Author + information
- Received September 24, 2014
- Accepted November 3, 2014
- Published online April 1, 2015.
- Sirtaz Adatya, MD∗∗ (, )
- Christopher T. Holley, MD∗,
- Samit S. Roy, MSPH∗,
- Hirad Yarmohammadi, MD∗,
- Amy Feng, BA∗,
- Peter Eckman, MD∗,
- Monica Colvin-Adams, MD∗,
- Ranjit John, MD∗ and
- Carolina Masri, MD†
- ∗Department of Medicine, Cardiovascular Division, University of Minnesota, Minneapolis, Minnesota
- †Department of Medicine, Division of Cardiology, University of Washington, Seattle, Washington
- ↵∗Reprint requests and correspondence:
Dr. Sirtaz Adatya, University of Minnesota, Medicine Cardiology Division, 420 Delaware Street, SE, MMC 508 Mayo Minneapolis, Minneapolis 55455.
Objectives This study investigated whether continuous AI and/or elevated mean arterial pressure (MAP) were associated with false positive results for flow obstruction in echocardiographic ramp speed tests in patients with a continuous-flow left ventricular assist device.
Background Failure to reduce the left ventricular end-diastolic diameter (LVEDD) with increasing device speeds in a ramp test is predictive of pump obstruction. Aortic insufficiency (AI) or increased MAP can diminish the ability to unload the left ventricle.
Methods LVEDD was plotted against device speed, and a linear function slope was calculated. A flat LVEDD slope (≥–0.16) was considered abnormal (suggestive of obstruction). Ramp test results were compared in patients with or without either AI or increased MAP at baseline speed, and receiver-operator characteristic (ROC) curves were constructed for predictors of device obstruction. Device thrombosis was confirmed by direct visualization of clot at explantation or on inspection by the manufacturer.
Results Of 78 ramp tests (55 patients), 36 were abnormal (18 true positive, 18 false positive), and 42 were normal (37 true negative, 5 false negative). In patients with AI, LVEDD slope was –0.14 ± 0.17, which was consistent with device obstruction (vs. –0.25 ± 0.11 in patients without AI; p < 0.001), despite no difference in mean lactate dehydrogenase concentration between the 2 groups (1,301 ± 1,651 U/l vs. 1,354 ± 1,365 U/l; p = 0.91). Area under the ROC curve (AUC) for LVEDD slope was 0.76 and improved to 0.88 after removal of patients with AI from the study. LVEDD slope in patients with MAP ≥85 mm Hg was similar to that for device obstruction (–0.18 ± 0.07) and was abnormal in 6 of the 12 ramp tests performed. Combining LVEDD slope with lactate dehydrogenase concentration increased the AUC to 0.96 as an indicator of device obstruction.
Conclusions Abnormal loading conditions due to AI or elevated MAP may result in false positive ramp tests.
- aortic insufficiency
- continuous-flow left ventricular assist device
- echocardiographic ramp test
- heart failure
- mean arterial pressure thrombosis
Dr. John has received research grants from Thoratec and HeartWare Inc.; and has been a consultant for Thoratec. Dr. Eckman is a consultant for Thoratec and HeartWare Inc. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Received September 24, 2014.
- Accepted November 3, 2014.
- American College of Cardiology Foundation