Profulla Kumar Sen

Abstract

One of the most eminent cardiothoracic surgeons of India, Profulla Kumar Sen (1915-1982) had a keen interest in research and in the subsequent clinical application of knowledge gained in the laboratory. His most significant contributions are his pioneering work on a transmyocardial acupuncture technique for treatment of ischemic myocardium, on heart transplantation in canine models and later in human beings, and on a new technique for aortic arch replacement. Transmyocardial laser revascularization of the 1990s was but an extension of his mechanical myocardial acupuncture for the treatment of ischemic heart disease, which he introduced 30 years earlier. On 16 February 1968, after many years of preparation through work with animal models, P.K. Sen and his team performed the 1st cardiac transplantation in India and the 6th in the world. (Tex Heart Inst J 2002;29:17–25)

One of the most eminent cardiothoracic surgeons of India, Profulla Kumar Sen (Fig. 1) had a sharp intellect and keen orientation towards scientific research that enabled him to surpass his peers and to contribute significantly to his field.

Fig. 1 Dr. Profulla Kumar Sen addresses the 1st National Conference on Pacemakers and Pacing in Bombay, October 1977.

(Photo courtesy of the Department of Cardiothoracic Surgery, King Edward Memorial Hospital, Bombay.)

Overview

P.K. Sen was born on 7 December 1915 at Calcutta, to a middle-class family. He had 1 sister. As the only son of a civil surgeon, Profulla became interested in surgery.^* He studied initially at a municipal school in Jamtada, a small town in the state of Bihar. He underwent his early college education at Victoria College of Sciences, Nagpur, and later took his MBBS degree at Seth G.S. Medical College, Bombay, where he attended from 1933 to 1938. In 1940, he then took his master's degree in surgery (with distinction) from the University of Bombay. Until his death on 22 July 1982 due to myocardial infarction, Dr. Sen held various posts at King Edward Memorial Hospital (KEM), Bombay. The department of cardiothoracic surgery at KEM was founded by him and now bears his name.

In 1954, Sen married Marie Barnes, an American from Philadelphia. She worked in a physiology laboratory, and they met while Sen himself was working in Philadelphia, at the University of Pennsylvania during 1950–1951. ¹ They had no children.

In addition to his stay in the United States, Dr. Sen traveled widely, visiting the United Kingdom, the Union of Soviet Socialist Republics, and other countries. Among his many awards were the Vishinskey Medal (USSR) and the Padma Bhushan, the highest award that India conferred on any scientist at that time.

He performed the full range of cardiac surgeries then available to him and was the pioneer, in India, of several procedures. Indeed Sen was the founder in India of cardiothoracic surgery as a subspecialty of surgery, for only pericardiectomy and ligation of patent ductus arteriosus had been tried before him. He was also the 1st to perform an intracardiac operation in his native country. Beginning with closed-heart surgeries (closed mitral valvotomy in 1952), ² P.K. Sen was soon closing atrial septal defects with the aid of hypothermia and inflow occlusion techniques (in 1957)—before doing so with the aid of extracorporeal circulation in March 1962. ³ Once the heart-lung machine became available, other open-heart operations like open commissurotomies, valve replacements, and repairs of congenital heart defects became routine. His most significant contributions are his pioneering work on a transmyocardial acupuncture technique for the treatment of coronary artery disease, on heart transplantation in canine models and later in human beings, and on a new technique for aortic arch replacement. His colleagues included Drs. T.P. Kulkarni, G.B. Parulkar, and M.D. Kelkar. He was in frequent touch with Drs. William Bigelow, Denton Cooley, Norman Shumway, Christiaan Barnard, Donald Ross, and Sir Brian Barrett-Boyes.

An excellent teacher, Dr. Sen enlivened his lectures with poetry, philosophy, and quotations from the history of medical science. He had a charismatic influence upon his students, who included Drs. R.A. Bhalerao, Sharad Panday, Nitu Madke, S.A. Padmavati, Sudhanshu Bhattacharya, M.S. Valiathan, and Arun Chaukar. When Sen ventured beyond the subject of surgery, he did so with authority, for he was both a poet and a painter; his paintings were exhibited twice in India and once in the United States.

