Early Heart Rate Recovery after a 6-min Walking Test Predicts Clinical Benefits in Patients after Percutaneous Aortic Valve Implantation.

BACKGROUND: It was hypothesized that the time-appropriate return to a resting heart rate (HR) after cessation of exercise could be a marker for predicting outcomes in patients with heart failure (HF). We aimed to evaluate the prognostic value of HR recovery in functional improvement among adults with severe aortic stenosis undergoing percutaneous aortic valve implantation (TAVI). METHODS: We performed a 6 min walk test (6MWT) in 93 individuals before TAVI and 3 months after the procedure. The change in walking distance was calculated. During the pre-TAVI 6MWT, we analyzed the differences between baseline HR, HR at the end of the test, and HR at the 1st, 2nd, and 3rd minute of recovery. RESULTS: After 3 months, 6MWT distances improved by 39 ± 63 m and reached a total of 322 ± 117 m. Multiple linear regression proved the differences between HR after 2 min of recovery and baseline HR in pre-TAVI after a 6MWT was the only significant predictor of waking distance improvement during follow-up. CONCLUSIONS: Our study suggests that analysis of HR recovery after a 6MWT may be a helpful and easy parameter to assess improvements in exercise capacity after TAVI. This simple method can help to identify patients in whom no significant benefit in functional improvement can be expected despite successful valve implantation.

Simultaneous placement of leadless pacemaker and dialysis catheter in patient with exhausted vasculature.

The problem with limited venous access may occur in patients receiving long-term hemodialysis treatment with no possibility of arteriovenous access or in patients with cardiac implantable electronic device-related infection leading to the removal of cardiac implantable electronic device. We present a case report where both situations occur simultaneously. Using recent development in cardiac pacing-leadless cardiac pacemaker-we manage to overcome the vascular access problem. The described case emphasizes the necessity of multispecialty collaboration and gains of new pacing technology in patients who need placement of vascular access for hemodialysis and cardiac implantable electronic device where vascular access is scarce.

A nitrogen-rich ligand as a scaffold for slow magnetic relaxation in dysprosium-based 0D and 1D architectures.

A recently designed nitrogen-rich ligand is successfully applied as a scaffold for lanthanide ions to show that the intricate chemistry of energetic materials can be combined with other fields of research, including that of molecular magnetism. Herein, we report the synthesis of two different types of molecular architectures using a single ligand template, in which the discrete monomer exhibits single-molecule magnet-like behaviour along with two well-isolated modes of magnetic relaxation.

Synthesis and Investigation of 2,3,5,6-Tetra-(1H-tetrazol-5-yl)pyrazine Based Energetic Materials.

The structures and properties of several energetic compounds based on a high-nitrogen-content anion, namely 2,3,5,6-tetra(1H-tetrazol-5-yl)pyrazine (H4 TTP) are reported here for the first time. These energetic salts were synthesized by reacting H4 TTP with various alkali metal hydroxides (sodium, potassium, rubidium, caesium) and N-based (ammonia, hydrazine, hydroxylamine, guanidine carbonate, aminoguanidine bicarbonate). The resulting materials were comprehensively characterized by multinuclear (1 H, 13 C) NMR spectroscopy, infrared spectroscopy, elemental analysis, DSC, as well as low-temperature single-crystal X-ray diffraction. Heats of formation for the metal-free species as well as detonation parameters were calculated. The presented energetic materials (EMs) show high thermal stability (207 °C≤Tdec ≤300 °C), while the metal-free ionic derivatives exhibit desirable properties such as detonation velocity (6873 m s-1 ≤VC-J ≤8364 m s-1 ), detonation pressure (14.3 GPa≤pC-J ≤24.9 GPa), and specific impulse (141.4≤Isp ≤192.5 s).

Synthesis and Investigation of Advanced Energetic Materials Based on Bispyrazolylmethanes.

