Low flow, low gradient severe aortic stenosis
- William H Gaasch, MD
William H Gaasch, MD
- Section Editor — Valvular Disease
- Professor of Medicine
- University of Massachusetts Medical School
- Tufts University School of Medicine
- Senior Consultant in Cardiology
- Lahey Clinic
Symptomatic patients with severe aortic stenosis (AS) generally have a substantial improvement in symptoms and increased survival after aortic valve replacement. These beneficial results can even be observed in those who have developed left ventricular (LV) dysfunction and heart failure [1,2]. However, not all such patients benefit from aortic valve replacement. In particular, the subset of patients with AS and a low transvalvular pressure gradient due to significant LV failure have considerable operative risk and limited potential for improvement with surgery .
Issues relating to low gradient AS will be reviewed here. The clinical presentation and treatment of AS are discussed separately. (See "Clinical manifestations and diagnosis of aortic stenosis in adults" and "Medical management of asymptomatic aortic stenosis in adults" and "Indications for valve replacement in aortic stenosis in adults", section on 'Low gradient aortic stenosis'.)
DEFINITION AND SPECTRUM OF DISEASE
The transaortic gradient depends upon the severity of the stenosis and upon flow rate, which is determined by the stroke volume and systolic ejection period. Most patients with symptomatic severe aortic stenosis (AS) have an aortic velocity of 4 m/s or higher, corresponding to a mean transvalvular pressure gradient of at least 40 mmHg and a valve area that is <1.0 cm2 (table 1B).
Low flow, low gradient severe AS (also referred to as low output, low gradient severe AS) is defined as a valve area ≤1.0 cm2 with an aortic velocity <4.0 m/s or mean transvalvular pressure gradient ≤40 mmHg . Low flow, low gradient severe AS occurs in the setting of a low flow rate across the valve either due to left ventricular (LV) systolic dysfunction with reduced LV ejection fraction (LVEF) or to small ventricular volumes with LV hypertrophy and a normal LVEF. When LVEF is normal, low flow is defined as a stroke volume index ≤35 mL/m2. Among 971 patients in the PARTNER trial, the following findings were reported :
●Low flow (LV stroke volume index ≤35 mL/m2) in 530 patients (55 percent)
- Carabello BA, Green LH, Grossman W, et al. Hemodynamic determinants of prognosis of aortic valve replacement in critical aortic stenosis and advanced congestive heart failure. Circulation 1980; 62:42.
- Smith N, McAnulty JH, Rahimtoola SH. Severe aortic stenosis with impaired left ventricular function and clinical heart failure: results of valve replacement. Circulation 1978; 58:255.
- Carabello BA. Is it ever too late to operate on the patient with valvular heart disease? J Am Coll Cardiol 2004; 44:376.
- Bonow RO, Carabello BA, Chatterjee K, et al. 2008 Focused update incorporated into the ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 1998 Guidelines for the Management of Patients With Valvular Heart Disease): endorsed by the Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. Circulation 2008; 118:e523.
- Herrmann HC, Pibarot P, Hueter I, et al. Predictors of mortality and outcomes of therapy in low-flow severe aortic stenosis: a Placement of Aortic Transcatheter Valves (PARTNER) trial analysis. Circulation 2013; 127:2316.
- Brogan WC 3rd, Grayburn PA, Lange RA, Hillis LD. Prognosis after valve replacement in patients with severe aortic stenosis and a low transvalvular pressure gradient. J Am Coll Cardiol 1993; 21:1657.
- Lund O. Preoperative risk evaluation and stratification of long-term survival after valve replacement for aortic stenosis. Reasons for earlier operative intervention. Circulation 1990; 82:124.
- Blitz LR, Gorman M, Herrmann HC. Results of aortic valve replacement for aortic stenosis with relatively low transvalvular pressure gradients. Am J Cardiol 1998; 81:358.
- Connolly HM, Oh JK, Schaff HV, et al. Severe aortic stenosis with low transvalvular gradient and severe left ventricular dysfunction:result of aortic valve replacement in 52 patients. Circulation 2000; 101:1940.
- Monin JL, Quéré JP, Monchi M, et al. Low-gradient aortic stenosis: operative risk stratification and predictors for long-term outcome: a multicenter study using dobutamine stress hemodynamics. Circulation 2003; 108:319.
- Nishimura RA, Grantham JA, Connolly HM, et al. Low-output, low-gradient aortic stenosis in patients with depressed left ventricular systolic function: the clinical utility of the dobutamine challenge in the catheterization laboratory. Circulation 2002; 106:809.
