405 Does diastolic function improve after the left ventricular pressure afterload is removed?
© Williams et al; licensee BioMed Central Ltd. 2008
Published: 22 October 2008
Patients having aortic stenosis will invariably develop left ventricular hypertrophy (LVH) secondary to the increased left ventricular (LV) pressure. This normal compensatory process to accommodate afterload over time impairs diastolic function. LV diastolic function represents, amongst many, the relationship between left ventricular inflow velocities and left atrial pressure. We have previously shown that Cardiac MRI (CMR) can evaluate diastolic function using the phase velocity mapping (PVM) sequence with high accuracy as compared to the traditional modality, Echocardiography. The CMR approach for diastolic function is fast, efficient and reproducible. Using CMR, the impact of relief of pressure afterload on diastolic function metrics following aortic valve replacement (AVR) for patients with aortic stenosis is currently not known.
We hypothesize that diastolic function following AVR in patients with severe but compensated aortic stenosis will improve over time.
Ten (10) patients were evaluated for diastolic changes serially over time (prior to aortic valve replacement, baseline, 6 months, one year and variably up to 4 years. The baseline and longest time point available were chosen for this evaluation. All patients were scanned on a GE Excite HD, version 12 software, 1.5 T scanner (Milwaukee, WI), utilizing phase velocity mapping: phase acquisition: slice selection, 2 nex, venc 200, matrix: 256 frequency, 192 phase, 60 cardiac phases in the short axis (SA) position. A PVM slice was placed at the tips of the mitral valve leaflets. The resultant temporal resolution was 16 ± 3 ms. Patient data was analyzed on a separate workstation using the Medis (The Netherlands) Mass Plus flow analysis program. The contours were manually drawn encircling the MV leaflets, throughout the diastolic phase of the cardiac cycle. 'e' and 'a' maximum velocities were measured across the entire ROI of the mitral inflow plane. Deceleration time (DT), representing the time from maximum 'e' to isoflow-time (baseline) slope was measured as a metric to further represent diastole, but more importantly to distinguish normal from a pseudo-normal pattern.
LVH in patients with pressure afterload, initially beneficial, becomes detrimental to diastolic function. Following aortic valve replacement in patients with severe aortic stenosis for relief of this afterload, diastolic function, as measured by E:A change improved both in direction and amplitude in 90% of the patients and, by DT, in 100% of the patients. Measurements, historically confined to echocardiography, are shown here to be relatively easy and fast to accomplish while yielding important additional information about physiologic metrics in this complex patient population.
This article is published under license to BioMed Central Ltd.