups, both of whom opposed the very concept of heart transplantation, many surgeons around the world were searching for the means to perform a heart transplant. It was Barnard, however, who defined for the rest of the world the concept of brain death and who deserves credit for making heart transplantation a reality.
Soon after Barnard’s transplant, the Texas Heart Institute became actively involved in cardiac transplantation. Within a year, surgeons here had performed 20 transplant operations, which put the Institute in the forefront of cardiac transplantation in the world.30 Unfortunately, none of those 20 patients lived more than 18 months: they all succumbed to rejection and infection. We, and others, became discouraged, and a moratorium was called on any further cardiac transplant procedures. In 1980, however, Barry Kahan31 introduced the new immunosuppressant cyclosporine, which he used to prevent rejection in renal transplant patients. With his permission and encouragement, we began using cyclosporine to prevent rejection in heart transplant patients. The introduction of cyclosporine gave surgeons the tool they needed to re-enter the field of cardiac transplantation. Shumway and colleagues32 maintained a determined interest in the field of cardiac transplantation during the precyclosporine era, and they demonstrated the logistics of organ procurement.
During this time, investigators were developing a mechanical
means of supporting the failing heart. One possibility, a total
artificial heart, was being developed by Domingo Liotta in our
laboratory. In 1969,
we33 used this heart
in the first bridge-to-transplant operation
(Figure 11) for a patient who could not be weaned from
cardiopulmonary bypass after an extensive ventricular reduction
procedure (what would be called the
Batista34 procedure
today). Three days after the artificial heart was implanted (the first
implantation of its kind in the world), a donor was found, and a heart
transplant operation was performed. Today, the bridge-to-transplant
operation has become a routine procedure, with a variety of circulatory
support devices available for use as a bridge.
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The left ventricular assist device is most commonly used
today as a bridge to transplant. In a 1980 request for a
proposal, the National Heart, Lung, and Blood Institute changed its
focus from the total artificial heart program to support development of
left ventricular assist devices. A number of devices resulted from that
development program. One such device, the HeartMate left ventricular
assist device (Thermo Cardiosystems, Woburn, MA), was the first fully
implantable device to receive approval from the US Food and Drug
Administration for implantation in humans as a bridge to transplant
(Figure 12). The HeartMate connects the left ventricle
to the ascending aorta. By unloading the left ventricle, the pump
allows the heart to rest and is proven to help in the recovery of at
least some left ventricular function in most
patients.35 Because
of the possibility of recovery and its track record for reliability,
the HeartMate device is now being tested in a controlled trial for
long-term use.
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Newer still are much smaller, continuous-flow pumps. One of
several under investigation is the Jarvik 2000, which is being
developed at the Texas Heart Institute with Robert
Jarvik.36 The device
is implanted into the apex of the left ventricle and rests in an
intracavitary position, which makes it very different from earlier left
ventricular assist devices
(Figure 13). The Jarvik 2000 shows promise as a bridge
to transplant and as long-term support for the heart; however, in the
United States, the Food and Drug Administration currently restricts its
use to a bridge. The device has been implanted in 7 patients. Two of
these patients have recently undergone transplant operations and are
doing well. In Oxford, England, the Jarvik system was implanted for
long-term support in 2 nontransplant candidates.
|
Summary
Cardiac surgery has undergone a rapid and extraordinary development during the past 50 years. Many operations that were once considered experimental are now routine, and thousands of open heart procedures are performed each year. In 1997, in the United States alone, surgeons performed 197 000 cardiovascular procedures, including 2300 heart transplant operations. These statistics are astonishing to both Dr Cooley, who began practicing >50 years ago, and Dr Frazier, who began practicing 30 years ago. Even with this increased practice, cardiac surgery remains what it has always been: a profession where art and science mix and where skill and decisiveness rule; these qualities are unlikely to change any time soon. The use of robotics for minimally invasive procedures and the minimally invasive procedures themselves can challenge even the deftest of hands and may subject the patient to added risk. Technology has certainly provided a new dimension to the practice of cardiovascular surgery; in our haste to embrace the future, however, we must not forget that we should be building on our past.
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CV surgery: aortic and vascular disease
CV surgery: coronary artery disease
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CV surgery: valvular disease
CV surgery: other