This post was authored by Valentin Fuster, MD, PhD, Editor-in-Chief of JACC.
Dr. William W. Parmley was a pioneer for all cardiovascular researchers, and I feel proud that JACC continues to honor his legacy by recognizing two up-and-coming investigators, as well as their mentors and institutional research programs through this prestigious award each year.
This year, we honor two young researchers working in areas of great clinical interest:
Muralidhar Padala, PhD, from Emory University
- Mentor: Robert Guyton, MD
- Manuscript: “Temporal Changes in Interpapillary Muscle Dynamics as an Active Indicator of Mitral Valve and Left Ventricular Interaction in Ischemic Mitral Regurgitation in Humans,” published in the November 4 issue of JACC
Pablo Martínez-Legazpi, MEng, PhD, from Hospital Gregorio Maranon/University of California, San Diego
- Mentors: Javier Bermejo, MD, PhD & Juan C. del Álamo, AeEng, PhD
- Manuscript: “Contribution of the Diastolic Vortex Ring to Left Ventricular Filling,” published in the October 21 issue of JACC
In the first paper, Padala and his colleagues from Emory set out to prove that in patients with ischemic mitral regurgitation (IMR), it is not the passive left ventricular size but the loss of lateral interpapillary muscle distance shortening that governs IMR severity. They evaluated 67 patients with IMR using cardiac magnetic resonance imaging.
They found that the loss of lateral interpapillary muscle shortening tethers the leaflet edges and impairs their systolic closure, resulting in mitral regurgitation, even in small ventricles. “Understanding the lateral dynamics of ventricle-valve interactions could aid the development of new repair techniques for ischemic mitral regurgitation,” the authors wrote in JACC.
After reading these results, it seems that we have been misguided in thinking that it was the dilatation of the ventricle in ischemic heart disease that leads to the dilatation of the annulus; therefore, annuloplasty may have been a procedure of choice. These exciting results could lead to new methods to treating ischemic mitral regurgitation.
Importantly, for the purposes of the Parmley award, this clinical research was built on previous studies in animal models, demonstrating the perseverance of the researchers to stick with a concept and see it through to assess its efficacy in humans.
In an equally exciting second paper, Martínez-Legazpi and his fellow researchers from two continents sought to understand the impact of intraventricular flow patterns on filling and to assess whether impaired fluid dynamics may be a source of diastolic dysfunction. Previously, little attention has been paid to the complex flow dynamic that occur during ventricular filling. The large vortical flow structures that develop during diastole appear particularly relevant.
To test their hypothesis, the researchers obtained 2D Doppler echocardiographic exams in 20 patients with nonischemic dilated cardiomyopathy (NIDCM), 20 patients with hypertrophic cardiomyopathy (HCM), and 20 control healthy volunteers.
Using a flow decomposition method, the researchers isolated the rotational velocity generated by the vortex ring from the surrounding flow in the left ventricle. Of great interest, the vortex was responsible for entering 13% of filling volume in the control group and 19% in the NIDCM group, but only 5% in the HCM group. Thus, the authors concluded that the diastolic vortex is responsible for entering a significant fraction of left ventricular filling volume at no energetic or pressure cost. In JACC, the authors summarized, “impaired vortex generation is an unreported mechanism of diastolic dysfunction in HCM and probably other causes of concentric remodeling.”
This paper will cause even seasoned cardiologists to return to their understanding of physiology to better understand the left ventricle filling volume. In fact, the authors of the editorial comment wrote that “the study symbolizes a shift in our thinking that the heart is just a simple pressure generating mechanism.”
Thus, this multidisciplinary team of engineers and cardiologists came together with a well-crafted study that may result in the development of more sophisticated measures of diastolic function to better understand left ventricular dynamics in diastole, as well as in subsequent systole.
These two individuals – Padala and Martínez-Legazpi, along with their mentors and supporting institutions – are wonderful examples of the success that can be achieved through perseverance in pursuing new clinical pathways.