site.btaProf. Dr Ivan Mitev, who Made the Bulgarian Scientific Discovery of the 20th Century: the Sixth Heart Tone

The discovery of the sixth heart tone by Prof. Dr Ivan Ivanov Mitev (1924-2006) was a long and complicated process, but was declared the Bulgarian scientific discovery of the 20th century, Prof. Mitev's son, Academician Prof. Dr Vanyo Mitev, said in a BTA interview.

Prof. Mitev submitted his discovery to the Institute of Inventions and Rationalizations (INRA) on July 27, 1972. In 1973 he published a paper in the journal Paediatrics, but it apparently went unnoticed. In May 1977, a French cardiology journal published his paper "Sixth Heart Tone" and many cardiologists from various countries requested a reprint. He received worldwide recognition. A lengthy procedure to validate this tone followed, Academician Vanyo Mitev pointed out.

He said that a postage stamp commemorating the sixth heart tone was issued in 1994, and this is the world's only stamp related to cardiology.

Here is the full text of the interview:

Prof. Mitev, your father Prof. Dr Ivan Mitev takes credit for discovering the sixth heart tone, which has been declared the Bulgarian scientific discovery of the 20th century. Tell us how Prof. Mitev made this remarkable scientific discovery, which is very important for medicine?

The discovery was a rather long and complicated process. "The hardest part was convincing myself first of all that what I was seeing was in fact a new heart tone. I was apprehensive lest I was dealing with something familiar. These experiences are hard to put into words. However, they are well known to every researcher," said my father, Prof. Dr Ivan Mitev.

Interestingly, millions of phonocardiograms are performed worldwide every year. The results are read by countless doctors, associate professors and professors, but it had never occurred to anyone that this was a distinct tone. Prof. Mitev submitted his discovery to the Institute of Inventions and Rationalizations (INRA) on July 27, 1972. In 1973 he published a paper in the journal Paediatrics, but it apparently went unnoticed. In May 1977, a French cardiology journal published his paper "Sixth Heart Tone" and many cardiologists from various countries requested a reprint. He received worldwide recognition! A lengthy procedure to validate this tone followed. The procedure was lengthy because the legal experts of INRA said it was a discovery rather than an invention or rationalization. Since no Bulgarian discovery registered so far, the registration procedure was very time-consuming complicated and required irrefutable proof. 

On January 12, 1979, INRA published the formula of Prof. Ivan Mitev's discovery in its bulletin. Further trials were forthcoming, the evidence of the existence of the sixth heart tone could be challenged within a year, or another contender who had previously claimed a discovery in this field could step forward.

On March 12, 1981, the second Bulgarian discovery was entered in the INRA's Golden Book, and the author, Dr Ivan Mitev, was presented with a diploma of discovery in the presence of State Council President and General Secretary of the Bulgarian Communist Party Central Committee Todor Zhivkov.

The world's only postage stamp related to cardiology was issued to commemorate Prof. Dr Ivan Mitev's discovery of the sixth heart tone. When and how did this happen?

The Sixth Hear Tone stamp was issued in 1994. 

How is the discovery of the sixth heart tone applied, and does it help diagnose heart diseases more accurately?

What is the sixth heart tone? Prof. Mitev had two hypotheses. One was that the tone was of vascular origin and was due to oscillations when the aorta stretched and a new contraction occurs at the end of systole. The other hypothesis is that the sixth heart tone originated within the heart and was due to oscillations arising in the ventricular wall during cardiac systole.

The tone so described was recorded in healthy persons and heart patients with isolated aortic valve insufficiency; in a relatively smaller number of patients with pure mitral stenosis and in myocarditis. In children, this tone is only pathological.

If a distinct sixth heart tone is observed in a child, it is a symptom of heart disease. In healthy children, this tone occurs rarely, in about 1%.

What other medical research is in Prof. Dr Ivan Mitev's legacy?

Prof. Ivan Mitev's candidate of sciences thesis dealt with infant mortality. It is even more relevant now. Already in the late 1950s he warned about the risk of population decline and was a great champion of natality promotion measures. Most importantly, the solutions that he proposed for years ahead are especially relevant today. That was the first thesis to be defended at the Scientific Institute of Paediatrics.

Your father worked at the Scientific Institute of Paediatrics. What were his scientific achievements at that Institute?

From 1960 until his retirement in 1989, Prof. Dr Ivan Mitev worked at the Scientific Institute of Paediatrics (now named after him -  Prof. Ivan Mitev Specialized Hospital for Active Treatment of Children's Diseases). He was an extremely original thinker. Let me tell you a story to illustrate this. An idea occurred to him that if cyclists, footballers, rowers and other athletes wore elastic leggings, it would improve the venous outflow and thus delay the onset of muscle fatigue. He had contacted professors of the Higher Institute of Physical Education (now the National Sports Academy) to carry out experiments in Belmeken. The professors in question were tardy in responding to the request, but the idea became public and the athletes of the then German Democratic Republic, who practised with Bulgaria's national athletes at Belmeken, took advantage of it. And so, at the 1980 Olympics in Moscow, the GDR rowers appeared in such leggings and won gold. Since then, elastic leggings have been used on a massive scale by top-class athletes, you just have to watch a football match.

