Interface-dependent phononic and optical properties of GeO/MoSO heterostructures.

The interface-dependent electronic, vibrational, piezoelectric, and optical properties of van der Waals heterobilayers, formed by buckled GeO (b-GeO) and Janus MoSO structures, are investigated by means of first-principles calculations. The electronic band dispersions show that O/Ge and S/O interface formations result in a type-II band alignment with direct and indirect band gaps, respectively. In contrast, O/O and S/Ge interfaces give rise to the formation of a type-I band alignment with an indirect band gap. By considering the Bethe-Salpeter equation (BSE) on top of G0W0 approximation, it is shown that different interfaces can be distinguished from each other by means of the optical absorption spectra as a consequence of the band alignments. Additionally, the low- and high-frequency regimes of the Raman spectra are also different for each interface type. The alignment of the individual dipoles, which is interface-dependent, either weakens or strengthens the net dipole of the heterobilayers and results in tunable piezoelectric coefficients. The results indicate that the possible heterobilayers of b-GeO/MoSO asymmetric structures possess various electronic, optical, and piezoelectric properties arising from the different interface formations and can be distinguished by means of various spectroscopic techniques.

Stable single-layers of calcium halides (CaX2, X = F, Cl, Br, I).

By means of density functional theory based first-principles calculations, the structural, vibrational, and electronic properties of 1H- and 1T-phases of single-layer CaX2 (X = F, Cl, Br, or I) structures are investigated. Our results reveal that both the 1H- and 1T-phases are dynamically stable in terms of their phonon band dispersions with the latter being the energetically favorable phase for all single-layers. In both phases of single-layer CaX2 structures, significant phonon softening occurs as the atomic radius increases. In addition, each structural phase exhibits distinctive Raman active modes that enable one to characterize either the phase or the structure via Raman spectroscopy. The electronic band dispersions of single-layer CaX2 structures reveal that all structures are indirect bandgap insulators with a decrease in bandgaps from fluorite to iodide crystals. Furthermore, the calculated linear elastic constants, in-plane stiffness, and Poisson ratio indicate the ultra-soft nature of CaX2 single-layers, which is quite important for their nanoelastic applications. Overall, our study reveals that with their dynamically stable 1T- and 1H-phases, single-layers of CaX2 crystals can be alternative ultra-thin insulators.

Mobile atheromatous plaque of the aortic arch diagnosed by transthoracic echocardiography prior to coronary artery bypass surgery. Which one would you choose: scepticism or wishful thinking?

A routine pre-operative chest X-ray of a patient admitted to our institution for an elective coronary artery bypass operation revealed a mildly dilated mediastinal silhouette, which led the cardiovascular surgery resident to schedule emergency transthoracic echocardiography (TTE), with a special note asking for detailed evaluation of the ascending aorta and aortic arch. TTE revealed a mobile atheroma at the aortic arch, which obliged the cardiac surgery team to modify their strategy to combined hemi-arcus aortae replacement and coronary artery bypass grafting (CABG). Although with transoesophageal echocardiography (TEE) a small portion of the ascending aorta may be obscured by the trachea, TEE provides higher resolution images than TTE. Therefore one can conclude that TEE is the imaging modality of choice for detecting aortic atheromatous plaques but in patients with low risk for stroke and aortic atheromas, a detailed TTE may be sufficient for the pre-operative assessment.

Serum high-sensitivity C-reactive protein, amyloid associated protein and N-terminal proBNP levels do not predict reversible myocardial ischaemia.

