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Competing Interests: The University of Alabama at Birmingham (UAB) and Auburn University co‐own the patent rights to the VTF method (Gupta and Denney are coinventors). Gupta and Denney are stakeholders in Arcus‐Med, LLC, which has licensed exclusive patent rights to the VTF method from UAB and AU. Gupta and Denney were 10% owners of Arcus-Med, LCC, during the conduct of the study. In addition, Gupta and Denney have applied for a patent for the VTF method. Gupta is the Chief Medical Officer, and Denney is the Chief Scientific Officer of Arcus-Med, LLC. Wells reports grants from NIH/NHLBI (K08 HL123940) and NIH/NCATS (UL1TR003096), during the conduct of the study; grants, personal fees from GSK, personal fees from AstraZeneca, grants from Bayer, personal fees from BI, grants, personal fees from Mereo BioPharma, outside the submitted work. Dransfield reports grant from NIH/NHLBI (1K24HL140108), during the conduct of the study; grants from the American Lung Association, Department of Defense, and Department of Veterans Affairs; personal fees from AstraZeneca, GlaxoSmithKline, Mereo, PneumRx/BTG, Pulmonx and Quark; contracted clinical trials from AstraZeneca, Boehringer Ingelheim, Boston Scientific, Gala, GlaxoSmithKline, Nuvaira, PneumRx/BTG, Pulmonx outside the submitted work. The authors report no other conflicts of interest in this work.

Background Pulmonary artery ( PA ) stiffness is associated with increased pulmonary vascular resistance ( PVR ). PA stiffness is accurately described by invasive PA impedance because it considers pulsatile blood flow through elastic PA s. We hypothesized that PA stiffness and impedance could be evaluated noninvasively by PA velocity transfer function ( VTF ), calculated as a ratio of the frequency spectra of output/input mean velocity profiles in PA s. Methods and Results In 20 participants (55±19 years, 14 women) undergoing clinically indicated right-sided heart catheterization, comprehensive phase-contrast and cine-cardiac magnetic resonance imaging was performed to calculate PA VTF , along with right ventricular mass and function. PA impedance was measured as a ratio of frequency spectra of invasive PA pressure and echocardiographically derived PA flow waveforms. Mean PA pressure was 29.5±13.6 mm Hg, and PVR was 3.5±2.8 Wood units. A mixed-effects model showed VTF was significantly associated with PA impedance independent of elevation in pulmonary capillary wedge pressure ( P=0.005). The mean of higher frequency moduli of VTF correlated with PVR (ρ=0.63; P=0.003) and discriminated subjects with low (n=10) versus elevated PVR (≥2.5 Wood units, n=10), with an area under the curve of 0.95, similar to discrimination by impedance (area under the curve=0.93). VTF had a strong inverse association with right ventricular ejection fraction (ρ=-0.73; P<0.001) and a significant positive correlation with right ventricular mass index (ρ=0.51; P=0.02). Conclusions VTF , a novel right ventricular- PA axis coupling parameter, is a surrogate for PA impedance with the potential to assess PA stiffness and elevation in PVR noninvasively and reliably using cardiac magnetic resonance imaging.

Background: Implantable cardioverter-defibrillators (ICDs) are generally considered a contraindication to magnetic resonance imaging (MRI)., Objective: The purpose of the ProMRI Phase C study, a multicenter, prospective, single-arm, nonrandomized study, was to evaluate the clinical safety of the Biotronik ProMRI Iforia ICD system during MRI., Methods: Patients were enrolled after ICD implantation, with either a dual-chamber DR-T or single-lead VR-T DX system. Study-defined, nondiagnostic cardiac or thoracic spine MRI was performed at least 1 week after enrollment. ICDs were placed into MRI mode with ventricular fibrillation (VF) detection/therapy programmed "off" before scan and restored to non-MRI mode after scan. Interrogation was performed before, immediately after, and 1 month post-MRI. The primary end-points were (1) ventricular pacing threshold increase >0.5 V from pre-MRI to 1 month post-MRI; (2) R-wave amplitude decrease >50% from pre-MRI to 1 month post-MRI or R-wave amplitude <5 mV at 1 month post-MRI; and (3) MRI and ICD system-related serious adverse device effects., Results: One hundred seventy patients were enrolled at 39 US centers. One hundred fifty-three patients underwent MRI (25.7% cardiac, 74.3% thoracic spine) and completed follow-up. Freedom from the primary end-points was met in all but 1 subject, in whom reduced R-wave amplitude was detected 1 month post-MRI. No serious adverse device effects occurred during the course of the study., Conclusion: These results demonstrate the clinical safety and efficacy of the ProMRI ICD system in patients subjected to thoracic spine and cardiac MRI imaging in 1.5-T scanners., (Copyright © 2015 Heart Rhythm Society. All rights reserved.)

