The Influence of Food Intake and Preload Augmentation on Cardiac Functional Parameters: A Study Using Both Cardiac Magnetic Resonance and Echocardiography

Abstract

(1) Background: To investigate how food intake and preload augmentation affect the cardiac output (CO) and volumes of the left ventricle (LV) and right ventricle (RV) assessed using cardiac magnetic resonance (CMR) and trans-thoracic echocardiography (TTE). (2) Methods: Eighty-two subjects with (n = 40) and without (n = 42) cardiac disease were assessed using both CMR and TTE immediately before and after a fast infusion of 2 L isotonic saline. Half of the population had a meal during saline infusion (food/fluid), and the other half were kept fasting (fasting/fluid). We analyzed end-diastolic (EDV) and end-systolic (ESV) volumes and feature tracking (FT) using CMR, LV global longitudinal strain (GLS), and RV longitudinal strain (LS) using TTE. (3) Results: CO assessed using CMR increased significantly in both groups, and the increase was significantly higher in the food/fluid group: LV-CO (ΔLV-CO: +2.6 ± 1.3 vs. +0.7 ± 1.0 p < 0.001), followed by increased heart rate (HR) (ΔHR: +12 ± 8 vs. +1 ± 6 p < 0.001). LV and RV achieved increased stroke volume (SV) through different mechanisms. For the LV, through increased contractility, increased LV-EDV, decreased LV-ESV, increased LV-FT, and GLS were observed. For the RV, increased volumes, increased RV-EDV, increased RV-ESV, and at least for the fasting/fluid group, unchanged RV-FT and RV-LS were reported. (4) Conclusions: Preload augmentation and food intake have a significant impact on hemodynamic and cardiac functional parameters. This advocates for standardized recommendations regarding oral intake of fluid and food before cardiac assessment, for example, TTE, CMR, and right heart catheterization. We also demonstrate different approaches for the LV and RV to increase SV: for the LV by increased contractility, and for the RV by volume expansion.

Keywords: cardiac magnetic resonance; food intake; heart failure; hemodynamic; preload augmentation; transthoracic echocardiography.

Figure 1

Study design. CMR: cardiovascular magnetic resonance; Echo: echocardiography; IV: intravenous.

Figure 2

Relationship between various parameters and indexed infusion. Scatterplot with linear regression for both groups (fasting/fluid and food/fluid) demonstrates the relationship between indexed infusion and pre–post differences in heart rate, stroke volume, indexed cardiac output, and ejection fraction for both the left and right ventricles. CO: cardiac output; HR: heart rate; LV: left ventricle; LVEF: left ventricle ejection fraction; RV: right ventricle; RVEF: right ventricle ejection fraction; SV: stroke volume.

Figure 3

Mean values of various parameters. Bar chart demonstrating cardiovascular magnetic resonance mean values and standard deviation before and after fluid infusion and +/− food. EDV: end-diastolic volume; ESV: end-systolic volume; LV: left ventricle; RV: right ventricle.

Figure 4

Heart rate response at four time points during the examination day. Line chart demonstrating the changes in heart rate during the examination day in the two subgroups. # indicating a significant difference from the pre-examination heart rate. Pre: pre-examination.