Herein we present the preparation and characterization of three new bispyrazolyl-based energetic compounds with great potential as explosive materials. The reaction of sodium 4-amino-3,5-dinitropyrazolate (5) with dimethyl iodide yielded bis(4-amino-3,5-dinitropyrazolyl)methane (6), which is a secondary explosive with high heat resistance (Tdec =310 °C). The oxidation of this compound afforded bis(3,4,5-trinitropyrazolyl)methane (7), which is a combined nitrogen- and oxygen-rich secondary explosive with very high theoretical and estimated experimental detonation performance (Vdet (theor)=9304 m s-1 versus Vdet (exp)=9910 m s-1 ) in the range of that of CL-20. Also, the thermal stability (Tdec =205 °C) and sensitivities of 7 are auspicious. The reaction of 6 with in situ generated nitrous acid yielded the primary explosive bis(4-diazo-5-nitro-3-oxopyrazolyl)methane (8), which showed superior properties to those of currently used diazodinitrophenol (DDNP).

Synthesis and Investigation of 2,6-Bis(picrylamino)-3,5-dinitro-pyridine (PYX) and Its Salts.

2,6-Bis(picrylamino)pyridine (1; pre-PYX) and 2,6-bis(picrylamino)-3,5-dinitropyridine (2; PYX) were synthesized using an improved literature method. Compounds 1 and 2 were reinvestigated in detail and the X-ray structures (1: ρ=1.698 g cm(-3) at 173 K; 2: ρ=1.757 g cm(-3) at 298 K) are given. The reactions of 2 with different bases, such as alkali metal hydroxides (sodium, potassium, rubidium, cesium), and N-bases (ammonia, hydrazine, hydroxylamine, guanidinium carbonate, aminoguanidine bicarbonate) are reported, as well as metathesis reactions producing energetic salts. Several energetic compounds were synthesized and characterized for the first time using vibrational (IR, Raman) and multinuclear NMR spectroscopy, mass spectrometry, elemental analysis, and DSC. The crystal structures of four energetic salts were determined using low temperature single-crystal X-ray diffraction. Heats of formation for the metal-free species were calculated using the Gaussian 09 software. Detonation parameters were estimated using the EXPLO5 program. The sensitivities towards impact, friction, and electrostatic discharge were also determined.

5,5'-Bis(2,4,6-trinitrophenyl)-2,2'-bi(1,3,4-oxadiazole) (TKX-55): Thermally Stable Explosive with Outstanding Properties.

The novel, thermally stable explosive 5,5'-bis(2,4,6-trinitro-phenyl)-2,2'-bi(1,3,4-oxadiazole) (TKX-55) is reported. This compound can be prepared by means of a facile synthetic procedure and shows outstanding properties (detonation velocity, detonation pressure, sensitivity toward mechanical stimuli, and temperature of decomposition). TKX-55 was isolated and characterized by means of mass spectrometry, multinuclear (1 H, 13 C) NMR spectroscopy, and vibrational spectroscopy (IR and Raman). The structure in the crystalline state was determined by low-temperature single-crystal X-ray diffraction. From the calculated standard molar enthalpy of formation (CBS-4M) and the densities, the Chapman-Jouguet detonation properties were predicted by using the EXPLO5 V6.01 thermochemical computer code. The sensitivity of TKX-55 towards impact, friction, and electrostatic discharge was determined. The shock reactivity (explosiveness) of TKX-55 was measured by applying the small-scale shock reactivity test.

Detection of subtle left ventricular systolic dysfunction in patients with significant aortic regurgitation and preserved left ventricular ejection fraction: speckle tracking echocardiographic analysis.

AIMS: The aim of this study was to characterize left ventricular (LV) mechanics in symptomatic and asymptomatic patients with moderate-to-severe or severe aortic regurgitation (AR) and preserved ejection fraction (left ventricular ejection fraction) using two-dimensional speckle tracking echocardiography (2D-STE). The association between baseline LV strain and development of indications for surgery in asymptomatic patients was also evaluated. METHODS AND RESULTS: A total of 129 patients with moderate-to-severe or severe AR and LVEF >50% (age 55 ± 17 years, 64% male, 53% asymptomatic at baseline) were included. Standard echocardiography and 2D-STE were performed at baseline. Compared with asymptomatic patients, symptomatic patients had significantly impaired LV longitudinal (-14.9 ± 3.0 vs. -16.8 ± 2.5%, P < 0.001), circumferential (-17.5 ± 2.9 vs. -19.3 ± 2.8%, P = 0.001), and radial (35.7 ± 12.2 vs. 43.1 ± 14.7%, P = 0.004) strains. Among 49 asymptomatic patients who were followed up, 26 developed indications for surgery (symptoms onset or LVEF ≤50%). These patients had comparable LV volumes, LVEF, and colour Doppler assessments of AR jet at baseline, but more impaired LV longitudinal (P = 0.009) and circumferential (P = 0.017) strains compared with patients who remained asymptomatic. Impaired baseline LV longitudinal (per 1% decrease, HR = 1.21, P = 0.04) or circumferential (per 1% decrease, HR = 1.22, P = 0.04) strain was independently associated with the need for surgery. CONCLUSION: Multidirectional LV strain was more impaired in symptomatic than in asymptomatic patients with moderate-to-severe or severe AR, despite preserved LVEF. In asymptomatic AR patients, longitudinal and circumferential strains identified patients who would require surgery during follow-up.

