The effect of implementation of a ramp test to optimize LVAD pump speed on clinical and echocardiographic outcomes.

Left ventricular mechanical assistance is the ultimate treatment option in
patients with end stage heart failure ineligible for transplant. A left
ventricular assist device (LVAD) is a pump that is connected to the left
ventricle and the aorta via an inflow and outflow cannula. The pump supports
the heart by withdrawing blood from the left ventricle and delivering it
directly into the aorta. Thereby, end-organ perfusion is improved.

The prognosis and clinical performance of patients with a left ventricular
assist device (LVAD) as destination therapy are strongly determined by the
remaining cardiac function. The speed of the LVAD pump influences the intrinsic
cardiac function by decompressing the left ventricle. An inadequately low speed
(rotations per minute) can result in left ventricular overload and mitral valve
insufficiency, while an increased speed may lead to a suction cascade with
leftward deviation of the interventricular septum, obstruction of the inflow
cannula, dilatation of the right ventricle and severe tricuspid regurgitation.
Within the normal speed range of the pump the septum is in midline position
between the two ventricles and the aortic valve opens partly as a result of
adequate left ventricular filling status and contraction. It is unknown whether
further adjustments of the pump speed within the approved range can improve
cardiac performance and clinical outcomes. Recently Uriel et al. presented the
Columbia Ramp Study in which they performed 52 speed optimization test in LVAD
patients with a HeartMate II device and corrected the device speed in 61% of
the patients, showing the clinical value of speed optimization. Follow-up data
of these patients were however not presented in the article.

In our centre speed settings are routinely assessed with a ramp test during
implantation in the operating room as well as in the immediate post-operative
phase. For this purpose the hemodynamic performance at different pump speeds is
assessed with the use of echocardiography after which the most optimal setting
is chosen. After discharge follow-up echocardiography is performed according to
the mission! LVAD protocol (Fig 2). At these follow-up visits, in some patients
it is noted that long-term unloading of the left ventricle alters the
ventricular geometry and function. Furthermore, as a consequence of LVAD
implantation exercise capacity increases which requires an increased cardiac
output. In this situation patients may potentially benefit from
echocardiographically re-evaluation of the different pump speed settings. For
this purpose, the ramp test routinely performed in the operating room and in
the immediate post-operative phase could be repeated. In the current study we
hypothesize that optimization of the pump speed to the ambulatory situation
improves clinical and echocardiographic performance at 3 months follow-up.

The objective of the current study is to assess the effect of speed
optimization on clinical and echocardiographic parameters at 3 months
follow-up.

The design is a prospective cohort study in which LVAD patients will function
as their own control over time.

Time frame:
1 month: Informing patients
3 months: Enrolling patients and baseline measurements
3 months: Follow-up measurements
3 months: Data analysis and writing article

Study patients will undergo adjustments to the pump speed of the HVAD. The HVAD
has an European Commercial approval since January 2009. Normal pump speed
recommended by the manufacturer is between 2400 and 3200 RPM (the motor speed
range is between 1800 and 4000 RPM). In the current study different pump speeds
within these limits will be assessed at baseline to determine the optimal speed
based on echocardiographic findings. The optimal pump speed will be maintained
for 3 months followed by clinical and echocardiographic re-evaluation of
performance.

All measurements will be performed during routine follow-up visits. Adjacent to
the routine examinations according to the Mission! LVAD protocol, at one moment
an extra echocardiography with additional images will be achieved, as well as
one extra quality of life assessment, 6 minute walking test and bicycle test.
These additional examinations will take approximately 2 hours.
No additional risk is expected from participation in this study as the
optimization protocol shows resemblance to the routinely performed pump speed
assessment in the post-operative phase on the intensive care unit. Pump speed
optimization will be performed within the normal speed range recommended by the
manufacturer.