Prof. Dr Ivan Mitev was also a long-serving national consultant in paediatrics. What was his success record in this field of medicine?

Prof. Ivan Mitev's success record in children's health care, in terms of organization, development, reduction of child mortality, etc., is by far not confined to his position as national consultant.

Right from entering the medical profession in 1950 and until his last breath, he prioritized improving children's health care. My father had vast organizational experience, with a zest for innovation at every level and a skill of handling people.

His first thesis dealt with infant mortality in Ruse District, which then included the present regions of Ruse, Razgrad and Silistra, where he was a district physician. He takes credit for organizing the work, training the staff and opening baby food dispensaries in those areas.

In 1950 he was an inspector at the Maternity and Childhood Division of the Ruse District Health Department. During that period, health care in the Ruse District and especially in the areas of Razgrad and Silistra was at an extremely low level, and infant mortality was high. From 1953 to 1960 Prof. Mitev headed that division. Dedicated and youthfully committed, he contributed significantly to the building and strengthening of health care in that part of Bulgaria. The several-fold decline in infant mortality over a historically short period of time bears convincing witness to his contribution. This is particularly true of the Ludogorie area.

In 1956 he experienced one of his critical situations as a physician and administrator: the effort to bring under control a polio epidemic that broke out in Ruse. "We closed schools, kindergartens and nurseries. Children were strictly confined to their homes. All day long, carts scattered chlorine in the streets. The city was deserted! Nobody advised us how to handle the situation," Prof. Ivan Mitev wrote in his notes. This challenge, too, was successfully overcome.

Prof. Mitev takes special credit for the start of construction of a new building of the regional hospital in Ruse, which was half built by the time he left and is successfully used even to date. Despite the enormous administrative burden and the dedication with which he carried it out, Prof. Mitev started writing his doctoral thesis on the problems of infant mortality and the organization of children's health care, which he successfully defended in 1962.

From 1960 until his retirement in 1989, Prof. Mitev worked at the Scientific Institute of Paediatrics in Sofia. He rose through the ranks there, from a research assistant through associate professor, professor, head of clinic, deputy director to director. He headed the Institute between the end of 1984 and the end of 1989, when it employed a staff of more than 700 and had a capacity of more than 600 beds. During that period, the Institute was a powerful medical, educational, scientific and organizational-methodological institution with great merits for the overall development of Bulgarian paediatrics and children's healthcare in Bulgaria. It was then that Bulgaria had the lowest infant mortality rate. Prof. Mitev takes a significant share of the credit for this, being an energetic, dedicated and experienced organized. It was also during that period that the Institute's new and modern building, the dream of generations of paediatricians, went under construction. His successors at the head of the Institute failed to complete this project, and until his last days Prof. Mitev was anguished by this failure.

The construction of the polyclinic building at the Institute, which is still functioning as a medical centre of the Specialized Hospital, is entirely his credit.

Prof. Mitev contributed substantially to the advancement of the Clinic of Rheumocardiology and  to addressing the problems of cardiovascular and rheumatological pathology among Bulgarian children. He focused his scientific pursuits on the prevention, diagnosis, treatment and rehabilitation of rheumocardiological diseases and in particular on blood-free functional diagnostics of cardiovascular diseases. A searching, restless spirit, Prof. Mitev produced more than 50 papers in these fields and was recognized as an inventor and rationalizer. In almost all of these papers, he was the only author.

The discovery of the sixth hear tone was the crowning achievement of his scientific quests, for which he was recognized as the second Bulgarian discoverer.

No small merit is due to Prof. Mitev for training several generations of Bulgarian physicians and for qualifying staff in paediatrics and especially in the first narrow paediatrics specialty: paediatric rheumocardiology.

His public activity, mainly dedicated to the development of paediatric healthcare in Bulgaria, was also enormous. Prof. Mitev was a long-serving national consultant in paediatrics and a methodical head of children's healthcare in several regions of Bulgaria. For almost ten years, he was the President of the Sofia Paediatric Society. He was a member of the editorial board of the journal Paediatrics. He actively contributed to the specialized and general press on the problems of children's healthcare. Three days before he succumbed to an insidious disease, Prof. Mitev took an article to the editorial office of a respected newspaper, containing to-the-point proposals for addressing Roma health and family problems. Unfortunately, these proposals went unheard yet again.