Modeling of lung-heart interaction

This work presents a three-stage model for simulating and studying correlations between respiratory pattern (volume, frequency) and HR fluctuations. This model simulates the process of oxygen diffusion in the alveoli and estimates the blood flow rate through the capillaries under the demand of a constant oxygenation level at the venous end of the pulmonary capillaries. When integrating flow rate over the entire volume of pulmonary capillaries, left atrium filling rate can be obtained and studied. Fluctuations in left atrium filling rate were displayed as a result of changes in total lung volume. This effect is suggested as an additional component that may contribute to the lung/heart interaction, together with other mechanisms such as the baroreflex, direct and indirect mechanical coupling or neural coupling influencing the stimuli of the sinus node.