A new approach to characterize cardiac sodium storage by combining fluorescence photometry and magnetic resonance imaging in small animal research.

Cardiac myocyte sodium (Na+) homoeostasis is pivotal in cardiac diseases and heart failure. Intracellular Na+ ([Na+]i) is an important regulator of excitation-contraction coupling and mitochondrial energetics. In addition, extracellular Na+ ([Na+]e) and its water-free storage trigger collagen cross-linking, myocardial stiffening and impaired cardiac function. Therefore, understanding the allocation of tissue Na+ to intra- and extracellular compartments is crucial in comprehending the pathophysiological processes in cardiac diseases. We extrapolated [Na+]e using a three-compartment model, with tissue Na+ concentration (TSC) measured by in vivo 23Na-MRI, extracellular volume (ECV) data calculated from T1 maps, and [Na+]i measured by in vitro fluorescence microscopy using Na+ binding benzofuran isophthalate (SBFI). To investigate dynamic changes in Na+ compartments, we induced pressure overload (TAC) or myocardial infarction (MI) via LAD ligation in mice. Compared to SHAM mice, TSC was similar after TAC but increased after MI. Both TAC and MI showed significantly higher [Na+]i compared to SHAM (around 130% compared to SHAM). Calculated [Na+]e increased after MI, but not after TAC. Increased TSC after TAC was primarily driven by increased [Na+]i, but the increase after MI by elevations in both [Na+]i and [Na+]e.

Differential Modulation of Markers of Oxidative Stress and DNA Damage in Arterial Hypertension.

Patients with arterial hypertension have an increased risk of developing tumors, particularly renal cell carcinoma. Arterial hypertension is linked to DNA damage via the generation of oxidative stress, in which an upregulated renin-angiotensin-aldosterone system plays a crucial role. The current study investigated surrogates of oxidative stress and DNA damage in a group of hypertensive patients (HypAll, n = 64) and subgroups of well (HypWell, n = 36) and poorly (HypPoor, n = 28) controlled hypertensive patients compared to healthy controls (n = 8). In addition, a longitudinal analysis was performed with some of the hypertensive patients. Markers for oxidative stress in plasma (SHp, D-ROM, and 3-nitrotyrosine) and urine (8-oxodG, 15-F2t-isoprostane, and malondialdehyde) and markers for DNA damage in lymphocytes (γ-H2AX and micronuclei) were measured. In HypAll, all markers of oxidative stress except malondialdehyde were increased compared to the controls. After adjustment for age, this association was maintained for the protein stress markers SHp and 3-nitrotyrosine. With regard to the markers for DNA damage, there was no difference between HypAll and the controls. Further, no significant differences became apparent in the levels of both oxidative stress and DNA damage between HypWell and HypPoor. Finally, a positive correlation between the development of blood pressure and oxidative stress was observed in the longitudinal study based on the changes in D-ROM and systolic blood pressure. In conclusion, we found increased oxidative stress in extensively treated hypertensive patients correlating with the level of blood-pressure control but no association with DNA damage.

Contrast-enhanced ultrasound for non-invasive differential diagnosis of unclear left atrial mass.

Transthoracic and transesophageal echocardiography detected a left atrial mass attached to the intra-atrialseptum. Intravenous contrast agent ruled out atrial thrombus, sugesting a left atrial myxoma. This highlights theimportance of contrast echocardiography for differential diagnosis of left atrial findings.

Ultra-high field cardiac MRI in large animals and humans for translational cardiovascular research.