Synthesis, characterisation and crystal structures of two bi-oxadiazole derivatives featuring the trifluoromethyl group.

The synthesis, characterisation, and crystal structure determination of the closely related compounds 3,3'-bi-(5-trifluoromethyl-1,2,4-oxadiazole) and 5,5'-bi-(2-trifluoromethyl-1,3,4-oxadiazole) are reported. These two compounds are known for their bioactivity; however, in this study they serve as model compounds to evaluate the suitability of the heterocyclic oxadiazole ring system for energetic materials when the fluorine atoms in the exocyclic CF3 groups are substituted successively by nitro groups. Quantum chemical calculations for the bi-1,3,4-oxadiazole derivatives with difluoronitromethyl, fluorodinitromethyl, and trinitromethyl groups have been carried out and predict promising energetic performances for both explosive and propulsive applications.

Effect of cardiac resynchronization therapy on the sequence of mechanical activation assessed by two-dimensional radial strain imaging.

Cardiac resynchronization therapy (CRT) induces left ventricular (LV) reverse remodeling by synchronizing LV mechanical activation. We evaluated changes in segmental LV activation after CRT and related them to CRT response. A total of 292 patients with heart failure (65 ± 10 years, 77% men) treated with CRT underwent baseline echocardiographic assessment of LV volumes and ejection fraction. Time-to-peak radial strain was measured for 6 midventricular LV segments with speckle-tracking strain imaging. Moreover, the time difference between the peak radial strain of the anteroseptal and the posterior segments was calculated to obtain LV dyssynchrony. After 6 months, LV volumes, segmental LV mechanical activation timings, and LV dyssynchrony were reassessed. Response to CRT was defined as ≥15% decrease in LV end-systolic volume at 6-month follow-up. Responders (n = 177) showed LV resynchronization 6 months after CRT (LV dyssynchrony from 200 ± 127 to 85 ± 86 ms; p <0.001) by earlier activation of the posterior segment (from 438 ± 141 to 394 ± 132 ms; p = 0.001) and delayed activation of the anteroseptal segment (from 295 ± 155 to 407 ± 138 ms; p <0.001). In contrast, nonresponders (n = 115) experienced an increase in LV dyssynchrony 6 months after CRT (from 106 ± 86 to 155 ± 112 ms; p = 0.001) with an earlier activation of posterior wall (from 391 ± 139 to 355 ± 136 ms; p = 0.039) that did not match the delayed anteroseptal activation (from 360 ± 148 to 415 ± 122 ms; p = 0.001). In conclusion, responders to CRT showed LV resynchronization through balanced lateral and anteroseptal activations. In nonresponders, LV dyssynchrony remains, by posterior wall preactivation and noncompensatory delayed septal wall activation.

Left atrial function by two-dimensional speckle-tracking echocardiography in patients with severe organic mitral regurgitation: association with guidelines-based surgical indication and postoperative (long-term) survival.