Treatment of the Ischemic Myocardium

Bilateral Internal Mammary Artery Ligation.

In the late 1940s and 1950s, interest in the internal mammary artery (IMA) as a source of blood for the ischemic heart was stimulated by Arthur Vineberg's experimental and subsequent clinical implantations of the IMA into the ventricular myocardium. ^4–6 Unfortunately, the results of his procedure were inconsistent, and documentation that the implant worked at all had to await the advent of coronary angiography.

Interest in the IMA as a source of blood for the myocardium persisted, however. Even as Vineberg struggled for the acceptance of his implants, other investigators reported improvement in myocardial perfusion after ligation of the IMA. ⁷ The rationale behind ligation was that IMA blood could be diverted through the pericardiacophrenic artery, to increase flow to the myocardium through collateral vessels. The pericardiacophrenic artery arises from the IMA near its origin (caudal end) and normally supplies the pericardium, diaphragm, and pleura. As early as the late 18th century, Albrecht Von Haller ⁸ reported the presence of extra-coronary–coronary anastomoses between the right coronary artery and branches arising from the pericardiac branch of the pericardiacophrenic artery. These vessels were again studied by L. Gross in the 1920s. ⁹ By the 1950s, the Italian surgeons De Marchi and Battezzati were attempting to reroute blood to the coronary circulation through existing collateral vessels, using the IMA pathway. ⁷

After conferring with Glover and Hufnagel about their trials of IMA ligation (70 cases and 60 cases, respectively), Sen was sufficiently encouraged to start his own clinical trial in 1957 with 5 patients. ¹⁰ Approaching through the 2nd intercostal space under local anesthesia with sedation, he ligated the internal mammary arteries near their origins on both sides. A respirator was kept on standby during the procedure, in case pneumothorax developed as a consequence of accidental entry of the pleura during surgery. Although Sen found striking improvement in his patients' symptoms (disappearance of angina in all cases), he admitted that objective evaluation of the results was difficult: there were no significant electrocardiographic changes following surgery, and the Master's test of exercise tolerance seems to have been inconclusive. Internal mammary artery ligation did not gain much popularity and went the way of the Vineberg procedure.

Direct Transmyocardial Acupuncture.

By 1960, it looked as if the possibility of improving myocardial perfusion through surgical procedures involving either the coronary or noncoronary vessels had been exhausted. ¹¹ Therefore, Sen turned his attention to the primitive cardiac circulation.

Sen and his team explored the reptilian heart, in which the myocardium is supplied chiefly by channels that arise directly from the cavities of the heart, with only a rim at the heart's periphery supplied by coronary vessels. They opened the Russell's viper heart and showed by dye studies that 11/12ths of the myocardium is supplied by these transmyocardial channels. ¹² In higher animals, these channels have nearly disappeared and persist only in rudimentary form, as thebesian circulation: the arteriae and venae cordis minimae. These vessels were described by Joseph Wearn in 1928, ¹³ who suggested that they could be a source of blood supply to the myocardium in distress. The amount of blood flowing through these vessels, however, remained a source of controversy.

Influenced by his study of the reptilian circulation, Sen went on to pioneer the technique of transmyocardial acupuncture. He 1st reported this technique in a paper read before the Silver Jubilee conference of the Association of Surgeons of India, in December 1964. ¹⁴

Dr. Sen's method consisted of multiple full-thickness acupuncture of the ventricular myocardium, in such a manner as to provide blood flow directly from the ventricles to the myocardium. Because this was an attempt to construct channels as seen in reptiles, he called this his “snake-heart operation.” He and his team experimented extensively in animals before proceeding to human beings, and then applied the operation only to the most acute cases.

