Alexander C. Bunck

Right ventricular–left ventricular interaction in adults with Tetralogy of Fallot: A combined cardiac magnetic resonance and echocardiographic speckle tracking study

OBJECTIVES To assess ventricular dysfunction and ventricular interaction after repair of Tetralogy of Fallot (ToF) employing echocardiography speckle-tracking and cardiac magnetic resonance imaging (CMR). BACKGROUND Severe pulmonary regurgitation and right ventricular (RV) dysfunction are common after repair of ToF and may also affect the shape and function of the left ventricle (LV). Recent studies suggest that LV dysfunction may be of particular prognostic value. METHODS AND RESULTS Twenty-one consecutive adults with repaired ToF (15 male, mean age 38 ± 11 years, 7 with severe PR) underwent a comprehensive echocardiographic exam including speckle-tracking analysis, CMR and cardiopulmonary exercise testing. Twenty-one subjects without relevant heart disease served as controls. Echocardiographically measured RV diameters correlated with RV volumes obtained from CMR (r=0.63; p=0.006). In addition, a close correlation was found between RV and LV function on CMR (r=0.74, p=0.002), speckle-tracking LV and RV peak longitudinal 2D strain (r=0.66, p=0.003) and mitral and tricuspid annular plain systolic excursion (r=0.71, p=0.0003). While LV ejection fraction was normal in the majority of patients and not different from controls, LV longitudinal strain was significantly reduced in ToF patients (-16.5 ± 3.3 vs. -20.5 ± 2.7%, p=0.0001). CONCLUSION Left and right ventricular function both by CMR and speckle-tracking is interrelated in adults with repaired ToF. Despite normal LV ejection fraction, 2D longitudinal strain is significantly reduced in ToF patients, suggesting subclinical LV myocardial damage. Considering the potential prognostic value of LV dysfunction in ToF, this measurement may gain importance and should be included in future outcome studies.

Cardiac magnetic resonance feature tracking??? a novel method to assess myocardial strain: Comparison with echocardiographic speckle tracking in healthy volunteers and in patients with left ventricular hypertrophy

BACKGROUND Left ventricular longitudinal strain (LV-LS) and strain rate (SR) are sensitive markers of early systolic dysfunction. AIM To evaluate the feasibility of a novel, cardiac magnetic resonance (CMR) based method known as feature tracking (FT) for the assessment of strain and SR, and to compare the CMR based results to those obtained on standard transthoracic echocardiography (TTE) in healthy volunteers and in patients with left ventricular hypertrophy cardiomyopathy (HCM). METHODS Overall, 20 healthy volunteers (ten male, mean age 24 ± 3 years) and 20 consecutive patients with HCM (12 male, mean age 47 ± 19 years) were included. Longitudinal and circumferential strain and SR of the left ventricle were measured on CMR at 1.5 Tesla and TTE and interobserver variability was assessed. RESULTS FT measurements were feasible in all subjects. A good agreement between global LV-LS measured on CMR (controls: 20.8 ± 3.0; HCM: 17.6 ± 3.8) and TTE (controls: 19.4 ± 2.1; HCM: 16.6 ± 2.9) was found, while the agreement was worse for circumferential strain and all SR measurements. For the left and right ventricles, interobserver reproducibility was higher for strain measurements compared to SR. Coefficients of variation were lowest for LV-LS (13.2%) by CMR. CONCLUSIONS FT analysis is a novel CMR based method for the analysis of myocardial strain and SR that is simple and correlates well with the echocardiographic measurements. Since CMR is unaffected by inadequate acoustic windows, FT may represent an attractive alternative to echocardiography in assessing the increasingly important parameters of myocardial deformation.