BACKGROUND: Left atrial (LA) mechanics in patients with severe mitral regurgitation (MR) remain largely unexplored. The aim of the present evaluation was to assess the effect of severe MR on LA function, its potential relation with conventional surgical indications, and long-term postoperative survival. METHODS: Two-dimensional speckle-tracking strain and volumetric indices of LA reservoir, conduit, and contractile function were assessed in 121 patients with severe MR and 70 controls. Patients were divided according to the presence (n = 46) or absence (n = 75) of one or more guidelines-based criteria for mitral surgery (symptoms, left ventricular ejection fraction ≤ 60%, left ventricular end-systolic diameter ≥ 40 mm, atrial fibrillation, or systolic pulmonary arterial pressure >50 mm Hg). RESULTS: In patients with severe MR compared with controls, significant LA reservoir and contractile dysfunction was observed, which was more pronounced in patients with mitral surgery indication (P < .05 for all strain and volumetric indices). Of all indices of LA function, LA reservoir strain was an independent predictor (odds ratio, 0.88; 95% confidence interval, 0.82-0.94; P < .001) and had the highest accuracy to identify patients with indications for mitral surgery (area under the receiver operating characteristic curve, 0.8; 95% confidence interval, 0.72-0.87). A total of 117 patients underwent mitral valve surgery. Patients with LA reservoir strain ≤24% showed worse survival at a median of 6.4 years (interquartile range, 4.7-8.7 years) after mitral surgery (P = .02), regardless the symptomatic status before surgery. LA reservoir strain, on top of mitral surgery indications, provided incremental predictive value for postoperative survival. CONCLUSIONS: Impaired LA reservoir strain in patients with severe organic MR relates to long-term survival after mitral valve surgery, independently of and incremental to current guidelines-based indications for mitral surgery.

Mitral valve geometry and hemodynamics after surgical mitral valve annuloplasty and implications for percutaneous treatment of patients with recurrent mitral regurgitation.

The feasibility of transcatheter mitral valve therapy (edge-to-edge or valve-in-ring technique) in patients with significant mitral regurgitation (MR) recurrence after surgical restrictive mitral valve annuloplasty remains unknown. The aim of the present study was to investigate the eligibility for transcatheter mitral valve therapy of high-surgical-risk patients with significant MR recurrence after initial successful restrictive mitral valve annuloplasty. A total of 47 patients (age 67 ± 10 years, 47% men) with significant MR recurrence (effective regurgitant orifice area ≥20 mm², regurgitant volume ≥30 ml/beat, or vena contracta ≥3 mm) after restrictive mitral valve annuloplasty were identified. The long-term outcome of patients dichotomized according to the surgical risk was evaluated. The echocardiographic parameters of mitral valve geometry and hemodynamics at the moment of diagnosis of MR recurrence were assessed to evaluate the eligibility for transcatheter valve therapy. During a median follow-up of 3 years, 23 patients (48.9%) died. The patients with a high-surgical risk (logistic European System for Cardiac Operative Risk Evaluation score ≥20%) had significantly worse long-term survival than those with a low-surgical risk (logistic European System for Cardiac Operative Risk Evaluation score <20%; 50% and 88%, respectively; p = 0.002). All high-surgical-risk patients showed geometric mitral valve features that would allow transcatheter mitral valve therapy (mitral annular area 7 ± 2.0 cm², coaptation length 6 ± 1.6 mm, anterior and posterior mitral leaflet length 24 ± 2.8 mm and 15 ± 3.1 mm, respectively). In conclusion, patients with significant MR recurrence after initial successful restrictive mitral valve annuloplasty and a high risk of redo mitral valve surgery had lower long-term survival rates than patients who could undergo repeat surgery.

Accuracy of three-dimensional versus two-dimensional echocardiography for quantification of aortic regurgitation and validation by three-dimensional three-directional velocity-encoded magnetic resonance imaging.

Quantitative assessment of aortic regurgitation (AR) remains challenging. The present study evaluated the accuracy of 2-dimensional (2D) and 3-dimensional (3D) transthoracic echocardiography (TTE) for AR quantification, using 3D 3-directional velocity-encoded magnetic resonance imaging (VE-MRI) as the reference method. Thirty-two AR patients were included. With color Doppler TTE, 2D effective regurgitant orifice area (EROA) was calculated using the proximal isovelocity surface area method. From the 3D TTE multiplanar reformation data, 3D-EROA was calculated by planimetry of the vena contracta. Regurgitant volumes (RVol) were obtained by multiplying the 2D-EROA and 3D-EROA by the velocity-time integral of AR jet and compared with that obtained using VE-MRI. For the entire population, 3D TTE RVol demonstrated a strong correlation and good agreement with VE-MRI RVol (r = 0.94 and -13.6 to 15.6 ml/beat, respectively), whereas 2D TTE RVol showed a modest correlation and large limits of agreement with VE-MRI (r = 0.70 and -22.2 to 32.8 ml/beat, respectively). Eccentric jets were noted in 16 patients (50%). In these patients, 3D TTE demonstrated an excellent correlation (r = 0.95) with VE-MRI, a small bias (0.1 ml/beat) and narrow limits of agreement (-18.7 to 18.8 ml/beat). Finally, the kappa agreement between 3D TTE and VE-MRI for grading of AR severity was good (k = 0.96), whereas the kappa agreement between 2D TTE and VE-MRI was suboptimal (k = 0.53). In conclusion, AR RVol quantification using 3D TTE is accurate, and its advantage over 2D TTE is particularly evident in patients with eccentric jets.