- Lauten J, Rost C, Breithardt OA, et al. Invasive hemodynamic characteristics of low gradient severe aortic stenosis despite preserved ejection fraction. J Am Coll Cardiol 2013; 61:1799.
- GORLIN R, GORLIN SG. Hydraulic formula for calculation of the area of the stenotic mitral valve, other cardiac valves, and central circulatory shunts. I. Am Heart J 1951; 41:1.
- Cannon SR, Richards KL, Crawford M. Hydraulic estimation of stenotic orifice area: a correction of the Gorlin formula. Circulation 1985; 71:1170.
- Burwash IG, Thomas DD, Sadahiro M, et al. Dependence of Gorlin formula and continuity equation valve areas on transvalvular volume flow rate in valvular aortic stenosis. Circulation 1994; 89:827.
- Grayburn PA. Assessment of low-gradient aortic stenosis with dobutamine. Circulation 2006; 113:604.
- Ford LE, Feldman T, Chiu YC, Carroll JD. Hemodynamic resistance as a measure of functional impairment in aortic valvular stenosis. Circ Res 1990; 66:1.
- Hachicha Z, Dumesnil JG, Bogaty P, Pibarot P. Paradoxical low-flow, low-gradient severe aortic stenosis despite preserved ejection fraction is associated with higher afterload and reduced survival. Circulation 2007; 115:2856.
- Jander N, Minners J, Holme I, et al. Outcome of patients with low-gradient "severe" aortic stenosis and preserved ejection fraction. Circulation 2011; 123:887.
- deFilippi CR, Willett DL, Brickner ME, et al. Usefulness of dobutamine echocardiography in distinguishing severe from nonsevere valvular aortic stenosis in patients with depressed left ventricular function and low transvalvular gradients. Am J Cardiol 1995; 75:191.
- Bermejo J, García-Fernández MA, Torrecilla EG, et al. Effects of dobutamine on Doppler echocardiographic indexes of aortic stenosis. J Am Coll Cardiol 1996; 28:1206.
- Lin SS, Roger VL, Pascoe R, et al. Dobutamine stress Doppler hemodynamics in patients with aortic stenosis: feasibility, safety, and surgical correlations. Am Heart J 1998; 136:1010.
- Blais C, Burwash IG, Mundigler G, et al. Projected valve area at normal flow rate improves the assessment of stenosis severity in patients with low-flow, low-gradient aortic stenosis: the multicenter TOPAS (Truly or Pseudo-Severe Aortic Stenosis) study. Circulation 2006; 113:711.
- Bergler-Klein J, Mundigler G, Pibarot P, et al. B-type natriuretic peptide in low-flow, low-gradient aortic stenosis: relationship to hemodynamics and clinical outcome: results from the Multicenter Truly or Pseudo-Severe Aortic Stenosis (TOPAS) study. Circulation 2007; 115:2848.
- Herrmann S, Störk S, Niemann M, et al. Low-gradient aortic valve stenosis myocardial fibrosis and its influence on function and outcome. J Am Coll Cardiol 2011; 58:402.
- Pereira JJ, Lauer MS, Bashir M, et al. Survival after aortic valve replacement for severe aortic stenosis with low transvalvular gradients and severe left ventricular dysfunction. J Am Coll Cardiol 2002; 39:1356.
- Quere JP, Monin JL, Levy F, et al. Influence of preoperative left ventricular contractile reserve on postoperative ejection fraction in low-gradient aortic stenosis. Circulation 2006; 113:1738.
- Lange RA, Hillis LD. Dobutamine stress echocardiography in patients with low-gradient aortic stenosis. Circulation 2006; 113:1718.
- Bergler-Klein J, Klaar U, Heger M, et al. Natriuretic peptides predict symptom-free survival and postoperative outcome in severe aortic stenosis. Circulation 2004; 109:2302.
- Weidemann F, Herrmann S, Störk S, et al. Impact of myocardial fibrosis in patients with symptomatic severe aortic stenosis. Circulation 2009; 120:577.
- DEFINITION AND SPECTRUM OF DISEASE
- Reduced LVEF
- - True stenosis
- - Pseudostenosis
- Normal LVEF
- DIFFERENTIATING TRUE STENOSIS FROM PSEUDOSTENOSIS
- Plasma brain natriuretic peptide
- Mitral annular plane systolic excursion
- PREDICTORS OF OUTCOME FROM SURGERY
- Contractile reserve
- Plasma BNP
- INFORMATION FOR PATIENTS
- SUMMARY AND RECOMMENDATIONS