Song's Innovative Aortic Root and Valve Reconstruction > Chest Surgery

In the 1960’s, at the dawn of cardiac surgery, the artificial heart valve developed by Professor Albert Starr was functionally so effective that valve replacement was easily accepted as the standard treatment for heart valve disease despite its many disadvantages. Then, the successful mitral valvuloplasty in the 1970’s by Carpentier suggested a new direction in treatment of valvular heart disease, going from valve replacement to valve repair. Mitral valvulopalsty became a major procedure for surgical treatment of the mitral valve insufficiency in the 1990’s. Encouraged by this success with the mitral valve, many trials of aortic valve repair were undertaken. Unfortunately, the mid- to long-term results did not show favorable durability which resulted in a belief by cardiac surgeons that successful aortic valvuloplasty was impossible. My motivation to begin a career in the research of aortic valvuloplasty was a skepticism I felt in regards to valve replacement as the ideal treatment for valve disease. As a surgical resident I witnessed several times fatal complications resulting from artificial valve replacement such as thrombosis or hemorrhage. In July 1984, I began a two year cardiothoracic surgical fellowship at Oregon Health Science University under the tutelage of Professor Albert Starr. During these two years of experience, I became even more convinced that valve replacement was not an ideal curative treatment method and believed that a more durable aortic valvuloplasty should and could be developed. Starting in July 1986 I reviewed the research studies regarding the aortic root and valve. I concluded that the real time characteristics of the aortic root while the heart was beating could be better understood if we looked at the histological characteristics of aortic root in relation to the pressure change and movement of aortic root at the same time. I then deduced that the development of a novel technique for aortic root and valve repair, applicable to all kinds of aortic root and valve disease, would be possible as long as we could design new surgical technique based on these research findings. Although the histological research at each structure was sufficient at that time, the study of aortic root movement in a beating heart was very limited.

However I deduced that research to better undertand the aortic root in motion would not be difficult if I used physical principles and applied them. I was assured that research on the aortic valve using physics would be possible for several reasons. Elasticity principles can be used to elucidate the histological structure of aortic root. Bernoulli’s principle can be applied to flowing blood in the opened aortic valve on systole, while, Pascal’s principle can be applied

to stagnant blood flow in the closed aortic valve on diastole. The formula of compression and expansion of gas can help us understand aortic root expansion according to pressure changes. Finally, the principles of dynamics help us learn more about left ventricular contraction and blood pumping. Based on my findings at that time I began my intensive research in March of 1987 to examine the structures and functions of aortic root in a beating heart using these principles.

Through this research, the changes in diameter, height, width, and shape of the aortic root were described based on the pressure and motion changes of adjacent structures such as the left ventricle, the left atrium and the ascending aorta. These physical changes at each part of the aortic root could be described quite accurately. In fact, all these assumptions were proved to be true 20 years later by when we had MRI to do more detailed research. By this approach the interactions that resulted in the development of valvular diseases were also identified. The mechanism of aortic leaflet injury due to aortic root dilatation was revealed. The cause of aortic valve prolapse by the diminished height of the commissure because of less expansile leaflet characteristics in severe aortic sinus dilatation was also proved. Additionally, the fact that the annulus dilatation was confined to the fibrous annulus in majority cases was verified.

Histological research of aortic root structures also contributed to not only understanding of the normal function and disease of the aortic root but also to the development of a new procedure. The relationship between the high expansion rate of the sinotubular junction (STJ) and the position of the commissures was proved. Discovery of the histological similarity of the aortic sinus wall and inter-leaflet triangle became an important basis for the tricuspidization technique in the case of bicuspid or quadricuspid leaflets. The histological characteristics of the leaflet led to the selection of the pericardium as a substitute. And the characteristics of the hinge portion of the leaflet led to the development of a surgical technique which requires suturing of the pericardium at the cuspal attachment in the ratio of 3:2. In March of 1992, the development of new surgical technique began based on our integrated understanding of the histological characteristics and aortic root movement according to pressure changes in each cycle in a beating heart. Based on the basic principle that “normalization of deformed aortic root wall structures can solve all aortic root wall diseases”, new procedures such as STJ reduction, anulus reduction, and aortic sinus reduction or replacement procedure to normalize the ratio of the diameter and the height in a diseased aortic root were developed in March of 1996. Then, leaflet reconstruction to convert the 2-D pericardial patch to a 3-D leaflet structure based on our research was accomplished in 1999. To systemize the surgery, the diameter of the STJ at the upper plane of the aortic root was set as a convenient standard and representative index.

