Gated 13N-NH3 PET before and during hemodialysis for the assessment of changes in myocardial perfusion, volumes and output of the left ventricle.

Dialysis induced hypotension is an important complication of the hemodialysis
(HD) treatment. Two factors play a crucial role in the aetiology of HD
hypotension: 1. A decrease in blood volume during HD. 2. The capacity of the
cardiovascular system to respond adequately to this decrease in blood volume.
Patients on renal replacement therapy have a variety of cardiac abnormalities.
Several studies have shown that cardiac output, and myocardial contractility
significantly falls during HD. At present it is not known if this reduction in
cardiac output is primarily caused by a reduction in filling pressure of the
left ventricle, induced by a decrease in venous return in combination with
diastolic dysfunction, or by myocardial ischemia leading to a decrease in
cardiac output through regional wall motion abnormalities. Positron emission
tomography (PET) is an advanced imaging technique that allows precise
quantification of myocardial perfusion, metabolism and volume and function of
the left ventricle.

First: to determine the technical and logistical feasibility of measuring
changes in myocardial perfusion and left ventricular function with gated
13N-NH3 PET before and during HD. Second: to compare changes in myocardial
perfusion and left ventricular function before and during hemodialysis.

Eight HD patients will be recruited to participate in the study. By applying
the protocol first in two HD patients we investigate whether or not it is
technically and logistically feasible to evaluate if changes in cardiac
behaviour during HD can be detected. If this is not feasible, the study will be
terminated. If this is feasible, then in an additional six patients we will
compare changes in myocardial perfusion and left ventricular function before
and during hemodialysis. Patients will undergo three gated 13N-NH3 PET
measurements in order to evaluate if changes in cardiac behaviour during HD can
be detected. The first gated 13N-NH3 PET will be performed 25 minutes prior to
the start of the HD treatment. Ten minutes after the start of HD, the second
scan will be performed. After the 2nd scan, patients will be transferred onto a
normal bed since this is more comfortable. The 3rd and last scan will be
performed 3 hours and 15 minutes after the start of HD. Since intra-vascular
volume depletion is most prominent when one nears the end of the HD treatment,
we, therefore, expect to find the largest difference with baseline in the last
hour of HD.

Patients will have to stay 25 minutes longer in the hospital than usual for a
conventional hemodialysis treatment. Two dialysis needles will be inserted in
the arterio-venous fistula, however, these needles should also have been
inserted without participating in this study. Patients will further undergo: 1)
The inconvenience of lying in the PET-camera for 1 hour and 15 minutes for the
first 2 scans, and an additional 40 minutes for the final scan. 2) The total
amount of radiation from the radiopharmaceuticals leads to a radiation exposure
of 3,2 mSv (1200 MegaBecquerel (MBq)) for the whole duration of the study for
each participating hemodialysis patient. Each bolus of 13N-NH3 contains 400
MBq.