Right ventricular function and survival following cardiac resynchronisation therapy.

OBJECTIVES: Right ventricular (RV) function is an important prognostic marker in heart failure. However, its impact on all-cause mortality following cardiac resynchronisation therapy (CRT) independent of confounding factors has not been evaluated. Furthermore, evidence concerning the effect of CRT on RV function is limited. The study's aims were to: (1) assess the prognostic importance of RV function among CRT recipients, and (2) characterise RV functional change following CRT and its determinants. DESIGN: Retrospective observational study. SETTING: Single tertiary centre. PATIENTS: A total of 848 CRT recipients (median age 65 years, 78% male, 60% ischaemic) underwent echocardiography before and 6 months after CRT. RV function was evaluated using tricuspid annular plane systolic excursion (TAPSE), with a ≤14 mm threshold indicating severe RV impairment. The primary endpoint was long-term all-cause mortality. RESULTS: Significant baseline RV dysfunction was observed in 286 (34%) individuals. After a median 44 months, 288 deaths occurred. RV impairment was associated with a greater incidence of all-cause mortality (log-rank p<0.001). Independent predictors of this endpoint were functional class, ischaemic aetiology, diabetes, atrial fibrillation, renal dysfunction, bigger left ventricular (LV) end-systolic volume, less LV dyssynchrony and reduced TAPSE. Importantly, TAPSE added prognostic value to these recognised prognostic parameters (likelihood-ratio test p<0.001). Furthermore, improvement in RV function after CRT was independent of the improvement in LV systolic function but significantly associated with the improvement in LV diastolic function. Importantly, a favourable RV functional response to CRT was associated with superior survival. CONCLUSIONS: RV function is an independent predictor of long-term outcome following CRT.

Global longitudinal strain predicts left ventricular dysfunction after mitral valve repair.

AIMS: Despite a successful surgical procedure and adherence to current recommendations, postoperative left ventricular (LV) dysfunction after mitral valve repair (MVr) for organic mitral regurgitation (MR) may still occur. New approaches are therefore needed to detect subclinical preoperative LV dysfunction. LV global longitudinal strain (GLS), assessed with speckle-tracking echocardiographic analysis, has been proposed as a novel measure to better depict latent LV dysfunction. The aim of this study was to investigate the value of GLS to predict long-term LV dysfunction after MVr. METHODS AND RESULTS: A total of 233 patients (61% men, 61 ± 12 years) with moderate-severe organic MR who underwent successful MVr between 2000 and 2009 were included. Echocardiography was performed at baseline and long-term follow-up (34 ± 20 months) after MVr. LV dysfunction at follow-up was defined as LV ejection fraction (EF) <50% and was present in 29 (12%) patients. A cut-off value of -19.9% of GLS showed a sensitivity and specificity of 90 and 79% to predict long-term LV dysfunction. By univariate logistic regression analysis, baseline LVEF ≤60%, LV end-systolic diameter (ESD) ≥40 mm, atrial fibrillation, presence of symptoms, and GLS >-19.9% were predictors of long-term LV dysfunction. By multivariate analysis, GLS remained an independent predictor of LV dysfunction (odds ratio 23.16, 95% confidence interval: 6.53-82.10, P < 0.001), together with LVESD. CONCLUSION: In a large series of patients operated within the last decade, MVr resulted in a low incidence of long-term LV dysfunction. A GLS of >-19.9% demonstrated to be a major independent predictor of long-term LV dysfunction after adjustment for parameters currently implemented into guidelines.

