BackgroundThe goal of our study is to examine the effect of stimulating a two-dimensional sheet of myocardial cells. We assume that the stimulating electrode is located in a bath perfusing the tissue.MethodsAn equation governing the transmembrane potential, based on the continuity equation and Ohm's law, is solved numerically using a finite difference technique.ResultsThe sheet is depolarized under the stimulating electrode and is hyperpolarized on each side of the electrode along the fiber axis.ConclusionsThe results are similar to those obtained previously by Sepulveda et al. (Biophys J, 55: 987–999, 1989) for stimulation of a two-dimensional sheet of tissue with no perfusing bath present.

Background:The 1μg cosyntropin test has some advantages over the 250μg test as a test of adrenal function. One of the concerns regarding the 1 μg test includes stability of the cosyntropin when reconstituted and stored. Classically the 5th percentile responses to cosyntropin in normal individuals have been used to define a normal response. Recent studies have shown that these normative values should be determined for individual assays.Materials and Methods:We performed a 1μg cosyntropin test using reconstituted and refrigerated (4-8° C) cosyntropin in saline solution in 49 non pregnant adults who were apparently healthy and had no exposure to exogenous glucocorticoids. The cosyntropin solution was stored for up to 60 days following reconstitution. We analysed the data for any association between duration of cosyntropin solution storage and the cortisol responses to cosyntropin administration.Results:The mean ± SD cortisol level at baseline, 30 and 60 min were-12.19 ± 3 μg/dl, 20.72 ± 2.63 μg/dl, 16.86 ± 3.33 μg/dl. The 5th percentile cortisol response at 30 min was 16.5 μg/dl (16.33 μg/dl rounded off). The correlation coefficients between number of days of cosyntropin solution storage and the cortisol responses at 30 and 60 min were (Spear mans rho = 0.06,-0.24 respectively) (P = 0.69 and 0.41). There were no differences in cortisol values whether the storage was for less than 30 days or more than 30 days (mean difference 0.25 μg/dl P = 0.44).Conclusion:The 5th percentile normative values determined for our assay is lower than what is currently being used clinically and in research publications. Prolonged refrigerated storage of cosyntropin solution does not affect the validity of the 1 μg cosyntropin test.

Context: Cardiac injury has been described in both acute COVID-19 and the multisystem inflammatory syndrome in children (MIS-C). Echocardiographic strain has been shown to be a sensitive measure of systolic function. Aims: We sought to describe strain findings in both the groups on initial presentation and follow-up. Settings and Design: A retrospective study analyzing echocardiograms of all patients presenting with acute COVID-19 infection and MIS-C at our institution between March 2020 and December 2020 was performed. Subjects and Methods: TOMTEC software was used for strain analysis in both the study groups (COVID-19 and MIS-C) and age-matched healthy controls. Strain was correlated with LV ejection fraction (EF) and serum troponin levels. Results: Forty-five patients (34 – MIS-C and 11 – COVID-19) met the inclusion criteria. There was a statistically significant decrease in LV longitudinal strain ( P < 0.001), LV circumferential strain ( P < 0.001), and left atrial strain ( P = 0.014) in the MIS-C group when compared to the control group. There was a statistically significant decrease in LV longitudinal strain ( P = 0.028) in the acute COVID-19 group. All patients with abnormal left ventricular EF (LVEF) had abnormal strain. However, 14 (41%) patients in the MIS-C group and 3 (27%) in the acute COVID-19 group had preserved LVEF but abnormal strain. There was a significant correlation with LV longitudinal strain ( P = 0.005) and LVEF ( P = 0.002) and troponin in patients with MIS-C. Abnormal strain persisted in one-third of patients in the MIS-C and acute COVID-19 groups on outpatient follow-up. Conclusions: Patients with MIS-C and acute COVID-19 can develop myocardial dysfunction as seen by abnormal strain. LV longitudinal strain correlates with cardiac injury as measured by serum troponin in patients with MIS-C. Strain may provide an additional tool in detecting subtle myocardial dysfunction. It can be routinely employed at diagnosis and at follow-up evaluation of these patients.

Background: Cardiac injury has been described in children with both acute COVID-19 and the multisystem inflammatory syndrome in children (MIS-C). Strain has been shown to be a sensitive measure of systolic function and can be used for detecting subclinical left ventricular (LV) dysfunction. We sought to describe strain findings in both groups on initial presentation and outpatient follow up. Methods: A retrospective study analyzing echocardiograms of all patients presenting with acute COVID-19 infection and MIS-C at our institution between March 2020 and December 2020 was performed. TOMTEC software was used for strain analysis in both study groups (COVID-19 and MIS-C) and age matched healthy controls. Regional strain was obtained and comparison amongst groups was performed using the Mann-Whitney U test. Strain was compared against LV ejection fraction (EF) as measured by 5/6 area length method. Results: 45 patients (34 MIS-C and 11 COVID-19) met inclusion criteria. There was a statistically significant decrease in LV longitudinal strain (p <0.001), LV circumferential strain (p <0.001) and left atrial strain (p = 0.014) in the MIS-C group when compared to the control group. There was a statistically significant decrease in LV longitudinal strain (p = 0.028) in the acute COVID-19 group. All patients with abnormal LVEF had abnormal strain. However 14 patients (41%) in the MIS-C group and 3 (27%) in the acute COVID-19 group had preserved LVEF but abnormal strain. Abnormal strain persisted in one-third of patients in the MIS-C and acute COVID-19 groups on outpatient follow up. Conclusion: Patients with MIS-C and acute COVID-19 can develop myocardial dysfunction as seen by abnormal strain. Strain may provide an additional tool in detecting subtle myocardial dysfunction. It can be routinely employed at diagnosis and at follow up evaluation of these patients.

Kawasaki disease is a well-known cause of acquired cardiac disease in the pediatric and adult population, most prevalent in Japan but also seen commonly in the United States. In the era of intravenous immunoglobulin (IVIG) treatment, the morbidity associated with this disease has decreased, but it remains a serious illness. Here we present the case of an adolescent, initially diagnosed with Kawasaki disease as an infant, that progressed to giant aneurysm formation and calcification of the coronary arteries. We review his case and the literature, focusing on the integral role of multimodality imaging in managing Kawasaki disease.