A Validated Smartphone-based Electrocardiogram Reveals Severe Bradyarrhythmias during Immobilizing Restraint in Mice of Both Sexes and Four Strains

Mouse handling and restraint affect behavior, physiology, and animal welfare, yet little information is available on how various mouse restraint methods affect cardiovascular parameters. We validated the use of a smartphone-based ECG sys- tem in mice by performing simultaneous smartphone and telemetry ECG recordings in conscious, restrained mice and in anesthetized mice. We observed that mice held in standard immobilizing restraint ("scruffing") experienced severe bradycardia. Mice of both sexes and 4 different strains (BALB/cJ, C57BL/6J, DBA/2J, and FVB/nJ) were restrained by 3 handlers using 3 different restraint methods: light restraint; 3-finger restraint, which creates a dorsal transverse fold of skin; and the standard immobilizing restraint, which creates a dorsal longitudinal fold of skin that results in a crease on the ventral neck. Regardless of the handler, immobilizing restraint, but not 3-finger restraint, produced severe bradycardia with irregular rhythm in all 4 strains and both sexes, with an average decrease in heart rate of 31%, or 211 bpm, and a maximal decrease of 79%, or 542 bpm. When evaluated using telemetry, immobilizing restraint produced severe arrhythmias such as junctional and ventricular escape rhythms, and second- and third-degree atrioventricular block. Sinus pauses were observed for an average of 4 min, but up to 6.8 min after release from immobilizing restraint. Atropine administration to C57BL/6J mice attenuated immobilizing restraint-induced bradycardia, supporting the hypothesis that pressure on cervical baroreceptors during stretching of the neck skin results in a vagally-mediated reflex bradycardia. Because of these profound cardiovascular effects, we recommend using the light or 3-finger restraint and avoiding or minimizing the use of immobilization restraint while handling mice.

Seven day continuous ambulatory electrocardiographic telemetric study with pocket electrocardiographic recording device for detecting hydroxychloroquin induced arrhythmias

BACKGROUND & AIMSThe use of hydroxycholoroquin for COVID 19 treatment and prophylaxis raised issues concerning its cardiac safety owing to possibility of QT prolongation and arrhythmias.1 There was no study on long term electrocardiographic telemetry monitoring of patients taking hydroxychloroquin and we planned a continuous electrocardiographic holter telemetry of these patients for a period of seven days.MethodsHealthcare workers taking hydroxycholoroquin as pre exposure prophylaxis, patients taking hydroxychloroquin were monitored by holter electrocardiographic telemetry with continuous beat to beat analysis for seven days with capacity to report any arrhythmic event or significant QT prolongation instantly to medical faculty.Results25 participants with mean age 42.4 ± 14.1 years, 40% females. 20% patients needed to stop HCQ. Four patients developed QT prolongation > 500 ms and needed to stop HCQ, one patient had accelerated idioventricular rhythm and stopped treatment. one had short episodes of atrial fibrillation. No malignant arrhythmia or ventricular arrhythmia or torsades were noted. No episode of significant conduction disturbance and arrhythmic death noted. Baseline mean QTc was 423.96 ± 32.18 ms, mean QTc corrected at 24 hours 438.93 ± 37.95, mean QTc 451.879 ± 37.99 at 48 hours, change in baseline mean QTc to max QTc was 30.74 ± 21.75 ms at 48 hours. All those develop QTc prolongation > 500 ms were greater than 50 years of age.ConclusionAmbulatory telemetry ECG monitoring seems to detect early QT prolongation and stopping drug timely prevented malignant arrhythmias. HCQ seems to have less risk of QT prolongation in young healthy individuals.

Arterial Oxygen Saturation in Anaesthetised Patients during Transfer from Induction Room to Operating Room

There is no published study that examines oxygenation of anaesthetised patients during transport from anaesthesia induction room to operating room. Arterial oxygen saturation (S a O 2 ) was measured in twenty-five anaesthetised patients before and during transfer to an adjacent operating room and continuously recorded on a calibrated chart recorder. A telemetry ECG recorder was used to detect cardiac dysrhythmias. All anaesthetists followed their usual anaesthetic practice. Patients ventilated via face-mask and via endotracheal tube were studied. During transfer patients were either apnoeic (n = 8) or breathing room air spontaneously (n= 17) Mean S a o 2 before induction was 95.4 (SD 2.5)%, was higher after induction of anaesthesia, 98.5 (SD 1.4)% and fell after transfer, 95.7 (SD 2.6)%. A fall in S a O 2 was recorded for 21 patients. No S a O 2 value below 90% was seen. The decrease in S a O 2 was related to the time taken to transfer the patients and spontaneous ventilation (Multiple regression analysis); it was not related to the body mass index although two of the greatest decreases were seen in obese patients. Transfer time averaged 51 seconds (range: 24–97 s). No changes in cardiac rhythm were seen. Transfer of anaesthetised patients was accompanied by variable falls in S a O 2 which related to duration of transfer and spontaneous breathing of room air and which were not associated with new dysrhythmias.