From 1964 through 1966, their 1st series of experiments involved dogs. ^11,12 They simulated myocardial infarction by ligating the left anterior descending (LAD) branch of the left coronary artery, then performed multiple transmyocardial acupunctures in the area of ischemia. The dogs that received no acupunctures served as controls. The surgical team used a 1.2-mm cannula for puncturing and made an average of 20 punctures per square centimeter. They introduced modifications in the procedure to refine their data, operating on some animals immediately after ligation of the LAD while waiting 24 or 48 hours in other cases. To rule out any role played by pericardial reaction and adhesions, some animals received partial-thickness punctures (not reaching the ventricular cavity) in a small island of the ischemic myocardium. Other animals received full-thickness punctures in the same small island.

Sen and his colleagues were able to report a significant improvement in the survival rate (60% vs 12% for controls) of the “snake-heart” dogs during the first 2 weeks of ligation. The area of infarct was reduced substantially; and pericardial reaction and adhesion did not contribute to this salvaging of tissue. The dogs that survived were euthanized after 3 to 8 weeks, and microscopic studies showed patency of the channels, which were filled with red blood cells at the conclusion of follow-up. The earlier the procedure was performed, the better was the salvaging of the myocardium. However, no significant difference was found in performing the procedure after 24 hours (rather than 48), which led the team to conclude that myocardial acupuncture must be performed within 24 hours of insult.

In 1967 and 1968, they performed another set of experiments, again in dogs, but this time to determine the best instrument to use for transmyocardial acupuncture. ^11,15 They used either a 1.2-mm cannula, with 15 to 20 punctures per square centimeter, or Elliot's scleral trephine (diameter of 1.5 mm), with which only 5 punctures per square centimeter could be made. In terms of survival, the 2 instruments yielded almost equal results. They also tried Silverman's biopsy needle (diameter of 1.5–2.0 mm), but the epicardium had to be sutured to prevent bleeding as these instruments punched out large bore holes. Protection of the myocardial tissue was best with the cannula. The investigators also varied the number of punctures by cannula and discovered that the greater the number of punctures, the better the result. On histopathologic study, they found a patent channel lined by endothelium 18 weeks after the procedure.

After accumulating the animal data, Sen and colleagues decided to proceed with their clinical trial. ¹⁵ They reported no clinical benefit in 4 patients who presented more than 24 hours after onset of myocardial infarction. One patient, however, had undergone transmyocardial acupuncture after accidental kinking of the LAD during open cardiac massage. Multiple acupunctures were made in the territory of the LAD, using a knobbed venoclysis cannula. The patient died of irreversible brain damage, but autopsy showed that the myocardial tissue was saved and that the area of infarct was minimal. Several groups tried this technique, with varied results. ^16–19 The work of John E. Hershey and Manuel White is noteworthy in that they compared the results of transmyocardial acupuncture with Vineberg's procedure and found acupuncture superior.^* Dr. Denton Cooley, of the Texas Heart Institute, also tried this technique. In a personal communication^** with Sen in 1968, he reported its use in patients undergoing prolonged cardiopulmonary bypass during coronary artery surgery.

In 1969, Roque Pifarre and colleagues pronounced myocardial perfusion by transmyocardial acupuncture “a physiologic impossibility.” ²⁰ The technique was not much tested in clinical trials, but experimental work to reveal its merits and demerits continued for some time. This concept was revisited in 1981 by M. Mirhoseini and M.M. Cayton ²¹ when they proposed creating transmyocardial channels with a laser apparatus. Since then, the technique has been revived as “transmyocardial laser revascularization” and is being used experimentally in combination with gene therapy. ²² Now its role in treating chronic coronary insufficiency is also under consideration. ²³ Recently, in a letter to the editor of the Texas Heart Institute Journal, Hershey reported his 14-year follow-up on a patient who received transmyocardial acupuncture in 1967; there he suggested that transmyocardial revascularization by mechanical puncture is possibly superior to transmyocardial revascularization by laser. ²⁴

Heart Transplantation

On 16 February 1968, P.K. Sen and his team performed the 1st cardiac transplantation in India and the 6th in the world. Among the 1st to consider heart transplantation as a possibility, they had prepared themselves for many years, through work with animal models.

