The effect of respiration on left and right heart function is alternating; during inspiration, left ventricular filling is restricted and left ventricular afterload is increased, so left heart function is diminished, and the opposite is true during exhalation. Under normal conditions, the effect of respiration on right and left heart function is not significant because the ventricular septum is in a state of relative tension. In resistance breathing and certain pathological conditions, respiration-induced septal oscillations increase and the alternating changes in the effect on left and right heart filling increase accordingly. It has been shown that during acute changes in chest pressure, left ventricular geometry changes, which causes changes in left ventricular filling. When acute chest pressure decreases, there are no significant changes in aortic systolic and mean pressures, slightly lower diastolic pressures, slightly increased pulse pressure, decreased cardiac output and output per beat, and no significant changes in heart rate.