Depressed regional deformation near anterior papillary muscle

1995 ◽  
Vol 269 (1) ◽  
pp. H262-H270 ◽  
Author(s):  
J. W. Holmes ◽  
Y. Takayama ◽  
I. LeGrice ◽  
J. W. Covell

The role of the papillary muscle in left ventricular function has received new attention. We hypothesized that regional mechanics of the left ventricular wall near the anterior papillary muscle are influenced by the papillary muscle insertion. We therefore studied three-dimensional regional mechanics in and near the anterior papillary muscle in anesthetized, open-chest dogs, using implanted radiopaque markers and biplane cineradiography. In seven dogs, deformation differed little between an anterior papillary muscle insertion site (PMA) and a more basal site (PMB) overlying the anterior papillary muscle. However, local shortening and wall thickening were depressed in both locations relative to anterior free wall sites (FWA, FWB) studied in five additional dogs. A distinct structural border was observed at the junction between the myocardial wall and anterior papillary muscle, which may preclude the use of homogeneous strain in that region. Data from within the anterior papillary muscle indicated that uniaxial measurements in the papillary muscle are extremely sensitive to the orientation of the measurement axis, possibly explaining the variety of papillary muscle shortening patterns reported by previous investigators.

Circulation ◽  
1996 ◽  
Vol 93 (3) ◽  
pp. 585-593 ◽  
Author(s):  
Yasuo Takayama ◽  
Jeffrey W. Holmes ◽  
Ian LeGrice ◽  
James W. Covell

2009 ◽  
Vol 11 (S1) ◽  
Author(s):  
Mitra Sahebazamani ◽  
Ijaz Ahmad ◽  
Geetha P Bhumireddy ◽  
Igor Klem ◽  
Joshua A Socolow ◽  
...  

2002 ◽  
Vol 80 (8) ◽  
pp. 804-810 ◽  
Author(s):  
Mark W Huang ◽  
Peter M Scholz ◽  
Harvey R Weiss

We tested the hypothesis that the effects of myocardial stunning would be reduced by cyclic GMP in rabbit hearts. In three groups of anesthetized open-chest New Zealand white rabbits, myocardial stunning was produced by 15 min of occlusion of the left anterior descending coronary artery followed by 15 min of reperfusion repeated twice. Either control vehicle (saline plus 1% dimethyl sulfoxide) or 8-bromo-cyclic GMP (8-Br-cGMP (10–4 and 10–3 M)) was topically applied to the left ventricular surface. Hemodynamic (left ventricular and aortic pressures) and functional parameters (wall thickening, delay in onset of wall thickening, and rate of wall thickening) were determined. Coronary blood flow (microspheres) and O2 extraction (microspectrophotometry) were used to determine myocardial O2 consumption (VO2). Myocardial stunning was observed in the control group through an increased delay in onset of myocardial wall thickening (29 ± 7 versus 55 ± 16 ms) and decreased maximal rate of wall thickening (20 ± 8 versus 11 ± 3 mm·s–1). After treatment with 8-Br-cGMP 10–4 and 10–3 M, stunning did not increase the delay (37 ± 5 versus 39 ± 7 and 39 ± 7 versus 28 ± 8 ms). Myocardial stunning did not significantly alter V02. 8-Br-cGMP 10–3 M significantly decreased subepicardial V02 (6.2 ± 0.8 versus 3.7 ± 0.6 mL O2·min–1·100 g–1) and insignificantly decreased subendocardial V02 (8.6 ± 0.9 versus 6.3 ± 1.2 mL O2·min–1·100 g–1) when compared with the vehicle-treated rabbits. We conclude that increasing cyclic GMP reduced the effects of myocardial stunning in the rabbit heart by ameliorating the delay in onset of wall thickening and decreasing the local O2 costs in the stunned region. Key words: cyclic GMP, myocardial stunning, O2 consumption, ischemia, reperfusion, wall thickening, rabbit.


