Sándor J. Kovács
Sándor J. Kovács (born August 17, 1947) is a Hungarian-American academic cardiologist and cardiovascular physiologist, best known for his work on the physiological dynamics of the human heart. He is a professor of medicine, physics, physiology, and biomedical engineering at Washington University in St. Louis.
Early life and education
Born in Budapest, Hungary, Kovács, with his parents and sister, fled Hungary at the time of the Hungarian Revolution of 1956. His earliest memories are of scarcity and hardship during the communist era. The family was interned in Austrian refugee camps until 1959, when they were allowed to immigrate to Brooklyn, New York. As Kovács recalled in an interview,
I remember there were no refrigerators, just iceboxes. And if you wanted chicken for dinner, you went to the market and brought home a live chicken, holding it by its feet.
Kovács graduated from Brooklyn Technical High School and earned a B.S. in engineering at Cornell University in 1969. He then went to Caltech, where he initially studied theoretical and applied mechanics, transferred to physics and worked with Kip S. Thorne, receiving a Ph.D. in theoretical physics in 1977. While at Caltech, he was influenced by many interactions with Richard Feynman and George Zweig, when the latter was interested in the physics and physiology of human hearing.
Determined to change from theoretical physics to medicine, Kovács entered an accelerated Ph.D. to M.D. program at the University of Miami that awarded him a medical degree after 22 months of concentrated study, in 1979.
Kovács' subsequent career has been entirely at Washington University in St. Louis. After an internship and residency at Barnes Hospital, he became an instructor in medicine in 1985, served as director of the cardiac catheterization laboratory at the St Louis VA Medical Center (1985-1990) advancing through the ranks to professor of medicine, with also appointments in physiology, biomedical engineering, and physics, in 2007.
The Kovács lab has pioneered theoretical frameworks for analyzing diastole by incorporating and modeling the suction pump role of the heart, and the dynamics of the four-chambered heart in the space of coordinates spanned by P (pressure), V (volume), and their time rates of change dP/dt and dV/dt. They then seek to validate the model predictions using human, in vivo physiologic measurements of pressures (high fidelity transducers) and flows (echocardiography) of masses and volumes of heart chambers (cardiac MRI).
Among the results from this work is that the so-called third heart sound, "S3", formerly taught to be pathological, is actually produced by all hearts, but is merely below the threshold of hearing of most physicians.
Additional advances include the 'Parametrized Diastolic Filling (PDF) Formalism' wherein the early, mechanical suction-initiated rapid filling portion of diastole (the echocardiographic Doppler E-wave) is modeled kinematically in analogy to the recoil, from rest, of a damped simple harmonic oscillator. The linearity of the model allows solution of the inverse problem of diastole, using the digitized clinical Doppler E-wave contour as input, and obtaining unique values of the PDF parameters, that characterize load, viscosity/relaxation and chamber stiffness for each E-wave analyzed.
Among its many applications the PDF formalism led to solution of the long sought 'load-independent index of diastolic function' (LIIDF) problem, and to the realization that left ventricular volume at diastasis is the in vivo equilibrium volume of the left ventricle.
Kovács spends about half of his time on clinical activities, especially performing cardiac catheterizations with the use of simultaneous echocardiography complemented by related cardiac MRI techniques.
- Shmuylovich L, Chung CS, Kovács SJ, Yellin E, Nikolic SD. Point-Counterpoint: Left ventricular volume during diastasis IS/IS NOT the physiologic in-vivo equilibrium volume and IS/IS NOT related to diastolic suction? Journal of Applied Physiology 2009 Dec 24. (JAPPL-01399-2009).
- Shmuylovich L, Kovács SJ. Stiffness and relaxation components of the exponential and logistic time-constants may be used to derive a load-independent index of isovolumic pressure decay. American Journal of Physiology Heart and Circulatory Physiology 2008 Dec 295(6):H2551-9. Epub 2008 Oct 24.
- Zhang W, Kovács SJ. The Diastatic Pressure-Volume Relationship Is Not the Same as the End-Diastolic Pressure-Volume Relationship. American Journal of PhysiologyHeart and Circulatory Physiology 2008doi:10.1152/ajpheart.00200.
- Riordan MM, Weiss EP, Meyer TE, Ehsani AA, Racette SB, Villareal D, Fontana L, Holloszy JO, Kovács SJ. The Effects of Caloric Restriction- and Exercise-Induced Weight Loss on Left Ventricular Diastolic Function. American Journal of Physiology Heart and Circulatory Physiology 2008 294:H1174-82.
- Chung CS, Kovács SJ. The Physical Determinants of Left Ventricular Isovolumic Pressure Decline: Model Prediction with in-vivo Validation. American Journal of Physiology, Heart and Circulatory Physiology 2008 294:1589-1596.
Kovács received the Sjöstrand Medal in Physiology from the Swedish Society of Clinical Physiology and Medicine in 2007. He was elected President of the Cardiovascular System Dynamics Society (CSDS) in 2006 and served until 2008. He is a recipient of the Öcsi Bácsi Award of Caltech's TAPIR Group. He is a distinguished foreign member of the Hungarian Society of Cardiology.
- Gwen Ericson, "Man of heart: Kovács uses nature's language, math, to solve the body's mysteries", Washington University in St. Louis Newsroom, Apr. 30, 2008.
- Washington University in St. Louis School of Medicine, "Sandor J. Kovacs"
- Gwen Ericson, "How do you measure a broken heart? Researchers find long-sought answer", Washington University in St. Louis Newsroom, Sept. 14, 2006
- Manson AL. Nudelman SP, Hagley MT, Hall AF, Kovács SJ, Jr.: Relationship of the third heart sound transmitral flow velocity deceleration. Circulation 1995;92:388-394.
- Manson McGuire A, Hagley MT, Hall AF, Kovács SJ, Jr.: Relationship of the fourth heart sound to atrial systolic transmitral flow decel. Am J Physiology (Modeling in Physiology) 1997:H1527-H1536.
- Kovács SJ, Jr., Barzilai B, Perez J. Evaluation of diastolic function with Doppler echocardiography: the PDF formalism. American J.of Physiology, 252, H178-H187, 1987.
- Shmuylovich L, Kovács SJ. A load-independent index of diastolic filling: model-based derivation with in-vivo validation in control and diastolic dysfunction subjects. Journal of Applied Physiology, 2006;101: 92-101.
- Shmuylovich L, Chung CS, Kovács SJ. Point:Left ventricular volume during diastasis is the physiological in vivo equilibrium volume and is related to diastolic suction. Journal of Applied Physiology, 2010;109: 606-608.
- Caltech TAPIR Group, "Öcsi Bácsi Award"