SciCombinator

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Journal: Circulation. Cardiovascular imaging

52

Excessive alcohol consumption is associated with cardiomyopathy, but the influence of moderate alcohol use on cardiac structure and function is largely unknown.

Concepts: Cardiology, Sociology

28

BACKGROUND: -Accurate measures are critical when attempting to distinguish normal from pathological changes in cardiac function during exercise, yet imaging modalities have seldom been assessed against invasive exercise standards. We sought to validate a novel method of biventricular volume quantification by cardiac magnetic resonance imaging (CMR) during maximal exercise. METHODS AND RESULTS: -CMR was performed on 34 subjects during exercise and free-breathing using an ungated real-time CMR (“RT-ungated”) sequence. ECG and respiratory movements were retrospectively synchronized enabling compensation for cardiac cycle and respiratory phase. Feasibility of RT-ungated imaging was compared with standard exercise CMR imaging with ECG gating (“gated”), Accuracy of RT-ungated CMR was assessed against an invasive standard (direct Fick) and reproducibility was determined following a second bout of maximal exercise. Ventricular volumes were able to be analyzed more frequently during high-intensity exercise using RT-ungated as compared with gated CMR (100% vs. 47%, p<0.0001) and with better inter-observer variability for RT-ungated (coefficient of variation CV=1.9% and 2.0% for left and right ventricular stroke volumes, respectively) than gated (CV=15.2% and 13.6%), p <0.01. Cardiac output determined by RT-ungated CMR proved accurate against the direct Fick method with excellent agreement (intraclass correlation coefficient R=0.96) which was highly reproducible during a second bout of maximal exercise (R=0.98). CONCLUSIONS: -By combining real-time ungated CMR with post-hoc analysis incorporating compensation for respiratory motion, highly reproducible and accurate biventricular volumes can be measured during maximal exercise.

Concepts: Scientific method, Cardiology, Heart, Nuclear magnetic resonance, Magnetic resonance imaging, Cardiac output, Covariance and correlation, Fick principle

28

BACKGROUND: -The myocardial extracellular volume fraction (MECVF) has been used to detect diffuse fibrosis. Estimation of MECVF relies quantification of the T1 relaxation time after contrast enhancement, which can be sensitive to equilibrium transcytolemmal water exchange. We hypothesized that MECVF, quantified with a parsimonious 2-space water-exchange model, correlates positively with the connective tissue volume fraction (CTVF) in a rodent model of hypertensive heart disease, while the widely used analysis based on assuming fast transcytolemmal water exchange could result in a significant underestimate of MECVF. METHODS AND RESULTS: -Nω-nitro-L-arginine-metyl-ester (L-NAME) or placebo was administered to 22 and 15 wild-type mice, respectively. MECVF was measured at baseline and 7-week follow-up by pre- and post-contrast T1 CMR imaging at 4.7 T, using a 2-space water-exchange model. CTVF was quantified, using Masson’s trichrome stain. L-NAME induced hypertrophy (weight-indexed LV mass 2.2±0.3 vs. 4.1±0.4 μg/g, p<0.001), and increased CTVF (8.6%±1.5 vs. 2.58%±0.6, p<0.001), compared to controls. MECVF was higher in L-NAME-treated animals (0.43±0.09 vs, 0.26±0.03, p<0.001), and correlated with CTVF and weight-indexed LV mass (r=0.842 and r=0.737 respectively, both P<0.0001). Neglecting transcytolemmal water-exchange caused a significant underestimate of MECVF changes. Ten patients with history of hypertension had significantly higher MECVF (0.446±0.063) compared to healthy controls 0.307±0.030, p<0.001). CONCLUSIONS: -CMR allowed detection of myocardial extracellular matrix expansion in a mouse model, and in patients with a history of hypertension. Accounting for the effects of transcytolemmal water exchange can result in a substantial difference of MECVF, compared to assuming fast transcytolemmal water exchange.

Concepts: Hypertension, Heart, Muscle, Nuclear magnetic resonance, Heart disease, Magnetic resonance imaging, Potassium, Masson's trichrome stain

27

-Risks associated with pediatric reconstructive heart surgery include injury of the sinoatrial node (SAN) and atrioventricular node (AVN), requiring cardiac rhythm management using implantable pacemakers. These injuries are result of difficulties in identifying nodal tissues intraoperatively. Here, we describe an approach based on confocal microscopy and extracellular fluorophores to quantify tissue microstructure and identify nodal tissue.

Concepts: Cardiology, Heart, Cardiac anatomy, Identification, Cardiac pacemaker, Sinoatrial node, Atrioventricular node, Electrical conduction system of the heart

26

-Left ventricular (LV) hypertrophy (LVH, high LV mass) is traditionally classified as concentric or eccentric based on LV relative wall thickness. We evaluated the prediction of subsequent adverse events in a new 4-group LVH classification based on LV dilatation (high LV end-diastolic volume [EDV] index) and concentricity (LVM/EDV((2/3))) in hypertensive patients.

Concepts: Hypertension, Cardiology, Left ventricular hypertrophy, Geometry, Ventricular hypertrophy, Aortic insufficiency, Cardiomegaly

26

-Diffuse interstitial fibrosis is present in diverse cardiomyopathies and associated with poor prognosis. We investigated whether MRI-based T1 mapping could quantify the induction and pharmacological suppression of diffuse cardiac fibrosis in murine pressure-overload hypertrophy.

Concepts: Fibrosis, Cardiac fibrosis

17

Cigarette smoking has been associated with higher risk of incident heart failure independent of coronary artery disease, but the impact of tobacco use on cardiac structure and function in the general population is uncertain. This study evaluated the relationship between smoking and echocardiographic measures in a large elderly cohort.

Concepts: Myocardial infarction, Cardiology, Heart, Tobacco, Cigarette, Nicotine, Artery, Coronary circulation

8

The choice of imaging techniques in patients with suspected coronary artery disease (CAD) varies between countries, regions, and hospitals. This prospective, multicenter, comparative effectiveness study was designed to assess the relative accuracy of commonly used imaging techniques for identifying patients with significant CAD.

Concepts: Coronary artery disease, Artery, Coronary circulation

7

In patients with hypertrophic cardiomyopathy and left ventricular outflow tract (LVOT) obstruction, but without basal septal hypertrophy, we sought to identify mitral valve (MV) and papillary muscle (PM) abnormalities that predisposed to LVOT obstruction, using echo and cardiac magnetic resonance.

Concepts: Cardiology, Heart, Hypertrophic cardiomyopathy, Mitral valve, Left ventricle, Papillary muscle, Cardiac anatomy, Chordae tendineae

6

The appropriate indication for coronary computed tomographic angiography (CTA) as a part of preoperative evaluation has not been defined yet. We investigated the value of coronary CTA in patients undergoing noncardiac surgery.

Concepts: Computed tomography angiography