1999 ◽  
Vol 276 (2) ◽  
pp. H595-H607 ◽  
Author(s):  
Kevin D. Costa ◽  
Yasuo Takayama ◽  
Andrew D. McCulloch ◽  
James W. Covell

Previous studies suggest that the laminar architecture of left ventricular myocardium may be critical for normal ventricular mechanics. However, systolic three-dimensional deformation of the laminae has never been measured. Therefore, end-systolic finite strains relative to end diastole, from biplane radiography of transmural markers near the apex and base of the anesthetized open-chest canine anterior left ventricular free wall ( n = 6), were referred to three-dimensional laminar microstructural axes reconstructed from histology. Whereas fiber shortening was uniform [−0.07 ± 0.04 (SD)], radial wall thickening increased from base (0.10 ± 0.09) to apex (0.14 ± 0.13). Extension of the laminae transverse to the muscle fibers also increased from base (0.08 ± 0.07) to apex (0.11 ± 0.08), and interlaminar shear changed sign [0.05 ± 0.07 (base) and −0.07 ± 0.09 (apex)], reflecting variations in laminar architecture. Nevertheless, the apex and base were similar in that at each site laminar extension and shear contributed ∼60 and 40%, respectively, of mean transmural thickening. Kinematic considerations suggest that these dual wall-thickening mechanisms may have distinct ultrastructural origins.


2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
J Zheng ◽  
G Fu ◽  
D Struppa ◽  
I Abudayyeh ◽  
M Yacoub ◽  
...  

Abstract Introduction Radiofrequency catheter ablation (CA) is an efficient antiarrhythmic treatment with a class I indication for idiopathic ventricular arrhythmia (IVA). The accurate prediction of the origins of IVA can significantly increase the procedure success rate, reduce operation duration and decrease the risk of complications. The present work proposes an ECG analysis algorithm to estimate 21 possible origins of idiopathic ventricular arrhythmia at a clinical-grade level accuracy, which include left coronary cusp (LCC), right coronary cusp (RCC), aortomitral continuity (AMC), summit, LCC-RCC commissure, left His bundle, mitral valve (MV), left septal including left anterior fascicle (LAF), left posterior fascicle (LPF), left anterior papillary muscle (LAPM), left posterior papillary muscle (LPPM), anterior cusp (AC), left cusp (LC), right cusp (RC), RVOT septal, free wall, right His bundle, tricuspid valve (TV), and right anterior papillary muscle (RAPM). Method A total of 18,612 ECG recordings extracted from 545 patients who underwent successful CA to treat IVA were proportionally sampled into training, validation and testing cohorts. We designed four classification schemes responding to different hierarchical levels of the possible IVA origins. The first scheme will help the operators to figure out the origin from epicardium of left ventricular summit, right, and left ventricle. The second one can separate origins from left/right outflow tract and left/right non-out flow tract, respectively. The third one is able to predict 18 anatomical locations, and the fourth scheme can distinguish 21 possible sites. For every classification scheme, we compared 98 distinct machine learning models with optimized hyperparameter values obtained through extensive grid search and reported an optimal algorithm with the highest accuracy scores attained on the validation cohorts. Results In the first classification scheme used to predict right ventricular endocardium, left ventricular endocardium, and epicardium of left ventricular summit, the model achieved an accuracy of 99.79 (99.41–99.89) and a F1-score of 99.84 (99.6–99.96). For scheme 2, the proposed method reached an accuracy of 99.62 (99.09–99.78) and a F1-score of 99.42 (98.79–99.75). For scheme 3, the model achieved an accuracy of 97.78 (96.76–98.41), a F1-score of 97.74 (94.15–99.73), and an adjusted accuracy of 98.53 (98.33–99.15). For scheme 4 that can distinguish 21 origin sites, the proposed model attained an accuracy of 98.24 (97.36–98.71), a F1-score of 98.56 (97.88–99.12) and an adjusted accuracy of 98.75 (98.35–99.38). Conclusion The proposed machine learning model can be immediately and effortlessly deployed to electrophysiology labs allowing cardiologists to predict the exact origins of arrhythmia and provide an optimum treatment plan both before and during the CA procedure. This approach will significantly reduce the CA procedure duration and the risk of complications. FUNDunding Acknowledgement Type of funding sources: Foundation. Main funding source(s): 2020 Natural Science Foundation of Zhengjiang Province Confusion matrix for classification schemes


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