In 1954, citing the possibility of heart transplantation, they began their 1st series of experiments in 17 mongrel dogs, to determine the effect of profound hypothermia. ^25,26 They hyperventilated their subjects at 48 breaths/min to reduce the risk of ventricular fibrillation and immersed them in cold brine to drop rectal temperatures to as low as 9 or 10 °C, producing cardiac arrest. Upon rewarming, cardiac arrest was reversed, but the dogs experienced severe weight loss, negative nitrogen balance, and reversible hair loss. Further, the tests showed that the chances of ventricular fibrillation developing upon cooling or rewarming were minimal; but because the heart was not handled, there could be no assumption that this result would hold during open-heart procedures.

On the basis of these results, Sen and his team next studied isolated heart-lung preparations in hypothermic adult dogs, in a series of 12 experiments. ²⁷ Their 1st heart-lung preparations, set on sterile cloths and artificially respirated at 18 breaths/min, functioned as self-sustained units with blood pumped from the right side into the lungs through the pulmonary arteries, then returned through the pulmonary veins. The left ventricle pumped blood into the coronary circulation, which returned it to the right side through the coronary sinus. The effective average beating time was only 10 minutes, during most of which sinus rhythm and nodal rhythm were maintained. Ventricular dysrhythmia was followed by ventricular fibrillation, atony, and death. Because these early cardiac deaths were attributed to asymmetry of circulation between the coronary and pulmonary beds, Sen and his coworkers tried clamping 1 pulmonary artery and injecting isotonic saline solution into the left ventricle, which increased the survival time to an average of 60 minutes. ²⁷

Sen concluded that heart-lung preparations could be transplanted but decided to await further technical advances before embarking upon transplant experiments. He wanted to further increase survival time and to consider the technical difficulty that he fore saw with systemic heparinization prior to transplantation.

The advent of the pump-oxygenator enabled experimental work on cardiac transplantation, and Sen was further encouraged after seeing the work of V.P. Demikhov during his visit to the USSR in 1962. During 1963 and 1964, Sen and his group performed about 100 experiments on dogs to study rejection and to learn the most suitable techniques for heart transplantation. ^28,29

Sixty “parasitic” neck transplants were performed through various modifications of the Mann technique (1933), ³⁰ chiefly to study the response of the heart to rejection and to anti-rejection drugs. The recipient's neck was dissected and the carotid arteries and jugular veins exposed. The donor heart was transplanted by means of carotid–subclavian arterial anastomosis and jugular vein–pulmonary arterial anastomosis (Fig. 2). Because these experiments were performed to study rejection, the effects of methotrexate and steroids were studied. In successfully transplanting 52 of the 60 hearts, they discovered that survival time was increased by the use of methotrexate (from a maximum of 10 days to 15) and that puppy hearts were superior to adult hearts in terms of survival. ²⁸ Heparin was essential for transplantation, as only 1 out of 3 procedures attempted without heparin was successful. Rejection, or what appeared to be the rejection phenomenon, started within a few days of transplantation, as exhibited by electrocardiographic changes, accumulation of pericardial fluid, reduction in cardiac contractility, and serial microscopic studies. ²⁹

Fig. 2 Diagram illustrates the circulation of a heart transplanted in the neck of a dog.

(From: Sen PK, Parulkar GB, Panday SR, Kinare SG. Homologous canine heart transplantation: a preliminary report of 100 experiments. Indian J Med Res 1965;53:674–84. Published by permission of the India Council of Medical Research.)

Thirty procedures were performed according to the Shumway method of homovital (allogeneic) isotopic transplantation, ³¹ mainly to become acquainted with the technique. Various modifications ²⁸ were applied in order to establish the most suitable technique: 5 procedures involved initial cooling, followed by transplantation without cooling; 15 involved initial cooling, followed by continuous cooling with cold saline solution during transplantation; 5 involved initial cooling, followed by perfusion of the left coronary artery during transplantation with blood from a pump-oxygenator; and the remaining 5 involved initial cooling followed by perfusion of both coronary arteries during transplantation. On the basis of these experiments, they concluded that continuous cooling was superior to coronary perfusion and was necessary for a viable transplant. Coronary perfusion was in any event technically difficult, because the conduits from the pump-oxygenator hindered surgery.

