Noninvasive assessment of systolic and diastolic left ventricular function in patients with chronic severe anemia: a combined M-mode, two-dimensional, and Doppler echocardiographic study.

Thirty-one patients with chronic severe anemia of more than 3 months' duration (hemoglobin less than 7 gm/dl) and no underlying heart disease were studied by means of M-mode, two-dimensional, and Doppler echocardiography; an equal number of normal control subjects was also studied. There are conflicting reports regarding the influence of chronic severe anemia on systolic myocardial function, but diastolic function has not been systematically assessed. It is also uncertain whether anemia alone can cause heart failure in a structurally normal heart. We therefore performed a detailed study of echocardiographic indexes of systolic and diastolic left ventricular function in these patients. We found that patients with anemia have significantly faster heart rates and lower diastolic and mean blood pressures than normal subjects. They also have a significantly elevated cardiac output and stroke volume and larger left ventricles. Left ventricular contractility, assessed by the end-systolic stress-dimension relationship, was enhanced. There was no systematic evidence of diastolic dysfunction by Doppler assessment of mitral inflow. There was also no clinical evidence of congestive heart failure. We conclude that chronic severe anemia leads to a hyperdynamic state with systolic hyperfunction and no impairment of diastolic function. Anemia does not lead to congestive heart failure in the absence of underlying heart disease.     

Investigation of rotameric conformations of substituted imidazo-[1,2-a]pyrazine: experimental and theoretical approaches

The different rotameric conformations of imidazo-[1,2-a]pyrazine have been synthesized and characterized by means of different experimental techniques, such as NMR, FTIR, and absorption spectroscopy and quantum chemical calculations. The different conformations were stabilized by hydrogen bonds, such as OH⋯N, ArH⋯N and ArH⋯ArH. The ground state optimizations and potential energy surface (PES) scanning profiles produced using density functional theory (DFT) show two stable rotameric forms for each molecule. The relative population of the conformations is affected by the strength of the hydrogen bonds. The calculated absorption spectra and isotopic shielding constants were acquired by time-dependent density functional theory (TD-DFT) and gauge invariant atomic orbitals (GIAO)-DFT, respectively. The strength of the hydrogen bonding interactions that resulted in the different conformations was studied by quantum theory of atoms in molecules (QTAIM).

The different rotameric conformations of imidazo-[1,2-a]pyrazine have been synthesized and characterized by means of different experimental techniques, such as NMR, FTIR, and absorption spectroscopy and quantum chemical calculations.     

Frequency- and orientation-dependent effects of mexiletine and quinidine on conduction in the intact dog heart

Myocardial conduction depends on the magnitude of the fast inward sodium current as well as on cardiac fiber orientation, with more rapid propagation along myocardial fibers than across them. Although antiarrhythmic drugs depress the sodium current in a frequency-dependent fashion in vitro, their effects on conduction in the intact ventricle have been less well studied. We therefore evaluated the frequency- and orientation-dependent actions of mexiletine, quinidine, and their combination on epicardial conduction in 24 pentobarbital-anesthetized dogs. These interventions were chosen because the time constant of recovery from sodium-channel blockade by mexiletine in vitro is shorter than that from blockade by quinidine, and because we have previously shown that the combination of these drugs is often clinically effective when single-agent therapy fails. An electrode array that permitted measurement of conduction times in multiple orientations over short segments of epicardium without contamination by rapid Purkinje fiber propagation or by latency or virtual cathode effects at the stimulus site was developed for these studies. In all animals, the atrioventricular node was destroyed by injection of formalin to permit measurements over a wide range of cycle lengths (250 to 1500 msec). In the absence of drugs, conduction in any direction was frequency independent. In the presence of mexiletine, however, frequency-dependent increases in conduction times were found at cycle lengths of 600 msec or less; these changes were significantly greater in orientations for which baseline conduction was rapid. Quinidine, on the other hand, increased conduction times at all tested cycle lengths without significant orientation-dependent effects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Outcomes of COVID-19 Complications and their Possibilities as Potential Triggers of Stroke

IntroductionThere is limited literature on coronavirus disease 2019 (COVID -19) complications such as thromboembolism, cardiac complications etc. as possible trigger for stroke. Hence, we aim to evaluate the prevalence and outcomes of COVID-19 related cardiovascular complications and secondary infection and their possibility as potential triggers for the stroke.MethodsData from observational studies describing the complications [acute cardiac injury (ACI), cardiac arrhythmias (CA), disseminated intravascular coagulation (DIC), septic shock, secondary infection] and outcomes of COVID‐19 hospitalized patients from December 1, 2019 to June 30, 2020, were extracted following PRISMA guidelines. Adverse outcomes defined as intensive care units, oxygen saturation less than 90%, invasive mechanical ventilation, severe disease, and in‐hospital mortality. The odds ratio and 95% confidence interval were obtained, and forest plots were created using random‐effects models. A short review of these complications as triggers of stroke was conducted.Results16 studies with 3480 confirmed COVID-19 patients, prevalence of ACI [38%vs5.9%], CA [26%vs5.3%], DIC [4%vs0.74%], septic shock [18%vs0.36%], and infection [30%vs12.5%] was higher among patients with poor outcomes. In meta-analysis, ACI [aOR:9.93(95%CI:3.95–25.00], CA [7.52(3.29–17.18)], DIC [7.36(1.24–43.73)], septic shock [30.12(7.56–120.10)], and infection [10.41(4.47–24.27)] had higher odds of adverse outcomes. Patients hospitalized with acute ischemic stroke and intracerebral hemorrhage, had complications like pulmonary embolism, venous thromboembolism, DIC, etc. and had poor outcomesConclusionThe complications like acute cardiac injury, cardiac arrhythmias, DIC, septic shock, and secondary infection had poor outcomes. Patients with stroke were having history of these complications. Long term monitoring is required in such patients to prevent stroke and mitigate adverse outcomes.