Introduction and History of Cardiac AnesthesiaChapter 1

From what we gather, it appears that the early history of anesthesia for operations on the heart is that of anesthesia itself starting from the late 1840s.

Some ingenious approaches were explored, such as placing the patient's head in a positive pressure box [Brauer (1904)) and Murphy (1905)] or operating within a negative pressure chamber with only the patient's head outside [Sauerbruch (1904)]; for a while, even into the 1940s, positive pressure ventilation via a tight-fitting mask was used.

It was during this era, when even antibiotics were not available to combat infection that the early cardiothoracic surgeries was performed in 1888, the American surgeon designed metal endotracheal tubes with a conical tip to occlude the larynx and added a bellows device to provide positive ventilation. This was first used and advocated as the best means of preventing pulmonary collapse during thoracic surgery by the surgeon Rudolph Matas in about 1899.5

The anesthetic agents in use were mostly ether, chloroform and nitrous oxide when cyclopropane was introduced as the new agent to clinical anesthesia by Ralph Waters in 1933 and was adopted by many cardiac anesthesiologists as an induction if not a maintenance agent. Its major drawback was its inflammability, which led to its ready replacement when halothane became available in the late 1950s. In 1952, Lucien Morris invented the copper kettle, which permitted more precise quantification of anesthetic dosing. Later, in this decade the temperature-compensated agent specific vaporizers (TEC) were introduced by Cyprane Limited of England.

In 1934, John Lundy of Mayo Clinic introduced thiopental into the practice of anesthesia and for many years it was used for both maintenance and induction. Muscle relaxants in the form of curare were first used in 1942 by Griffith and Johnson of Montreal and later in 1947 by Stephens to facilitate thoracic surgery.

Although mechanical ventilators were developed as early as 1907 (the Draeger Pulmotor),and Crafoord introduced his commercially available Spiropulsator in 1940 and Blease the “pulmoflator” after world war II, the use of ventilators in the operating room was not readily accepted until the late 1950s. ”Modern” ICU–type ventilators (e.g. Bennett, Bird) did not appear until the 1960s.

Postoperative recovery rooms were established around world war II and although an American Study Commission report published in 1947 suggested that they could improve outcome, they did not become common until the mid-1950s. Open heart surgeries gave way to the development of surgical intensive care units in the early 1960s.

In, 1994, Dobel outlined the anesthetic management of the patient in whom Dr Gross first ligated a PDA in 1938. Anesthesia was provided by a nurse anesthetist (Betty Lank), who used a tight-fitting adult mask that was shrunk (with alcohol) and strapped to the child's face. Monitoring included a finger on the superficial temporal pulse. The anesthetic agent used was cyclopropane. Blood was available but was not needed for Crafoord's first coarctation repairs, accomplished in 1944.6 Anesthesia consisted of a mixture of cyclopropane and nitrous oxide administered via an airtight endotracheal tube using controlled ventilation provided by a spiropulsator.

Between 1946 and 1950, the first papers on cardiac anesthesia appeared. These put forth the challenges of providing anesthesia for severely cyanotic and debilitated children undergoing systemic-to-pulmonary artery shunt operations.

The common method of anesthetic management included heavy premedication with morphine and scopolamine, induction with cyclopropane (with or without ether), endotracheal intubation although some tried mask—only ventilation. Most used controlled ventilation (with or without use of curare). The Waters to-and-fro carbon dioxide absorbing canister closed system was usually used. The monitoring methods and fluid management were not discussed in detail except a warning against fluid overload. Usually a cannula was placed in the saphenous vein of an ankle, and plasma was administered.

Between 1952 and 1955, the first papers on providing anesthesia for mitral commissurotomies were published. Moderate premedication including phenobarbital and morphine or meperidine was usually recommended. All groups emphasized the importance of using the lightest possible anesthesia but employed different agents to accomplish this goal. Continuous ECG monitoring was employed by all, some using an oscilloscope. All started large-bore intravenous access and had blood available, including blood pumps and means of giving intra-arterial transfusions, but all emphasized the need to minimize fluid and blood administration to avoid fluid overload. All patients were extubated at the end of the case but given supplemental oxygen postoperatively. Several groups employed paravertebral or intercostal blocks for postoperative analgesia. All authors emphasized the need to move or change the patient's position slowly and gently while the patient was still under anesthesia or emerging, to avoid hemodynamic instability.

