Optocardiography and Electrophysiology Studies of Ex Vivo Langendorff-perfused Hearts

Swift, Luther; Jaimes, Rafael; McCullough, Damon; Burke, Morgan; Reilly, Marissa; Maeda, Takahiro; Zhang, Hanyu; Ishibashi, Nobuyuki; Rogers, Jack M.; Posnack, Nikki Gillum

doi:10.3791/60472-v

Cited by 1 publication

(1 citation statement)

References 60 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Programmed electrical stimulation was implemented by placing two small stimulation electrodes (Harvard Biosciences, Holliston MA) on the right atrium and left ventricle. An electrophysiology stimulator (Bloom: Fisher Medical, Wheat Ridge CO) was set to 1 ms pulse width at 1.5x the minimum threshold current (~0.7-1.2 mA) 43 . To assess sinus node recovery time (SNRT), spontaneous sinus activity was suppressed via fast atrial pacing (20 beats, S1-S1) and SNRT was measured as the time delay between the last paced beat and the first spontaneous P-wave.…”

Section: Electrophysiology Measurementsmentioning

confidence: 99%

Evidence for the cardiodepressive effects of the plasticizer di-2-ethylhexylphthalate (DEHP)

Swift,

Roberts,

Pressman

et al. 2023

Preprint

Self Cite

View full text Add to dashboard Cite

Background: Di(2)ethylhexylphthalate (DEHP) is commonly used in the manufacturing of plastic materials, including intravenous bags, blood storage bags, and medical grade tubing. Prior studies demonstrated that DEHP can leach from plastic medical products, which can result in inadvertent patient exposure. Further, in vitro studies suggest that DEHP may act as a cardiodepressive agent by slowing the beating rate of isolated cardiomyocytes. Objective: In this study, we investigated the direct effects of acute DEHP exposure on cardiac electrophysiology. Methods: DEHP concentrations were measured in red blood cell (RBC) units stored between 7 and 42 days (23 to 119 ug/mL). Using these concentrations as a guide, Langendorff-perfused heart preparations were exposed to DEHP (15 to 90 minutes) and the impact on cardiac electrophysiology metrics were quantified. Secondary studies used human induced pluripotent stem cell derived cardiomyocytes (hiPSCCM) to measure the effect of DEHP exposure on conduction velocity over a prolonged period of time (15 to 180 minutes). Results: In intact rat heart preparations, sinus activity remained stable following acute exposure to lower doses of DEHP (25 to 50 ug/mL), but sinus rate declined by 43% and sinus node recovery time prolonged by 56.5% following 30 minute exposure 100 ug/ml DEHP. DEHP exposure also exerted a negative dromotropic response, as indicated by a 69.4% longer PR interval, 108.5% longer Wenckebach cycle length, and increased incidence of atrioventricular uncoupling. Pretreatment with doxycycline, a matrix metalloproteinase inhibitor, partially rescued the effects of DEHP on sinus activity, but did not ameliorate the effects on atrioventricular conduction. DEHP exposure prolonged the ventricular action potential and effective refractory period but had no measurable effect on intracellular calcium transient duration. Follow-up studies using hiPSCCM demonstrated that DEHP slows electrical conduction in a time (15 min to 3 hours) and dose-dependent manner (10 to 100 ug/mL). Discussion: DEHP exposure perturbs cardiac electrophysiology in a dose- and time-dependent manner. Future studies are warranted to investigate the impact of DEHP exposures on human health, with special consideration for clinical procedures that employ plastic materials.

show abstract

Section: Electrophysiology Measurementsmentioning

confidence: 99%