Purpose: To evaluate the relationship between left ventricular (LV) twist, shear, and twist-per-volume and the severity of mitral regurgitation (MR). Primary MR is a valvular disorder that induces LV dysfunction. There exist several measures of LV rotational mechanics, but it remains unclear which measure of LV dysfunction best accords with the severity of MR. We hypothesized that LV systolic twist-per-volume slope would decrease with increasing severity of MR because of both decreases in rotational mechanics and increases in stroke volumes., Materials and Methods: Normal subjects (n = 54), moderate MR patients (n = 29), and severe MR patients (n = 54) were studied. Magnetic resonance imaging (MRI) was performed on a 1.5T scanner and grid-tagged LV images were collected at the LV base and LV apex. Measures of LV rotational mechanics were derived from tagged images using Fourier Analysis of STimulated echoes (FAST)., Results: Peak systolic twist-per-volume slope was significantly different for all pairwise comparisons (P < 0.0001) and compared to normal subjects (-0.14 ± 0.05°/mL) was decreased in moderate MR (-0.12 ± 0.04°/mL) and further decreased in severe MR (-0.07 ± 0.03°/mL)., Conclusion: Peak systolic twist-per-volume slope significantly decreased with increasing severity of MR and is therefore a suitable quantitative imaging biomarker for LV dysfunction in patients with MR., (© 2014 Wiley Periodicals, Inc.)

Background: Torsion shear angle φ is an important measure of left ventricular (LV) systolic and diastolic functions. Here we provide a novel index utilizing LV normalized torsion shear angle φ ^ volume V ^ loop to assess LV diastolic functional properties. We defined the area within φ ^ V ^ loop as torsion hysteresis area, and hypothesized that it may be an important global parameter of diastolic function. We evaluated the φ ^ changes to increased V ^ during early diastole - d φ ^ / d V ^ as a potential measure of LV suction., Methods: Sixty resistant hypertension patients (HTN), forty control volunteers were studied using cardiovascular magnetic resonance with tissue tagging. Volumetric and torsional parameters were evaluated., Results: HTN demonstrated concentric remodeling with preserved ejection fraction. HTN had significantly decreased normalized early filling rate, early diastolic mitral annulus velocity and E/A (1.33 ± 1.13 vs. 2.19 ± 1.07, P < 0.0001) vs. control. Torsion hysteresis area was greater (0.11 ± 0.07 vs. 0.079 ± 0.045, P < 0.001) and peak - d φ ^ / d V ^ at early diastole was higher (10.46 ± 8.51 vs. 6.29 ± 3.85, P = 0.002) than control. Torsion hysteresis area was significantly correlated with E/A (r = -0.23, P = 0.025). Thirteen HTN patients had both E/A ratio < 1.12 (Control mean E/A-1SD) and torsion hysteresis area > 0.12 (Control mean torsion hysteresis area + 1SD)., Conclusions: Torsion hysteresis area and peak early diastolic - d φ ^ / d V ^ were significantly increased in hypertensive concentric remodeling. The φ ^ V ^ loop takes into account the active and passive recoil processes of LV diastolic and systolic phases, therefore provides a new global description of LV diastolic function.

