Micelles of a diblock copolymer composed of poly(ethylene oxide) and poly(2-tetrahydropyranyl methacrylate) (PEO-b-PTHPMA) in aqueous solution could be disrupted by high-frequency ultrasound (1.1 MHz). It was found that, upon exposure to a high-intensity focused ultrasound (HIFU) beam at room temperature, the pH value of the micellar solution decreased over irradiation time. The infrared spectroscopic analysis of solid block copolymer samples collected from the ultrasound irradiated micellar solution revealed the formation of carboxylic acid dimers and hydroxyl groups. These characterization results suggest that the high-frequency HIFU beam could induce the hydrolysis reaction of THPMA at room temperature resulting in the cleavage of THP groups. The disruption of PEO-b-PTHPMA micelles by ultrasound was investigated by using dynamic light scattering, atomic force microscopy, and fluorescence spectroscopy. On the basis of the pH change, it was found that the disruption process was determined by a number of factors such as the ultrasound power, the micellar solution volume and the location of the focal spot of the ultrasound beam. This study shows the potential to develop ultrasound-sensitive block copolymer micelles by having labile chemical bonds in the polymer structure, and to use the high-frequency HIFU to trigger a chemical reaction for the disruption of micelles.
Background
- The prognosis of idiopathic dilated cardiomyopathy (DCM) patients has improved remarkably in recent decades with guideline-directed medical therapy (GDMT). Left ventricular reverse remodeling (LVRR) is one of the major therapeutic goals. Whether myocardial fibrosis or inflammation would reverse associated with LVRR remains unknown.
Methods
- A total of 157 prospectively enrolled DCM patients underwent baseline and follow-up CMR examinations with a median interval of 13.7 months (interquartile range: 12.2-18.5 months). LVRR was defined as an absolute increase in LV ejection fraction (LVEF) of >10% to the final value of ≥ 35% and a relative decrease in LV end-diastolic volume (EDV) of >10%. Statistical analyses were performed using paired t-test and student t-test, logistic regression analysis, and linear regression analysis.
Results
- Forty-eight (31%) patients reached LVRR. At baseline, younger age, worse NYHA class, new-onset heart failure, lower LVEF, absence of late gadolinium enhancement (LGE), lower myocardial T2, and extracellular volume (ECV) were significant predictors of LVRR. During the follow-up, patients with and without LVRR both showed a significant decrease of myocardial native T1 (LVRR: [baseline]1303.0±43.6ms; [follow-up]1244.7±51.8ms; without LVRR: [baseline]1308.5±80.5ms; [follow-up]1287.6±74.9ms, both p < 0.001), matrix and cellular volumes while no significant difference was observed in T2 or ECV values after treatment.
Conclusions
- In idiopathic DCM patients, the absence of LGE, lower T2, and ECV values at baseline are significant predictors of LVRR. The myocardial T1, matrix, and cell volume decrease significantly in patients with LVRR after GDMT.
Purpose To measure left ventricular (LV) myocardial strain with cine magnetic resonance (MR) imaging and a deformable registration algorithm (DRA) and to assess the prognostic value of myocardial strain in patients with light-chain (AL) amyloidosis. Materials and Methods In this prospective study, 78 consecutive patients with AL amyloidosis who underwent contrast material-enhanced cardiac MR imaging were enrolled at West China Hospital. LV myocardial strains and late gadolinium enhancement (LGE) were evaluated. Association between myocardial strain and all-cause mortality was analyzed with the stepwise Cox regression model. Results Global longitudinal strain (GLS) and global circumferential strain (GCS) were significantly lower in the no or nonspecific LGE group compared with the subendocardial LGE and transmural LGE groups (mean GLS, -10% ± 3 [standard deviation] vs -7% ± 3 vs -4% ± 1; P < .001) (mean GCS, -13% ± 3 vs -11% ± 3 vs -7% ± 2; P < .001). GLS and GCS were reduced in patients without clinical cardiac amyloidosis (mean GLS, -13% ± 3 vs -16% ± 2; P = .005) (mean GCS, -16% ± 1 vs -19% ± 2; P = .02). Circumferential and radial strains were impaired in basal segments in accordance with the distribution of LGE. Multivariate Cox analysis revealed that GCS (hazard ratio [HR] = 1.16 per 1% absolute decrease; 95% confidence interval [CI]: 1.03, 1.31; P = .02) and the presence of transmural LGE (HR = 1.75; 95% CI: 1.10, 2.80; P = .02) were independent predictors of all-cause mortality after adjustment for LV ejection fraction, right ventricular ejection fraction, LV mass index, GLS, and global radial strain. Conclusion Strain parameters derived with cine MR imaging-based DRA may be a new noninvasive imaging marker with which to evaluate the extent of cardiac amyloid infiltration and may offer independent prognostic information for all-cause mortality in patients with AL amyloidosis.
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