AIM: The aim of this study was to detect any relationship between serum high-sensitivity C-reactive protein (hs-CRP), serum amyloid-associated protein (SAA) and N-terminal pro B-type natriuretic peptide (NT-proBNP) levels, and reversible myocardial ischaemia during cardiovascular exercise tests and to determine whether these biomarkers could predict transient myocardial ischaemia. METHODS: Ninety-six patients (36 women, 60 men, mean age 57 ± 8.5 years) were included in the study. Venous blood samples were taken from patients before and 15 minutes after exercise testing. SAA and hs-CRP were analysed using immunonephelometric assays (Dade-Behring, BN II, Marburg, Germany). NT-proBNP (pg/ml) was determined using the immulite 1 000 chemiluminescence immunoassay system (Siemens Medical Solution Diagnostics, Deerfiled, USA). Forty-eight patients (18 women, 30 men) with positive exercise tests were allocated to the exercise-positive group and 48 (18 women, 30 men) with negative exercise tests were put in the exercise-negative group. Coronary angiography was performed on all patients in the exercise-positive group. RESULTS: There was no difference between the levels of hs-CRP, SAA and NT-pro-BNP before and after exercise testing in both of the exercise groups. CONCLUSION: Serum levels of hs-CRP, SAA and NT-proBNP could not predict the occurrence of reversible myocardial ischaemia during exercise. Large-scale clinical studies are needed to clarify the status of hs-CRP, SAA and NT-proBNP with exercise.

Noncompaction cardiomyopathy and dextroversion of the heart.

The prevalence of patients with noncompaction is reported to be 0.014% on echocardiographic examination. The estimated incidence of dextroversion (dextrocardia with isolated reversal of the heart with normally positioned visceral organs) is 1:2,800, while the real incidence of dextroversion and left ventricular noncompaction is still not known; to our knowledge only two cases have been reported in the literature. Noncompaction can generally be diagnosed using echocardiography; however, in the case reported here cardiac magnetic resonance imaging was important for the definitive diagnosis of dextroversion and noncompaction, because no adequate echocardiographic images could be obtained.

Post-infarction ventricular septal defect: triggered by Valsalva manoeuvre?

Post-infarction ventricular septal defect (VSD) is a fatal mechanical complication of myocardial infarction. Although the incidence has decreased to less than 1% after the extensive use of reperfusion strategies, post-infarction VSD still carries a high mortality risk. Management is controversial, whether to wait for surgery after a stabilisation period or to perform emergency surgery when diagnosed. We report on a case of post-infarction VSD that was detected with severe haemodynamic instability, beginning immediately after the patient's Valsalva manoeuvre on the sixth day of a non-reperfused inferior myocardial infarction. In the early period, the post-infarction VSD was repaired via a trans-aneurismal approach.

Congenital absence of the left circumflex coronary artery and an unusually dominant course of the right coronary artery.

Congenital absence of the left circumflex artery (LCX) is a very rare congenital anomaly of the coronary circulation, and only a few cases have been reported in the literature. We report on a 55-year-old female with atypical chest pain. Routine coronary angiography showed a normal left anterior descending coronary artery (LAD), no LCX and a dominant right coronary artery (RCA), which continued beyond the crux, running the full course of the LCX and terminating in the left atrial branch. Neither aortography nor pulmonary angiography showed a separate ostium for the LCX. There were no atherosclerotic lesions in the coronary arteries, or ischaemia on stress myocardial perfusion imaging. Multidetector row computed tomography (MDCT) was performed to confirm the diagnosis.

Role of enoxaparin resistance in recurrent chest pain in the intensive care unit.

To investigate the relationship between anticoagulation treatment and drug resistance in chest pain, levels of factor Xa residual activity were determined in patients seen in intensive care with recurrent chest pain and compared with levels in patients who had no ischaemic events during hospitalization. A total of 122 patients aged 18 - 75 years who were admitted to hospital with acute coronary syndrome and treated with enoxaparin were included. Of these, 62 patients had recurrent chest pain while hospitalized (group A) and 60 patients had an uneventful follow-up period (group B). Patients requiring primary percutaneous transluminal coronary angioplasty and/or treatment with glycoprotein IIb/IIIa inhibitors, and those with renal failure, a high risk of bleeding or receiving anti-inflammatory drugs were excluded from the study. Median levels (+/- interquartile range) of factor Xa residual activity were significantly higher in group A compared with group B (0.68 +/- 0.29 IU/ml versus 0.34 +/- 0.33 IU/ml). It is concluded that enoxaparin resistance, resulting in high levels of factor Xa residual activity, should be considered in patients with recurrent ischaemia.

