Abstract 15168: The Impact of Normal Saline Infusion on Myocardial Deformation: Mechanistic Insight Into the Frank-Starling Law
Background: The Frank-Starling Law states that cardiac stroke volume increases in response to increase in left ventricular (LV) end-diastolic volume (preload). Analysis of novel, sensitive markers of regional LV function has the potential to identify mechanistic underpinnings of this fundamental cardiac principle. The aim of this study was to examine changes in myocardial mechanical parameters in response to increase in preload.
METHODS: Conventional and novel parameters of LV systolic and diastolic function were assessed with 2-D, tissue Doppler, and speckle tracking echocardiography in healthy male subjects (n=10, age = 24±3 yrs) before and after infusion of weight-based normal saline (2.4±0.2 L).
RESULTS: In accordance with the Frank-Starling mechanism, saline infusion produced a significant increase in LV end diastolic volume (Δ17%, p<0.001), stroke volume (Δ20%, p<0.0001), and cardiac output (Δ26%, p<0.0001; Table). Differences were observed with respect to which distinct parameters of myocardial deformation changed in response to saline infusion. Specifically, systolic LV apical rotation increased significantly (pre=8.7±1.2 vs. post=13.6±4.9, ↑ 56%; p=0.04) while there was no significant change in myocardial strains (Table). The early diastolic parameters of peak relaxation velocity (Δ12%, p=0.005) and peak untwisting rate (Δ27%, p=0.05) also increased significantly in response to saline challenge.
CONCLUSION: The Frank-Starling Law can be explained by specific myocardial mechanical parameters including LV apical rotation and early diastolic untwisting. Future work is required to translate these findings into populations with cardiac diseases characterized by impaired response to preload challenge, such as heart failure with preserved ejection fraction.
- © 2013 by American Heart Association, Inc.