COVID-19 and postural tachycardia syndrome: a case series

Background Postural tachycardia syndrome (PTS) is a novel identified sequela of COVID-19 infection. This observational study describes clinical presentation, testing, and treatment response in seven patients diagnosed with PTS following COVID-19 infection. Case summary A total of seven active patients (three collegiate athletes, one recreational athlete, two registered nurses, one hospitality employee), age 24 ± 6 years, and six females were followed for a mean of 152 ± 105 days after contracting COVID-19. Tilt table was performed to establish the diagnosis. The most common presenting symptoms were palpitations (7/7), dyspnoea (6/7), and gastrointestinal complaints (5/7). One patient required hospitalization for symptom management. The mean latency of PTS onset following COVID-19 was 21 ± 15 days. Electrocardiograms (ECGs) demonstrated sinus rhythm in all patients, one with resting sinus tachycardia. Echocardiogram demonstrated normal systolic and diastolic left ventricular function in all patients. On tilt table testing, baseline heart rate (HR) was 72 ± 12 with maximum HR reaching 136 ± 13. Six of seven patients failed to respond to supportive therapy alone, and two patients failed medical management with ivabradine, midodrine, and/or metoprolol. Of three severely symptomatic patients, two demonstrated some degree of clinical recovery with intravenous immunoglobulin (IVIG). Discussion This novel case series describes the development of PTS in the context of COVID-19 infection. Severity of symptoms and response to treatment was heterogeneous. Interestingly, patients were poorly responsive to traditional PTS treatments, but IVIG showed potential as a possible therapeutic strategy for refractory PTS in two patients, particularly following COVID-19 infection.

Abstract 14258: Modulation of Kynurenine Pathway to Prevent Brain Injury After Cardiac Arrest and Cardiopulmonary Resuscitation in Mice

Introduction: Kynurenine pathway (KP) is emerging as one of the potential components affecting cardiac arrest (CA) outcomes. The aim of this study is to evaluate the effects of KP inhibition through genetic deletion of the rate-limiting enzyme of the KP, indoleamine-2,3-dyoxygenase (IDO) on survival and neurological outcome after CA. Methods and Results: Sixteen adult male wild-type (WT) and IDO-deleted (IDO -/- ) mice were subjected to 8 min untreated CA followed by resuscitation. At baseline heart rate and mean arterial pressure (MAP) did not differ among groups. At the time of return of spontaneous circulation, 30 and 60 min later, MAP was higher in the IDO -/- group compared to the WT one (p=0.0005). IDO -/- mice showed higher survival compared to WT at 7 days after CA (68.5% in IDO -/- vs 37.5% in WT; log rank p=0.036). Neurological function was higher in IDO -/- than in WT mice during the 7 days following CA (p=0.0124). IDO -/- mice also showed an improved locomotor function compared to WT mice (p=0.037). Brain magnetic resonance imaging (MRI) with diffusion tensor imaging (DTI) sequences showed a reduction in fractional anisotropy in the external capsule of the corpus callosum in WT mice compared to IDO -/- mice at 7 days after resuscitation (p=0.015). We then treated additional IDO -/- mice with L-kyn 15 min before CA, to revert the IDO -/- phenotype. Brain MRI with diffusion-weighted imaging (DWI) sequences and histological analysis were performed 24h after CA in WT, IDO -/- , and IDO -/- +L-Kyn mice. Brain MRI revealed restriction of water diffusivity 24h after CA in WT mice. IDO-deletion reduced water diffusion abnormalities while the beneficial effect was reverted in the L-kyn group (p=0.01). Degenerating neurons in the frontal cortex, represented as Fluoro-Jade B positive cells, were more numerous in WT compared to IDO -/- mice; L-kyn halted this IDO deletion-induced reduction in degenerating cells (p=0.05). Conclusion: KP inhibition improves survival and neurological outcome after CA. The neuroprotective effect of IDO-deletion was associated with preservation of brain white matter microintegrity and with reduction of cerebral cytotoxic edema. Reversal of these beneficial effects by L-kyn administration in IDO -/- mice further confirm the KP role in CA outcome.

