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Remodeling of the sarcomeric cytoskeleton in cardiac ventricular myocytes during heart failure and after cardiac resynchronization therapy.

ABSTRACT: Sarcomeres are the basic contractile units of cardiac myocytes. Recent studies demonstrated remodeling of sarcomeric proteins in several diseases, including genetic defects and heart failure. Here we investigated remodeling of sarcomeric ?-actinin in two models of heart failure, synchronous (SHF) and dyssynchronous heart failure (DHF), as well as a model of cardiac resynchronization therapy (CRT). We applied three-dimensional confocal microscopy and quantitative methods of image analysis to study isolated cells from our animal models. 3D Fourier analysis revealed a decrease of the spatial regularity of the ?-actinin distribution in both SHF and DHF versus control cells. The spatial regularity of ?-actinin in DHF cells was reduced when compared with SHF cells. The spatial regularity of ?-actinin was partially restored after CRT. We found longitudinal depositions of ?-actinin in SHF, DHF and CRT cells. These depositions spanned adjacent Z-disks and exhibited a lower density of ?-actinin than in the Z-disk. Differences in the occurrence of depositions between the SHF, CRT and DHF models versus control were significant. Also, CRT cells exhibited a higher occurrence of depositions versus SHF, but not DHF cells. Other sarcomeric proteins did not accumulate in the depositions to the same extent as ?-actinin. We did not find differences in the expression of ?-actinin protein and its encoding gene in our animal models. In summary, our studies indicate that HF is associated with two different types of remodeling of ?-actinin and only one of those was reversed after CRT. We suggest that these results can guide us to an understanding of remodeling of structures and function associated with sarcomeres.

SUBMITTER: Lichter JG

PROVIDER: S-EPMC4077200 | biostudies-literature | 2014 Jul

REPOSITORIES: biostudies-literature

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Remodeling of the sarcomeric cytoskeleton in cardiac ventricular myocytes during heart failure and after cardiac resynchronization therapy.

Lichter Justin G JG Carruth Eric E Mitchell Chelsea C Barth Andreas S AS Aiba Takeshi T Kass David A DA Tomaselli Gordon F GF Bridge John H JH Sachse Frank B FB

Journal of molecular and cellular cardiology 20140320

Sarcomeres are the basic contractile units of cardiac myocytes. Recent studies demonstrated remodeling of sarcomeric proteins in several diseases, including genetic defects and heart failure. Here we investigated remodeling of sarcomeric α-actinin in two models of heart failure, synchronous (SHF) and dyssynchronous heart failure (DHF), as well as a model of cardiac resynchronization therapy (CRT). We applied three-dimensional confocal microscopy and quantitative methods of image analysis to stud ...[more]

PMID: 24657727

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Project description:BackgroundCardiac resynchronization therapy (CRT) produces acute changes in electric resynchronization that can be measured noninvasively with electrocardiographic body surface mapping (ECGi). The relation between baseline acute electrophysiology metrics and their manipulation with CRT and reverse remodeling is unclear.ObjectiveTo test (ECGi) derived parameters of electrical activation as predictors of volumetric response to CRT.MethodsECGi was performed in 21 patients directly following CRT implant. Activation parameters (left ventricular total activation time [LVtat], global biventricular total activation time [VVtat], global left/right ventricular electrical synchrony [VVsync], and global left ventricular dispersion of activation times [LVdisp]) were measured at baseline and following echocardiographically optimized CRT. Remodeling response (>15% reduction left ventricular end-systolic volume) was assessed 6 months post CRT.ResultsPatients were aged 68.9 ± 12.1 years, 81% were male, and 57% were ischemic. Baseline measures of dyssynchrony were more pronounced in left bundle branch block (LBBB) vs non-LBBB. ECGi demonstrated a trend of greater interventricular dyssynchrony between responders and nonresponders that did not reach statistical significance (VVsync: -45.7 ± 22.4 ms vs -25.1 ± 29.3 ms, P = .227). Remaining activation parameters were similar between responders and nonresponders (VVtat 101 ± 22.0 ms vs 98.9 ± 23.4 ms, P = .838; LVtat 86.4 ± 17.1 ms vs 85.1 ± 27.7 ms, P = .904; LVdisp 28.2 ± 6.3 ms vs 27.0 ± 8.7 ms, P = .726). In volumetric responders activation parameters were significantly improved with CRT compared to nonresponders: VV sync (-45.67 ± 22.41 ms vs 2.33±18.87 ms, P = .001), VVtat (101 ± 22.04 ms vs 71 ± 14.01 ms, P = .002), LVtat (86.44 ± 17.15 ms vs 67.67 ± 11.31 ms, P = .006), and LVdisp (28.22 ± 6.3 ms vs 21.56 ± 4.45 ms, P = .008).ConclusionBaseline ECGi activation times did not predict CRT volumetric response. Volumetric responders exhibited significant improvements in ECGi-derived metrics with CRT. ECGi does not select CRT candidates but may be a useful adjunct to guide left ventricle lead implants and to perform postimplant CRT optimization.

Project description:Background Patients with recurring heart failure (HF) following cardiac resynchronization therapy fare poorly. Their management is undecided. We tested remote hemodynamic-guided pharmacotherapy. Methods and Results We evaluated cardiac resynchronization therapy subjects included in the CHAMPION (CardioMEMS Heart Sensor Allows Monitoring of Pressure to Improve Outcomes in New York Heart Association Class III Heart Failure Patients) trial, which randomized patients with persistent New York Heart Association Class III symptoms and ≥1 HF hospitalization in the previous 12 months to remotely managed pulmonary artery (PA) pressure-guided management (treatment) or usual HF care (control). Diuretics and/or vasodilators were adjusted conventionally in control and included remote PA pressure information in treatment. Annualized HF hospitalization rates, changes in PA pressures over time (analyzed by area under the curve), changes in medications, and quality of life (Minnesota Living with Heart Failure Questionnaire scores) were assessed. Patients who had cardiac resynchronization therapy (n=190, median implant duration 755 days) at enrollment had poor hemodynamic function (cardiac index 2.00±0.59 L/min per m2), high comorbidity burden (67% had secondary pulmonary hypertension, 61% had estimated glomerular filtration rate <60 mL/min per 1.73 m2), and poor Minnesota Living with Heart Failure Questionnaire scores (57±24). During 18 months randomized follow-up, HF hospitalizations were 30% lower in treatment (n=91, 62 events, 0.46 events/patient-year) versus control patients (n=99, 93 events, 0.68 events/patient-year) (hazard ratio, 0.70; 95% CI, 0.51-0.96; P=0.028). Treatment patients had more medication up-/down-titrations (847 versus 346 in control, P<0.001), mean PA pressure reduction (area under the curve -413.2±123.5 versus 60.1±88.0 in control, P=0.002), and quality of life improvement (Minnesota Living with Heart Failure Questionnaire decreased -13.5±23 versus -4.9±24.8 in control, P=0.006). Conclusions Remote hemodynamic-guided adjustment of medical therapies decreased PA pressures and the burden of HF symptoms and hospitalizations in patients with recurring Class III HF and hospitalizations, beyond the effect of cardiac resynchronization therapy. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT00531661.

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Remodeling of the sarcomeric cytoskeleton in cardiac ventricular myocytes during heart failure and after cardiac resynchronization therapy.

Publications

Remodeling of the sarcomeric cytoskeleton in cardiac ventricular myocytes during heart failure and after cardiac resynchronization therapy.

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