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SSC – Perspectives On Medical Advances Matthew Iain Stewart [090001931] The Evolution of Surgery in the Treatment of Fallot’s Tetralogy Introduction “Any surgeon who would attempt an operation of the heart should lose the respect of his colleagues” T. H. Billroth 18931 Nowadays cardiac surgery is seen as a viable option to preserve and prolong life. However in 1893 this view was not shared by many and rightly so. As at that time, any “attempt” to operate on the heart would unquestionably result in the death of a patient. An emphatic contradiction of the moral conduct to “never do harm ”, as advocated within the original Hippocratic Oath.2 The heart remained surgical taboo for a further fifty years, so what transpired over the past seventy years to turn cardiac surgery from controversial killer to the worldwide savior it is today? The potential of surgery and its advances were unleashed by not only the confirmation of germ theory but also its acceptance, the establishment of a blood transfusion service and the discovery of antibiotics and anaethesia in the nineteenth century. This essay aims to explore three of the four epochs in the development of cardiac surgery – surgery on the heart’s major vessels, closed-heart surgery and open-heart surgery – by highlighting the progression in the treatment of a common type of heart defect in children called Fallot’s tetralogy. The Four Epochs It is useful to appreciate the anatomy of the heart and its role within the circulatory system of the body as it is linked with how the development of cardiac surgery was divided into its four epochs. The heart is composed of two sets of chambers, the left atrium and ventricle aligned with the right atrium and ventricle. The atria are located superiorly to the ventricles. The left side is split from the right side by a thick wall of muscle called the septum. The basic function of the heart is to pump oxygenated blood around the body. The right side of the heart pumps venous blood (de-oxygenated blood) to the lungs to become oxygenated and the left side pumps arterial blood (oxygenated blood) to the body to be used in various reactions. Venous blood from the superior and inferior parts of the body drains into the right atrium (RA) of the heart via the superior and inferior vena cavae, respectively. From here the blood is pumped through the tricuspid valve into the right ventricle (RV), it is then propelled through the pulmonary valve into the pulmonary artery which divides and enters each lung. In the lungs the blood is oxygenated and the carbon dioxide removed and returned back to the heart through the pulmonary veins into the left atrium (LA). The oxygenated blood is driven through the mitral valve into the left ventricle where it is expelled through the aortic valve into the aorta to be transported around the body. Anatomy of the Heart & Blood Circulation – the internal and external structures of the heart and the flow of blood within the heart (Diagram from reference 3) Interventricular Septum Applying these anatomical principles, the evolution of cardiac surgery over the past seventy years can be separated into four pivotal periods. During the first, between the 1930’s and early 1940’s, the heart itself largely remained untouched, however the large vessels rising from it were operated on to provide palliative care caused by defects within the heart. The start of the second epoch coincided with the conclusion of the Second World War in 1945 and ended in the 1950’s, as the force majeure of war impelled the medical world to deliver advancements in blood transfusion, antibiotics and antiseptics, which provided key components for closed-heart surgery. The third epoch falls between the early 1950’s and early 1960’s, and includes the pivotal event that allows the transmission from closed-heart surgery to openheart surgery, in the arrival of the pump. The fourth and final epoch of cardiac surgery began in the late 1960’s with the first heart transplantation. Fallot’s Tetralogy Before analyzing the surgical techniques in the treatment of Fallot’s tetralogy, it is important to address what defects are being corrected. This congenital defect gains its namesake from the French physician Etienne Louis Fallot who in 1888 described the following four irregularities.4 1. Right ventricular outflow obstruction, where the pulmonary artery and valve is narrowed, 2. Overriding aorta, where the aorta is shifted over the right ventricle and ventricular septal defect instead of only the left ventricle, 3. Ventricular septal defect, a hole between the right and left ventricle, 4. Right ventricular hypertrophy, an enlargement of the muscular wall of the right ventricle.5 These lead to a shunting of non-oxygenated blood through the hole in the ventricular septum, resulting in the blood by-passing the lungs and preventing oxygenation. The ultimate consequence is that the