The Influence of Body Position on Determining Aerobic Exercise Intensity for Healthy Individuals

To verify the influence of the resting heart rate (RHR) measurement on different positions in the calculation of VO2max intensities in young individuals of both sexes. Methods: A cross-sectional study with a correlational design with a sample of 22 men and 11 women, aged 27.8 ± 6.5 years and 29.0 ± 8.6 years, respectively, healthy, active and sedentary, who performed the stress test on a treadmill until fatigue. For the treatment of the data, a repeated measures ANOVA was carried out with Bonferroni’s post hoc test. Results: The comparison of the mean values of baseline heart rate (Bhr) between the groups of women and men showed significant differences (t = 2.329; gl 31; p = 0.027). However, no significant differences were noted for lying (t = 0.057; gl 31; p = 0.95), sitting (t = 0.196 gl 31; p = 0.85) or standing (t = −0.290; gl 31; p = 0.77). But in the analysis of the intensities of the RHR in different positions, the calculations with baseline and lying HR were significantly different (p < 0.05). Conclusion: The determination of aerobic training intensities by RHR method must observe the heart rate measurement at rest in the sitting and/or standing positions minutes before the training session.

Remote Assessment of Executive Function in Preschool-Aged Children: Feasibility and Associations with Cardiac Measures

Assessment of executive function in young children is amongst the most commonly used cognitive assessments; however, there is a paucity of childhood executive function assessment methods which can be used remotely. Here, we present a novel adaptation of two child-friendly variants of the Stroop task (i.e., “Day-Night”; “Happy-Sad”), which were conducted remotely with a small (N=40) sample of 3-to 5-year-old children of mothers with depression, taking part of a larger clinical trial. During the assessment, children’s heart rate at baseline and during each task was measured using wrist-worn heart rate monitors. The tasks showed good feasibility in this sample, as the majority of children (80%) completed both tasks, with wide variability in task performance and completion time observed across children. Correlation analyses showed that older age and slower resting heart rate were related to better performance and faster completion time on each task. Follow-up regression analyses including age, household income, baseline heart rate, and heart rate reactivity as predictors accounted for significant variability in task performance and completion time for the Day-Night and Happy-Sad tasks. In the final models, age was a significant predictor of task performance and completion time across both tasks. Resting heart rate was not a significant predictor of task performance for either task, but was a significant predictor of completion time across tasks; children with slower resting heart rate completed the tasks faster. Despite limitations, our findings support the feasibility of online, remote assessment of executive function in young children with implications for researchers and clinicians during the Covid-19 pandemic and beyond.

Comparing predictors of permanent pacemaker insertion after TAVR in new-generation versus early generation heart valves

Introduction Transcatheter Aortic Valve Replacement (TAVR) has emerged as the standard of care for patient with severe aortic stenosis. Conduction abnormalities leading to permanent pacemaker (PPM) implantation is one of the most common complication after TAVR. Newer generation valves (NGV) such as Sapien S3, XT and Evolut are widely being used in real time practice. The aim of this analysis is to compare the predictors associated with increased risk of PPM implantation after TAVR in newer generation valves (NGV) as compared to older generation valves (OGV). Methods A comprehensive literature search was performed in PubMed, Embase, and Cochrane to identify relevant trials. Summary effects were calculated using a DerSimonian and Laird random-effects model as odds ratio with 95% confidence intervals for all the clinical endpoints. Results 18 observational studies with 16,004 patients were identified. The incidence of PPM implantation after TAVR in our analysis was 8.9%. For the NGV, right bundle branch block (RBBB) and atrioventricular (AV) block were independent predictors of PPM insertion after TAVR. Baseline heart rate, presence of atrial fibrillation, and baseline intraventricular conduction delay were not significant predictors. However, for the OGV, risk of PPM implantation after TAVR was higher in presence of RBBB, depth of implant, valve size/annulus size, presence of atrial fibrillation and post-procedure AV block. Conclusions Our analysis identified 2 factors that were significantly associated with increased risk of PPM insertion after TAVR in NGV compared to 6 factors with OGV. With the increasing physician expertise with TAVI and use of NGV, the incidence of post TAVR PPM insertion has reduced but baseline RBBB and AV conduction block still continue to be significant predictors of increased PPM insertion after TAVR. FUNDunding Acknowledgement Type of funding sources: None.

Comparison of the anti-nociceptive effect of dexmedetomidine with that of clonidine immediately prior to propofol injection in alleviating propofol injection pain

