A study on premature ventricular contractions caused byultrasound exposure with microbubbles using cultured ventricular muscle cells

Abstract

It has been shown that diagnostic ultrasound examination using a contrast agent cancause premature ventricular contractions (PVCs). In this study, we investigated a usefulness ofa new technique using cultured cardiac myocytes to study mechanisms of PVC production.Cardiac myocytes were isolated from neonatal rats and cultured on a cover glass. The coverglass was attached to an observation chamber in which it was possible to observe changes inmyocytes during ultrasound exposure. In the experiments, cardiac myocytes were exposed topulsed ultrasound in the presence and absence of microbubbles. The pressure amplitudes(peak-negative pressures) were set at 5 steps, −0.28, −0.55, −0.73, −0.92 and −1.1 MPa,and threshold pressure to produce a PVC was recorded. The results showed that the presence ofmicrobubbles attached to a cell reduces threshold pressure for producing PVCs, and it wasconcluded that our method is useful for studying the mechanisms of PVC production.