patient is centrally cyanosed and described as having blue baby syndrome. Right ventricular outflow obstruction and the ventricular septal defect are of particular clinical relevance as these abnormalities are amenable to surgical correction.6 The First Epoch – Blalock/Taussig Operation Helen Brooke Taussig was born in Cambridge, Massachusetts, in 1898. Although a bright and promising student she was unrighteously rejected from Harvard, her first choice medical school, as doors were still closed to women at the time. She was accepted into the more liberal Boston University School of Medicine, however she transferred to John Hopkins, acquiring her medical degree in 1927. After completing a pediatric internship she was hired as the director of a newly established cardiac clinic at her alma mater’s hospital. She approached each case with a functional attitude, analyzing each pathological abnormality on the principle of the changes in blood flow that ensues and the clinical picture it triggers.7 Taussig noted that in children with a veno-arterial intracardiac shunt, cyanosis was dependent on the pulmonary blood flow, which can be measured using fluoroscopy8 (a technique for viewing real-time moving images9). A decreased flow leads to a more profound cyanosis.10 More important was her experiences with the ductus arteriosus, a connection between the pulmonary trunk and aorta, which in fetal life diverts blood away from the unexpanded lungs, but normally closes after birth when the lungs are viable.11 Due to the varying times it takes the ductus to close after birth, she found that patients with Fallot’s tetralogy tended to become cyanosed following the closure of the ductus. From this Taussig proposed the manufacture of an artificial ductus by connecting or ‘anastomosing’ a systemic artery, such as the aorta, to the pulmonary trunk.8 In theory non-oxygenated blood in the aorta passes through the ductus into the pulmonary trunk and back into the lungs to become oxygenated.6 Taussig initially attempted to persuade Robert Gross to join her, however her endeavors were unsuccessful and she recruited her new surgical colleague Alfred Blalock. On the 29th of November 1944 Blalock performed the first systemic-pulmonary anastomosis operation on a fifteen-month-old girl with Fallot’s tetralogy. William Longmire was first assistant, Merel Harmel was anaethesiologist, and Vivian Thomas and Helen Taussig were on hand to offer advice. The overall operation lasted less than an hour and a half. The child left the hospital two months later alert, active, tolerating feedings and having gained weight. However this recovery was short lived with the patient sadly dying five days after a second shunt operation six months later. During the surgery Blalock performed an end-toside anastomosis, joining the ‘end’ of left subclavian artery to the ‘side’ of the left pulmonary artery. Originally the subclavian artery was selected, as without the availability of the heart-lung machine, it was necessary to preserve blood flow through one lung while the anastomosis was being implemented. Blalock reflected on the technical difficulty of manipulating the tiny left subclavian artery. So in his next two operations he opted to switch the left subclavian artery for the brachiocephalic artery. The second operation, an end-to-side anastomosis between the brachiocephalic artery and the left pulmonary artery took place on the 3rd of February 1945. The second patient was an elevenyear-old girl with tetralogy of Fallot who before the operation was exhausted after walking just thirty feet and panted when moving from a wheelchair to the examining table. The results were outstanding, an uneventful post-operative period facilitated an incredible recovery and three weeks later the patient could walk sixty feet without panting. Seven days later, brimming with confidence from the convincing results in the second case, Blalock altered his procedure to perform an end-to-side anastomosis between the brachiocephalic artery and the right pulmonary artery on a six-year-old boy who was unable to walk. This operation released the potential of the Blalock/Taussig operation and Taussig later wrote: “The child later woke up in the operating room and asked, “Is the operation over?” When Dr. Blalock said “Yes,” the child said “May I get up now?” from that moment on he was a happy and active child.”12 Variations on the Blalock/Taussig operation have since emerged, notably the following year in 1946 William Potts, Sidney Smith and Stanley Gibson developed a direct side-to-side anastomosis between the descending aorta and pulmonary artery. The key involving an ingenious clamp that allowed the flow of blood through the aorta during surgery. Although the Potts/Smith shunt was technically easier to perform than the classical Blalock/Taussig operation it presented several postoperative complications including, excessive pulmonary blood flow, distortion of the pulmonary artery, and problems during subsequent complete tetralogy of Fallot repair. Accordingly the Potts/Smith shunt was phased out.13, 14 Within two years, 500 patients underwent the Blalock/Taussig operation. However its benefits as palliative surgery were limited and it was not a definitive correction. Over a five-year follow-up of each patient multiple shunts closed or shrank requiring a second operation. Neurological defects occurred in a quarter of patients where the brachiocephalic artery was involved. 