Selective beat averaging to evaluate ventricular repolarization adaptation to deconditioning after 5 days of head-down bed rest

The study of QT/RR relationship is important for the clinical evaluation of possible risk of ventricular tachyarrhythmia. Our aim was to assess the effects of 5-days of head-down (-6 degrees) bed-rest (HDBR) on ventricular repolarization. High fidelity 12-leads Holter ECG was acquired before (PRE), the last day of HDBR (HDT5), and five days after its conclusion (POST). X, Y, Z leads were derived (inverse Dower matrix) and vectorcardiogram computed. Selective beat averaging applied to the night period resulted in averages preceded by the same stable heart rate (for each 10 msec bin amplitude, in the range 900-1200 msec). For each template (i.e., one for each bin), T-wave maximum amplitude (Tmax), T wave area, R-Tapex and R-Tend were computed. Results (in 8 male volunteers) showed that, compared to PRE, at HDT5 both R-Tapex and R-Tend resulted significantly shortened (-5% and -3%, respectively), together with a decrease in T-wave area (-7%), while Tmax was unchanged. At POST, duration parameters showed a trend towards their control values (-1.5% and -3%, respectively) while amplitude parameters resulted restored. Despite the short-term BR, cardiac adaptation to deconditioning affected ventricular repolarization during the night period. © 2012 CCAL

Quantitative characterization of mitral annulus and leaflets from transesophageal 3D echocardiography

We propose and validate a novel algorithm for the segmentation and quantification of the mitral annulus (MA) and mitral leaflets (ML) from transesophageal real-time 3D echocardiography volumes in a closed mitral valve (MV) configuration. Following initialization of 8 MA points and of the coaptation line, the MA and the anterior and posterior ML are automatically obtained in 3D. Once segmented, several morphological parameters, including local ML thickness and tenting, are obtained. Validation versus manual tracings was performed in 33 patients: 9 controls, with normal MA dimensions, 12 patients with dilative cardiomyopathy and 12 after MV repair with insertion of annuloplasty ring on the posterior MA region. MA and ML segmentations showed a high level of accuracy when compared with manual tracings, with errors of the order of the voxel size. Computed parameters were comparable with those found in literature for healthy MV. The potential clinical applicability to different MV pathologies, as well as repaired valves with implanted annular rings, was favorably tested. © 2013 CCAL

Selective beat averaging to evaluate ventricular repolarization adaptation to deconditioning after 5-days of head-down bed-rest

The study of QT/RR relationship is important for the clinical evaluation of possible risk of ventricular tachyarrhythmia. Our aim was to assess the effects of 5-days of head-down (-6 degrees) bed-rest (HDBR) on ventricular repolarization. High fidelity 12-leads Holter ECG was acquired before (PRE), the last day of HDBR (HDT5), and five days after its conclusion (POST). X, Y, Z leads were derived (inverse Dower matrix) and vectorcardiogram computed. Selective beat averaging applied to the night period resulted in averages preceded by the same stable heart rate (for each 10 msec bin amplitude, in the range 900-1200 msec). For each template (i.e., one for each bin), T-wave maximum amplitude (Tmax), T wave area, R-Tapex and R-Tend were computed. Results (in 8 male volunteers) showed that, compared to PRE, at HDT5 both R-Tapex and R-Tend resulted significantly shortened (-5% and -3%, respectively), together with a decrease in T-wave area (-7%), while Tmax was unchanged. At POST, duration parameters showed a trend towards their control values (-1.5% and -3%, respectively) while amplitude parameters resulted restored. Despite the short-term BR, cardiac adaptation to deconditioning affected ventricular repolarization during the night period. © 2012 CCAL

A patient-specific computational analysis from imaging for annuloplasty ring assessment for the treatment of ischemic mitral regurgitation

Ischemic mitral regurgitation (IMR) is usually treated through restrictive annuloplasty via rigid rings which constrain the annular shape, or flexible rings, which preserve annular dynamics