MedicalResearch.com Interview with
Mark Oldham, M.D.
Assistant Professor of Psychiatry
Medical Director, PRIME Medicine
Proactive Integration of Mental Health Care in Medicine
University of Rochester Medical Center
MedicalResearch.com: What is the background for this study?
Response: Patients who have undergone coronary artery bypass graft (CABG) surgery and, specifically, those who have been placed on cardiopulmonary bypass (CPB) have received attention for the potential effects of such procedures on brain health. Heart valve surgery patients have received far less attention, which often leaves clinicians to extrapolate the data from CABG cohorts to their patients preparing to undergo valve surgery. However, there are many reasons why this is far less than ideal, especially as the CABG literature increasingly points to person- and procedure-specific factors as the determinants of postoperative cognitive outcomes.
MedicalResearch.com Interview with:
Josep Rodés-Cabau MD
Quebec Heart and Lung Institute,
Quebec City, QC, Canada
Medical Research: What is the background for this study? What are the main findings?
Dr. Rodés-Cabau: Hemolysis is the breakdown of red blood cells (RBC) in the body. There are many different causes of hemolysis, however a common cause is when RBCs traverse foreign substances, such as inserted heart valve prostheses. The biological interaction between the RBC and a foreign substance may cause RBC lysis/destruction. Furthermore, in the setting of turbulent blood flow, such as when a prosthetic heart valve is starting to leak, the degree of hemolysis could reflect the severity and duration of this leak. In the absence of valve leaks, hemolysis rates and severity may simply reflect how biocompatible a foreign/prosthetic valve is within the body. The lower the hemolysis rate and severity, the more biocompatible the valve/foreign body.
There are many different brands and generations of prosthetic heart valves that have been implanted in humans during the prior decades. The early-generation surgically implanted valves caused quite severe hemolysis requiring re-operation when possible. Modern-day surgical heart valves now have superior designs and rarely cause significant hemolysis. Nevertheless the rates of sub-clinical (or biochemical) hemolysis are around 30% for modern-day mechanical heart valves.
Nowadays, certain patients are eligible to undergo transcatheter aortic valve implantation (TAVI), a revolutionary means of valve replacement without the need for open heart surgery. However to-date, the biocompatibility of these new transcatheter heart valves has not been tested in humans in vivo. We systematically evaluated hemolysis rates and its associated factors in a large consecutive series of patients undergoing TAVI at the Quebec Heart & Lung Institute, Quebec, Canada.
We found that the rate of transcatheter heart valve hemolysis was 15%, lower than that reported for modern-day mechanical surgically implanted valves. No patient demonstrated severe hemolysis. The presence of a size mismatch between the patient and transcatheter valve (termed prosthesis patient mismatch) significantly associated with the likelihood of hemolysis. Indirect measurements of wall shear stress also associated with hemolysis rates.
MedicalResearch.com Interview with:
Joanna Chikwe MD
Department of Cardiovascular Surgery
Mount Sinai Medical Center and
Natalia N. Egorova, PhD
Department of Health Evidence and Policy,
Icahn School of Medicine at Mount Sinai
New York, New York
Medical Research: What are the main findings of the study?
Answer: This is one of the largest studies to date on the long-term outcomes of patients after aortic valve replacement. We found that bioprosthetic valves are as safe as mechanical valves in younger patients (age 50-69) – specifically, long-term death rates and stroke risk were very similar in patients who had either valve type. The main differences lay in the risk of other long-term complications: patients who had bioprosthetic valves were more likely to need repeat surgery in the long-term, whereas patients who had mechanical valves were more likely to experience a major bleeding event.