Modification of cardiac function by synchronized oscillating acceleration

The sensitivity of selected cardiovascular (CV) responses to the physical stressor of External whole-body oscillating Acceleration Synchronized with the Electrocardiogram (EASE) was analyzed in 8 chronically instrumented tranquilized dogs. A sinusoidal acceleration wave form was imposed on the supine animals along the spinal (+/- Gz) axis at a constant amplitude of +/- 0.75 G, and a frequency equal to the paced-heart frequency (2--3 Hz). When the peak force was positive in early systole, and negative in early diastole, changes in myocardial oxygen consumption (MVo2, + 8%), mean coronary flow (MCF, + 8%), stroke volume (SV, + 15%), cardiac work (CW, + 19%) and the time derivative of left ventricular pressure (dP/dt, + 18%) were minimal in comparison to nonoscillatory control values. When the peak force was positive in early diastole and negative in late diastole and early systole, changes in MVo2 (+ 41%), MCF (+ 39%), SV (+ 33%), CW (+ 50%), and dP/dt (+ 31%) were maximal. Thus the capability of EASE to produce a range of desired sustained CV responses provides a basis for its potential diagnostic/therapeutic applications.