Echocardiographic assessment of left bundle branch–related strain dyssynchrony:a comparison with tagged MRI

\u3cp\u3eRecent studies have shown the efficacy of myocardial strain estimated using speckle tracking echocardiography (STE) in predicting response to cardiac resynchronisation therapy. This study focuses on circumferential strain patterns, comparing STE-acquired strains to tagged-magnetic resonance imaging (MRI-T). Second, the effect of regularisation was examined. Two-dimensional parasternal ultrasound (US) and MRI-T data were acquired in the left ventricular short-axis view of canines before (n = 8) and after (n = 9) left bunch branch block (LBBB) induction. US-based strain analysis was performed on Digital Imaging and Communications in Medicine data at the mid-level using three overall methods (“Commercial software,” “Basic block-matching,” “regularised block-matching”). Moreover, three regularisation approaches were implemented and compared. MRI-T analysis was performed using SinMod. Normalised regional circumferential strain curves, based on standard six or septal/lateral segments, were analysed and cross-correlated with MRI-T data. Systolic strain (SS) and septal rebound stretch (SRS) were calculated and compared. Overall agreement of normalised circumferential strain was good between all methods on a global and regional level. All STE methods showed a bias (≥4% strain) toward higher SS estimates. Pre-LBBB, septal and lateral segment correlation was excellent between the Basic (mean ρ = 0.96) and regularised (mean ρ = 0.97) methods and MRI-T. The Commercial method showed a significant discrepancy between the two walls (septal ρ = 0.94, lateral ρ = 0.68). Correlation with MRI-T reduced between pre- and post-LBBB (Commercial ρ = 0.79, Basic ρ = 0.82, mean regularised ρ = 0.86). Septal strain patterns and SRS varied with the STE software and type of regularisation, with all STE methods estimating non-zero SRS values pre-LBBB. Absolute values showed moderate agreement, with a bias for higher strain from STE. SRS varied with the type of software and extra regularisation applied. Open efforts are needed to understand the underlying causes of differences between STE methods before standardisation can be achieved. This is particularly important given the apparent clinical value of strain-based parameters such as SRS.\u3c/p\u3

Noninvasive pulmonary transit time:a new parameter for general cardiac performance

\u3cp\u3eIntroduction: Pulmonary transit time (PTT) assessed with contrast-enhanced ultrasound (CEUS) is a novel tool to evaluate cardiac function. PTT represents the time for a bolus of contrast to pass from the right to the left ventricle, measured according to the indicator dilution principles using CEUS. We investigated the hypothesis that PTT is a measure of general cardiac performance in patient populations eligible for cardiac resynchronization therapy (CRT). Methods: The study population consisted of heart failure patients referred for CRT with NYHA class II–IV, left ventricular ejection fraction (LVEF)≤35% and QRS≥120 ms. CEUS, ECG, and blood were analyzed, and participants completed a quality of life questionnaire at baseline and 3 months after CRT implantation. Normalized PTT (nPTT) was calculated to compensate for the heart rate. Correlations were assessed with Pearson's or Spearman's coefficients and stratified for rhythm and NYHA class. Results: The study population consisted of 94 patients (67 men) with a mean age of 70±8.9 years. (n)PTT was significantly correlated with left ventricular parameters (r\u3csub\u3es\u3c/sub\u3e=−.487, P<.001), right ventricular parameters (r=−.282, P=.004), N-terminal pro-B-type natriuretic peptide (NT-proBNP) (r\u3csub\u3es\u3c/sub\u3e=.475, P<.001), and quality of life (r\u3csub\u3es\u3c/sub\u3e=.364, P<.001). Stronger significant correlations were found in patients in sinus rhythm. Conclusion: CEUS-derived PTT and nPTT correlate to a fair degree with measures of systolic and diastolic function, NT-pro-BNP, and quality of life. As CEUS-derived PTT can be obtained easily, noninvasively and at the bedside, it is a promising future measure of general cardiac performance.\u3c/p\u3

Assessment of left bundle branch related strain dyssynchrony:a comparison with tagged MRI

\u3cp\u3eMechanical dyssynchrony caused by left bundle branch block (LBBB) negatively affects cardiac performance and can be treated by cardiac resynchronization therapy. Cardiac strain derived from ultrasound (US) images can be used to quantify and visualise this dyssynchrony at a regional level. Speckle tracking echocardiography is the most commonly used technique, however commercially available methods use extensive post-processing techniques resulting in loss of key local information. In this study, we measure strain using US images of the canine left ventricle (LV) and compare this with tagged cardiac magnetic resonance imaging (CMR), the current gold standard for medical strain imaging.\u3c/p\u3