ABSTRACT
AIMS: To determine the diagnostic information contained in cardiac pulsatile pressure waves as expressed in the Doppler signals recorded over the right lung. METHODS AND RESULTS: The pulsatile characteristics of the pulmonary vascular system were studied by means of the novel pulse Doppler technology in 38 control volunteers, 31 patients with atrial fibrillation (AF) and 7 patients with atrial flutter. The Doppler velocity waveforms recorded were interpreted in relation to the cardiac cycle mechanical events that generate them: Ventricular systole (S), diastole (D) and presystolic left atrial contraction (A). It was demonstrated that in all cases of AF, wave-A was absent. With longer diastole a high frequency velocity waves were visible. It is assumed that they represent the atrial mechanical fibrillation. In the patients with atrial flutter, the single A-wave was replaced by a waveform termed F, the frequency of which exactly matched that of the flutter wave on the ECG. The F-wave had both a positive and negative component. CONCLUSION: The lung Doppler signals contain distinct signatures typical of arrhythmias such as AF and atrial flutter that can be used for both diagnosis and to gain insight into the nature of the phenomena.
Subject(s)
Arrhythmias, Cardiac/physiopathology , Echocardiography, Doppler/methods , Pulmonary Artery/diagnostic imaging , Pulmonary Artery/physiopathology , Ventricular Dysfunction, Left/diagnostic imaging , Ventricular Dysfunction, Left/physiopathology , Aged , Arrhythmias, Cardiac/complications , Arrhythmias, Cardiac/diagnostic imaging , Female , Humans , Image Interpretation, Computer-Assisted/methods , Male , Pulsatile Flow , Reproducibility of Results , Sensitivity and Specificity , Ventricular Dysfunction, Left/etiologyABSTRACT
AIMS: To overcome the limitations due to ultrasound attenuation by the air in the lungs, in order to study the pulmonary system using an advanced signal processing technology. METHODS AND RESULTS: Pulsed spectral Doppler signals were obtained over the chest wall using a signal processing and algorithm package (transthoracic parametric Doppler, TPD, EchoSense Ltd, Haifa, Israel) in conjunction with a non-imaging Doppler device (Viasys Healthcare, Madison, WI, USA) coupled with an electrocardiogram. The signals picked up by a transducer positioned at various locations over the chest wall, were treated for noise, analysed parametrically and displayed in terms of both velocity and power originating from moving ultrasound reflectors. Clear reproducible lung Doppler signals (LDS) were recorded. Up to five bidirectional triangular waves with peak velocities of 20-40 cm/s, that survived the 40 dB/cm attenuation of the lung, were recorded during each cardiac cycle. The first signal coincides with early ventricular systole, the second with late systole, the third and fourth with diastole, and the last with atrial contraction. CONCLUSION: LDS originate from different elements and phases of cardiac activity that generate mechanical waves which propagate throughout the lung and are thus expressed in pulsatile changes in ultrasound reflections. While such signals could originate either from pulsatile blood flow or reflections from movement of the blood vessel--alveolar air interface, the experimental evidence points towards the tissue--air interface movements due to vessel expansion as the origin. The LDS can potentially be an important tool for diagnosing and characterizing cardio-pulmonary physiological states and diseases.