Sen and his associates also performed 5 “booster-heart” transplants after the method of V.P. Demikhov ³² (Fig. 3), again for the purpose of mastering the technique. They then proceeded with 5 canine heart-lung transplants in accordance with their own suggestion of 1956, ²⁷ but they applied the cardiopulmonary bypass technique learned during their study of homovital heart transplantation. These total heart-lung transplants were technically easier and faster than the homovital heart transplants.

Fig. 3 Diagram (after Demikhov) of a “booster” heart within the chest on the left side. The superior vena cava of the donor heart is joined to the pulmonary vein of the recipient heart and the aorta of the donor heart to the subclavian artery of the recipient, thereby assisting the recipient's left-side circulation.

LA = left atrium; RA = right atrium

(From: Symposium on Human Heart Transplantation. Team from Seth Gordhandas Sunderdas Medical College and King Edward Memorial Hospital, Bombay. J Indian Med Assoc 1968;51:542–63. Published by permission of the Indian Medical Association.)

After these experiments in heart-transplantation technique, Sen and his colleagues turned their attention to maintaining the viability of the myocardium after death. Because they foresaw difficulty in obtaining donor hearts from live persons, they undertook a study of cadaveric perfusion. ²⁹ In 1965, they chose 100 medium-sized mongrel puppies, which were killed by a variety of means: anoxia, overdose of succinylcholine, induction of ventricular fibrillation by electric shock, or exsanguination. After varying periods of cessation of electrical activity of the heart (up to a maximum of 20 minutes), the cadavers were perfused by means of a pump-oxygenator, to maintain the viability of the donor hearts. Sen and his team used upper-body perfusion (40 cases) (Fig. 4A), total-body perfusion (20 cases) (Fig. 4B), isolated heart perfusion (10 cases), isolated heart-lung perfusion (15 cases), and crossed viviperfusion (15 cases). They maintained perfusion for an hour or two, after which these hearts were transplanted into the necks of adult dogs as parasitic transplants by the technique that they had learned earlier. They concluded that such perfusions were able to maintain the viability of the heart. Although none of the perfusion methods appeared to be superior to the rest, the best results were obtained when perfusion was started within 5 minutes of death. These experiments with cadaveric perfusion were to prove helpful in planning the 1st clinical attempt. ²⁹

Fig. 4 Diagrams show partial (A) and total (B) body perfusion in a dog.

(From: Symposium on Human Heart Transplantation. Team from Seth Gordhandas Sunderdas Medical College and King Edward Memorial Hospital, Bombay. J Indian Med Assoc 1968;51:542–63. Published by permission of the Indian Medical Association.)

Before attempting clinical application, Dr. Sen again visited the USSR, where he reviewed the work of Demikhov and came to believe that the rejection phenomenon was a result of anoxic insult suffered during or before transplantation. The specialized stapling-suture devices developed in the Sklinfasovsky Institute, Moscow, by Gudov, Androsov, and others had enabled Demikhov and coworkers ^32,33 to perform anastomosis quickly and thereby reduce ischemic time to achieve long-term survival (up to 2.5 years) of their booster cardiac homografts. ²⁹ After 1965, Sen reproduced the experimental work of various investigators, most notably that of Kondo and coworkers ³⁴ in cardiac transplantation under surface hypothermia.

The astonishing news on 3 December 1967—that Christiaan Barnard ³⁵ of South Africa had performed the 1st human cardiac transplant—gave a sense of urgency to investigators worldwide who were close to clinical application of what they had learned in the laboratory. As a last step, Sen and his team studied human cadavers for details of the operative anatomy as it pertained to both donor and recipient.

Clinical Application.

