Cardiovascular magnetic resonance feature-tracking assessment of myocardial mechanics: Intervendor agreement and considerations regarding reproducibility.

AIM: To assess intervendor agreement of cardiovascular magnetic resonance feature tracking (CMR-FT) and to study the impact of repeated measures on reproducibility. MATERIALS AND METHODS: Ten healthy volunteers underwent cine imaging in short-axis orientation at rest and with dobutamine stimulation (10 and 20 µg/kg/min). All images were analysed three times using two types of software (TomTec, Unterschleissheim, Germany and Circle, cvi(42), Calgary, Canada) to assess global left ventricular circumferential (Ecc) and radial (Err) strains and torsion. Differences in intra- and interobserver variability within and between software types were assessed based on single and averaged measurements (two and three repetitions with subsequent averaging of results, respectively) as determined by Bland-Altman analysis, intraclass correlation coefficients (ICC), and coefficient of variation (CoV). RESULTS: Myocardial strains and torsion significantly increased on dobutamine stimulation with both types of software (p<0.05). Resting Ecc and torsion as well as Ecc values during dobutamine stimulation were lower measured with Circle (p<0.05). Intra- and interobserver variability between software types was lowest for Ecc (ICC 0.81 [0.63-0.91], 0.87 [0.72-0.94] and CoV 12.47% and 14.3%, respectively) irrespective of the number of analysis repetitions. Err and torsion showed higher variability that markedly improved for torsion with repeated analyses and to a lesser extent for Err. On an intravendor level TomTec showed better reproducibility for Ecc and torsion and Circle for Err. CONCLUSIONS: CMR-FT strain and torsion measurements are subject to considerable intervendor variability, which can be reduced using three analysis repetitions. For both vendors, Ecc qualifies as the most robust parameter with the best agreement, albeit lower Ecc values obtained using Circle, and warrants further investigation of incremental clinical merit.

Real-time phase-contrast flow MRI of haemodynamic changes in the ascending aorta and superior vena cava during Mueller manoeuvre.

AIM: To evaluate the potential of real-time phase-contrast flow magnetic resonance imaging (MRI) at 40 ms resolution for the simultaneous determination of blood flow in the ascending aorta (AA) and superior vena cava (SVC) in response to reduced intrathoracic pressure (Mueller manoeuvre). MATERIALS AND METHODS: Through-plane flow was assessed in 20 healthy young subjects using real-time phase-contrast MRI based on highly undersampled radial fast low-angle shot (FLASH) with image reconstruction by regularized non-linear inversion. Haemodynamic alterations (three repetitions per subject = 60 events) were evaluated during normal breathing (10 s), inhalation with nearly closed epiglottis (10 s), and recovery (20 s). RESULTS: Relative to normal breathing and despite interindividual differences, reduced intrathoracic pressure by at least 30 mmHg significantly decreased the initial peak mean velocity (averaged across the lumen) in the AA by -24 ± 9% and increased the velocity in the SVC by +28 ± 25% (p < 0.0001, n = 23 successful events). Respective changes in flow volume per heartbeat were -25 ± 9% in the AA and +49 ± 44% in the SVC (p < 0.0001, n = 23). Flow parameters returned to baseline during sustained pressure reduction, while the heart rate was elevated by 10% (p < 0.0001) after the start (n = 24) and end (n = 17) of the manoeuvre. CONCLUSIONS: Real-time flow MRI during low intrathoracic pressure non-invasively revealed quantitative haemodynamic adjustments in both the AA and SVC.

Current role of cardiac and extra-cardiac pathologies in clinically indicated cardiac computed tomography with emphasis on status before pulmonary vein isolation.