14 So the hunt for a surgical cure was still on. The Second Epoch – Closed-Heart Surgery Although not the first closed-heart surgery, the second step in the treatment of Fallot’s tetralogy followed in quick succession. Having made an incision into the wall of the heart, the surgeon would ‘blindly’ dilate the constricted pulmonary pathway with a knife or finger, while the heart remained beating. This more elegant solution, called a ‘Pulmonary Valvotomy’, avoided two of the potential problems of the Blalock/Taussing shunt, the failure of the shunt to grow with the child and the harmful effects of an increased flow within the pulmonary circulation. The aim was to restore the normal haemodynamics of the heart, however as the ventricular septal defect remains open, the symptoms of breathlessness will not completely be alleviated and the surgery remained palliative. In 1926 Thomas Holmes Sellors qualified from the Middlesex Hospital and University, in London. Here, working as a thoracic surgeon, he developed and pioneered the surgical solution to pulmonary stenosis. On the 4th of December 1947 he carried out the first pulmonary valvotomy on a cyanotic, twenty-year-old patient with tetralogy of Fallot. On palpation of the exposed heart he felt a firm structure, indicative of a pulmonary valve that had not undergone perforation. Using a tenotomy knife he made an incision through the right ventricle, and then skillfully sliced the valve in two directions to open it.15 In 1947, Lord Russell Brock began his search for the surgical correction of pulmonary stenosis at Guy’s Hospital, also in London. As many patients with Fallot’s tetralogy did not have pulmonary stenosis, he proposed a method of diagnosis using a cardioscope in the early moments of the operation. He would insert the scope through an incision made into the left pulmonary artery thus allowing direct vision to examine the pulmonary valve. However after three unsuccessful trials, Brock concluded that it was too dangerous to insert the cardioscope through the pulmonary artery and temporarily stopped operating. Furthermore he had taught himself to make the diagnosis through external palpation of the main pulmonary artery, making the procedure redundant and hence abandoned. After the invention of a new valvulotome and dilating forceps Brock was ready to return. On the 16th of February 1948 he made a diagnosis of pulmonary stenosis while operating on an eighteen-year-old girl suffering from Fallot’s tetralogy. First he passed the new vavulotome through the wall of the right ventricle, and passed it with ease through the valve and into the pulmonary trunk. Next the forceps were inserted and dilated the stenotic valve. The patient survived and her cyanosis was vastly improved. He performed two more successful operations one three days later and a third in March. Within a year the operation had matured and he added an additional instrument to his repertoire, a special punch for the management of infunidbular stenosis. By the end of 1952 he performed this operation successfully on over sixty patients and he started to perform the pulmonary valvotomy in patients with pulmonary stenosis as the sole malformation. Despite the difficulty of the operations, the reward was great and Brock wrote: “we are in large part recompensed for the long and difficult hours by seeing the almost miraculous change in the children and in witnessing the joy and relief of the parents when they see their children running about happily and without effort like other children.”16 The Third Epoch – Open-Heart Surgery Despite the revelations of these two techniques they were still only palliative. The next logical progression in the treatment of Fallot’s tetralogy was to combine dilating the narrowed pulmonary valve with repair of the hole caused by the ventricular septal defect. In order to close the septal defect the heart would have to be ‘opened up’ so that the internal structures could be intricately inspected. As the brain is permanently damaged if deprived of oxygenated blood for five minutes, unfortunately even the simplest open-heart operation takes fifteen minutes. Two options eventually became available for surgeons and their teams to conquer this (minimum) ten minute difference. One option involved taking over the function of the heart – the ‘pump’, the other by reducing the brain’s requirement for oxygen – induced hypothermia. Previous work