A key step in translational cardiovascular research is the use of large animal models to better understand normal and abnormal physiology, to test drugs or interventions, or to perform studies which would be considered unethical in human subjects. Ultrahigh field magnetic resonance imaging (UHF-MRI) at 7 T field strength is becoming increasingly available for imaging of the heart and, when compared to clinically established field strengths, promises better image quality and image information content, more precise functional analysis, potentially new image contrasts, and as all in-vivo imaging techniques, a reduction of the number of animals per study because of the possibility to scan every animal repeatedly. We present here a solution to the dual use problem of whole-body UHF-MRI systems, which are typically installed in clinical environments, to both UHF-MRI in large animals and humans. Moreover, we provide evidence that in such a research infrastructure UHF-MRI, and ideally combined with a standard small-bore UHF-MRI system, can contribute to a variety of spatial scales in translational cardiovascular research: from cardiac organoids, Zebra fish and rodent hearts to large animal models such as pigs and humans. We present pilot data from serial CINE, late gadolinium enhancement, and susceptibility weighted UHF-MRI in a myocardial infarction model over eight weeks. In 14 pigs which were delivered from a breeding facility in a national SARS-CoV-2 hotspot, we found no infection in the incoming pigs. Human scanning using CINE and phase contrast flow measurements provided good image quality of the left and right ventricle. Agreement of functional analysis between CINE and phase contrast MRI was excellent. MRI in arrested hearts or excised vascular tissue for MRI-based histologic imaging, structural imaging of myofiber and vascular smooth muscle cell architecture using high-resolution diffusion tensor imaging, and UHF-MRI for monitoring free radicals as a surrogate for MRI of reactive oxygen species in studies of oxidative stress are demonstrated. We conclude that UHF-MRI has the potential to become an important precision imaging modality in translational cardiovascular research.

Non-invasive assessment of tissue sodium content in patients with primary adrenal insufficiency.

Objective: Replacement therapy in primary adrenal insufficiency (PAI) with corticosteroids modulates sodium homeostasis. Serum sodium is, however, prone to osmotic shifts induced by several additional factors besides corticosteroids and does not always reliably reflect treatment quality. Non-osmotic tissue storage can be visualized by sodium MRI (23Na-MRI) and might better reflect corticosteroid activity. Design: Longitudinal study of 8 patients with newly diagnosed PAI and cross-sectional study in 22 patients with chronic PAI is reported here. Comparison was made with matched healthy controls. Methods: Using a 23Na-MRI protocol on a 3T scanner, relative sodium signal intensities (rSSI) to signal intensities of the reference vial with 100 mmol/L of sodium were determined in the muscle and skin of the lower calf. Results: In newly diagnosed patients, tissue rSSI (median, range) were reduced and significantly increased after treatment initiation reaching levels similar to healthy controls (muscle: from 0.15 (0.08, 0.18) to 0.18 (0.14, 0.27), P = 0.02; skin: from 0.12 (0.09, 0.18) to 0.18 (0.14, 0.28), P < 0.01). Muscle rSSI was significantly higher in patients with chronic PAI compared to controls (0.19 (0.14, 0.27) vs 0.16 (0.12, 0.20), P < 0.01). In chronic PAI, skin rSSI significantly correlated with plasma renin concentration. Conclusion: 23Na-MRI provides an additional insight into sodium homeostasis, and thus the quality of replacement therapy in PAI, as tissue sodium significantly changes once therapy is initiated. The increased tissue sodium in patients with chronic PAI might be an indication of over-replacement.

Primary hyperaldosteronism induces congruent alterations of sodium homeostasis in different skeletal muscles: a 23Na-MRI study.

Background: Sodium homeostasis is disrupted in many cardiovascular diseases, which makes non-invasive sodium storage assessment desirable. In this regard, sodium MRI has shown its potential to reveal differences in sodium content between healthy and diseased tissues as well as treatment-related changes of sodium content. When different tissues are affected disparately, simultaneous assessment of these compartments is expected to provide better information about sodium distribution, reduce examination time, and improve clinical efficiency. Objectives: The objectives were (1) to investigate sodium storage levels in calf and pectoral muscle in healthy controls and patients and quantify changes following medical treatment and (2) to demonstrate homogeneous disruption in skeletal muscle sodium storage in patients with primary hyperaldosteronism (PHA). Methods: We assessed sodium storage levels (relative sodium signal intensity, rSSI) in the calf and pectoral muscles of eight patients with PHA prior and after treatment and 12 age- and sex-matched healthy volunteers. Results: Calf and pectoral muscle compartments exhibited similar sodium content both in healthy subjects (calf vs pectoral rSSI: 0.14 ± 0.01 vs 0.14 ± 0.03) and PHA patients (calf vs pectoral rSSI: 0.19 ± 0.03 vs 0.18 ± 0.03). Further, we observed similar treatment-related changes in pectoral and calf muscles in the patients (proportional rSSI change calf: 26%; pectoral: 28%). Conclusion: We found that sodium was distributed uniformly and behaved equally in different skeletal muscles in Conn's syndrome. This allows to measure both heart and skeletal muscle sodium signals simultaneously by a single measurement without repositioning the patient. This increases 23Na-MRI's clinical feasibility as an innovative technique to monitor sodium storage.