Background: Propofol is the drug of choice for induction of anaesthesia because of its rapid onset and short duration of action, easy titration, and favourable profile for side effects. But three out of five patients experience pain on injection of propofol. Alleviation of Propofol injection pain (PIP) is thus a major concern and several interventions have been investigated to alleviate the pain associated with propofol injection. Clonidine was found to alleviate the pain of injected propofol effectively. Dexmedetomidine is also an alpha-2 adrenoceptor agonist but is more selective than clonidine and has analgesic and sedative properties. The aim of the study was to compare the anti-nociceptive effect of dexmedetomidine with that of clonidine immediately prior to propofol injection in alleviating propofol injection pain.Methods: A randomized controlled study was conducted on 60 patients admitted in Malla Reddy Institute of Medical Sciences, undergoing elective surgeries under general anaesthesia (GA) for 2 years from October 2015 to September 2017. The patients were randomly divided into two groups (30 each). Group A was administered intravenous injection clonidine 0.5 µg/kg. Group B was administered intravenous injection dexmedetomidine 0.5 µg/kg.Results: In the present study, difference between the study groups in their mean age, mean weight, gender, ASA grading was not found to be statistically significant. The difference between the groups in incidence of pain on propofol injection was found to be significant statistically. The mean baseline heart rate was declining and mean arterial blood pressure was increasing in both the groups but the difference was not found to be statistically significant.Conclusions: Pre-treatment with 0.5 µg/kg of IV dexmedetomidine is more effective as compared to IV clonidine in alleviating propofol injection pain.

Ivabradine: A Potential Therapeutic for Children With Refractory SVT

Background: In April 2015, ivabradine was approved by the Food and Drug Administration for the treatment of patients with coronary artery disease and heart failure (HF). The use of this medication has been linked with improved clinical outcomes and reduced rates of hospitalization in patients with symptomatic HF and a baseline heart rate of 70 bpm and above. Nonetheless, little is known about the use of ivabradine in pediatric patients with supraventricular tachycardia (SVT). This use is not well-studied and is only endorsed by a few case reports and case series.Aim: This study discusses the off-label utilization of ivabradine in pediatric patients with SVT, and highlights its efficacy in treating treatment-resistant (refractory) SVT.Methods: We conducted a retrospective single-center observational study involving pediatric patients with SVT treated at our center between January 2016 and October 2020. We identified the total number of patients with SVT, and the number of patients with refractory SVT treated with Ivabradine. Similarly, we performed a thorough review of the databases of PubMed, Medline and Google Scholar to compare the clinical course of our patients to those described in the literature.Results: Between January 2016 and October 2020, 79 pediatric patients with SVT were seen and treated at our center. A treatment-resistant SVT was noted only in three patients (4%). Ivabradine was used in these patients as a single or combined therapy. The rest (96%) were successfully treated with conventional anti-arrhythmics such as β-blockers, flecainide, and other approved medications. In the ivabradine group, successful reversal to sinus rhythm was achieved in two of the three patients (66%), one patient was treated with a combination therapy of amiodarone and ivabradine, and the other patient was treated only with ivabradine.Conclusion: Overall, promissory results are associated with the use of ivabradine in pediatric patients with refractory SVT. Ivabradine appears to be a safe and well-tolerated medication that can induce adequate suppression of SVT, complete reversal to sinus rhythm, and effective enhancement of left ventricular function.

Serum Theophylline Concentrations in very Preterm Neonates Receiving Intravenous Aminophylline for Apnea

Objective: To determine the percentage of neonates who achieved therapeutic theophylline level (TTL) after receiving standard IV loading/maintenance aminophylline doses. To assess factors associated with achieving therapeutic theophylline concentrations and to describe adverse effects of aminophylline.Materials and Methods: This was a pilot, cross-sectional study. Preterm neonates ≤34 weeks’ gestation for which aminophylline was indicated for treatment of apnea were enrolled. Standard IV aminophylline dosage is 8 mg/kg loading dose, followed by 1.5 mg/kg maintenance dose every 8 hours. Serum theophylline concentrations were measured prior to the 8th maintenance dose. Descriptive statistics, univariate and multivariate analyses were performed.Results: Twenty-five neonates (52% female) were enrolled: mean (standard deviation) gestational age and birth weight were 30.4 (2) weeks and 1,277 (415) grams, respectively. Aminophylline was initiated at a median (25%tile, 75%tile) postnatal age of 4 (1, 8) days. Baseline heart rate prior to the loading dose was 153 (13) beats-per-minute. Sixty percent of neonates achieved a therapeutic theophylline level. In the univariate analysis, being male and postnatal age ≤5 days were associated with successfully achieving a TTL. After adjusting for gender, postnatal age ≤5 days was the only factor associated with achieving a TTL (adjusted odds ratio 17.7, 95% confidence interval: 1.9, 164.4). Tachycardia and feeding intolerance were observed in 44% and 24% of neonates, respectively.Conclusion: Current IV aminophylline dosing conditions in Thailand achieved TTL in approximately two-thirds of neonates, suggesting therapeutic drug monitoring is beneficial for guiding dosing. A higher maintenance dose could be considered for neonates older than 5 days.