using general body hypothermia had been carried out frequently before it application in the treatment of Fallot’s tetralogy. In the late 1940’s William Bigelow carried out ‘sham’ cardiac operations on dogs. In 1953 John Lewis and Mansur Taufic performed the first repaired of an atrial septal defect when they reduced the patient’s body temperature to 28C. From that point onward the induction of hypothermia became standard practice in cardiac surgical technique. Multiple methods to induce hyperthermia were available to the practicing surgeon, Lewis and Taufic used a refrigerated blanket, Henry Swan of the University of Colorado, preferred immersion in an ice-cold both, while Brock favoured an external circuit in which venous blood was passed through a cooling coil. However the operating time provided by this level of cooling was still too short for the correction of more complicated and multiple abnormalities such as in Fallot’s tetralogy. In the late 1950’s Charles Drew experimented with profound hypothermia reducing the body temperature to 15C, which gave him the time he needed to carry out the operation.17 A long-term solution was still needed, the function of heart and lungs would need to be maintained by some other means than themselves, long enough for the surgeon and their team to complete the operation. In 1931 John Gibbon formed the theory for extracorporeal circulation while working nights. This was an audacious idea as in the 1950’s death was still defined as the cessation of heart beat, so for a doctor to stop a patients heart and then restart it seemed ludicrous to many. Gibbon’s ‘boss’ Edward Churchill shared this negative viewpoint and in fact the only person who appeared to share his vision was the Russian Professor S. S. Brukhonenko, who had conducted some crude experiments on dogs. Most people believed that a machine could not be capable to deliver suitable conditions for the vast and complex functions of the heart, lung and circulatory system. Gibbon was not deterred and by 1953 with the help of his wife Mary Hopkins he had produced a machine capable of delivering consistently reliable results in animals. Unfortunately for Gibbon only one of the four open-heart operations he participated in survived, an eighteen-year-old woman, Celia with an atrial septal defect. Disheartened by his failures Gibbon conceded he was out of his depth, he felt he didn’t posses the surgical skill or psychological stamina to continue and returned to the library. With the successes of hypothermia in open-heart surgery and the failures of the pump, the future of the cardiac surgery and the heart-lung machine looked doomed. Nevertheless the work of Gibbon was picked up by two men in Minnesota, Walter Lillehai at the University of Minneapolis and John Kirklin at the Mayo Clinic in Rochester, and between them they would lay the foundation for modern cardiac surgery. Lillehai was not a cardiac surgeon, but he was a talented general surgeon, and as a surgical resident he had participated in many common cardiac procedures. Lillehai’s success came from developing a technique called cross-circulation, where the blood of the patient was not passed through an oxygenator such as the heart-lung pump but through a human volunteer. The genius of this technique was that the artificial, man-made methods of oxygenation of the blood were replaced by the most natural and physiological substitute. In August 1954 he initiated the third step by completing the first total surgical correction of tetralogy of Fallot in an 11 year-old boy. The pulmonary valve was dilated and the ventricular septal defect was closed using a suture or patch depending on size. In a oneyear period that began in the spring of 1945, Lillehai completed forty-five open-heart operations using cross-circulation in extremely ill patients, with two-thirds of the patients surviving. It was clear, however, that crosscirculation was not the definitive answer as it exposed the healthy donor to unacceptable risk. So focus was returned to advancing the pump developed by Gibbon. Lillehai chose to work on a previous idea where oxygen was bubbled outside the patient’s body in a reservoir circulated through patient and returned debubbled. Kirklin believed the principles behind Gibbon’s pump were sound and instead of designing a new machine he began to modify Gibbon’s. In March 1955 Kirklin and his team were ready to begin, and they used their machine in the treatment of intracardiac surgery in infants and children and by May 1955 they performed eight operations with four survivors and by October of the same year had performed thirty-eight operations with sixteen survivors. Bearing in mind that most of the patients had end stage congenital heart disease with ventricular septal defects and extensive pulmonary hypertension and without intervention would have certainly died the results were greatly encouraging. Kirklin had clearly demonstrated the worth