How Does the Left Ventricle Work? Ventricular Rotation as a New Index of Cardiac Performance

Although simple cylindrical or ellipsoidal left ventricular (LV) geometry with transverse or circumferential muscle contraction has been traditionally used to estimate LV performance, the estimated LV ejection fraction (EF) with muscle fiber shortening up to 20% is less than 50% of maximum, which is lower than the normal EF observed in routine clinical practice. Thus, oblique fiber orientation and LV rotation, in addition to radial thickening and longitudinal shortening, is predicted as an essential component of effective LV pumping. This was confirmed by animal experiments using surgically implanted markers or invasive sonomicrometry. Demonstration of the muscle band extending from the pulmonary artery to the aorta, which connects the ventricular myocardium, both right ventricle and LV as a continuous band (muscle band theory) provides an anatomical backbone of helical configuration of the cardiac muscle band with descending and ascending segments wrapping the LV apex. Moreover, sequential, non-simultaneous, activation and contraction of the helicoids muscle band contributes to LV rotation or twist motion. Recently, magnetic resonance imaging and speckle tracking echocardiography (STE) techniques have provided an excellent noninvasive way to measure LV rotation and twist, which is expected to contribute to a more thorough evaluation of both LV systolic and diastolic function. Initial animal experiments showed that quantification of apical rotation or LV twist using STE is more accurate for estimating LV systolic function than conventional EF under a variety of LV inotropic conditions, irrespective of coronary ligation. As de-rotation or the untwisting rate can also be measured by STE, the role of ventricular untwisting as a temporal link between LV relaxation and suction can be addressed. Further clinical investigations are needed to determine the real clinical impact of these new indices of LV mechanical function

WATCHFUL OBSERVATION VERSUS EARLY AORTIC VALVE REPLACEMENT FOR SYMPTOMATIC PATIENTS WITH LOW-GRADIENT SEVERE AORTIC STENOSIS AND PRESERVED EJECTION FRACTION

Brief Communications Arising: arising from X. Dong, B. Milholland & J. Vijg Nature 538, 257–259 (2016); doi:10.1038/nature19793. Comments by: Beer, J.A.A. de, Bardoutsos, A. & Janssen, F. (2017)

Extreme Drug Resistance in Acinetobacter baumannii Infections in Intensive Care Units, South Korea

BACKGROUND: Difference in adaptability responses to stress has been observed amongst bird species, strains, and individuals. Components of the HPA axis, one of the internal systems involved in homeostasis re-establishment following stress, could play a role in this variability of responses. The aim of the present study was 1) to identify genes involved in the regulation of adrenal activity following ACTH stimulation and 2) to examine adrenal genes differentially expressed in individuals with high and low plasma corticosterone response following ACTH treatment. RESULTS: Analysis with 21 K poultry oligo microarrays indicated that ACTH treatment affected the expression of 134 genes. Several transcripts assigned to genes involved in the adrenal ACTH signaling pathway and steroidogenic enzymes were identified as differentially expressed by ACTH treatment. Real-time PCR on 18 selected genes confirmed changes in transcript levels of 11 genes, including MC2R, CREM, Cry, Bmal1, Sqle, Prax1, and StAR. Only 4 genes revealed to be differentially expressed between higher and lower adrenal responders to ACTH treatment. CONCLUSION: The results from the present study reveal putative candidate genes; their role in regulation of adrenal functions and adaptability to stress should be further investigated