| Biography: Dr. Najjar received his bachelor's degree, magna cum laude, from Harvard College, and his M.D. degree from Yale University, where he was elected to the AOA honor society. He completed his internship and residency training at Johns Hopkins Hospital. He subsequently completed his cardiovascular fellowship at Johns Hopkins University, with advanced training in cardiomyopathy and heart transplantation. He joined the Laboratory of Cardiovascular Science in 2000, and became the head of the Human Cardiovascular Studies Unit in 2002. |
| Overview: Research interests focus on cardiac and vascular structure and function, and include 1) characterizing their determinants to identify potential targets for interventions; 2) exploring how they interact with and influence cardiovascular aging and reserve, both in the absence and in the presence of sub-clinical as well as clinical diseases; and 3) evaluating how they modulate the response to standard and novel therapies for hypertension and heart failure. Research interests also include exploring non-pharmacological interventions in heart failure. |
| The research agenda of the Human Cardiovascular Studies Unit includes four major programs. The first program focuses on exploring the age-associated changes in vascular structure and function, including arterial wall thickness and compliance, how they interact with aging, lifestyle, the environment, and various disease states, and how they impact the structure and function of the heart. The second program investigates traditional, as well as, novel cardiovascular risk factors, with particular attention to vascular structure and function, in an attempt to elucidate the pathophysiological basis for the dominant role of age as a potent risk factor for cardiovascular diseases. The third program comprises clinical research studies in congestive heart failure. We have an interest in both systolic heart failure as well as the elusive diastolic heart failure, which afflicts and is particularly burdensome in the elderly. The fourth program is a translational cardiovascular research program that is actively being developed, and which, we hope, will capitalize on the exciting bench research findings and discoveries made in the Laboratory of Cardiovascular Science as well as other laboratories within the NIA. |
| Describing the age-associated changes in cardiovascular structure and function is one of the central tenets of the Laboratory of Cardiovascular Science. There is a growing body of evidence that increased thickening and stiffening of large arteries, endothelial dysfunction, and the ensuing increases in systolic and pulse pressure, in otherwise apparently healthy older individuals, formerly thought to be part of "normal" aging, precede and predict a higher risk for developing clinical cardiovascular disease. We are interested in characterizing the determinants of the age-associated changes in both vascular and cardiac structure and function, with particular emphasis on exploring the properties of the vasculature, including arterial wall thickness and compliance, investigating how they interact with aging, lifestyle, the environment, and various disease states. We are also exploring how they impact the structure and function of the heart. Indeed, ventricular-vascular interaction, or "coupling," is an important and largely under-appreciated determinant of cardiac performance. Normal ventricular-vascular coupling determines optimal left ventricular stroke work, cardiac efficiency, and ejection fraction. We therefore believe that much insight into the structural and functional alterations and adaptations of the cardiovascular system, as well as the cardiovascular reserve, may be gleaned from examination of the coupling between the heart and the vasculature. We are also studying interventions that modulate specific features of cardiovascular structure and function, especially those identified as deleterious or "risky." |
| Age is the dominant risk factor for cardiovascular diseases, yet the increased risk associated with aging has remained largely elusive. The accumulating evidence implicating the role of the age-associated changes in vascular structure and function as independent risk factors for cardiovascular diseases and outcomes, suggests that aging itself must alter the vascular substrate so as to promote the development, progression and manifestations of cardiovascular diseases. It is thus our hypothesis that the age-associated alterations in cardiovascular structure and function may explain, in part, the increased cardiovascular risk associated with aging. We are therefore interested in studying the impact of traditional cardiovascular risk factors, as well as novel risk factors such as markers of inflammation and the metabolic syndrome, on cardiovascular structure and function. We are applying state-of-the-art imaging modalities to better characterize coronary as well as carotid arterial atherosclerosis, to evaluate the influence of vascular properties (including arterial thickness and stiffness) on the relationship between age and atherosclerosis. By relating the dissociation between physiologic and chronologic aging to atherosclerosis, we expect to define (and compare) "successful" versus "usual" versus "accelerated" cardiovascular aging. |
| We have a clinical interest in congestive heart failure. Congestive heart failure is a clinical syndrome that affects approximately 5 million Americans. It is estimated that 400,000 new cases are diagnosed every year. The annual expenditure is estimated at 15 to 40 billion dollars annually. The prevalence and incidence of heart failure increase exponentially with age. There is a ten-fold increase in the incidence of this syndrome between the fifth and the ninth decades of life, such that its prevalence is estimated at 10% among those over the age of 80. Our clinical research studies address aspects of both systolic heart failure as well as diastolic heart failure, which afflicts and is particularly burdensome in the elderly. Epidemiologic data indicate that up to 40% of patients with CHF have normal ejection fractions. However, there is a paucity of studies on this distinct clinical entity. As a result, the pathophysiology of heart failure with preserved systolic function remains poorly elucidated, and effective therapies - which are badly needed - have not been developed yet. |