Modeling autosomal recessive cutis laxa type 1C in mice reveals distinct functions for Ltbp-4 isoforms

Recent studies have revealed an important role for LTBP-4 in elastogenesis. Its mutational inactivation in humans causes autosomal recessive cutis laxa type 1C (ARCL1C), which is a severe disorder caused by defects of the elastic fiber network. Although the human gene involved in ARCL1C has been discovered based on similar elastic fiber abnormalities exhibited by mice lacking the short Ltbp-4 isoform (Ltbp4S−/−), the murine phenotype does not replicate ARCL1C. We therefore inactivated both Ltbp-4 isoforms in the mouse germline to model ARCL1C. Comparative analysis of Ltbp4S−/− and Ltbp4-null (Ltbp4−/−) mice identified Ltbp-4L as an important factor for elastogenesis and postnatal survival, and showed that it has distinct tissue expression patterns and specific molecular functions. We identified fibulin-4 as a previously unknown interaction partner of both Ltbp-4 isoforms and demonstrated that at least Ltbp-4L expression is essential for incorporation of fibulin-4 into the extracellular matrix (ECM). Overall, our results contribute to the current understanding of elastogenesis and provide an animal model of ARCL1C.

Non-invasive imaging of bioresorbable coronary scaffolds using CT and MRI: First in vitro experience

BACKGROUND Accurate assessment of coronary stents after PCI using non-invasive imaging remains challenging despite technological improvements. New bioresorbable vascular scaffolds (BVS) have recently become available promising improved non-invasive imaging properties, which however have not be examined specifically yet. Therefore we investigated CT and MRI visualization properties of the only two CE-marked coronary BVSs. METHODS The Abbott Absorb and the Elixir DESolve BVS were placed in plastic tubes filled with contrast agent and scanned with a latest generation CT respectively MR system. For CT image quality was assessed by two blinded, independent readers and in-scaffold diameter difference as well as in-scaffold attenuation difference were measured. For MRI in-scaffold signal intensity, in-scaffold lumen visibility and in-scaffold signal homogeneity were measured. RESULTS In CTA both BVSs showed no significant difference to nominal tube diameter (DESolve 101%, Absorb 100%) and to nominal tube attenuation (DESolve 96%, Absorb 98%) and were both rated with the highest score for unrestricted lumen visualization. In MRA both BVSs showed unimpaired signal intensity (DESolve 103%, Absorb 100%), lumen visibility (DESolve 92%, Absorb 89%) and lumen homogeneity (DESolve SD 7.1%, Absorb SD 9.5%) when compared to the unstented tube. There was no significant difference between CTA and MRA results of both BVSs. CONCLUSIONS Coronary BVSs show no relevant impairment for subjective and objective measures of in-stent lumen visualization by CT and MRI and will therefore allow reliable non-invasive assessment of coronary artery patency after PCI with deployment of a BVS, which is an (additional) advantage when compared to conventional stents.

Quantitative comparison of 4D MRI flow measurements to 3D computational fluid dynamics simulation of cerebrospinal fluid movement in the spinal subarachnoid space

Computational fluid dynamic (CFD) simulations have provided detailed information about the complex flow and pressure field within the cerebrospinal fluid (CSF) system. The solutions of these simulations are sensitive to boundary conditions and thus need validation with in vivo measurements. However, validation of CFD flow results and MRI CSF flow measurements have been limited to through-plane pcMR measurements. Recent advancements in MRI flow measurement technology has enabled measurement of the 4D flow field within the spinal subarachnoid space (SSS), superior sagittal sinus and ventricles of the brain. Alterations in cerebrospinal fluid (CSF) dynamics have been associated with neurological symptoms and formation of Syringomyelia in patients with Chiari malformation and spinal stenosis. In these patients, analysis of morphology alone has proved to be insufficient in explaining the absence or presence of symptoms. In the present study, we compare quantitatively 4D flow measurements to CFD analysis within the SSS (C1-T1, cervical spinal segment) of a healthy volunteer without any lesions at the craniocervical junction or the cervical spinal canal.