of the heart-lung machine in open-heart surgery. Conclusion As a medical student with an interest in both paediatrics and surgery the surgical treatment of Fallot’s Tertalogy gave me a chance to cover both topics. I was aware of some of the techniques used in modern day surgery but this essay gave me the opportunity to understand the foundations from where modern day techniques have evolved. The heart is anatomically the most complex organ of the body and it is its intricacy and the previous taboo towards cardiac surgery that has drawn me to it. Surgery is associated with a steep learning curve, with a living drama in the literal life-or-death contest being played out on the operating table. Without the psychological determination of many surgeons the treatment of Fallot’s tetralogy would not be where it is today. It is essential to appreciate the condition that surgeons would have been presented with. Nowadays babies born with Fallot’s tetralogy are operated on within the first year of life, so no surgeon will ever see the “pitiful” sate of the patients Kirlin described. In my opinion, which is one I share with Lord Brock, the Blalock/Taussig operation was “so outstanding that it altered the whole approach to cardiology.”18 The genius that lies in treating the congenital cardiac abnormality, Fallot’s tetralogy, by creating a second congenital cardiac abnormality, a patent ductus arteriousus, will rarely be succeeded. For me this study has stimulated a greater interest in the varying techniques used in the management of congenital cardiac defects, particularly those tetralogy of Fallot. Within the following year I hope to witness firsthand this management by arranging multiple visits to the Ninewells operating theatres to further my medical education. REFERENCES: 1. James Le Fanu. 1999 Little Brown and Company. The Rise and Fall Of Modern Medicine. Twelve Defining Moments, Chapter 6 – 1955: OpenHeart Surgery – The Last Frontier. Page 82 2. Ludwig Edeistein, Owsel Temkin, C Lilian Temkin. 1987 John Hopkins University Press. Ancient Medicine. Page 6 3. Today I Found Out: How The Heart Works. C2010 [cited 2011 May 11]. Available from: http://www.todayifoundout.com/index.php/2010/09/howthe-heart-works/ 4. Whonamedit? Fallots’ tetralogy. [cited 2011 May 11]. Available from: http://www.whonamedit.com/synd.cfm/2281.html 5. P. Kumar and M. Clark (editors). 2009 Elsevier Limited. Kumar and Clark – 7th Edition. Chapter 13 – Cardiovascular Disease – Congenital Heart Disease. Page 779 6. James Le Fanu. 1999 Little Brown and Company. The Rise and Fall Of Modern Medicine. Twelve Defining Moments, Chapter 6 – 1955: OpenHeart Surgery – The Last Frontier. Page 88 7. Louis J. Acierno. 1994 The Parthenon Publishing Group. The History Of Cardiology. Section 2 Structural Abnormalities, Part B Congenital Abnormalities, Chapter 13 – Congenital Abnormalities. Page 171 8. Peter Fleming. 1997 Amsterdam – Atlanta. A Short History Of Cardiology. Chapter 13 – Cardiac Surgery. Page 219 9. Wikipedia: Fluoroscopy. [Modified 2011 May]. [cited 2011 May 12]. Available from: http://en.wikipedia.org/wiki/Fluoroscopy 10. Louis J. Acierno. 1994 The Parthenon Publishing Group. The History Of Cardiology. Section 6 Therapeutic Modalities, Chapter 29 – Surgical Modalities. Page 655 11. P. Kumar and M. Clark (editors). 2009 Elsevier Limited. Kumar and Clark – 7th Edition. Chapter 13 – Cardiovascular Disease – Congenital Heart Disease. Page 777 12. H. Taussig. Knowledge of Congenital Malformation of the Heart. Page 772* 13. V. N. Singh. Emedicine – Tetralogy Of Fallot: Surgical Perspective Treatment & Management. [Updated 2008 November 13]. [Cited 2011 May 14]. Available from: http://emedicine.medscape.com/article/904652-treatment#a1128 14. Louis J. Acierno. 1994 The Parthenon Publishing Group. The History Of Cardiology. Section 6 Therapeutic Modalities, Chapter 29 – Surgical Modalities. Page 656 15. T. Holmes Sellors. 1948 Surgery of Pulmonary Stenosis: A Case in which the Pulmonary Valve was Successfully Divided. [Lancet, I:988]* 16. Brock. Surgery of Pulmonary Stenosis. Page 406* 17. Peter Fleming. 1997 Amsterdam – Atlanta. A Short History Of Cardiology. Chapter 13 – Cardiac Surgery. Page 225 18. Letters from Lord Brock to Mark Ravitch. 1965 September. [Cited by Raymond Hurt in The History of Cardiothoracic Surgery] * Taken from – S. L. Johnson. 1970 The John Hopkins Press. The History of Cardiac Surgery 1896-1955. Notes. Bibliography: James Le Fanu: The Rise & Fall Of Modern Medicine. Little, Brown and Company, London, 1999. Stephen L. Johnson: The History of Cardiac Surgery 1896-1955. The John Hopkins Press, United States, 1970 Louis J. Acierno: The History of Cardiology. The Parthenon Publishing Group, Carnforth, 1994. Peter Fleming: A Short History Of Cardiology. Amsterdam – Atlanta, Netherlands, 1997. Knut Haeger, revised and updated by Sir Roy Calne: The Illustrated History of Surgery. Harold Starke, Spain, 2000