Reasearch on correlation between lung ultrasound findings of interstitial lung diseases and cardiac involvement

Abstract

Objective To assess the relationship between lung ultrasonography and cardiac involvement (pulmonary artery systolic pressure, right ventricular function) in patients with interstitial lung diseases(ILD) by integrative cardiopulmonary ultrasound (also called thoracic ultrasound, TUS). Methods Seventy two patients with clinically diagnosed ILD were investigated at the Department of Respiratory Medicine in our hospital. The tranditional echocardiographic parameter included pulmonary arterial systolic pressure(PASP), tricuspid regurgitation area(ATR), main pulmonary artery diameter(DMPA), left pulmonary artery diameter (DLPA), right pulmonary artery diameter(DRPA), right ventricular outflow tract dimensions at the proximal or subvalvular level(DRVOT1), right ventricular outflow tract dimensions at the distal or pulmonic valve(DRVOT2), right ventricular basal diameter(RVTD), mid-right-ventricular diameter(RVDm), tricuspid annular plane systolic excursion(TAPSE), left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter (LVEDd). Tissue Doppler parameters includpeak velocity of tricuspid annulus (S′, e′, a′) and myocardial performance index(MPI); Two-dimensional speckle tracking imaging(2D-STI) parameter was right ventricular global strain(RVGLS). The number of B lines and the performance of pleural line were evaluated by lung ultrasound.Statistical analysis was performed on the above TUS indexes. Results ①With the use of PASP higher than 36mmHg as the criterion for pulmonary hypertension(PH), all patients were divided into group ILDPH and group ILDNPH, comparison of TUS parameters in two groups, several parameters had statistical difference including ATR, RVD, RVDm, RPA, RVGLS, MPI, FAC, the number of B lines and the grade of pleural line. ②According to the degree of pleural involvement, all patients were divided into severe group and mild-moderate group, in the comparison of echocardiographic parameters, only ATR, RPA and RVGLS had statistic difference. ③A positive correlation was found between the number of B lines and PASP(r=0.547), a weak correlation was found between the grade of pleural line and PASP or RVGLS. ④A cut off more than 35 B lines had 95.8% sensitivity, 37.5% specificity in predicting elevated PASP(>36 mmHg), and the area under the ROC curve was 0.707. Conclusions TUS can effectively assess ILDs. With the disease progresess, the structure or function of right ventricular will gradually damaged.Lung ultrasound can not only evaluate the changes of lung in ILD, but also indirectly reflect PASP and the function of right ventricle, and it combined with echocardiography can provide more useful information for clinical diagnosis and management of ILDs. Key words: Integrative cardiopulmonary ultrasound; Interstitial lung diseases; Pulmonary hypertension; Ventricular function, right