Dynamic fluctuations in blood and spleen radioactivity: Splenic contraction and relation to clinical radionuclide volume calculations

Abstract

Alterations in the blood radioactivity affect ventricular volume calculations using count-based radionuclide ventriculography. To study this phenomenon, the effect of time, posture and supine exercise on blood radioactivity, red blood cell count and splenic radioactivity was evaluated. The red blood cell count, and blood, splanchnic and splenic radioactivity remained stable in five patients studied at rest in the supine position. On standing, blood radioactivity increased 10 +/- 3% (standard error of the mean), and abdominal radioactivity decreased 14.5 +/- 6.5% (both p less than 0.05). In 10 patients, splenic radioactivity decreased after supine exercise by 49 +/- 7%, while blood radioactivity increased 10.5 +/- 1.5% and red blood cell count increased 7.5 +/- 1.5% (all p less than 0.001). Splenic radioactivity increased gradually after exercise and decreased after a second exercise period. In the exercising patients, blood radioactivity increased by 14.5% and correlated with an increase in the red blood cell count (r = 0.57, p = 0.01, 19 samples from 10 patients). Reduction in splenic radioactivity also correlated with the increase in red blood cell count (r = -0.51, p = 0.025). The data demonstrate splenic shrinkage in human beings and an inverse relation between changes in splenic and blood radioactivity. These dynamic fluctuations emphasize the need for simultaneous blood sampling for accurate calculation of left ventricular volume and high-light the importance of regional volume shifts during exercise.

Prostacyclin Causes Splenic Dilation and Haematological Change in Dogs

“…Physical exercise has been found to be associated with increased production of PGI 2 in humans 25–27 . Interventions stimulating sympathetic nerve activity have been demonstrated to induce contraction of the spleen, with a subsequent increase in haematocrit and haemoglobin concentrations in the peripheral blood in humans, 28–33 although these findings are in contrast with the view of earlier studies showing no reservoir function for blood cells in the human spleen 34,35 . The present findings in dogs cannot be extrapolated simply to the clinical situation, but suggest that PGI 2 may play a role to relieve exercise‐induced splenic contraction, in addition to the adrenergic neurotransmission, and thereby reduce blood cell concentrations and blood viscosity.…”

Exercise induced hemoconcentration following spleen contraction in subjects with COPD

“…prolonging apnea duration [4]. Splenic contribution of Hb to the circulating blood volume has also been observed in healthy subjects during exercise [10][11][12] and more recently during altitude simulation by normobaric hypoxia [13,14]. This suggests that spleen contraction may be an emergency response triggered in a number of circumstances involving hypoxia.…”

Responses of the human spleen to exercise

“…Although a few smallscale early studies based on changes in haemoglobin and haematocrit found no change in volumes of the human spleen with exercise (Dill, Talbott, & Edwards, 1930;Ebert & Stead, 1941), at least nine more recent studies of maximal effort (Agostoni et al, 1999;Allsop et al, 1992;Flamm et al, 1990;Froelich, Strauss, Moore, & McKusick, 1988;Laub et al, 1993;Lodin-Sundström, Schagatay, Schagatay, & Engan, 2014;Otto, Rona du Toit, Pretorius, Lötter, & van Aswegen, 1995;Sandler et al, 1984), mostly using the more precise technologies of technetium scintigraphy or ultrasound, found splenic contractions of 11-66% (average 42%), with a corresponding increase in circulating red blood cell volumes. Decreases of splenic volume have also been observed with various forms of apnoea (Baković et al, 2005;Baković, Valic, Eterović, Vukovic, Obad et al, 2003;Espersen, Frandsen, Lorentzen, Kanstrup, & Christensen, 2002;Hurford et al, 1990;Inoue, Nakajima, Mizukami, & Hata, 2013;Lodin-Sundström & Schagatay, 2010;Palada et al, 2007;Prommer et al, 2007;Richardson et al, 2005;Schagatay, Andersson, Hallen, & Pålsson, 2001;Schagatay, Haughey, & Reimers, 2005) (Table I), hypoxia (Lodin-Sundström & Schagatay, 2010;Richardson, Lodin, Reimers, & Schagatay, 2008), infusion of adrenaline (Baković, Pivac, Zubin Maslov, Breskovic, & Damonja et al, 2013;Knecht, Jost, Gmür, Burger, & Fehr, 1988), drowning (probably a response to a combination of hypoxia and cooling) (Haffner, Graw, & Erdelkamp, 1994) and splenic nerve stimulation (a very much smaller response than seen in horses) (Ayers et al, 1972), with changes in total red cell volume abolished by splene...…”