Introduction Normative comprehensive echocardiographic measurements data for healthy Indians are not available while data for American and European population is available from American Society of echocardiography and European Society of Cardiology/European Association of Cardio-Vascular Imaging and their publications. Available studies of Indian subjects are small and report only limited measurements with focus on left ventricular (LV) volumes. Objective We aim to provide comprehensive normative echocardiographic data for healthy Indians from a large sample size. Methods A retrospective cross-sectional single-center study of 707 healthy Indian adults age and sex segregated which presented detailed and comprehensive echocardiographic measurements including two-dimensional, M-mode, tissue Doppler imaging, speckle tracking echocardiography, chamber volumes, LV ejection fraction (LVEF), global longitudinal strain (GLS), segmental longitudinal strain and effort tolerance. Results Our findings show healthy Indians, as compared to US and European population, to have higher relative wall thickness. LV volumes, LV mass, LVEF and effort tolerance that were within American Society of Echocardiography described ranges for chamber quantification. Higher GLS values were observed in Indian population compared to European and American population. Women had higher LVEF and GLS values as compared to men and both showed a gradual decline with aging. Conclusion We present normal reference values for echocardiographic measurements in healthy Indian population, which could be used for future reference and comparison work.

Pairing an environmental context with repeat opioid use (ROU) can result in increased tolerance to the effects of the opioid. This context-dependent tolerance has been extensively studied with respect to the analgesic effects of opioids, yet a knowledge gap exists in understanding whether there is context-dependent tolerance that develops in opioid induced respiratory depression (OIRD). While activity in the Locus Coeruleus (LC), the primary noradrenergic center of the brain, is involved in cue-reward related behaviors, it also enhances breathing in response to changes in blood gas homeostasis. The objective of this study is to investigate the role of the LC in context-dependent respiratory tolerance. Adult mice expressing GCaMP in the noradrenergic cells of the LC underwent a ROU protocol consisting of an initial five-day period of context pairing where each mouse was administered fentanyl (0.7mg·kg-1·day-1; i.p.) in a distinctive fentanyl-paired context (FP), and saline was administered in different distinctive saline-paired (SP) context. Following context pairing, each mouse was administered fentanyl in both the FP and SP, while LC activity and breathing were simultaneously assessed using fiber photometry and unrestrained whole body plethysmography, respectively. Independent of context, fentanyl administration caused LC activity to increase and become rhythmic during OIRD (n=6). In the FP, however, the OIRD nadir occurred 10 min after fentanyl in all subjects (n=6/6); whereas the OIRD nadir in the SP occurred 5 min after fentanyl administration in the majority of subjects (n=5/6). The difference in time to OIRD nadir corresponded to a greater amount of LC activity in the FP prior to fentanyl (n=5 of 6, p=0.03) and during OIRD (n=5 of 6, p=0.021). These results implicate the potential involvement of LC activity and increased central noradrenergic status in producing context-dependent tolerance delaying the OIRD nadir. Our findings may be leveraged to better predict and/or mitigate overdose-related deaths associated with ROU. NIH: R01NS107421; R01HL163965; R01DA057767 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Introduction: Pulmonary hypertension (PH) is characterized by pulmonary vascular remodeling, right heart failure, and reduced survival. PH can be PH without left ventricular (LV) dysfunction – pulmonary arterial hypertension (PAH) - (Dana point Class I) and PH with LV dysfunction – pulmonary venous hypertension (PVH) - (Dana point Class II). Whatever the underlying cardiac disease, the presence of PH in patients with heart failure is associated with poor prognosis. Right ventricular dysfunction by ventricular interdependence can cause LV dysfunction. Objective: We aim to provide a distinction between PAH and PVH by echocardiography. Methods: Retrospective cross-sectional single-center data of 1075 subjects having PH as defined by echocardiography was collected. These were segregated into mild, moderate, and severe categories. The same cohort of PH subjects was also segregated by E/e’ derived pulmonary capillary wedge pressure (PCWP) values. Echocardiographic measurements and effort tolerance in Mets were analyzed. Data for 707 normal subjects were taken from an earlier published study on normative echocardiographic measurements of healthy Indians. Results: Our findings show that PAH and PVH can be distinguished using PCWP value >15 mmHg obtained by applying Nagueh’s formulaon E/e’. Conclusion: We recommend that PCWP derived from E/e’ should be reported with pulmonary artery systolic pressure measurement to distinguish between PAH and PVH.