Hemodynamics of paradoxical severe aortic stenosis: insight from a pressure–volume loop analysis
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Controversy exists about the pathophysiology of different hemodynamic subgroups of AS. In particular, the mechanism of the paradoxical low-flow, low-gradient (PLFLG) AS with preserved ejection fraction (EF) is unclear.
A total of 41 patients with severe, symptomatic AS were divided into the following 4 subgroups based on the echocardiographically determined hemodynamics: (1) normal-flow, high-gradient (NFHG) AS; (2) low-flow, high-gradient AS; (3) paradoxical low-flow, low-gradient (PLFLG) AS with preserved EF and (4) low-flow, low-gradient (LFLG) AS with reduced EF. As part of the comprehensive invasive examinations, the analyses of the PV loops were performed with the IntraCardiac Analyzer (CD-Leycom, The Netherlands).
PLFLG was characterized by small left ventricular volumes as well as a decreased cardiac index, a decreased systolic contractility and a lower stroke work, than the conventional NFHG AS. Alterations in effective arterial elastance (2.36 ± 0.67 mmHg/ml in NFHG versus 3.01 ± 0.79 mmHg/ml in PLFLG, p = 0.036) and end-systolic elastance (3.72 ± 1.84 mmHg/ml in NFHG versus 5.53 ± 2.3 mmHg/ml in PLFLG, p = 0.040) indicated impaired vascular function and increased chamber stiffness.
The present study suggests that the hemodynamics of PLFLG AS can be explained by two mechanisms: (1) stiffness of the small left ventricle with reduced contractility, and (2) increased afterload due to the impairment of vascular function. Both mechanisms have similarities to those of heart failure with preserved EF. This type of remodeling may explain the poor prognosis of PLFLG AS.
KeywordsAortic stenosis Pressure–volume loops Hemodynamics
Aortic valve stenosis
Aortic valve area
B-type natriuretic peptide
Heart failure with preserved ejection fraction
Paradoxical low-flow, low-gradient
Stroke volume index
Relaxation time constant
This work was supported by the German Heart Foundation/German Foundation of Heart Research (F/32/12).
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