How the left ventricle remodels in response to a high-volume stimulus is important in evaluating the endurance athlete's heart. Marathoners and patients with isolated, moderate chronic compensated mitral regurgitation (MR) represent physiologic and pathologic forms of eccentric left ventricular (LV) remodeling in response to intermittent and chronic volume overload, respectively. Thus, in this study, magnetic resonance imaging with tissue tagging and 3-dimensional data analysis at rest were performed in 19 marathoners (mean age 39 ± 10 years, 47% women), 17 patients with isolated MR without coronary artery disease or medical therapy (mean age 46 ± 5 years, 53% women), and 24 controls (mean age 45 ± 8 years, 50% women). Marathoners and patients with MR had approximately 35% greater LV end-diastolic volume indexes, approximately 50% greater end-systolic volume indexes, and approximately 34% greater LV stroke volume indexes (p <0.0001) compared to controls. However, marathoners' hearts had increased long-axis length, while those of patients with MR did not differ from the hearts of controls. The hearts of patients with MR had greater LV global and apex sphericity compared to those of marathoners and controls (p <0.0001). Marathoners had normal LV mass/volume ratios and wall thicknesses, whereas these were significantly decreased in the MR group. In marathoners, the baseline LV work rate was similar to that in controls and higher in patients with MR compared to controls. In conclusion, marathoners' hearts achieve elevated stroke volume at rest with adherence to an elliptical shape defined by 3-dimensional geometry and mass/volume ratio. Thus, a comprehensive evaluation of LV geometry and mass/volume ratio may be important in the evaluation of the athlete's heart., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Purpose: In the absence of additional ischemic insults, the peri-infarct region surrounding the infarct myocardium can recover function. T2 weighted MRI signal is sensitive to edema and used to detect peri-infarct, salvageable myocardium. The main purpose of this study was to investigate the alterations in myocardial strain in the peri-infarct myocardium as compared to normal and infarct myocardium., Materials and Methods: Comprehensive MRI of the myocardium was performed in five pigs 6-7 days following coronary artery occlusion-reperfusion myocardial injury. MRI included tagged cine images for myocardial strain, T2weighted (T2w)-images and late gadolinium enhancement (LGE) for assessing myocardial viability. Automated signal intensity thresholds were used to define tissue edema and myocardial infarct. Maximum-shortening strains were analyzed in the infarct, peri-infarct and normal myocardial sectors. The results were correlated with triphenyltetrazolium-chloride (TTC) and hemotoxylin-eosin stained tissue images., Results: We found an excellent correlation of LGE with TTC (r = 0.94, P < 0.05). T2w-images markedly overestimated the infarct size (25 +/- 3%). Both the healthy and peri-infarct myocardial sectors had higher myocardial strain than infarct myocardial sectors (P < 0.05). Clear demarcation between infarct and non-infarct myocardium was noted on histology., Conclusion: Peri-infarct myocardium continues to demonstrate T2 signal enhancement to at least 7 days, but this region has preserved mechanical function. T2-weighted imaging and myocardial strain measurements provide complementary information and both may be useful for characterization of the peri-infarct myocardium.

Background: Short-axis summation (SAS) method applied for right ventricular (RV) volumes and right ventricular ejection fraction (RVEF) measurement with cardiac MRI is time consuming and cumbersome to use. A simplified RVEF measurement is desirable. We compare two such methods, a simplified ellipsoid geometric method (GM) and visual estimate, to the SAS method to determine their accuracy and reproducibility., Methods: Forty patients undergoing cine cardiac MRI scan were enrolled. The images acquired were analyzed by the SAS method, the GM (area and length measurement from two orthogonal planes) and visual estimate. RVEF was calculated using all three methods and RV volumes using the SAS and GM. Bland-Altman analysis was applied to test the agreement between the various measurements., Results: Mean RVEF was 49 +/- 12% measured by SAS method, 54 +/- 12% by the GM, and 49 +/- 11% by visual estimate. There were similar bias and limits of agreement between the visual estimate and the GM compared to SAS. The interobserver variability showed a bias close to zero with limits of agreement within +/-10% absolute increments of RVEF in 35 of the patients. The RV end-diastolic volume by GM showed wider limits of agreement. The RV end-systolic volume by GM was underestimated by around 10 ml compared to SAS., Conclusion: Both the visual estimate and the GM had similar bias and limits of agreement when compared to SAS. Though the end-systolic measurement is somewhat underestimated, the geometric method may be useful for serial volume measurements.