Percutaneous reduction of mitral valve regurgitation using the MitraClip system - immediate and 90-day follow-up of 3 cases.

Treatment of hemodynamically significant valvular heart diseases has been the domain of cardiac surgery for decades. However, a promising novel method is the MitraClip system, involving percutaneous connection of insufficient valve leaflets with special cobalt-chrome clips. Our study presents clinical characteristics, course of treatment with the MitraClip system, and immediate and 90-day clinical and echocardiographic follow-up of the first 3 patients treated in our institution. Subsequently, based on data from the literature and our own experience, the current position around the world, and the target group of patients who are most likely to benefit from treatment using the MitraClip system, are discussed.

Myocardial structural alteration and systolic dysfunction in preclinical hypertrophic cardiomyopathy mutation carriers.

BACKGROUND: To evaluate the presence of myocardial structural alterations and subtle myocardial dysfunction during familial screening in asymptomatic mutation carriers without hypertrophic cardiomyopathy (HCM) phenotype. METHODS AND FINDINGS: Sixteen HCM families with pathogenic mutation were studied and 46 patients with phenotype expression (Mut+/Phen+) and 47 patients without phenotype expression (Mut+/Phen-) were observed. Twenty-five control subjects, matched with the Mut+/Phen- group, were recruited for comparison. Echocardiography was performed to evaluate conventional parameters, myocardial structural alteration by calibrated integrated backscatter (cIBS) and global and segmental longitudinal strain by speckle tracking analysis. All 3 groups had similar left ventricular dimensions and ejection fraction. Basal anteroseptal cIBS was the highest in Mut+/Phen+ patients (-14.0±4.6 dB, p<0.01) and was higher in Mut+/Phen- patients as compared to controls (-17.0±2.3 vs. -22.6±2.9 dB, p<0.01) suggesting significant myocardial structural alterations. Global and basal anteroseptal longitudinal strains (-8.4±4.0%, p<0.01) were the most impaired in Mut+/Phen+ patients as compared to the other 2 groups. Although global longitudinal strain was similar between Mut+/Phen- group and controls, basal anteroseptal strain was lower in Mut+/Phen- patients (-14.1±3.8%, p<0.01) as compared to controls (-19.9±2.9%, p<0.01), suggesting a subclinical segmental systolic dysfunction. A combination of >-19.0 dB basal anteroseptal cIBS or >-18.0% basal anteroseptal longitudinal strain had a sensitivity of 98% and a specificity of 72% in differentiating Mut+/Phen- group from controls. CONCLUSION: The use of cIBS and segmental longitudinal strain can differentiate HCM Mut+/Phen- patients from controls with important clinical implications for the family screening and follow-up of these patients.

Changes in left ventricular function after mitral valve repair for severe organic mitral regurgitation.

BACKGROUND: Limited data are available on the changes in left ventricular (LV) contractile function at long-term follow-up after mitral valve repair (MVr). Moreover, assessment of LV systolic function in patients undergoing MVr is troublesome with current methods, given that mitral regurgitation is characterized by increased preload and decreased afterload, potentially masking LV dysfunction. The aim of this study was to assess the value of LV global strain (longitudinal and circumferential) measured by speckle tracking analysis for detecting changes in contractile function after MVr. METHODS: A total of 122 patients with organic mitral regurgitation who underwent successful MVr at an early stage (LV ejection fraction>60%, LV end-systolic diameter<40 mm) were included. Echocardiography was performed at baseline and at short-term (∼7 days) and long-term (1 to 3 years) follow-up after MVr. RESULTS: At baseline, LV ejection fraction and LV global strain were higher in patients than in 40 normal control individuals. By contrast, LV forward stroke volume was higher in control individuals than in patients. At short-term follow-up, a significant decrease in LV ejection fraction and LV global strain was noted as a consequence of changes in loading conditions. At long-term follow-up, LV ejection fraction and LV global strain improved significantly. Correction of LV strain for LV size showed a subtle impairment of myocardial contractility at baseline, which significantly improved over time after MVr, together with the improvement in LV forward stroke volume. CONCLUSIONS: Mitral valve repair for organic mitral regurgitation results in a significant increase in LV myocardial contractility as measured by LV global strain corrected by LV size.