Evaluation of respiratory influences on left ventricular function by means of echocardiographic approach

A procedure to automatically extract the beat-to-beat series of well-known clinical parameters from the left ventricular volume signal obtained by the acoustic quantification technique is validated in normal subjects and chronic heart failure patients (NYHA class II-III). The end systolic and diastolic volume, the contribution of the atrial contraction to the ventricular filling and the ejection fraction provide a vivid distinction between normal and pathological subjects. However a large amount of variability at the respiratory frequency is observed. The respiratory-related variability of the left ventricular volume parameters could be related to the capability of the heart to adapt to changes of the venous return and, therefore, could be used as an index of the cardiac mechanical efficiency.