Even more challenging was the provision of anesthesia for patients of severe aortic regurgitation for insertion of ball valve prosthesis in the descending aorta. This were first performed by Dr Charles Huffnagel of Georgetown University (without the benefit of left heart or cardiopulmonary bypass) in September 1952. The anesthetic management of these patients was described by John A, O’Donnell and Thomas F McDermott in 1955. All 42 patients were in medically irreversible congestive cardiac failure and 40% had intractable angina pectoris. From their earlier experience, it was realized that these patients do not tolerate a depth of anaesthesia to permit endotracheal intubation. They therefore intubated these patients with topical anesthesia, induced very light general anesthesia with a small dose of pentothal and maintained them on nitrous oxide and oxygen supplemented with intravenous morphine or small amounts of ether. Phenylephrine was the agent used to keep the systolic arterial pressure above 100 mm Hg. Two 15-gauge intravenous needles were placed. The radial artey was surgically exposed, not for monitoring but to use if needed to withdraw blood to treat extreme hypertension during aortic crossclamping or to give intra-arterial transfusion in the case of catastrophic 7hemorhage. Blood transfusion replaced blood loss and an electric defibrillator was always available. In 1954, SJ Evelyn and I Mackay reviewed their anesthetic techniques and results with cardiac anesthesia in 820 cases operated at the Toronto General Hospital. Their hospital mortality rates were remarkable: tetralogy of Fallot (shunts; 342 patients), 6%; PDA (133 patients), 0%; coarctation (29 patients), 0%; mitral valve surgery (260 patients), 6%.

Not much is known about the anesthetic techniques used for open heart direct-vision surgeries with moderate surface-induced hypothermia. Lewis indicated that anesthesia was induced with pentothal and curare, patients were intubated, and ECG and rectal temperature were monitored. Swan indicated that anesthesia was also induced with pentothal and maintained with cyclopropane and ether, or with ether alone.

Robert W Virtue with Henry Swan in Denver elaborated on the anesthetic management in their 1955 report of their first 100 cases done under hypothermia with brief periods of circulatory arrest. Monitoring included ECG, EEG blood pressure by auscultation. Patients were cooled to less than 35°C sometimes 33°C to 31°C and deliberately hyperventilated to achieve respiratory alkalosis, which they believed reduced the incidence of ventricular fibrillation. They measured right atrial pH (at the patient's temperature) just before arrest and aimed it to be greater than 7.5 (alpha–stat management). After arrest, 100% oxygen was administered, with nitrous oxide (50%) added if required. Patients were extubated when they were breathing adequately. Common complications were ventricular fibrillation and postoperative hemorragic shock and mortality rate was high.

In 1953 Dr John Gibbon used the heart-lung machine developed by him to successfully close an ASD in an 18 year old female patient. In his dictated operative notes Dr Gibbon only mentioned that the patient was anesthetized with intravenous pentothal with an endotracheal tube and manual assistance to ventilation. Direct blood pressure readings were made via a needle inserted in the right brachial artery that was connected to a mercury manometer. The veins in both ankles were cannulated for administration of intravenous fluids. The patient was quite light at the end of the operation and was awake and talking one hour after the operation. Many other patients did not survive and according to Anthony Dobell who was a surgery resident under Dr Gross, “A major factor in the deaths of the children was poor ventilation prior to going on cardiopulmonary bypass”. There were no physician anesthesiologists at Jefferson at that time and of course mechanical ventilators had not been developed. Some of the children were already moribund by the time they were connected to the heart-lung machine. Thus at Jefferson, lack of expertise in anesthesia, pediatric cardiology and cardiac pathology all played a part in the initial failures.8

