Premature ventricular contractions during triggered imaging with ultrasound contrast

Background: Premature ventricular contractions (PVCs) were observed during triggered second harmonic imaging of a contrast agent for myocardial perfus ion assessment, with continuous infusion of the contrast agent. Further inv estigation into the relation of this phenomenon to both ultrasound energy a nd the contrast agent was carried out during a subsequent bolus-versus-infu sion study. Methods and Results: Two open-label studies in healthy male volunteers were performed. The initial study was a dose-response study in 10 subjects, whi ch compared 3 infusion rates. Each volunteer received 3 continuous infusion s with different infusion rates of the contrast agent for either 10 (n = 6) or 20 (n = 4) minutes. End-systolic triggered imaging with a mechanical in dex (MI) of 1.5 was used throughout this part of the study. The second stud y compared bolus injection with a continuous infusion in 9 volunteers, with a single-dose level but different imaging modalities: end-systolic and end -diastolic triggered imaging at MIs of both 1.1 and 1.5. Spontaneous baseli ne PVCs were uncommon: 10 in 344 minutes (0.03 PVC/min, maximal 1 PVC/min) of baseline imaging. During end-diastolic triggering, no increase in PVCs w as seen, irrespective of MI. A significant increase to 1.06 PVC/min (P < .0 01) was seen during end-systolic imaging with an MI of 1.5, but not with an MI of 1.1, The increase in WC rate was dose-dependent in the initial study . Conclusion: Imaging of contrast agents with high acoustic pressures can cau se PVCs if end-systolic triggering is used. This effect is related to both the dose of contrast agent and acoustic pressure. It does not occur during end-diastolic triggered imaging. Precautionary measures would include using lower MIs or end-diastolic triggering.