Hemodynamic and echocardiographic responses to acute interruption of left ventricular assist device support: relevance to assessment of myocardial recovery

Abstract

Background: Assessment of myocardial recovery during left ventricular assist device (LVAD) support is difficult to perform both safely and effectively. We developed a test involving short-term interruption of LVAD support with measurements of several hemodynamic and echocardiographic parameters at rest and, whenever possible, after exercise, to investigate inotropic reserve.

Methods: After full heparinization, the HeartMate I XVE device was switched off. MAP, heart rate (HR), ejection fraction (EF) and left ventricular dimensions were measured on switching off, after 5, 10 and 15 minutes, and after 6-minute walk (6MW).

Results: In total, 207 serial tests were performed on 22 patients. A total of 97.6% of the patients tolerated the tests. Of the 202 tolerated tests, 130 were performed on 16 patients who had their device explanted due to myocardial recovery (recovered group), and 72 on 6 patients who did not recover and were transplanted (non-recovered group). After device discontinuation there was an immediate drop in mean arterial blood pressure (MAP), a rise in HR, a reduction in EF and increases in ventricular dimensions. These changes tended to be more marked in the non-recovered group. After 6MW, the recovered group had a significant rise in HR and EF and a non-significant increase in MAP, whereas, the non-recovered group there was a significant drop in MAP compensated by a rise in HR. The distance walked in the recovered group was significantly higher (544 +/- 102 vs 418 +/- 109 meters, p < 0.05). MAP, pulse pressure and EF were strong predictive factors for recovery.

Conclusions: Acute discontinuation of the device to assess recovery is safe and well tolerated and is followed by specific changes in hemodynamic and echocardiographic parameters. This helps in the assessment of recovery, particularly with regard to findings taken after exercise.