Diagnosis of cardiac transthyretin amyloidosis based on multimodality imaging

in delimitation to other causes of hypertrophy such as increased afterload in hypertension and aortic stenosis or genetic primary hypertrophic cardiomyopathy [1]. For further differential diagnosis, a cardiac magnetic resonance imaging (MRI) was performed which in addition to the morphological changes seen on echocardiography revealed extensive, predominantly patchy enhancement of the septal myocardium and a band-like, subendocardial enhancement of the right ventricle and the lateral wall of the left ventricle (Fig. 1b, c). This heterogeneous enhancement pattern would be consistent with cardiac amyloidosis. With no signs of acute myocardial edema on T2 black blood imaging and preserved systolic function, a diffuse inflammatory process, which is a potential differential diagnosis of extensive myocardial late enhancement, was deemed highly unlikely. At presentation in our clinic, the patient showed lower leg edema and severe limitation of physical capacity. Further evaluation of family history did not reveal any clear hint of familial cardiac disease. Laboratory investigation demonstrated no significant abnormalities apart from slight impairment of renal function. With suspicion of infiltrative cardiac disease such as amyloidosis, we performed right-ventricular endomyocardial biopsy which showed mild hypertrophy of cardiac myocytes without evidence of amyloidosis, storage disease, or myocarditis. Despite the strong clinical suspicion of a false-negative biopsy result we decided not to repeat biopsy due to the fragility of the patient and a hemodynamically relevant supraventricular tachycardia during the first procedure, but to seek for noninvasive clarification. Based on MRI tissue characterization cardiac amyloidosis was very likely. Most cases of cardiac amyloidosis occur in monoclonal light-chain gammopathy (AL) or transthyretin amyloidosis (ATTR) [2–5]. In AA amyloidosis Sirs: In December 2015, a 79-year-old woman was transferred to our heart failure clinic for further assessment of a morphologic hypertrophic cardiomyopathy. The patient had an unremarkable medical history except long-standing arterial hypertension, which was well controlled. She presented with severe limitation during ordinary activity with dyspnea New York Heart Association class III and typical presentation of stable angina pectoris. In addition, she complained about intermittent claudication after a short walking distance. 1 month earlier she presented to the emergency department with suspicion of an acute coronary syndrome with elevated troponin Tand ST depression in the 12-lead ECG. Invasive coronary angiography was performed which excluded coronary heart disease. Transthoracic echocardiography showed severe concentric biventricular myocardial hypertrophy with preserved systolic ejection fraction and impaired diastolic function with restrictive filling pattern. Bi-atrial enlargement and pericardial effusion were present. Analysis of global longitudinal strain showed preserved strain in the left-ventricular apex and considerably reduced longitudinal strain in the mid and basal segments, a socalled pattern of relative apical sparing (Fig. 1a), which is suggestive of infiltrative processes such as amyloidosis

82-jähriger Mann mit akutem Koronarsyndrom und unklarer Arthropathie

Ein 82-jahriger Mann stellte sich wegen eines akuten Koronarsyndroms vor. Laborchemisch konnten neben einem erhohten Troponin T (1,44 µg/l) erhohte Werte fur Kreatinin (1,26 mg/dl) und Harnsaure (8,1 mg/dl) nachgewiesen werden. Die klinische und computertomographische Untersuchung zeigt zwei pathologische Befunde an Handen (Abb.1A+B) und Fusen.

26-jähriger Mann mit Thoraxschmerzen und unspezifischen Arthralgien

Ein 26-jähriger Mann stellte sich wegen linksthorakaler Schmerzen vor. Das Ruhe-EKG zeigte den oben abgebildeten Befund (qAbb. 1A). Bei der klinischen Untersuchung klagte der Patient über unspezifische Arthralgien; zudem fiel ein angedeutetes Schmetterlingserythem auf. Laborchemisch zeigten sich erhöhte Herzenzyme und eine positive Immunologie (Nachweis von antinukleären und Doppelstrang-DNA-Antikörpern). Nach Ausschluss einer koronaren Makroangiopathie mittels Herz-CT erfolgte eine kardiale MRT-Untersuchung (qAbb. 1B–C). Ruhe-EKG und Kardio-MRT zeigen insgesamt drei pathologische Befunde.

Cerebrospinal Fluid Dynamics in the Cervical Spine: Importance of Fine Anatomical Structures

Fine anatomical structures, including nerve roots and denticulate ligaments, can significantly influence cerebrospinal fluid (CSF) dynamics inside the spinal subarachnoid space (SSS). In this study, we completed computational fluid dynamics (CFD) simulations based on subject specific geometries of the cervical spine with and without idealized fine structures (nerve roots and denticulate ligaments, NRDL). The results show that NRDL had a significant impact on CSF dynamics in terms of velocity distribution, flow streamlines, bidirectional nature of the flow and the pressure drop.