In 1954, Walton Lillehei and his colleagues at the University of Minnesota initiated a series of direct-vision intracardiac surgery with total CPB using the patient's parent as the “heart-lung machine” (controlled cross-circulation). Anesthesia in these patients was induced with nitrous oxide/cyclopropane and then maintained with pentothal and curare; anesthesia in donors was induced and maintained with pentothal and curare. During CPB, the donor was hyperventilated (two to three times normal values) to induce a respiratory alkalosis and counter balance the metabolic acidosis that regularly occurred during the low-flow (34 to 40 mL/kg/minute) perfusion of the patient. No mention of monitoring, invasive lines, nor fluid management other than blood administration was made. The duration of CPB ranged from 9 to 28 minutes. Of the first eight patients (age 5 months to 5 years) who underwent VSD closure, six survived. According to Arens, Fred van Bergen and Joe Buckley administered anesthesia to the patient while Jim Matthews and Earl Schultz cared for the father donor for the first successful case.

In 1956, the first relevant textbook,’Anesthesia for Surgery of the Heart’ was published by Kenneth K Keown of Hahnemann Medical College. The book detailed the cardiac anesthesia possible during that decade. It was the time when cardiac surgeons and cardiac anesthetists were teaming up, signifying the importance of teamwork and he lists the important teams practising at that time (Table 2).

He also summarized the expected mortality rates and emphasized the role of the anesthethesiologist in ensuring that the patient was fit for surgery, the use of checklists for equipment and supplies and the avoidance of short cuts.

Over the next four years, several groups practised varied techniques and reviewed their experiences in delivering anesthesia care for patients undergoing open heart surgery with the use of mechanical heart-lung machines.

These reports reflected major differences of opinion regarding the optimal oxygenator, flow rates, lung management, control of arterial pressure, need to add carbon dioxide, or anesthetic agents to the extracorporeal circuit during surgery and type of monitoring. The range of management varied from a detailed protocol like at the Mayo Clinic to a minimalistic approach like at Bayor/Texas Children's Hospital in Houston.

At Mayo Clinic flows were kept at 2.4 L/minute/m² (60 to 200 mL/kg/minute) and ether was administered via a vaporizer on the oxygenator. Intra-arterial pressure, venous pressure, rectal temperature, EEG, ECG, in-line venous saturation, and arterial blood gases were monitored.Fluid and blood balance was meticulously monitored and written, detailed protocol for step-by-step management was published. Vasopressor drugs and resuscitation drugs were prepared and made ready.

At the other extreme was the practice at Houston (Cooley and Keats). They monitored only one lead of the ECG (and not invasive arterial pressure, venouspressure, EEG, or temperature), ran flows of 35 to 50 mL/kg/minute (adults and infants, respectively), and administered only d-tubocurarine during CPB.

Halothane, though introduced into anesthesia in 1957 was hesitantly used for cardiac surgery because of concern about its myocardial and respiratory effects. However, the desire for a potent, nonexplosive agent led the groups at Mayo Clinic and Indiana University to explore the use of low concentrations (less than 0.8% to 1.0%) in 50% nitrous oxide for adults and children open and closed cardiac surgery. From then halothane remained the favored agent until the landmark article by Edward Lowenstein et al. at the Massachusetts General Hospital in 1969.

High dose morphine (0.5 to 3 mg/kg) was used by Lowenstein and his team as the main anesthetic in 1100 patients because it was devoid of myocardial depression and was considered as the agent of choice in patients with minimal cardiac reserve (e.g. end-stage valvular and coronary artery disease).This approach rapidly became popular and the combination of high-dose narcotics with oxygen and muscle relaxants came to be known as the “cardiac anesthetic”. Thereafter for the next 10 years, morphine was the main narcotic until it was replaced by the synthetic narcotics, fentanyl initially in doses of 50 to 100 µg/kg as popularized in the United States by Theodore H Stanley of the University of Utah. The side effects of morphine like vasodilation and the need for volume expansion were overcome with the use of fentanyl.10

Both authors emphasized the desirability of generous premedication, adequate depth of anesthesia, invasive monitoring of arterial and central venous pressure, frequent measurements of arterial blood gases and serum potassium, postoperative endotracheal ventilation with adequate analgesia and sedation for 4 to 24 hours and close cardiovascular surveillance in the intensive care unit. Wynands emphasized the importance of maintaining arterial pressures close to baseline and keeping the hematocrit at about 40 percent. Viljoen advocated intermittent administration of nitroglycerine intramuscularly, and in 1976 Joel Kaplan, then at Emory University, introduced the use of nitroglycerine infusions during coronary artery disease.

