Abstract
Background: Limited invasive (electromagnetic) ascending aortic (AA) flow wave contour indicates impaired left ventricular (LV) function in the elderly. However, conventional non-invasive (Doppler) recordings have not shown similar aging change. Aim: To illustrate changes in AA flow and carotid pressure waves in an apparently normal cohort, using cardiac magnetic resonance imaging (CMRI). Methods: Fifty subjects (aged 21–70 years; 28 males) underwent velocity-encoded CMRI of the thoracic aorta using a 1.5T system (Signa, GEMS, Waukesha, USA). AA flow was measured non-invasively by subtracting simultaneous forward and backward flow velocity across the AA cross-section. DR⅓ was determined as ratio of difference in flow velocity between systolic peak and one-third of deceleration phase to peak flow velocity. Comparisons were made between young (≤50 years; n=30) and older subjects (>50 years; n=20). Results: Peak AA flow velocity decreased substantially (P50 years) (P<0.0001) from young (66.7 ± 17.7 cm/s) to older subjects (47.7 ± 12.7 cm/s). This could be associated with the age-related increase in aortic diameter. The substantial differences between CMRI flow waveforms and Doppler are due to the use of the outer flow envelope (highest particle flow) to estimate flow across the aortic cross-section with Doppler. However, late systolic flow was relatively lower in the older than in the younger subjects, with flow concavity in older persons (corresponding to greater augmentation of the pressure waveform), represented as DR⅓, which declined from 78% (≤50 years) to 69% (>50 years) (P<0.001). These features are explicable on the basis of LV impairment from early and increased wave reflection during systole, and suggest reduction of wave reflection as a strategy for treating heart failure in the elderly. Conclusion: AA flow waves recorded by CMRI showed aging changes, which are not apparent in conventional Doppler flow patterns. Our finding warrants further use of AA CMRI flow and pressure waveforms to characterize aging changes and ill-effects of stiffened central arteries. Findings support predictions of Westerhof and O'Rourke (J Hypertens 1995;13:943–952) and the force/velocity interpretations of Miyashita et al. (Heart Vessels 1994;9:30–39) and Chiu et al. (Circ Res 1992;70:530–535).
| Original language | English |
|---|---|
| Pages (from-to) | E143 |
| Number of pages | 1 |
| Journal | Hypertension |
| Volume | 63 |
| Issue number | 6 |
| Publication status | Published - Jun 2014 |
| Event | Annual Scientific Meeting of the High Blood Pressure Research Council of Australia (HBPRCA) (35th : 2013) / Annual Scientific Meeting of the Australian Atherosclerosis Society (AAS) (39th : 2013) - Melbourne, Australia, Australia Duration: 5 Dec 2013 → 7 Dec 2013 |