Splenic Rhythms and Postprandial Dynamics in Physiology, Portal Hypertension, and Functional Hyposplenism: A Review.

BACKGROUND: Before the discovery of immunological and haematological functions of the spleen, it had for centuries been considered to be a digestive organ of variable size with a role in the portal vein system and nutritional metabolism. In the 19th and 20th centuries, volume changes in the spleen related to nutrition were studied using plethysmographic measurements. Rhythmical and regulatory functions of the spleen were demonstrated in the haemodynamics of the splanchnic region and were described as a "hepatolienal pendulum," a "Windkessel function," or a "pressure compensation." These studies were mainly published in German-speaking countries and have not, as far as is known, been discussed in the English-speaking world so far. SUMMARY: This review explores the historical development of the rhythmical regulatory function of the spleen in the splanchnic region. Older studies and results are followed up in the modern literature, wherever possible, up to the present. The clinical relevance is illustrated with portal hypertension (with congestive or hyperdynamic splenomegaly), coeliac disease, and chronic inflammatory bowel diseases (with functional hyposplenism). Key Message: The spleen's rhythmical regulatory function in nutrition is based on an autonomous rhythm comprising cycles of contractions and dilations of the spleen of around 1 min. These cycles can be influenced by sympathetically mediated single contractions with a release of pooled blood or by portal vein congestion. After food ingestion, the spleen responds either with contraction according to a vasomotor reaction or postprandial congestion with significant increases in volume. The spleen's rhythmical function is lost in the clinical picture of portal hypertension or in coeliac disease and chronic inflammatory bowel diseases. In the aforementioned gastrointestinal diseases, we recommend taking more account of the haemodynamics between the spleen, liver, and intestine. New innovative techniques for recording splenograms are required which, besides elastographic measurements of spleen stiffness, could offer an important tool for early detection, diagnosis, and therapeutic evaluation.

Does the Spleen Have a Function in Digestion? Medical History, Phylogenetic and Embryological Development of the Splenogastric System.

BACKGROUND: Before the spleen was discovered to be a lymphatic blood organ, it had for centuries been considered to be a digestive organ. Concepts of a regulative, secretory and resorptive function in the digestive system were based mainly on a postulated connection between the stomach and the spleen. Splenogastric vascular connections have recently been rediscovered by modern surgery. SUMMARY: To test the hypothesis that the spleen has a digestive function, this article reviews the literature focusing on the interaction between the spleen and the stomach. We examine the historical medical view of the spleen and stomach system and the reasons why a digestive function was abandoned in the 17th and 18th centuries. We then review the rediscovery of the splenogastric system and the present-day state of knowledge (anatomical origin, variability, haemodynamics) and present it in terms of the phylogenetic and embryological development of the spleen and stomach system. Key Message: Splenogastric arteries and gastrosplenic veins form a portal system which directly connects the spleen and stomach parenchyma. Despite its mesodermal anlage, phylogenetically and embryologically the spleen is intimately interconnected with the entodermal stomach parenchyma but detaches from this in the course of development. Further study is required to establish whether the splenogastric system is merely an evolutive remnant or actually a part of a functioning spleen-stomach system as postulated in complementary and integrative medicine.

Postprandial dynamics of splenic volume in healthy volunteers.

Throughout the history of medicine, many functions have been attributed to the spleen and numerous researchers have focused on a postulated digestive function. Beginning in 1825, systematic animal studies showed evidence for a postprandial increase in splenic volume (SV) with a peak 30 min to five hours after food intake. Since the introduction of imaging techniques, two studies have been conducted on humans, revealing a decrease in SV 30 to 45 min postprandially. The aim of this study was to examine possible postprandial changes in SV over a period of seven hours. The ethics-approved, randomized crossover study included 10 healthy volunteers, who received a standardized meal (3,600 kJ) on one study day and fasted on the other. Sonographic measurements were obtained at six measurement points on each day. Thirty minutes after the meal, SV increased significantly by 38.2 ± 51.2 cm3 (17.3%; p = .04) compared to the baseline measurement and decreased gradually afterward. In males, SV 30 min after the meal was 70.2 ± 21.6 cm3 higher (p = .002) compared to the fasting condition and 60 min later it was still significantly increased. The apparent SV increase after food intake is discussed in relation to hemodynamic changes in the splanchnic region. It seems plausible that the spleen has a rhythmic and regulative function within the portal system, something which warrants further research and should be taken more into account in nutritional physiology.