Right coronary artery arising from the pulmonary trunk.

The prevalence of coronary artery anomalies is reported to be around 0.3-1 %. An anomalous origin of the right coronary artery (RCA) is a rare condition but may lead to myocardial ischemia and sudden death. Diagnosis is mainly made by conventional coronary arteriography. Nowadays, multislice computed tomography is a new noninvasive imaging technique with excellent spatial resolution which can detect the origin and course of an anomalous coronary vessel. Here we report on a 67-year-old woman with an anomalous origin of the RCA arising from the pulmonary trunk. The anomaly was diagnosed by cardiac catheterization and confirmed by multislice computed tomography.

N-acetylcysteine versus N-acetylcysteine + theophylline for the prevention of contrast nephropathy.

BACKGROUND: The use of N-acetylcysteine or theophylline in specific subgroups of patients has been suggested to reduce the incidence of contrast-induced nephropathy (CIN) in patients undergoing angiographic procedures. Our purpose was to compare the use of N-acetylcysteine versus N-acetylcysteine + theophylline for the prevention of CIN. MATERIALS AND METHODS: We randomized 217 patients with estimated glomerular filtration rate (eGFR) (calculated by Modification of Diet in Renal Disease formula) between 30 and 60 mL min(-1) 1.73 m(-2) who were undergoing coronary angiography to three prophylactic treatment groups: Group 1: Intravenous hydration with isotonic saline (1 mL kg(-1) h(-1) for 12 h before and after contrast, n = 72). Group 2: Intravenous hydration with isotonic saline (1 mL kg(-1) h(-1) for 12 h before and after contrast)+ N-acetylcysteine (600 mg p.o. twice daily the preceding day and the day of angiography, n = 73). Group 3: Intravenous hydration with isotonic saline (1 mL kg(-1) h(-1) for 12 h before and after contrast)+ N-acetylcysteine + theophylline (600 mg N-acetylcysteine p.o. and 200 mg theophylline p.o. twice daily for the preceding day and the day of angiography, n = 72). The incidence of CIN (0.5 mg dL(-1) increase in serum creatinine from the baseline value 48 h after intravascular injection of contrast) was compared in three groups. RESULTS: Of the 217 patients, 12 patients (5.5%) experienced CIN. Five patients (6.9%) in group 1, seven patients (9.6%) in group 2 and zero (0%) patients in group 3 experienced CIN (P < 0.033). CONCLUSION: Among patients with eGFR between 30 and 60 mL min(-1) 1.73 m(-2) undergoing coronary angiography, oral administration of N-acetylcysteine + theophylline in addition to saline hydration has a beneficial effect in the prevention of CIN.

What should be the primary treatment in atrial fibrillation: ventricular rate control or sinus rhythm control with long-term anticoagulation?

Recent trials have favoured ventricular rate control in atrial fibrillation (AF) management, however the present study investigated whether the restoration and maintenance of sinus rhythm with long-term anticoagulation therapy was superior in terms of embolic events and death in 534 patients with an AF duration > 48 h. Patients were randomized and received sinus rhythm control with either aspirin (group 1) or warfarin (group 2), or they were given ventricular rate control (group 3). Cardioversion to sinus rhythm was attempted in 425 patients and was successful in 387 (91.1%) of them. After 3 years' follow-up there were 12, two and 15 embolic events in groups 1, 2 and 3 respectively (significant difference between groups 1 and 2, and 2 and 3) and overall mortalities were four, two and 12, respectively (significant difference between groups 2 and 3). It is concluded that patients with an AF duration > 48 h might benefit considerably from sinus rhythm restoration and long-term warfarin therapy in terms of embolic events and mortality.