The National Heart, Lung, and Blood Institute convened a Working Group of investigators on August 20, 2004, in McLean, Virginia to evaluate the current state of knowledge regarding interactions between the cardiovascular system and the kidney, to identify critical gaps in our knowledge, understanding, and application of research tools, and to develop specific recommendations for NHLBI in cardio-renal interactions related to heart failure and other cardiovascular diseases congenital heart disease.
The Working Group focused on cardio-renal connections in which abnormalities of cardiac function were not preceded by a known diagnosis of chronic kidney disease, such that acute and chronic renal responses are due to primary impairment of cardiac function. Among patients hospitalized for decompensated heart failure, worsening renal function predicts adverse cardiovascular outcomes. Since these patients are routinely excluded, clinical heart failure trials provide little evidence or information on which to base therapy for heart failure patients experiencing worsening renal function. As a result, treatment for these patients is largely empirical. The lack of formal interaction across clinical disciplines, with insight into the diverse factors that affect both cardiac and renal function, has also limited our recognition, understanding, and potential therapies for cardio-renal dysregulation in heart failure. New and effective therapies need to be identified for the treatment and prevention of this challenging syndrome. The deliberations and considerations of this Working Group should broaden the perspective and enhance understanding across traditional specialty boundaries.
A working definition of cardio-renal dysregulation was introduced and served as the basis of subsequent discussion and recommendations. In heart failure, it is the result of interactions between the kidneys and other circulatory compartments that increase circulating volume and symptoms of heart failure and disease progression are exacerbated. At its extreme, cardio-renal dysregulation leads to what is termed "cardio-renal syndrome" in which therapy to relieve congestive symptoms of heart failure is limited by further decline in renal function. It is clear that our current understanding of cardio-renal connections is inadequate to explain many of the clinical observations in heart failure or to direct its therapy. Further investigation is required to elucidate the pathways by which integration of the cardiovascular and renal systems effectively maintains volume regulation in order to develop effective therapies.
The following recommendations are proposed. They focus primarily on clinical studies in subsets of patients with heart failure:
The report will be posted on the NHLBI public web site with a link to the journal or journals where the report is published.
Frank Evans, Ph.D., NHLBI, NIH
John Fakunding, Ph.D.