WORK-REST REGIMEN AND NIGHT/DAY REGIMEN - TWO NEW FUNCTIONS IN A NEW CARDIOMYOSTIMULATOR (LD-PACE II) DESIGNED FOR CARDIAC BIOASSIST

Abstract

LD-PACE II, a new cardiomyostimulator was manufactured by CCC del Uruguay with the support of the Illini Group, Chicago, Illinois. The LD-PACE II was designed for use in cardiomyoplasty, aorto myoplasty, and skeletal muscle ventricle. All parameters specified as programmable can be changed in a noninvasive manner (using a programming interface wand connected to a computer using the Windows 95/98 environment). Most of the functions of the new stimulator are similar to functions of previously used devices (Transform, Medtronic; EKS 445, Russia), however new two functions could be extremely important fo clinical use based on experimental research. 1. Work-rest regimen. In the conventional stimulation regimen, the latissimus dorsi muscle (LDM) works 24 hours daily with no rest except for short periods between contractions. The LD-PACE II is able to deliver alternating periods of muscle contractions and rest. Work and rest periods may be programmed independently between 1 and 120 minutes in increments of one minute. The work-rest regimen may be useful clinically if muscle contractions are needed for cardiac assist postoperatively. Morphological (light microscopy, transmission electron microscopy) and electrophysiological data show that a short period of work followed by a long period of rest does not damage the ischemic muscle. 2. Night/day regimen. This feature is also brand new. It allows for a change in the ratio of muscle contractions according to a patient's activity level. During the day the cardiosynchronization ratio may be set from 1:1 to 1:4 and during the night it may be set for 1:8 to 1:16. This allows the LDM to have a long rest period, prevents overuse, and prolongs battery life. Data confirmed that there is no depression in hemodynamics when the ratio is slowed or turned off during the night. The first tests of the LD-PACE II in Milwaukee, WI, Detroit, MI and Paris (France) showed good functional ability of a high caliber.