Author + information
- Nadav Nahumi, BA,
- Ulrich Jorde, MD and
- Nir Uriel, MD∗ ( )()
- ↵∗Mechanical Circulatory Support Program, Division of Cardiology, Columbia University Medical Center/New York Presbyterian Hospital, 622 West 168th Street, PH-12, Room 134, New York, New York 10032
We would like to add a letter to our paper previously published by Uriel et al. (1).
We are honored to have been contacted by many centers nationally and internationally about our ramp test. However, it has come to our attention that some centers performing the test are unfortunately having issues analyzing their collected data. To ensure that such technical issues do not limit the applicability of the ramp study in clinical decision making, we propose to add a brief elaboration of our analysis in addition to a downloadable, pre-formatted Excel spreadsheet.
As we know, left ventricular end-diastolic diameter (LVEDD), power, and pulsatility index (PI) are expected to change with the manipulation of a patient's left ventricular assist device (LVAD) speed in a well-functioning pump. For our ramp protocol, we start at 8,000 RPM and increase the LVAD speed by 400-RPM increments. For our linear fit analysis, each 400-RPM increment is given a value of 1 “speed change.” Therefore, the values of the dependent variables (LVEDD, power, and PI) are plotted against the number of 400-RPM speed changes (i.e., 8,000 = 0; 8,400 = 1; 8,800 = 2, and so on). A numerical slope can then be generated via the Excel function: = slope (dependent variable, number of speed changes) as seen in Figure 1. For this example, the LVEDD slope = −0.149.
The spreadsheet in the Online Appendix contains randomly generated sample data. These sample data have been analyzed by the 2 methods that we have detailed. The extra sheets that are attached have been pre-formatted to generate the diagnostic ramp graphs and slopes that we refer to in the paper.
To access the Excel spreadsheet, please see the online version of this article.
Please note: Dr. Jorde is a consultant for Thoratec, Jarvik, and HeartWare; and has received honoraria from Thoratec. Dr. Uriel has received speaker honoraria from HeartWare. Mr. Nahumi has reported that he has no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation