Kamal R. Khabbaz, MD

The multidisciplinary Valve Research Group primarily investigates the dynamic behavior of heart valves in both normal and pathologic states. Heart valves are complex 3-dimensional (3D) structures that undergo dynamic changes during the cardiac cycle. Investigating this behavior is of critical importance in understanding the pathophysiology of and devising management strategies for valvular disease.

Together with Dr. Feroze Mahmood and a multidisciplinary Valve Research Group, normal and abnormal size, shape, and geometric parameters pertaining to the mitral, tricuspid, and aortic valves are being researched. In addition, we are studying the impact different surgical interventions (e.g., aortic valve replacement and mitral annuloplasty) have on native valve function and surrounding anatomy. To accomplish this, we analyze 3D echocardiographic data using commercially available software, including Philips Qlab and TomTec Image Arena. These software programs enable us to dynamically track and measure anatomical changes in a clinically feasible fashion.

We are currently extending similar analyses to normal and pathologic tricuspid valves, leading to a more robust understanding of tricuspid valve behavior. Investigations are also underway to investigate the in vivo effects of different annuloplasty devices on dynamic valve motion and geometry. These data and analyses hold significant potential in furthering the evidence base for valve repair strategies and surgical decision-making toward achieving the best outcomes.

The Valve Research Group is involved with multiple national and international universities engaged in devising new methods of interrogating valvular structures using 3D echocardiography. We are continuing our collaboration with Cardiology and Vascular and Endovascular Surgery on multiple projects, including clinical trials:

• Multi-Center Experience with the Rapid Deployment EDWARDS INTUITY Valve System for Aortic Valve ReplaceMent (TRANSFORM Trial, Protocol Number 2011-02): The purpose of this clinical investigation is to assess the safety and effectiveness of the investigational EDWARDS INTUITY Valve System in subjects with aortic stenosis or stenosis-insufficiency requiring replacement of the native aortic valve.
• Clinical Trial of the On-X Valve Using Low Dose Anticoagulation: The purpose of this study is to define the lowest level of required antithrombotic therapy for mitral or aortic valve replacement using the On-X Valve.
• Medtronic Core Valve U.S. Pivotal Trial–Extreme Risk Patients; Medtronic CoreValve® U.S. Pivotal Trial – High Risk Surgical Patients; Medtronic CoreValve® U.S. Continued Access Study; Medtronic CoreValve® U.S. Expanded Use Study; Medtronic CoreValve® SURTAVI Trial: The purpose of this study is to determine the safety and efficacy of the Medtronic CoreValve® System in the treatment of symptomatic severe aortic stenosis in high-risk and very high-risk subjects who need aortic valve replacement.
• Early Feasibility Study of the CardiAQ™ Transcatheter Mitral Valve (TMV) System with Transseptal Delivery System for the Treatment of Moderate to Severe Mitral Regurgitation REPRISE III: REpositionable Percutaneous Replacement of Stenotic Aortic Valve through Implantation of Lotus™ Valve System-Randomized Clinical Evaluation

Several studies are in progress; those completed so far have shown promising results. The results of one study demonstrate that left-ventricular outflow tract area is significantly underestimated by two-dimensional (2D) measurements when compared with 3D data.

This underestimation of the LVOT area with 2D echocardiography potentially overestimates the degree of aortic stenosis (AS). Such errors in assessing disease severity can have important clinical consequences vis-à-vis the decision to operate vs. not operate. In another study, we describe the workflow in development and use of a customizable left-sided pulsatile heart model in which patient-specific, 3-dimensionally printed patient valves can be modeled under physiological intracardiac pressures. The model allows for TEE visualization and promotes familiarization of heart anatomy, surgical equipment, and imaging workflow for trainees.

We have also successfully demonstrated the use of 3D echocardiography in analyzing mitral valve geometry in patients with functional mitral valve regurgitation (FMR). Previously, the understanding of annular dynamics in FMR was largely limited to information derived from animal models.

The Valve Research Group has been recognized and granted the status of a hospital "core laboratory" for 3D printing, establishing a state-of-the-art 3D printing laboratory. We have recently begun 3D printing patient-specific mitral valves for creation of silicone replicas to be placed in our state-of-the-art pulse duplicator device, which generates realistic pulsatility and allows for TEE visualization. Additionally, multiple echocardiography simulators serve as a dedicated simulation laboratory.

I teach residents in our ACGME-accredited Cardiothoracic Surgery Residency Program as well as postgraduate fellows. I also teach BIDMC General Surgery residents (PGY-3) in cardiac surgery techniques, and continue to teach a course on echocardiography at Harvard Medical School (HMS). In addition, I teach third and fourth-year HMS students rotating on cardiothoracic surgery and an elective in thoracic and cardiovascular surgery for fourth-year HMS students.

Multi-Center Experience with the Rapid Deployment EDWARDS INTUITY Valve System for Aortic Valve ReplaceMent (TRANSFORM Trial). Edwards Lifesciences, 2014-2024; PI: Kamal Khabbaz, MD (Co-Investigator: David Liu, MD)

O'Gara BP, Mueller A, Gasangwa DVI, Patxot M, Shaefi S, Khabbaz K, Banner-Goodspeed V, Pascal-Leone A, Marcantonio ER, Subramaniam B. Prevention of early postoperative decline: A randomized, controlled feasibility trial of perioperative cognitive training. Anesth Analg 2020;130(3):586-595.

Van Mieghem NM, Popma JJ, Deeb GM, Yakubov SJ, Serruys PW, Windecker S, Søndergaard L, Mumtaz M, Gada H, Chetcuti S, Kleiman NS, Kodali S, George I, Teefy P, Kiaii B, Oh JK, Kappetein AP, Chang Y, Mugglin AS, Reardon MJ; SURTAVI Trial Investigators; Clinical Trial. Complete 2-year results confirm Bayesian analysis of the SURTAVI trial. JACC Cardiovasc Interv 2020;13(3):323-331.

Mufarrih SH, Qureshi NQ, Khabbaz KR, Mahmood F, Sharkey A. Curious case of mitral and tricuspid regurgitation. J Cardiothorac Vasc Anesth 2020;Sep 15:S1053-0770(20)31008-9. Fatima H, Matyal R, Mahmood F, Baribeau Y, Khabbaz KR. Ischemic mitral regurgitation: To fix or not to fix. J Cardiothorac Vasc Anesth 2020;34(9):2532-2535.

Fatima H, Mahmood F, Sehgal S, Belani K, Sharkey A, Chaudhary O, Baribeau Y, Matyal R, Khabbaz KR. Artificial intelligence for dynamic echocardiographic tricuspid valve analysis: A new tool in echocardiography. J Cardiothorac Vasc Anesth 2020;34(10):2703-2706.

Liu S, Bose R, Ahmed A, Maslow A, Feng Y, Sharkey A, Baribeau Y, Mahmood F, Matyal R, Khabbaz K. Artificial intelligence-based assessment of indices of right ventricular function. J Cardiothorac Vasc Anesth 2020;34(10):2698-2702.