[Echocardiographic findings of pulsus paradoxus: cardiovascular changes due to respiration (author's transl)]

Echocardiographic studies were performed in two cases with pulsus paradoxus (Case 1: a 13-year-old boy, acute viral pericarditis with massive pericardial effusion; Case 2: a 25-year-old woman, status asthmaticus) and in a normal subject when his intra-airway pressure rapidly fell on a deep negative level, e.g., during Mueller maneuver. During inspiration in both clinical cases, the anterior mitral leaflet showed a diminished diastolic excursion, and the right ventricular dimension increased accompanied by a reciprocal decrease in the left ventricular dimension. In Case 2, in addition, an abrupt downward motion of the ventricular septum was present in early diastole during inspiration. In experimental study of a normal subject, similar respiratory changes in mitral ans septal motions and the similar respiratory interaction between the right and left ventricles were also observed during Mueller maneuver. Our observations suggest left ventricular filling and left ventricular end-diastolic volume decrease during inspiration in the presence of pulsus paradoxus. These are compatible with the pulmonary pooling hypothesis, and also support the hypothesis that pulsus paradoxus may be caused by competition of the ventricles for filling within a relatively fixed pericardial space. The mechanism of the abrupt downward septal motion in early diastole was also discussed.