Estimation of Cardiac Function with Rotary Blood Pump

Kin-ichi Nakata, MD,1 Kenji Akiyama, MD,1 Yoshiyuki Sankai, PhD,2 Motomi Shiono, MD,1 Yukihiko Orime, MD,1 Youichi Saito, MD,1 Mitumasa Hata, MD,1 Akira Sezai, MD,1 Tomokazu Minami, MD,1 and Nanao Negishi, MD1

Background: A rotary blood pump may be implanted as a bridge to cardiac transplantation. Also, mechanical, histological, and biochemical improvements have been described in cardiac function after the implantation of a left ventricular assists device (LVAD). Thus there is considerable enthusiasm that LVAD might be used as a bridge to the recovery of myocardial function. Unlike a pulsatile pump, however, we cannot stop the rotary blood pump to estimate cardiac function. If the rotary blood pump stops, back flow will occur. In this study, a new method was examined that can estimate cardiac function without stopping the pump.
Materials and Methods: Twelve pigs were subjected to this acute study. The pump was implanted as an LVAD with an inlet cannula inserted into the left ventricle and the outlet cannula into the ascending aorta. The assist ratio was changed to 75%, from 25%. The relationship between the dp/dt of the left ventricle pressure and the differentiated pump flow rate was examined. Also, cardiac function was changed by epinephrine loading to estimate this method under hyperdynamic heart conditions.
Results: There was high positive correlation between the dp/dt of left ventricle pressure and differentiated the pump flow rate to 75% assisted ratio, from 25%. This relationship was established under hyperdynamic conditions.
Conclusion: This method is simple and useful for estimating the cardiac function without pump stoppage. (Ann Thorac Cardiovasc Surg 2007; 13: 240-246)

Key words: left ventricular assists device, rotary blood pumps, cardiac transplantation

1Department of Cardiovascular Surgery, Nihon University School of Medicine, Tokyo, Japan, and 2Control & Biomedical Engineering Mechanics, University of Tsukuba, Tsukuba, Japan

Received September 5, 2006; accepted for publication October 23, 2006
Address reprint requests to Kin-ichi Nakata, MD, Department of Cardiovascular Surgery, Nihon University School of Medicine, 2–11–1 Hikarigaoka, Nerima-ku, Tokyo 179–0072, Japan.