PURPOSE: The aim of this study was to assess the incidence of cardiac and significant extra-cardiac findings in clinical computed tomography of the heart in patients with atrial fibrillation before pulmonary vein isolation (PVI). MATERIALS AND METHODS: 224 patients (64 ±â€Š10 years; male 63 %) with atrial fibrillation were examined by cardiac 64-slice multidetector CT before PVI. Extra-cardiac findings were classified as "significant" if they were recommended to additional diagnostics or therapy, and otherwise as "non-significant". Additionally, cardiac findings were documented in detail. RESULTS: A total of 724 cardiac findings were identified in 203 patients (91 % of patients). Additionally, a total of 619 extra-cardiac findings were identified in 179 patients (80 % of patients). Among these extra-cardiac findings 196 (32 %) were "significant", and 423 (68 %) were "non-significant". In 2 patients (1 %) a previously unknown malignancy was detected (esophageal cancer and lung cancer, local stage, no metastasis). 203 additional imaging diagnostics followed to clarify the "significant" findings (124 additional CT, costs 38 314.69 US dollars). Overall, there were 3.2 cardiac and 2.8 extra-cardiac findings per patient. Extra-cardiac findings appear significantly more frequently in patients over 60 years old, in smokers and in patients with a history of cardiac findings (p <0.05). CONCLUSION: Cardiac CT scans before PVI should be screened for extracardiac incidental findings that could have important clinical implications for each patient.

Real-time phase-contrast flow MRI of the ascending aorta and superior vena cava as a function of intrathoracic pressure (Valsalva manoeuvre).

OBJECTIVE: Real-time phase-contrast flow MRI at high spatiotemporal resolution was applied to simultaneously evaluate haemodynamic functions in the ascending aorta (AA) and superior vena cava (SVC) during elevated intrathoracic pressure (Valsalva manoeuvre). METHODS: Real-time phase-contrast flow MRI at 3 T was based on highly undersampled radial gradient-echo acquisitions and phase-sensitive image reconstructions by regularized non-linear inversion. Dynamic alterations of flow parameters were obtained for 19 subjects at 40-ms temporal resolution, 1.33-mm in-plane resolution and 6-mm section thickness. Real-time measurements were performed during normal breathing (10 s), increased intrathoracic pressure (10 s) and recovery (20 s). RESULTS: Real-time measurements were technically successful in all volunteers. During the Valsalva manoeuvre (late strain) and relative to values during normal breathing, the mean peak flow velocity and flow volume decreased significantly in both vessels (p < 0.001) followed by a return to normal parameters within the first 10 s of recovery in the AA. By contrast, flow in the SVC presented with a brief (1-2 heartbeats) but strong overshoot of both the peak velocity and blood volume immediately after pressure release followed by rapid normalization. CONCLUSION: Real-time phase-contrast flow MRI may assess cardiac haemodynamics non-invasively, in multiple vessels, across the entire luminal area and at high temporal and spatial resolution. ADVANCES IN KNOWLEDGE: Future clinical applications of this technique promise new insights into haemodynamic alterations associated with pre-clinical congestive heart failure or diastolic dysfunction, especially in cases where echocardiography is technically compromised.

Electrogram configuration and detection of supraventricular tachycardias by a morphology discrimination algorithm in single chamber ICDs.

BACKGROUND: Inappropriate ICD therapy for supraventricular tachycardia (SVT) remains a significant problem. A morphology-based algorithm (Wavelet) compares baseline and tachycardia electrograms (EGM). For this analysis different EGM sources can be programmed. This study evaluates the performance of Wavelet using two different EGM configurations (SVC-Can and RV-Can) for the detection of exercise-induced SVT. METHODS: Patients with a Medtronic model 7230 single chamber ICD and a dual coil lead were included. For each EGM source (SVC-Can or RV-Can), a baseline EGM template was acquired and the morphology similarity to this template (match percentage) was evaluated for 10-15 beats at different heart rates during exercise testing. The lower VT detection limit was programmed to 600 ms (therapies off). RESULTS: A total of 28 patients (66.9 +/- 4.7 years, 93% men) and 5,824 intracardiac QRS complexes were analyzed. With the RV-Can source, a consistently high similarity to the baseline EGM template was observed (< or =100 bpm: 90.90 +/- 0.56%; >100 bpm: 90.24 +/- 0.55%, P > 0.05). In contrast, SVC-Can was associated with a lower match percentage at baseline and a significant decrease at higher heart rates (< or =100 bpm: 77.91 +/- 2.65%; >100 bpm: 59.05 +/- 5.65%, P < 0.005). Accordingly, the specificity for appropriate detection of exercise-induced SVT was higher with RV-Can (21/21 episodes) than with SVC-Can (8/18 episodes, specificity 100% vs 44%; P < 0.0001). CONCLUSION: The RV-Can configuration appears to be superior to SVC-Can as EGM source for appropriate SVT detection with the Wavelet algorithm.