Open AccessVariations of Intrathoracic Amount of Blood as a Reason of ECG Voltage Changes
Author(s) -
Saltykova Marina,
Capderou Andre,
Atkov Oleg,
Gusakov Victor,
Konovalov Gennagiy,
Voronin Leonid,
Kaspranskiy Rustem,
Morgun Valeriy,
Bailliart Olivier,
Cermack Milan,
Vaïda Pierre
Publication year - 2003
Publication title -
annals of noninvasive electrocardiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.494
H-Index - 48
eISSN - 1542-474X
pISSN - 1082-720X
DOI - 10.1046/j.1542-474x.2003.08410.x
Subject(s) - supine position , qrs complex , medicine , hypergravity , cardiology , blood volume , amplitude , electrocardiography , anesthesia , physics , optics
Background: It is known that electroconduction of intrathoracic organs and tissues significantly influences the ECG voltage. It changes during therapy or exercise test due to redistribution and/or volume variations of blood and body fluids and their electroconductivity variations. This fact must be taken into consideration during interpretation of corresponding ECG. But there are no quantitative estimations of this influence on human ECG. The goals of this study were to estimate the influence of variations of thoracic electroconduction, and heart volume on QRS voltage in humans, due to gravity change. Methods: ECGs of 26 healthy volunteers were analyzed in upright and supine position. Experimental conditions—acute change of gravity—are created in a special aircraft flying on Kepler's parabola trajectory. Each parabola includes phases of normo‐, hypergravity (blood shifts in caudal direction), and microgravity (blood redistributes in cranial direction). Amplitude of QRS in Frank leads in all phases has been analyzed. 2‐D echo studies for six subjects were used for estimation of heart volume change. Results: In an upright position during hypergravity the amplitude of R wave in Z increases in 95% of cases (mean 0.19 mV). During microgravity amplitude of R wave in Z decreases in 95% (mean 0.24 mV). In supine position changes of QRS voltage are not significantly. Conclusion: Blood redistribution during gravity change leads to changes of QRS voltage, which is more expressed and steady on R in Z lead: an average near 0.2 mV. It is due to the balance between two factors: (a) changes of degree of short circuiting by variations in the amount of blood in thorax (b) changes of distance between heart and electrodes as a result of change in the position, form, and volume of the heart.