Recognizing the importance of integrating cardiology into the practice of anesthesiology, a symposium on this topic, edited by Arthur Keats, was published in the August 1970 issue of Anesthesiology.

Allen Ream et al. from Stanford published an article in 1982, which led to a rethinking of the proper management of pCo₂ and pH during hypothermic CPB and a near-complete shift from pH-stat to alpha-stat management during that decade.

A year later, the paper by Sebastian Reiz of Umea, Sweden, raised concern about the risk of coronary steal with isoflurane and led to a flurry of experimental and clinical studies on this topic.

Two years later another influential study by Stephen Slogoff and Arthur Keats of the Texas Heart Institute in Houston documented the frequency of intraoperative myocardial ischemia during coronary artery surgery and showed that it was associated with postoperative myocardial infarction. They also showed that an anesthesiologist can have an impact on the incidence of this problem. This paper helped initiate the intense study for the prevention of perioperative ischemia, that continues to the present day.

In 1986, another study by Nancy Nussmeier and Slogoff demonstrated that use of high-dose (40 mg/kg) thiopental (to produce isoelectric EEG) reduced the rate of postoperative neuropsychiatric dysfunction after open ventricle operations. The general application of this was challenged and generated much interest in the incidence, cause, and prevention of perioperative neurological dysfunction.

In 1989, two similar papers were published. One from Slogoff and Keats at the Texas Heart Institute and the other from Kenneth Tuman and colleagues at Rush-Prebyterian-St Luke's Medical Center in Chicago, documenting in large prospective studies (more than 1,000 patients each) what cardiac anesthesiologists had been saying since 1946: that the choice of anesthetic agents does not significantly affect outcome.11

Until the mid-1950s, monitoring was rarely mentioned. The anesthesiologists heavily depended on their five senses, awareness, and clinical acumen.

Soon paper recorders were replaced by oscilloscopic monitors which facilitated continuous ECG monitoring. A major advance in ECG monitoring occurred in 1976, when Joel Kaplan advocated the use of the V5 lead to detect myocardial ischemia in patients with coronary artery disease.

In 1954, Dr Code Smith at Toronto Hospital for Sick Children introduced thesimple but effective esophageal stethoscope, which was particularly useful in thoracic surgery.

Sphygmomanometer could no longer provide reliable arterial pressure monitoring when CPB began to be used in cardiac surgery in the mid-1950s. invasive arterial lines were introduced not only to monitor pressure but also to measure arterial blood gases. Initially these were often placed in the radial artery by cutdown by the surgeons, and it was not until the late 1960s that anesthesiologists began to place these lines percutaneously.

Blood gas analysis was a difficult and time consuming process and was infrequently performed until the late 1950s, when Clark, SEveringhaus, and Astrup introduced their pO₂, PCO₂, and pH electrodes. Even then, it took a few years until blood gas analysis was common place.

A common concern after bypass was the estimation of blood volume status and evaluation of ventricular function. Venous pressure monitoring was introduced, initially from catheters placed in arm veins and external jugular veins and then from central lines placed via the groin or arm veins or placed directly into the right atrium at the time of surgery.

However, as early as 1963, the Mayo Clinic group called attention to the frequent discrepancies between central venous (right atrial) and left atrial pressure and described placing catheters directly into the left atrium to monitor function and filling of the left side of the heart. Subsequently, many authors advocated monitoring of left atrial pressure in this manner.

There was a revolutionary change in monitoring in 1970 when the balloon- tipped PAC was introduced by Swan, Ganz, and colleagues. The cardiac surgery/anesthesia team at Massachusetts General Hospital was among the first to advocate use of the PAC in cardiac surgery. Soon, percutaneous introduction of PAC was made available and rapidly became the approach of choice for most anesthesiologists.

