Assessment of distribution and evolution of Mechanical dyssynchrony in a porcine model of myocardial infarction by cardiovascular magnetic resonance

Abstract

BackgroundWe sought to investigate the relationship between infarct and dyssynchrony post- myocardial infarct (MI), in a porcine model. Mechanical dyssynchrony post-MI is associated with left ventricular (LV) remodeling and increased mortality.MethodsCine, gadolinium-contrast, and tagged cardiovascular magnetic resonance (CMR) were performed pre-MI, 9 ± 2 days (early post-MI), and 33 ± 10 days (late post-MI) post-MI in 6 pigs to characterize cardiac morphology, location and extent of MI, and regional mechanics. LV mechanics were assessed by circumferential strain (eC). Electro-anatomic mapping (EAM) was performed within 24 hrs of CMR and prior to sacrifice.ResultsMean infarct size was 21 ± 4% of LV volume with evidence of post-MI remodeling. Global eC significantly decreased post MI (-27 ± 1.6% vs. -18 ± 2.5% (early) and -17 ± 2.7% (late), p < 0.0001) with no significant change in peri-MI and MI segments between early and late time-points. Time to peak strain (TTP) was significantly longer in MI, compared to normal and peri-MI segments, both early (440 ± 40 ms vs. 329 ± 40 ms and 332 ± 36 ms, respectively; p = 0.0002) and late post-MI (442 ± 63 ms vs. 321 ± 40 ms and 355 ± 61 ms, respectively; p = 0.012). The standard deviation of TTP in 16 segments (SD16) significantly increased post-MI: 28 ± 7 ms to 50 ± 10 ms (early, p = 0.012) to 54 ± 19 ms (late, p = 0.004), with no change between early and late post-MI time-points (p = 0.56). TTP was not related to reduction of segmental contractility. EAM revealed late electrical activation and greatly diminished conduction velocity in the infarct (5.7 ± 2.4 cm/s), when compared to peri-infarct (18.7 ± 10.3 cm/s) and remote myocardium (39 ± 20.5 cm/s).ConclusionsMechanical dyssynchrony occurs early after MI and is the result of delayed electrical and mechanical activation in the infarct.

Myocardial T1-mapping at 3T using saturation-recovery: reference values, precision and comparison with MOLLI

“…The values of observer variability characteristics obtained in this study are well in line with previous reports [27, 35–38]. However, some studies from specialized centers achieved consistently higher inter- and intra-observer variability, with ICCs > 0.99 [27, 29, 39]. This difference might be explained by the limited clinical experience of our readers.…”

“…For MOLLI, ECV-values between 0.25 and 0.27 have been reported at 1.5T [9, 15, 26] and between 0.26 and 0.28 at 3T [26–29]. Furthermore, the slight increase in ECV-values between the two post-contrast time points has been previously observed with MOLLI at 3T [29], and the ECV deviation between the two time points is in agreement with previous reports (0.258–0.272 for times between 10 and 25 min [28]. Close agreement of SAPPHIRE ECV-values are obtained with a previous study at 1.5T (ECV: 0.20 [9]).…”

Circulating Level of miR-378 Predicts Left Ventricular Hypertrophy in Patients with Aortic Stenosis

“…However, approximately 10–20% of the patients with critically severe AS do not have LVH. A recent study showed that the extent of LVH did not necessarily correlate with the severity of AS [9]. This evidence suggested that the pathogenesis and regulation of LVH was complicated and not fully understood yet.…”

Compressed sensing for rapid late gadolinium enhanced imaging of the left atrium: A preliminary study

“…After undersampling the k-space data, coil compression with principal component analysis [16, 17] was performed on the measured k-space data and the data was compressed into 4 virtual coils. Each coil was reconstructed separately and then the results combined with the square root of sum of squares.…”

“…Each coil was reconstructed separately and then the results combined with the square root of sum of squares. As discussed in [16, 17], coil compression reduces the total number of coils required to reconstruct the image and hence reduces the reconstruction time. Experiments were performed to see how many virtual coils are necessary to reconstruct images without any loss of image quality due to coil compression.…”