Within a month of Christiaan Barnard's 1st cardiac transplantation procedure, Sen and his colleagues were planning their own. ^29,36 As a suitable recipient, they chose a 27-year-old man who had been admitted to their cardiology ward before Barnard's historic operation and who was still there—suffering from chronic progressive cardiomyopathy, with cardiac failure refractory to medical treatment. During 5 months of hospitalization, the patient had received intensive treatment for cardiac failure without improvement in effort tolerance, dyspnea, or cardiac size. He also had evidence of restrictive lung disease on chest radiography. After receiving an explanation of the risks, the patient agreed to cardiac transplantation on 13 January 1968 and was transferred to the surgical ward. Supportive therapy was continued throughout the preoperative period. ²⁹

On 16 February 1968, a 20-year-old woman presented at the emergency ward at King Edward Memorial Hospital in an unconscious state after sustaining a severe head injury in a train accident. Bitemporal exploratory burr holes revealed extensive cerebral lacerations and contusions, and the patient's vital signs deteriorated rapidly over the next few hours. Her blood group (O positive) matched that of the recipient, so she was selected as a donor. ^29,36

At about 8 hours after the donor's admission, she was moved to the “donor room,” adjacent to the main operating theatre where the recipient lay. In the absence of an Indian law on brain death, the donor heart could not be harvested until it had ceased to beat. After total cessation of cardiac activity, the donor was rapidly heparinized and put on partial bypass. After her chest was opened and her major veins clamped, the donor was put on total cardiopulmonary bypass and her ventricles were vented to prevent distention. Her body was cooled to an esophageal temperature of 16 °C. ^29,36

As the donor was placed on cardiopulmonary bypass, the recipient's chest was opened and his major cardiac vessels dissected. The recipient was placed on cardiopulmonary bypass through the femoral vessels, and the superior vena cava was cannulated through the right atrium (his jugular vein was too small for cannulation). The recipient's temperature was brought down to 30 °C.

The donor's heart was perfused for as long as possible by dissecting the aorta last. The excision took about 4 minutes, after which the heart was put in a bowl of Ringer's lactate at 4 °C. The donor's heart was transferred immediately to the main operating theatre, where it was perfused by a pump-oxygenator at a flow rate of 250 mL/min. The heart started beating in the bowl.

The recipient's heart was then excised, except for atrial margins left for anastomosis. At the outset of transplantation, the aorta was sutured 1st to provide for coronary perfusion. Immediately upon perfusion, the heart resumed beating with vigor and had to be electrically defibrillated to enable further suturing. All told, the procedure took 2 hours, during which the heart was perfused every few minutes by releasing the aortic clamp. After disconnection of the fibrillator electrodes, the heart spontaneously resumed normal rhythm.

However, 15 minutes after the patient had been weaned from cardiopulmonary bypass, the right ventricle began to enlarge rapidly and had to be vented, while the left side worked normally. The cause of this right-sided failure was almost certainly peripheral pulmonary vascular resistance, as suggested by a good response to acetylcholine injections directly into the pulmonary artery. The heart stopped functioning 3 hours after transplantation. This patient, unfortunately, had serious problems complicating his poor cardiac status: restrictive lung disease, kyphoscoliosis, a small left hemithorax, and factors that impeded prolonged cardiopulmonary bypass (a short neck, a high larynx, and a trachea that deviated to the left). At autopsy, both lungs were found to be partly collapsed and adherent to the chest wall; they also showed bullous emphysema. ²⁹

On 13 September 1968, Sen and his team attempted another transplant. In this instance, the recipient was a 22-year-old man and the donor a 25-year-old woman (again, brain dead). The technique was the same, except that hydrocortisone was used for immunosuppression. This time the heart functioned for 14 hours, before the patient died of anuria. Autopsy showed pulmonary hypertension, multiple pulmonary emboli, and renal tubular damage. ³⁶

After this, no further transplants were attempted in India for many years, because India lacked proper laws concerning brain death and organ donation. ³⁷ Only after 1993, when a proper law came into force, ³⁸ did Prof. P. Venugopal at All India Institute of Medical Sciences (AIIMS) perform a successful cardiac transplant in India. This took place in 1994.