Joel Kaplan helped to popularize the use of the PAC during cardiac surgery and emphasized its role in the early diagnosis of myocardial ischemia (although the latter is now largely discounted).12

Not only did the PAC allow estimation of the left atrial pressure, but it also provided access to mixed venous blood for oxygen analysis. In 1972, the PAC was modified to permit the easy monitoring of cardiac output by thermodilution.

Although cardiac anesthesiologists were among the first and strongest proponents of the use of the PAC, they were also among the first to point out its limitations and to indicate that not all cardiac surgical patients require a PAC.

From the very beginning in 1955, the Mayo Clinic group used EEG monitoring during CPB and advocated its value as a monitor of anesthetic depth as well as integrity of cerebral perfusion.

Transesophageal Doppler was first described in 1971 and transesophageal M-mode in 1976. In 1980, Masayuki Matsumoto, Yasu Oka, and others at Albert Einstein College of Medicine in the Bronx perceived the future of TEE in cardiac anesthesia when they described the use of M-mode TEE for continuous monitoring of left ventricular function in 21 patients during cardiac surgery. However, M-mode TEE was difficult to apply except by the extremely sophisticated clinician.

Between 1977 and 1980, primitive two-dimentional TEE scanners were described but it was not until Souquet, Schluter, and Hanrath introduced their phased array transducer system mounted on the end of a gastroscope that TEE became a practical reality.

Prototypes were used jointly by cardiology fellow P Kremer and anesthesiologists Micheal Cahalan and Micheal Roizen at University of California in San Francisco (UCSF). In the 1982 meeting of the American Society of Anesthesiology, they created the TEE “revolution” when they presented their results in monitoring cardiac and vascular surgery patients with this new TEE probe. They described its usefulness in assessing filling and function of the left ventricle, myocardial ischemia, and intracardiac air.

RF Cucchiara and colleagues at the Mayo Clinic described its usefulness in detecting air embolism during neurosurgery while the UCSF group described its superiority over ECG in detecting myocardial ischemia.

In 1987 Cahalan et al. and Clement and deBruijn at Duke University wrote review articles on the use of TEE in anesthesiology.

In 1986, Hewlett-Packard introduced color flow Doppler with TEE, and Norbert deBruijn and collegues at Duke University reviewed their early experience with this new technology. In the same year pulsed wave Doppler was added to TEE, and in 1989, biplane probes first became available.

The Society of Cardiovascular Anesthesiologists in conjunction with the American Society of Anesthesiologists have developed the practice guidelines 13for perioperative TEE in 1996. In collaboration with the American Society of Echocardiography they helped initiate the first examination in perioperative TEE, which was administered by the National Board of Echocardiography in 1998. Today TEE is one of the defining characteristics of a cardiac anesthesiologist.

In the beginning, these aspects consisted of intimate knowledge of the pathophysiology of congenital heart disease and how various anesthetic techniques interact with this pathophysiology. Later was added the pathophysiology of valvular heart disease, and finally that of coronary artery disease.

Next was required knowledge of the entirely new techniques that surgeons used to manage these patients: initially hypothermia, then CPB and all of its nuances including deep hypothermic circulatory arrest, coronary perfusion, cardioplegia, and retrograde cerebral perfusion.

In recent years, this has included minimally invasive techniques such as port access system. Advanced monitoring techniques, not usually used in noncardiac anesthesia at the time they were introduced were on the list of new skills required of the cardiac anesthesiologist. These included ECG, EEG, arterial lines, and central venous and left atrial pressure monitoring; next the PAC; and most recently, TEE. Intimate knowledge of blood coagulation and anticoagulation and the administration of blood products (often in large quantities) and of various drugs to modify coagulation was required.

Finally, a thorough understanding of the pathophysiology of abnormal hemodynamic states and manipulation with potent and often novel hemodynamic active agents and mechanical assist devices was required.

Cardiac anesthesiologists have been responsive by developing techniques that facilitate new procedures in cardiac surgery, such as minimal access surgery, transmyocardial laser, the Batista operation, valve repair and use of stentless valves, more aggressive neonatal surgery, and fast-tracking.