Introduction

Cystic fibrosis (CF) is an autosomal recessive hereditary disease with a chronic, progressive, multisystemic course (1,2). The patients show a deficiency of the gene coding for the transmembrane conductance regulator protein (CFTR) (2,3). CF is a systemic disease causing multiple organ malfunctions (5). The classical triad of signs include suppurative chronic obstructive pulmonary disease, pancreatic insufficiency and high sweat electrolyte levels (7). Pulmonary injury developing out of chronic lung infection and inflammation is the most important morbidity and mortality factor (4). Pulmonary vasoconstriction develops following alveolar hypoxia resulting from pulmonary damage. This, in its turn, contributes to the development of cor pulmonale, its most frequent cardiac complication (7,8). Pulmonary hypertension, myocardial fibrosis and chronic infection combine to cause right ventricular (RV) dysfunction. Left ventricular (LV) dysfunction has also been identified in CF as a result of the cellular and molecular changes caused by the disease (5,9,22). Alterations of the structure in both ventricles have been reported in 20-47% of the cases in postmortem studies (5,6). Even though CFTR-related cardiac effects are not entirely elucidated, a commonly proposed hypothesis is a disturbance of regulatory functions over calcium channel-related resting membrane potentials and action potentials (9).
Conventional transthoracic echocardiography (TTE) and Doppler echocardiography performed as standard assessments of cardiac function may help identify cardiac involvement in patients with CF. These examinations are, however, often insufficient to demonstrate the presence of early-stage, subclinical cardiac dysfunction. Tissue Doppler echocardiographic imaging (TDI) and two-dimensional speckle tracking echocardiography (STE) are helpful in detecting the presence of subclinical cardiac dysfunction in the early stages of CF (10,11,12).
The objective of this study was to investigate the possibility of a superiority of TDI and STE over standard echocardiography techniques for studying cardiac function in CF patients.