Effects of rest and exercise on cardiac blood volume determinations.
OBJECTIVE
The purpose of this study was to investigate the changes in blood activity during rest, exercise and recovery, and to assess its influence on left ventricular (LV) volume determination using the count-based method requiring blood sampling.


METHODS
Forty-four patients underwent rest-stress radionuclide ventriculography; Tc-99m-human serum albumin was used in 13 patients (Group I), red blood cells was labeled using Tc-99m in 17 patients (Group II) in vivo, and in 14 patients (Group Ill) by modified in vivo/in vitro method. LV volumes were determined by a count-based method using corrected count rate in blood samples obtained during rest, peak exercise and after recovery.


RESULTS
In group I at stress, the blood activity decreased by 12.6 +/- 5.4%, p < 0.05, as compared to the rest level, and increased by 25.1 +/- 6.4%, p <0.001, and 12.8 +/- 4.5%, p < 0.05, above the resting level in group II and III, respectively. This had profound effects on LV volume determinations if only one rest blood aliquot was used: during exercise, the LV volumes significantly decreased by 22.1 +/- 9.6%, p < 0.05, in group I, whereas in groups II and III it was significantly overestimated by 32.1 +/- 10.3%, p < 0.001, and 10.7 +/- 6.4%, p < 0.05, respectively. The changes in blood activity between stress and recovery were not significantly different for any of the groups.


CONCLUSIONS
The use of only a single blood sample as volume aliquot at rest in rest-stress studies leads to erroneous estimation of cardiac volumes due to significant changes in blood radioactivity during exercise and recovery.
Topuzović
N
N
Department of Nuclear Medicine, Radiation Protection and Pathophysiology, Osijek Clinical Hospital, Osijek, Croatia.
D000328:Adult; D001794:Blood Pressure; D001810:Blood Volume; D003326:Coronary Circulation / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D015637:Gated Blood-Pool Imaging; D006339:Heart Rate; D006801:Humans; D008875:Middle Aged; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012146:Rest / Q000502:physiology*; D013668:Technetium Tc 99m Aggregated Albumin; D016277:Ventricular Function, Left
D019275:Radiopharmaceuticals; D013668:Technetium Tc 99m Aggregated Albumin