Abstract 326: Direct Ventricular Compression Improves Mechanical Synchrony of the Acutely Failing Heart
Introduction: Mechanical dyssynchrony during acute cardiac failure contributes to ventricular dysfunction. Direct Mechanical Ventricular Actuation (DMVA) provides non-blood-contacting augmentation of systolic and diastolic ventricular function. The purpose of this study was to determine if DMVA can improve mechanical synchrony in the acutely failing heart.
Methods: New Zealand white rabbits (n = 10) were anesthetized, underwent sternotomy, and instrumented for arterial pressures and aortic flow. A 10 MHz transvascular ultrasound probe acquired two-chambered, long-axis transesophageal ventricular images. Heart failure (50% of baseline cardiac output) was modeled using a titrated Esmolol drip. Phenylephrine maintained mean arterial pressure between 60 -70 mm Hg as needed. LV images were analyzed using Siemens speckle tracking software. The LV was divided into six regions which were analyzed for peak strain rate and time to peak strain rate. Average peak systolic and diastolic strain rates were used to assess global myocardial function. Synchrony was determined by analyzing the standard deviation of regional time differences between peak systolic strain rates (dyssynchrony index).
Results: Systolic and diastolic global strain rates were significantly reduced during failure and significantly augmented to near normal during DMVA support. Following a similar relationship, DMVA significantly improved mechanical synchrony during acute heart failure. Recovery strain rates and synchrony were significantly improved vs. failure but did not return to baseline values.
Conclusion: DMVA effectively augments myocardial function in the acutely failing heart. The improvements in pump function are associated with normalization of mechanical synchrony. DMVA’s ability to restore mechanical synchrony during resuscitative ventricular support has favorable implications on cardiac recovery.
- Ventricular assist devices
- Acute heart failure
- Intraventrocular dysshynchrony
- Strain rate
- © 2012 by American Heart Association, Inc.