Abstract
Background Although ultrasound (US) is widely used in cardiology, little is known about the effects of US energy on cardiac performance. This study aimed to investigate the mechanical effects of high-intensity continuous US energy (1.0 MHz with 3 different intensities) on cardiac performance. Methods and Results Either left ventricular (LV) pressure or aortic blood flow (ABF) was evaluated in open-chest guinea pigs (n=30) under surface ECG monitoring. LV systolic pressure and ABF increased significantly (ie, maximum percent increases in these parameters were 2.5%, 3.1% and 7.1% for LV systolic pressure and 9.4%, 4.9% and 8.8% for mean ABF at intensities of 0.06, 0.67 and 2.90 W/cm2, respectively). LV end-diastolic pressure was reduced significantly by US (5.3±0.9 to 4.8±0.8, 5.5 ±1.3 to 4.8±1.0 and 5.8±2.0 to 5.0±1.2 mmHg, respectively), indicating positive inotropic and lusitropic effects and resultant ABF augmentation. Local temperature was not significantly changed. ECG showed neither chronotropic action nor arrhythmogenesis. Conclusions Although the basic mechanisms of these phenomena remain unclear, this pilot study of the short-term effects of US energy on cardiac performance suggests the possibility of physical therapy for heart failure. (Circ J 2006; 70: 1356 - 1361)