Prevalence and determinants of the precursor stages of heart failure: results from the population-based STAAB cohort study.

AIMS: Prevention of heart failure relies on the early identification and control of risk factors. We aimed to identify the frequency and characteristics of individuals at risk of heart failure in the general population. METHODS AND RESULTS: We report cross-sectional data from the prospective Characteristics and Course of Heart Failure Stages A-B and Determinants of Progression (STAAB) cohort study investigating a representative sample of residents of Würzburg, Germany. Sampling was stratified 1:1 for sex and 10:27:27:27:10 for age groups of 30-39/40-49/50-59/60-69/70-79 years. Heart failure precursor stages were defined according to American College of Cardiology/American Heart Association: stage A (risk factors for heart failure), stage B (asymptomatic cardiac dysfunction). The main results were internally validated in the second half of the participants. The derivation sample comprised 2473 participants (51% women) with a distribution of 10%/28%/25%/27%/10% in respective age groups. Stages A and B were prevalent in 42% and 17% of subjects, respectively. Of stage B subjects, 31% had no risk factor qualifying for stage A (group 'B-not-A'). Compared to individuals in stage B with A criteria, B-not-A were younger, more often women, and had left ventricular dilation as the predominant B qualifying criterion (all P < 0.001). These results were confirmed in the validation sample (n = 2492). CONCLUSION: We identified a hitherto undescribed group of asymptomatic individuals with cardiac dysfunction predisposing to heart failure, who lacked established heart failure risk factors and therefore would have been missed by conventional primary prevention. Further studies need to replicate this finding in independent cohorts and characterise their genetic and -omic profile and the inception of clinically overt heart failure in subjects of group B-not-A.

Increased myocardial sodium signal intensity in Conn's syndrome detected by 23Na magnetic resonance imaging.

AIMS: Sodium intake has been linked to left ventricular hypertrophy independently of blood pressure, but the underlying mechanisms remain unclear. Primary hyperaldosteronism (PHA), a condition characterized by tissue sodium overload due to aldosterone excess, causes accelerated left ventricular hypertrophy compared to blood pressure matched patients with essential hypertension. We therefore hypothesized that the myocardium constitutes a novel site capable of sodium storage explaining the missing link between sodium and left ventricular hypertrophy. METHODS AND RESULTS: Using 23Na magnetic resonance imaging, we investigated relative sodium signal intensities (rSSI) in the heart, calf muscle, and skin in 8 PHA patients (6 male, median age 55 years) and 12 normotensive healthy controls (HC) (8 male, median age 61 years). PHA patients had a higher mean systolic 24 h ambulatory blood pressure [152 (140; 163) vs. 125 (122; 130) mmHg, P < 0.001] and higher left ventricular mass index [71.0 (63.5; 106.8) vs. 55.0 (50.3; 66.8) g/m2, P = 0.037] than HC. Compared to HC, PHA patients exhibited significantly higher rSSI in the myocardium [0.31 (0.26; 0.34) vs. 0.24 (0.20; 0.27); P = 0.007], calf muscle [0.19 (0.16; 0.22) vs. 0.14 (0.13; 0.15); P = 0.001] and skin [0.28 (0.25; 0.33) vs. 0.19 (0.17; 0.26); P = 0.014], reflecting a difference of +27%, +38%, and +39%, respectively. Treatment of PHA resulted in significant reductions of the rSSI in the myocardium, calf muscle and skin by -13%, -27%, and -29%, respectively. CONCLUSION: Myocardial tissue rSSI is increased in PHA patients and treatment of aldosterone excess effectively reduces rSSI, thus establishing the myocardium as a novel site of sodium storage in addition to skeletal muscle and skin.