The templates for aortic sinus reduction and leaflet reconstruction based on the STJ diameter were developed to simplify the surgical process. Sizers to measure the STJ diameter and sizers to measure the diameters of the fibrous part and the muscular part of the annulus separately were developed. Additionally, leaflet retractors to secure an adequate surgical visual field and a knot slider to assist in tying in a deep and narrow area were invented. The rings and strips for the STJ and annulus reduction plasty were also developed. A provals from the KFDA in Korea and CE certification by European Union were obtained.

Through these developments, the new procedures were established as simple surgical procedures only based on determination of the STJ diameter. In 1997, this procedure was presented domestically under the title of “Novel Aortic Valvuloplasty”. At the 9th Aortic Surgery Symposium held in New York, U.S.A. on April of 2004, this surgical procedure was presented under the title of “Novel Technique of Aortic Valvuloplasty” This new procedure was then applied with wider indications to all the aortic root and valve diseases starting in March of 2007 after learning from our previous experiences. I am very confident that the results of this new repair procedure are much more superior to those of valve replacement. Looking back upon the past 26 years, I feel relieved and pleased that I could arrive at my final destination much like sailor finally discovering a new world by focusing only at the North Star.

This book contains not only the concepts and the methods to safely apply and use the procedure, but also the most important facts about structures, the functions, and the patho-physiology of disease development in the aortic root. Last but not least, I sincerely want to thank you all for the contribution to the growth of this procedure into an ideal operative technique. I also want to show my gratitude to the 1,200 patients who have undergone this surgery and recovered in the last 15 years. I also want to thank the late Professor Young-Kyoon Lee (Fig. 1) for his unyielding support and teachings even in his last days and his contribution to the heart surgeon that I’ve become. I would like to dedicate this book to my great teacher, Professor Albert Starr (Fig. 2) for the inspiration for the development of new procedure while I was at Oregon Health Sciences University. I also thank to my most respectable teacher and professor Aftab Ahmad for his kind teaching during my stay in Portland, Oregon. And I appreciate the Chairman of the Board of Directors in Konkuk University, Ms. Kyung Hee Kim who supported me consistently in spite of many obstacles. I also deeply want to thank to all the co-authors for sharing their vast knowledge and staying right beside me throughout the development of new procedure. I want to express my great appreciation and love for my wife Hyuk Soon for her supports and for my son Joon Young and my daughter-in-law Hyun Suh, and for my daughter Yoon Ju and my son-in-law Dong Hwan for their help in many aspects during the research. Finally, I dare to express my appreciation to God for giving me the opportunity and wisdom to do this research and develop this procedure.

Meong Gun Song

Section I Fundamentals _ 13

chapter 1. Introduction _ 15

chapter 2. Determination of research methods for aortic root and valve _ 27

chapter 3. Terminology _ 35

Section II Functional structure of aortic root _ 39

chapter 4. Functional structure of aortic root wall _ 41

chapter 5. Functional structure of aortic valve leaflet _ 69

Section III Analysis of aortic root disease _ 83

chapter 6. Registration of patients who have new procedure _ 85

chapter 7. Aortic regurgitation due to leaflet problem _ 89

chapter 8. Aortic stenosis _ 95

chapter 9. Aortic root wall disease _ 107

chapter 10. Mechanism of aortic root dilatation in connetive tissue disease _ 121

chapter 11. New procedure in special disease classified as ‘other disease’ _ 127

Section IV Surgical methods of new procedure _ 133

chapter 12. Principle and composition of new procedure _ 135

chapter 13. Operative management from skin incision to removal

of diseased valve _ 145

chapter 14. Evaluation of aortic root and determination of STJ diameter_ 155

chapter 15. Correction of aortic leaflet _ 167

chapter 16. Reduction or fixation of STJ _ 187

chapter 17. Reduction or replacement of aortic sinus wall _ 197

chapter 18. Reduction of aortic annulus _ 215

chapter 19. Relief of associated LVOTO_ 221

Section V Disease specified new procedure _ 227

chapter 20. New procedure in aortic root aneurysm _ 229

chapter 21. New procedure in aortic stenosis _ 241

chapter 22. New procedure in aortic regurgitation with leaflet disease _ 251

chapter 23. New procedure in infective endocarditis _ 259

chapter 24. New procedure in aortic regurgitation associated with

subarterial type VSD _ 277

chapter 25. New procedure in sinus of Valsalva aneurysm(rupture) _ 287

chapter 26. New procedure in the patients with previous AVR _ 303

chapter 27. Determination of new commissures in abnormal location

of coronary ostia _ 319

chapter 28. New procedure in aortic dissection _ 325

Section VI Experience of new procedure _ 337

chapter 29. Developmental experience of new procedure _ 339

chapter 30. Results and analysis of aortic valve repair procedure _ 347

Index _ 352