Abstract 550: Early Diastolic Strain Rate: Is It Truly Preload Independent?
Background: It has been suggested that early diastolic strain rate is preload independent in humans; however, there is little objective data with which to support or refute this claim. To determine the preload independence, or dependence, of global early diastolic strain rate, we measured this index in healthy young and elderly men as preload was manipulated using lower body negative pressure (LBNP) and rapid saline infusion.
Methods: Ten healthy young (20 – 35 years of age) and 19 healthy elderly (60 – 76 years of age) men underwent right heart catheterization with simultaneous transthoracic tissue Doppler echocardiography. Pulmonary capillary wedge pressure (PCWP) and global early diastolic strain rate (GEDSR), a measure integrating the entire left ventricular myocardium in the apical 4-chamber view, were measured at two baselines and during two phases of preload altering maneuvers: LBNP (−15 and −30 mmHg) and rapid saline infusion (15 and 30 ml/kg). For each individual, a linear regression relating GEDSR and PCWP was performed. Statistical comparisons were made with unpaired Student’s t-tests.
Results: See Table 1⇓. Baseline GEDSR was lower in the elderly as noted by the large baseline difference and the diminished mean intercept. GEDSR responded similarly to preload manipulation in the young and elderly as evidenced by the similar linear regression slopes. The mean r^2 was 0.58 in the young and 0.41 in the elderly.
Conclusion: Global early diastolic strain rate (GEDSR) is in fact preload dependent, with approximately half of the variability in GEDSR accounted for by the variability in PCWP. The slope of this relationship is highly conserved between age groups although overall, GEDSR does decrease with age.