Myocardial Fibrosis Predicts 10-Year Survival in Patients Undergoing Aortic Valve Replacement.

Background Long-term data on evolution and clinical impact of myocardial fibrosis in valvular heart disease are scarce. Methods and Results In this 10 years' extension of a prospective study in patients undergoing conventional aortic valve replacement because of symptomatic severe aortic valve stenosis, the impact of myocardial replacement fibrosis (MRF) on long-term outcome was assessed. Endomyocardial biopsies were acquired during aortic valve replacement in 58 consecutive patients. MRF was graded using the calculated percentage area of fibrosis and patients categorized as severe (n=21), mild (n=15), and no fibrosis (n=22). Echocardiography including strain imaging, as well as cardiovascular magnetic resonance, to assess late gadolinium enhancement was performed at baseline, 1, and 10 years after aortic valve replacement. Death of any cause occurred in 21 patients (38.9%): 3 (14.3%) in the group without MRF, 6 (42.9%) in the mild MRF group, and 12 (63.2%) in the severe MRF group ( P=0.006), resulting in the lowest cumulative survival for patients with severe MRF (log-rank P=0.003). In the group without MRF, none died of cardiovascular cause. MRF was found to be an independent predictor of survival (hazard ratio, 1.271; 95% CI, 1.032-1.564; P=0.024). Conclusions This 10-year follow-up study underlines the profound impact of replacement fibrosis with regard to cardiac and all-cause mortality in patients undergoing aortic valve replacement for severe aortic valve stenosis. Integrating cardiovascular magnetic resonance and echocardiographic functional imaging beyond ejection fraction quantification could help in clinical decision making to stratify patient prognosis with regard to myocardial longitudinal function and prevalence of replacement fibrosis.

Frequency and prognostic impact of mid-expiratory flow reduction in stable patients six months after hospitalisation for heart failure with reduced ejection fraction.

AIM: This study investigates the prevalence and prognostic impact of central and small airways obstruction (CAO and SAO) in patients with stable heart failure (HF). METHODS & RESULTS: Spirometry was performed in 585 outpatients (mean age 65±12years, 75% male) six months after hospitalisation for acute decompensation secondary to HF with ejection fraction <40%. We assessed forced expiratory volume in the first second (FEV1), forced vital capacity (FVC) and mid-expiratory flow (MEF) at 50% of FVC. CAO was defined by FEV1/FVC <0.7. SAO was defined by FEV1/FVC ≥0.7 plus MEF <60% of predicted value. CAO and SAO were excluded in 359 patients (61% of all). MEF <60% predicted was found in 226 patients (39% of all), among those 88 with CAO (15% of all) and 138 (24% of all) with SAO. During a twelve month follow-up, 42 patients (7.2%) died. Mortality rates of patients with CAO and SAO were comparable (12.5% and 10.9%, respectively, p=0.74), and both higher than in patients without airways obstruction (4.5%, both p<0.01). In univariable Cox regression analysis, both CAO and SAO were associated with 2-fold increased all-cause mortality risk (hazard ratios [95% confidence intervals]: 2.78 [1.33-6.19], p=0.007 and 2.51 [1.24-5.08], p=0.010, respectively). Adjustment for determinants of CAO and SAO, prognostic markers of heart failure and comorbidities attenuated the association of mortality with CAO but not with SAO. CONCLUSIONS: SAO is more common than CAO and indicates an increased mortality risk in HF. Thus, reduced MEF may be a feature of patients at risk and merits special attention in HF management.