Evaluation of Aortic Stenosis Severity: New Challenges, New Solutions

Abstract

Aortic stenosis (AS) is now very frequently encountered, to the extent that aortic valve replacement (AVR) has become the second most frequently performed cardiac surgical procedure. Concomitantly, the most frequently encountered etiology and physiopathology of this entity have changed considerably. Indeed, 30 years ago, patients with AS were typically younger individuals with either rheumatic heart valve disease or congenitally bicuspid aortic valves. The reduction in aortic valve area (AVA) was usually fixed and due to a fusion of the valvular commissures, and the primary disease was deemed to be limited to the valve, without any particular involvement of the left ventricle, the ascending aorta, or the rest of the vascular tree. In contrast, AS is at present most frequently encountered in older individuals, and the most prevalent etiology is a degenerative process that is more or less akin to a variant form of atherosclerosis. The result of this process is valve leaflet thickening with decreased mobility but typically without commissural fusion. Hence, the reduction in AVA is not fixed and will vary in relation with prevailing hemodynamic conditions (i.e., the valve will tend to open more in response to an increase in cardiac output). In addition, these individuals frequently have other manifestations of atherosclerosis, such as decreased systemic arterial compliance, which may contribute to an additional increase in left ventricular (LV) hemodynamic load, and/or coronary artery disease, resulting in a decrease in LV function beyond that which would have been expected if the disease had been purely limited to the valve. Indeed, a reduction in systemic arterial compliance entails an increase of both the systolic and pulse pressure (e.g., for a similar stroke volume, the blood pressure can be 160/80 mm Hg instead of 120/80 mm Hg), in which case the LV systolic pressure given a peak-to-peak valvular gradient of 50 mm Hg could be ±210 mm Hg instead of ±170 mm Hg. Likewise, the coexistence of myocardial ischemia due to coronary artery disease may entail a decrease in ejection fraction beyond that expected for a given degree of AS severity. Hence, the clinical presentation of the disease is often much more complex and multifaceted than previously believed, and clinicians are often faced with new diagnostic and therapeutic challenges requiring new solutions. Such challenges and solutions are elegantly illustrated by two reports in the current issue of JASE. 1 Lee S.-P. Kim Y.-J. Kim J.-H. Park K. Kim K.-H. Kim H.-K. et al. Deterioration of myocardial function in paradoxical low-flow severe aortic stenosis: two-dimensional strain analysis. J Am Soc Echocardiogr. 2011; 24: 976-983 Abstract Full Text Full Text PDF PubMed Scopus (24) Google Scholar , 2 Iwahashi N. Nakatani S. Umemura S. Kimura K. Kitakaze M. Usefulness of plasma B-type natriuretic peptide in the assessment of disease severity and prediction of outcome after aortic valve replacement in patients with severe aortic stenosis. J Am Soc Echocardiogr. 2011; 24: 984-991 Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar Deterioration of Myocardial Function in Paradoxical Low-Flow Severe Aortic Stenosis: Two-Dimensional Strain AnalysisJournal of the American Society of EchocardiographyVol. 24Issue 9PreviewThe diagnosis and management of paradoxical low-flow (PLF) aortic stenosis (AS) is challenging in clinical practice. In addition, its pathophysiology has not been fully understood. The aim of this study was to test the hypothesis that left ventricular (LV) myocardial function is deteriorated in PLF AS and that it is closely related to global LV afterload. Full-Text PDF Usefulness of Plasma B-Type Natriuretic Peptide in the Assessment of Disease Severity and Prediction of Outcome after Aortic Valve Replacement in Patients with Severe Aortic StenosisJournal of the American Society of EchocardiographyVol. 24Issue 9PreviewThe diagnostic and prognostic value of plasma B-type natriuretic peptide (BNP) level in isolated aortic stenosis (AS) has not been fully understood. Full-Text PDF