Aortic Arch Replacement

Aortic arch replacement requires a great deal of skill. Since Denton Cooley 1st described the procedure in 1952, ³⁹ it has faced problems in the maintenance of perfusion through vital structures and in the prevention of cardiac failure as a consequence of aortic clamping at both ends. The conventional technique at that time was to provide perfusion by direct cannulation of the innominate, left carotid, and femoral arteries. This procedure, however, was associated with cerebral deficits arising from the subclavian steal phenomenon. Accordingly, Cooley and coworkers developed a new technique for perfusion during aortic arch replacement, which they presented at the 40th scientific session of the American Heart Association, on 22 October 1967. ⁴⁰ It involved a complex extracorporeal system consisting of separate pumps for innominate, left carotid, left subclavian, and femoral artery cannulae. Still the procedure had certain drawbacks, such as a risk of cerebral embolism, hindrance by cannulae during the procedure, and temporary cessation of the blood supply to the brain during implantation of arteries into the prosthetic graft.

Sen and his colleagues introduced a simple modification to remove these drawbacks, which they reported in 1973. ⁴¹ They proposed the creation, a few days before aortic arch replacement, of a right subclavian-to-left carotid bypass using a Dacron graft (Fig. 5A), a procedure that could be performed under local anesthesia. This obviated the need to cannulate near the aneurysm, thereby reducing the chances of embolization and freeing the surgeon of the multiple cannulae. At the time of operation, the right axillary artery was dissected and cannulated to provide circulation not only through the right subclavian and right carotid arteries but through the left carotid and innominate arteries—enabling a single pump to supply the brain on both sides (Fig. 5B). The ends of the aortic arch were clamped and the lower arch perfused through the femoral cannula. The right side was drained through the right atrium. After the arch had been excised and the Dacron graft sutured in place, the branches of the arch were anastomosed to the graft, except for the left subclavian artery, which was permanently perfused by the bypass from the right subclavian (Fig. 5C). This reduced the time for total arch replacement to 55 minutes after initiation of bypass.

Fig. 5 A) Right subclavian–left carotid artery shunt done as the 1st stage of aortic arch replacement in a case of fusiform aneurysm. B) After excision of the aneurysm. The right axillary cannula perfuses not only the right subclavian and right carotid arteries but also the left carotid artery through the shunt, thus perfusing almost the entire brain. The lower part of the body receives blood through the femoral artery cannula. C) Note that the left carotid artery has not been anastomosed to the graft, as it is now supplied through the right subclavian-to-left carotid artery shunt.

(From Panday SR, Parulkar GB, Chaukar AP, Sen PK. Simplified technique for aortic arch replacement. First-stage right subclavian-to-left carotid artery bypass. Ann Thorac Surg 1974;18:186–90. With permission of Elsevier Science.)

Through this simplified technique, Sen and colleagues were able to overcome the drawbacks of the previous technique.

Other Work

Dr. Sen made a number of other contributions to cardiovascular surgery and cardiology. He published some original observations on vascular diseases that he grouped under the name nonspecific aortoarteritis. ^42–44 Indeed his monograph on this subject ⁴⁵ has become a standard reference work. He also contributed to cardiac radiology by experimenting with nuclear isotopes. ⁴⁶ His other works encompassed vascular pathology, ^47–50 constrictive pericarditis, ^51,52 and Ebstein's anomaly ⁵³ and other congenital heart diseases. ^{54, 55}

Conclusion

P.K. Sen had a keen interest in experimental and clinical research to discover the basic nature of disease and to apply that knowledge to treatment. He was well ahead of his time, for the transmyocardial laser revascularization of the 1990s was only an extension of his mechanical myocardial acupuncture for the treatment of ischemic heart disease. That Sen performed the world's 6th heart transplant (and the 1st in India) speaks volumes about his quest to be in the forefront. Unfortunately, he was impeded in those early days of cardiac transplantation by the absence of a law on brain death, which meant that donor hearts could be harvested only after they had ceased to beat.

Acknowledgment

I would like to sincerely thank Dr. A. Sampath Kumar, Professor, Department of Cardiothoracic and Vascular Surgery, All India Institute of Medical Sciences, for reviewing my manuscript and offering helpful suggestions.